From 83a8c90b49b33f38817f78eed231886df461b974 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Tue, 3 May 2022 17:01:08 +0900
Subject: [PATCH 01/33] Make clicking "Unknown" language do nothing.

https://github.com/tipsy/profile-summary-for-github/issues/97
---
 src/main/resources/vue/components/_charts.vue | 20 +++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/src/main/resources/vue/components/_charts.vue b/src/main/resources/vue/components/_charts.vue
index c1ccb0f..2822eb8 100644
--- a/src/main/resources/vue/components/_charts.vue
+++ b/src/main/resources/vue/components/_charts.vue
@@ -1,4 +1,6 @@
 <script>
+    const UNKNOWN_LANGUAGE = "Unknown";
+
     function donutChart(objectName, data) {
         let canvas = document.getElementById(objectName);
         if (canvas === null) {
@@ -6,6 +8,12 @@
         }
         let userId = data.user.login;
         let labels = Object.keys(data[objectName]);
+
+        /**
+         * The language index of <code>UNKNOWN_LANGUAGE</code>
+         * @type {Number}
+         */
+        let indexOfUnknownLanguage = -1;
         let values = Object.values(data[objectName]);
         let colors = createColorArray(labels.length);
         let tooltipInfo = null;
@@ -17,6 +25,7 @@
         if (["langRepoCount", "langStarCount", "langCommitCount"].indexOf(objectName) > -1) {
             // if the dataset is language-related, load color-profile
             labels.forEach((language, i) => colors[i] = languageColors[language]);
+            indexOfUnknownLanguage = labels.indexOf(UNKNOWN_LANGUAGE);
         }
         if (objectName === "repoCommitCount") {
             tooltipInfo = data[objectName + "Descriptions"]; // high quality programming
@@ -52,19 +61,26 @@
                             if (tooltipInfo !== null) {
                                 return wordWrap(tooltipInfo[data["labels"][tooltipItem["index"]]], 45);
                             }
+
+                            if (tooltipItem.index === indexOfUnknownLanguage) {
+                                return "No specific language";
+                            }
                         }
                     },
                 },
                 onClick: function (e, data) {
                     try {
                         let label = labels[data[0]._index];
+                        const isUnknownLanguage = (data[0]._index === indexOfUnknownLanguage);
                         let canvas = data[0]._chart.canvas.id;
                         if (canvas === "repoStarCount" || canvas === "repoCommitCount") {
                             window.open("https://github.com/" + userId + "/" + label, "_blank");
                             window.focus();
                         } else {
-                            window.open("https://github.com/" + userId + "?utf8=%E2%9C%93&tab=repositories&q=&type=source&language=" + encodeURIComponent(label), "_blank");
-                            window.focus();
+                            if (!isUnknownLanguage) {
+                                window.open("https://github.com/" + userId + "?utf8=%E2%9C%93&tab=repositories&q=&type=source&language=" + encodeURIComponent(label), "_blank");
+                                window.focus();
+                            }
                         }
                     } catch (ignored) {
                     }

From 6bd15d4a07061680966c821c3168d4d0ace29c4b Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Wed, 18 May 2022 12:43:20 +0900
Subject: [PATCH 02/33] Implement user cache using embedded H2.

---
 pom.xml                            |   6 +
 src/main/kotlin/app/UserService.kt | 239 +++++++++++++++++++++++++----
 2 files changed, 215 insertions(+), 30 deletions(-)

diff --git a/pom.xml b/pom.xml
index 07d0b82..a3b7c9e 100644
--- a/pom.xml
+++ b/pom.xml
@@ -58,6 +58,12 @@
             <version>${kotlin.version}</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>com.h2database</groupId>
+            <artifactId>h2</artifactId>
+            <version>2.1.212</version>
+            <scope>runtime</scope>
+        </dependency>
     </dependencies>
 
     <build>
diff --git a/src/main/kotlin/app/UserService.kt b/src/main/kotlin/app/UserService.kt
index 3f4d423..f0949e4 100644
--- a/src/main/kotlin/app/UserService.kt
+++ b/src/main/kotlin/app/UserService.kt
@@ -1,12 +1,24 @@
 package app
 
 import app.util.CommitCountUtil
+import com.fasterxml.jackson.core.JsonParser
+import com.fasterxml.jackson.databind.DeserializationContext
+import com.fasterxml.jackson.databind.JsonNode
+import com.fasterxml.jackson.databind.deser.std.StdDeserializer
+import com.fasterxml.jackson.databind.module.SimpleModule
+import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
+import com.fasterxml.jackson.module.kotlin.readValue
 import org.eclipse.egit.github.core.Repository
 import org.eclipse.egit.github.core.RepositoryCommit
 import org.eclipse.egit.github.core.User
+import org.eclipse.egit.github.core.UserPlan
 import org.slf4j.LoggerFactory
 import java.io.Serializable
+import java.sql.DriverManager
 import java.time.Instant
+import java.time.LocalDateTime
+import java.time.temporal.ChronoUnit
+import java.util.Date
 import java.util.concurrent.ConcurrentHashMap
 import java.util.stream.IntStream
 import kotlin.streams.toList
@@ -14,6 +26,7 @@ import kotlin.streams.toList
 object UserService {
 
     private const val pageSize = 100
+    private const val urlToDb = "jdbc:h2:mem:userinfo"
     private val log = LoggerFactory.getLogger("app.UserCtrlKt")
     private val repo = GhService.repos.getRepository("tipsy", "profile-summary-for-github")
     private val watchers = ConcurrentHashMap.newKeySet<String>()
@@ -29,41 +42,13 @@ object UserService {
         val remainingRequests by lazy { GhService.remainingRequests }
         val hasFreeRemainingRequests by lazy { remainingRequests > (freeRequestCutoff ?: remainingRequests) }
         return Config.unrestricted()
-                || Cache.contains(user)
+                || (lookUpInCache(user) != null)
                 || hasFreeRemainingRequests
                 || (remainingRequests > 0 && hasStarredRepo(user))
     }
 
     fun getUserProfile(username: String): UserProfile {
-        if (Cache.invalid(username)) {
-            val user = GhService.users.getUser(username)
-            val repos = GhService.repos.getRepositories(username).filter { !it.isFork && it.size != 0 }
-            val repoCommits = repos.parallelStream().map { it to commitsForRepo(it).filter { it.author?.login.equals(username, ignoreCase = true) } }.toList().toMap()
-            val langRepoGrouping = repos.groupingBy { (it.language ?: "Unknown") }
-
-            val quarterCommitCount = CommitCountUtil.getCommitsForQuarters(user, repoCommits)
-            val langRepoCount = langRepoGrouping.eachCount().toList().sortedBy { (_, v) -> -v }.toMap()
-            val langStarCount = langRepoGrouping.fold(0) { acc, repo -> acc + repo.watchers }.toList().sortedBy { (_, v) -> -v }.toMap()
-            val langCommitCount = langRepoGrouping.fold(0) { acc, repo -> acc + repoCommits[repo]!!.size }.toList().sortedBy { (_, v) -> -v }.toMap()
-            val repoCommitCount = repoCommits.map { it.key.name to it.value.size }.toList().sortedBy { (_, v) -> -v }.take(10).toMap()
-            val repoStarCount = repos.filter { it.watchers > 0 }.map { it.name to it.watchers }.sortedBy { (_, v) -> -v }.take(10).toMap()
-
-            val repoCommitCountDescriptions = repoCommitCount.map { it.key to repos.find { r -> r.name == it.key }?.description }.toMap()
-            val repoStarCountDescriptions = repoStarCount.map { it.key to repos.find { r -> r.name == it.key }?.description }.toMap()
-
-            Cache.putUserProfile(UserProfile(
-                    user,
-                    quarterCommitCount,
-                    langRepoCount,
-                    langStarCount,
-                    langCommitCount,
-                    repoCommitCount,
-                    repoStarCount,
-                    repoCommitCountDescriptions,
-                    repoStarCountDescriptions
-            ))
-        }
-        return Cache.getUserProfile(username)!!
+        return (lookUpInCache(username) ?: generateUserProfile(username))
     }
 
     private fun hasStarredRepo(username: String): Boolean {
@@ -97,6 +82,110 @@ object UserService {
         listOf()
     }
 
+    private fun createTableIfAbsent() {
+        val connection = DriverManager.getConnection(urlToDb)
+        val statement = connection.createStatement()
+
+        statement.execute(
+        "CREATE TABLE IF NOT EXISTS userinfo (" +
+            "id VARCHAR2 PRIMARY KEY," +
+            "timestamp TIMESTAMP WITH TIME ZONE, " +
+            "data JSON" +
+            ")"
+        )
+    }
+
+    private fun lookUpInCache(username: String): UserProfile? {
+        val connection = DriverManager.getConnection(urlToDb)
+
+        createTableIfAbsent()
+
+        val preparedStatement = connection.prepareStatement(
+        "SELECT " +
+            "timestamp, " +
+            "data " +
+            "FROM userinfo " +
+            "WHERE id = ?"
+        )
+        preparedStatement.setString(1, username)
+
+        val result = preparedStatement.executeQuery()
+        result.use {
+            // guaranteed to be at most one.
+            if (it.next()) {
+                val timestamp = it.getTimestamp(1).toLocalDateTime()
+                val diffInHours = ChronoUnit.HOURS.between(timestamp, LocalDateTime.now())
+                if (diffInHours <= 6) {
+                    val json: String = it.getString(2)
+
+                    log.debug("cache hit: {}", json)
+
+                    val simpleModule = SimpleModule()
+                    simpleModule.addDeserializer(UserProfile::class.java, UserProfile.Deserializer())
+
+                    val objectMapper = jacksonObjectMapper()
+                    objectMapper.registerModule(simpleModule)
+
+                    return objectMapper.readValue<UserProfile>(json)
+                }
+            }
+        }
+
+        log.debug("cache miss for username: {}", username)
+
+        return null
+    }
+
+    private fun saveInCache(userProfile: UserProfile) {
+        val connection = DriverManager.getConnection(urlToDb)
+
+        createTableIfAbsent()
+
+        val json = jacksonObjectMapper().writeValueAsString(userProfile)
+
+        val preparedStatement = connection.prepareStatement(
+        "MERGE INTO userinfo (id, timestamp, data) KEY (id) " +
+            "VALUES (?, CURRENT_TIMESTAMP(), ? FORMAT JSON)"
+        )
+
+        preparedStatement.setString(1, userProfile.user.login)
+        preparedStatement.setString(2, json)
+
+        preparedStatement.execute()
+    }
+
+    private fun generateUserProfile(username: String): UserProfile {
+        val user = GhService.users.getUser(username)
+        val repos = GhService.repos.getRepositories(username).filter { !it.isFork && it.size != 0 }
+        val repoCommits = repos.parallelStream().map { it to commitsForRepo(it).filter { it.author?.login.equals(username, ignoreCase = true) } }.toList().toMap()
+        val langRepoGrouping = repos.groupingBy { (it.language ?: "Unknown") }
+
+        val quarterCommitCount = CommitCountUtil.getCommitsForQuarters(user, repoCommits)
+        val langRepoCount = langRepoGrouping.eachCount().toList().sortedBy { (_, v) -> -v }.toMap()
+        val langStarCount = langRepoGrouping.fold(0) { acc, repo -> acc + repo.watchers }.toList().sortedBy { (_, v) -> -v }.toMap()
+        val langCommitCount = langRepoGrouping.fold(0) { acc, repo -> acc + repoCommits[repo]!!.size }.toList().sortedBy { (_, v) -> -v }.toMap()
+        val repoCommitCount = repoCommits.map { it.key.name to it.value.size }.toList().sortedBy { (_, v) -> -v }.take(10).toMap()
+        val repoStarCount = repos.filter { it.watchers > 0 }.map { it.name to it.watchers }.sortedBy { (_, v) -> -v }.take(10).toMap()
+
+        val repoCommitCountDescriptions = repoCommitCount.map { it.key to repos.find { r -> r.name == it.key }?.description }.toMap()
+        val repoStarCountDescriptions = repoStarCount.map { it.key to repos.find { r -> r.name == it.key }?.description }.toMap()
+
+        val userProfile = UserProfile(
+            user,
+            quarterCommitCount,
+            langRepoCount,
+            langStarCount,
+            langCommitCount,
+            repoCommitCount,
+            repoStarCount,
+            repoCommitCountDescriptions,
+            repoStarCountDescriptions
+        )
+
+        saveInCache(userProfile)
+
+        return userProfile;
+    }
 }
 
 data class UserProfile(
@@ -111,4 +200,94 @@ data class UserProfile(
         val repoStarCountDescriptions: Map<String, String?>
 ) : Serializable {
     val timeStamp = Instant.now().toEpochMilli()
+
+    class Deserializer(valueClass: Class<*>?): StdDeserializer<UserProfile>(valueClass) {
+        constructor(): this(null)
+
+        override fun deserialize(jsonParser: JsonParser?, context: DeserializationContext?): UserProfile {
+            if (jsonParser == null || context == null) {
+                throw RuntimeException()
+            }
+
+            val userProfileNode: JsonNode = jsonParser.codec?.readTree(jsonParser) ?: throw RuntimeException()
+
+            val userNode = userProfileNode.get("user")
+            val user = User()
+            user.isHireable = userNode.booleanValue()
+            user.createdAt = Date(userNode.longValue())
+            user.collaborators = userNode.intValue()
+            user.diskUsage = userNode.intValue()
+            user.followers = userNode.intValue()
+            user.following = userNode.intValue()
+            user.id = userNode.intValue()
+            user.ownedPrivateRepos = userNode.intValue()
+            user.privateGists = userNode.intValue()
+            user.publicGists = userNode.intValue()
+            user.publicRepos = userNode.intValue()
+            user.totalPrivateRepos = userNode.intValue()
+            user.avatarUrl = userNode.textValue()
+            user.blog = userNode.textValue()
+            user.company = userNode.textValue()
+            user.email = userNode.textValue()
+            user.gravatarId = userNode.textValue()
+            user.htmlUrl = userNode.textValue()
+            user.location = userNode.textValue()
+            user.login = userNode.textValue()
+            user.name = userNode.textValue()
+            user.type = userNode.textValue()
+            user.url = userNode.textValue()
+
+            val planNode = userNode.get("plan")
+            user.plan = if (planNode.isNull) null else context.readValue(planNode.traverse(), UserPlan::class.java)
+
+            val quarterCommitCount: MutableMap<String, Int> = parseInt(userProfileNode.get("quarterCommitCount"))
+            val langRepoCount: MutableMap<String, Int> = parseInt(userProfileNode.get("langRepoCount"))
+            val langStarCount: MutableMap<String, Int> = parseInt(userProfileNode.get("langStarCount"))
+            val langCommitCount: MutableMap<String, Int> = parseInt(userProfileNode.get("langCommitCount"))
+            val repoCommitCount: MutableMap<String, Int> = parseInt(userProfileNode.get("repoCommitCount"))
+            val repoStarCount: MutableMap<String, Int> = parseInt(userProfileNode.get("repoStarCount"))
+            val repoCommitCountDescriptions: MutableMap<String, String?> = parseString(userProfileNode.get("repoCommitCountDescriptions"))
+            val repoStarCountDescriptions: MutableMap<String, String?> = parseString(userProfileNode.get("repoStarCountDescriptions"))
+
+            return UserProfile(
+                user,
+                quarterCommitCount,
+                langRepoCount,
+                langStarCount,
+                langCommitCount,
+                repoCommitCount,
+                repoStarCount,
+                repoCommitCountDescriptions,
+                repoStarCountDescriptions
+            )
+        }
+
+        private fun parseInt(jsonNode: JsonNode): MutableMap<String, Int> {
+            val map: MutableMap<String, Int> = mutableMapOf()
+            if (!jsonNode.isNull) {
+                val fieldNames = jsonNode.fieldNames()
+                while (fieldNames.hasNext()) {
+                    val key = fieldNames.next()
+                    val value = jsonNode[key].intValue()
+                    map[key] = value
+                }
+            }
+
+            return map
+        }
+
+        private fun parseString(jsonNode: JsonNode): MutableMap<String, String?> {
+            val map: MutableMap<String, String?> = mutableMapOf()
+            if (!jsonNode.isNull) {
+                val fieldNames = jsonNode.fieldNames()
+                while (fieldNames.hasNext()) {
+                    val key = fieldNames.next()
+                    val value = jsonNode[key].textValue()
+                    map[key] = value
+                }
+            }
+
+            return map
+        }
+    }
 }

From 84f8914403cc144a27e12ce37ee6eb178a05549e Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Thu, 19 May 2022 11:28:21 +0900
Subject: [PATCH 03/33] Separate caching to its own service

https://github.com/tipsy/profile-summary-for-github/issues/110
---
 src/main/kotlin/app/Cache.kt        |  58 --------
 src/main/kotlin/app/CacheService.kt |  86 ++++++++++++
 src/main/kotlin/app/UserProfile.kt  | 112 ++++++++++++++++
 src/main/kotlin/app/UserService.kt  | 198 +---------------------------
 4 files changed, 201 insertions(+), 253 deletions(-)
 delete mode 100644 src/main/kotlin/app/Cache.kt
 create mode 100644 src/main/kotlin/app/CacheService.kt
 create mode 100644 src/main/kotlin/app/UserProfile.kt

diff --git a/src/main/kotlin/app/Cache.kt b/src/main/kotlin/app/Cache.kt
deleted file mode 100644
index b07a644..0000000
--- a/src/main/kotlin/app/Cache.kt
+++ /dev/null
@@ -1,58 +0,0 @@
-package app
-
-import java.io.*
-import java.time.Instant
-import java.time.temporal.ChronoUnit.HOURS
-import java.util.concurrent.ConcurrentHashMap
-import java.util.concurrent.Executors
-
-object Cache {
-
-    private const val path = "cache/userinfo"
-    private val userProfiles = readUserProfilesFromDisk()
-    private val fileSaveExecutor = Executors.newSingleThreadExecutor()
-
-    // Put userProfile in cache, then serialize cache and write it to disk
-    fun putUserProfile(userProfile: UserProfile) {
-        userProfiles[userProfile.user.login.toLowerCase()] = userProfile
-        fileSaveExecutor.execute {
-            ByteArrayOutputStream().let {
-                ObjectOutputStream(it).writeObject(userProfiles)
-                File(path).apply {
-                    if (!exists()) {
-                        parentFile.mkdirs()
-                        createNewFile()
-                    }
-                    writeBytes(it.toByteArray())
-                }
-            }
-        }
-    }
-
-    fun getUserProfile(username: String) = userProfiles[username.toLowerCase()]
-    fun contains(username: String) = getUserProfile(username) != null
-    fun invalid(username: String): Boolean = getUserProfile(username)?.let {
-        HOURS.between(Instant.ofEpochMilli(it.timeStamp), Instant.now()) > 6
-    } ?: true
-
-    // Read cache from disk, return empty map if no cache file exists
-    @Suppress("UNCHECKED_CAST")
-    private fun readUserProfilesFromDisk(): ConcurrentHashMap<String, UserProfile> {
-        try {
-            File(path).apply {
-                if (exists()) {
-                    ObjectInputStream(ByteArrayInputStream(readBytes())).let {
-                        val obj = it.readObject()
-
-                        if (obj is ConcurrentHashMap<*, *>)
-                            return obj as ConcurrentHashMap<String, UserProfile>
-                    }
-                }
-            }
-        } catch (e: Exception) {
-        }
-
-        return ConcurrentHashMap()
-    }
-
-}
diff --git a/src/main/kotlin/app/CacheService.kt b/src/main/kotlin/app/CacheService.kt
new file mode 100644
index 0000000..2a3d6f1
--- /dev/null
+++ b/src/main/kotlin/app/CacheService.kt
@@ -0,0 +1,86 @@
+package app
+
+import com.fasterxml.jackson.databind.module.SimpleModule
+import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
+import com.fasterxml.jackson.module.kotlin.readValue
+import org.slf4j.LoggerFactory
+import java.sql.DriverManager
+import java.time.LocalDateTime
+import java.time.temporal.ChronoUnit
+
+object CacheService {
+    private const val urlToDb = "jdbc:h2:mem:userinfo"
+    private val log = LoggerFactory.getLogger(CacheService.javaClass)
+
+    private fun createTableIfAbsent() {
+        val connection = DriverManager.getConnection(urlToDb)
+        val statement = connection.createStatement()
+
+        statement.execute(
+            "CREATE TABLE IF NOT EXISTS userinfo (" +
+            "id VARCHAR2 PRIMARY KEY," +
+            "timestamp TIMESTAMP WITH TIME ZONE, " +
+            "data JSON" +
+            ")"
+        )
+    }
+
+    fun lookUpInCache(username: String): UserProfile? {
+        val connection = DriverManager.getConnection(urlToDb)
+
+        createTableIfAbsent()
+
+        val preparedStatement = connection.prepareStatement(
+            "SELECT " +
+            "timestamp, " +
+            "data " +
+            "FROM userinfo " +
+            "WHERE id = ?"
+        )
+        preparedStatement.setString(1, username)
+
+        val result = preparedStatement.executeQuery()
+        result.use {
+            // guaranteed to be at most one.
+            if (it.next()) {
+                val timestamp = it.getTimestamp(1).toLocalDateTime()
+                val diffInHours = ChronoUnit.HOURS.between(timestamp, LocalDateTime.now())
+                if (diffInHours <= 6) {
+                    val json: String = it.getString(2)
+
+                    log.debug("cache hit: {}", json)
+
+                    val simpleModule = SimpleModule()
+                    simpleModule.addDeserializer(UserProfile::class.java, UserProfile.Deserializer())
+
+                    val objectMapper = jacksonObjectMapper()
+                    objectMapper.registerModule(simpleModule)
+
+                    return objectMapper.readValue<UserProfile>(json)
+                }
+            }
+        }
+
+        log.debug("cache miss for username: {}", username)
+
+        return null
+    }
+
+    fun saveInCache(userProfile: UserProfile) {
+        val connection = DriverManager.getConnection(urlToDb)
+
+        createTableIfAbsent()
+
+        val json = jacksonObjectMapper().writeValueAsString(userProfile)
+
+        val preparedStatement = connection.prepareStatement(
+            "MERGE INTO userinfo (id, timestamp, data) KEY (id) " +
+            "VALUES (?, CURRENT_TIMESTAMP(), ? FORMAT JSON)"
+        )
+
+        preparedStatement.setString(1, userProfile.user.login)
+        preparedStatement.setString(2, json)
+
+        preparedStatement.execute()
+    }
+}
diff --git a/src/main/kotlin/app/UserProfile.kt b/src/main/kotlin/app/UserProfile.kt
new file mode 100644
index 0000000..a251ed4
--- /dev/null
+++ b/src/main/kotlin/app/UserProfile.kt
@@ -0,0 +1,112 @@
+package app
+
+import com.fasterxml.jackson.core.JsonParser
+import com.fasterxml.jackson.databind.DeserializationContext
+import com.fasterxml.jackson.databind.JsonNode
+import com.fasterxml.jackson.databind.deser.std.StdDeserializer
+import org.eclipse.egit.github.core.User
+import org.eclipse.egit.github.core.UserPlan
+import java.io.Serializable
+import java.util.Date
+
+data class UserProfile(
+    val user: User,
+    val quarterCommitCount: Map<String, Int>,
+    val langRepoCount: Map<String, Int>,
+    val langStarCount: Map<String, Int>,
+    val langCommitCount: Map<String, Int>,
+    val repoCommitCount: Map<String, Int>,
+    val repoStarCount: Map<String, Int>,
+    val repoCommitCountDescriptions: Map<String, String?>,
+    val repoStarCountDescriptions: Map<String, String?>
+) : Serializable {
+    class Deserializer(valueClass: Class<*>?): StdDeserializer<UserProfile>(valueClass) {
+        constructor(): this(null)
+
+        override fun deserialize(jsonParser: JsonParser?, context: DeserializationContext?): UserProfile {
+            if (jsonParser == null || context == null) {
+                throw RuntimeException()
+            }
+
+            val userProfileNode: JsonNode = jsonParser.codec?.readTree(jsonParser) ?: throw RuntimeException()
+
+            val userNode = userProfileNode.get("user")
+            val user = User()
+            user.isHireable = userNode.booleanValue()
+            user.createdAt = Date(userNode.longValue())
+            user.collaborators = userNode.intValue()
+            user.diskUsage = userNode.intValue()
+            user.followers = userNode.intValue()
+            user.following = userNode.intValue()
+            user.id = userNode.intValue()
+            user.ownedPrivateRepos = userNode.intValue()
+            user.privateGists = userNode.intValue()
+            user.publicGists = userNode.intValue()
+            user.publicRepos = userNode.intValue()
+            user.totalPrivateRepos = userNode.intValue()
+            user.avatarUrl = userNode.textValue()
+            user.blog = userNode.textValue()
+            user.company = userNode.textValue()
+            user.email = userNode.textValue()
+            user.gravatarId = userNode.textValue()
+            user.htmlUrl = userNode.textValue()
+            user.location = userNode.textValue()
+            user.login = userNode.textValue()
+            user.name = userNode.textValue()
+            user.type = userNode.textValue()
+            user.url = userNode.textValue()
+
+            val planNode = userNode.get("plan")
+            user.plan = if (planNode.isNull) null else context.readValue(planNode.traverse(), UserPlan::class.java)
+
+            val quarterCommitCount: MutableMap<String, Int> = parseInt(userProfileNode.get("quarterCommitCount"))
+            val langRepoCount: MutableMap<String, Int> = parseInt(userProfileNode.get("langRepoCount"))
+            val langStarCount: MutableMap<String, Int> = parseInt(userProfileNode.get("langStarCount"))
+            val langCommitCount: MutableMap<String, Int> = parseInt(userProfileNode.get("langCommitCount"))
+            val repoCommitCount: MutableMap<String, Int> = parseInt(userProfileNode.get("repoCommitCount"))
+            val repoStarCount: MutableMap<String, Int> = parseInt(userProfileNode.get("repoStarCount"))
+            val repoCommitCountDescriptions: MutableMap<String, String?> = parseString(userProfileNode.get("repoCommitCountDescriptions"))
+            val repoStarCountDescriptions: MutableMap<String, String?> = parseString(userProfileNode.get("repoStarCountDescriptions"))
+
+            return UserProfile(
+                user,
+                quarterCommitCount,
+                langRepoCount,
+                langStarCount,
+                langCommitCount,
+                repoCommitCount,
+                repoStarCount,
+                repoCommitCountDescriptions,
+                repoStarCountDescriptions
+            )
+        }
+
+        private fun parseInt(jsonNode: JsonNode): MutableMap<String, Int> {
+            val map: MutableMap<String, Int> = mutableMapOf()
+            if (!jsonNode.isNull) {
+                val fieldNames = jsonNode.fieldNames()
+                while (fieldNames.hasNext()) {
+                    val key = fieldNames.next()
+                    val value = jsonNode[key].intValue()
+                    map[key] = value
+                }
+            }
+
+            return map
+        }
+
+        private fun parseString(jsonNode: JsonNode): MutableMap<String, String?> {
+            val map: MutableMap<String, String?> = mutableMapOf()
+            if (!jsonNode.isNull) {
+                val fieldNames = jsonNode.fieldNames()
+                while (fieldNames.hasNext()) {
+                    val key = fieldNames.next()
+                    val value = jsonNode[key].textValue()
+                    map[key] = value
+                }
+            }
+
+            return map
+        }
+    }
+}
diff --git a/src/main/kotlin/app/UserService.kt b/src/main/kotlin/app/UserService.kt
index f0949e4..0b32f3e 100644
--- a/src/main/kotlin/app/UserService.kt
+++ b/src/main/kotlin/app/UserService.kt
@@ -1,24 +1,9 @@
 package app
 
 import app.util.CommitCountUtil
-import com.fasterxml.jackson.core.JsonParser
-import com.fasterxml.jackson.databind.DeserializationContext
-import com.fasterxml.jackson.databind.JsonNode
-import com.fasterxml.jackson.databind.deser.std.StdDeserializer
-import com.fasterxml.jackson.databind.module.SimpleModule
-import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
-import com.fasterxml.jackson.module.kotlin.readValue
 import org.eclipse.egit.github.core.Repository
 import org.eclipse.egit.github.core.RepositoryCommit
-import org.eclipse.egit.github.core.User
-import org.eclipse.egit.github.core.UserPlan
 import org.slf4j.LoggerFactory
-import java.io.Serializable
-import java.sql.DriverManager
-import java.time.Instant
-import java.time.LocalDateTime
-import java.time.temporal.ChronoUnit
-import java.util.Date
 import java.util.concurrent.ConcurrentHashMap
 import java.util.stream.IntStream
 import kotlin.streams.toList
@@ -26,7 +11,6 @@ import kotlin.streams.toList
 object UserService {
 
     private const val pageSize = 100
-    private const val urlToDb = "jdbc:h2:mem:userinfo"
     private val log = LoggerFactory.getLogger("app.UserCtrlKt")
     private val repo = GhService.repos.getRepository("tipsy", "profile-summary-for-github")
     private val watchers = ConcurrentHashMap.newKeySet<String>()
@@ -42,13 +26,13 @@ object UserService {
         val remainingRequests by lazy { GhService.remainingRequests }
         val hasFreeRemainingRequests by lazy { remainingRequests > (freeRequestCutoff ?: remainingRequests) }
         return Config.unrestricted()
-                || (lookUpInCache(user) != null)
+                || (CacheService.lookUpInCache(user) != null)
                 || hasFreeRemainingRequests
                 || (remainingRequests > 0 && hasStarredRepo(user))
     }
 
     fun getUserProfile(username: String): UserProfile {
-        return (lookUpInCache(username) ?: generateUserProfile(username))
+        return (CacheService.lookUpInCache(username) ?: generateUserProfile(username))
     }
 
     private fun hasStarredRepo(username: String): Boolean {
@@ -82,78 +66,6 @@ object UserService {
         listOf()
     }
 
-    private fun createTableIfAbsent() {
-        val connection = DriverManager.getConnection(urlToDb)
-        val statement = connection.createStatement()
-
-        statement.execute(
-        "CREATE TABLE IF NOT EXISTS userinfo (" +
-            "id VARCHAR2 PRIMARY KEY," +
-            "timestamp TIMESTAMP WITH TIME ZONE, " +
-            "data JSON" +
-            ")"
-        )
-    }
-
-    private fun lookUpInCache(username: String): UserProfile? {
-        val connection = DriverManager.getConnection(urlToDb)
-
-        createTableIfAbsent()
-
-        val preparedStatement = connection.prepareStatement(
-        "SELECT " +
-            "timestamp, " +
-            "data " +
-            "FROM userinfo " +
-            "WHERE id = ?"
-        )
-        preparedStatement.setString(1, username)
-
-        val result = preparedStatement.executeQuery()
-        result.use {
-            // guaranteed to be at most one.
-            if (it.next()) {
-                val timestamp = it.getTimestamp(1).toLocalDateTime()
-                val diffInHours = ChronoUnit.HOURS.between(timestamp, LocalDateTime.now())
-                if (diffInHours <= 6) {
-                    val json: String = it.getString(2)
-
-                    log.debug("cache hit: {}", json)
-
-                    val simpleModule = SimpleModule()
-                    simpleModule.addDeserializer(UserProfile::class.java, UserProfile.Deserializer())
-
-                    val objectMapper = jacksonObjectMapper()
-                    objectMapper.registerModule(simpleModule)
-
-                    return objectMapper.readValue<UserProfile>(json)
-                }
-            }
-        }
-
-        log.debug("cache miss for username: {}", username)
-
-        return null
-    }
-
-    private fun saveInCache(userProfile: UserProfile) {
-        val connection = DriverManager.getConnection(urlToDb)
-
-        createTableIfAbsent()
-
-        val json = jacksonObjectMapper().writeValueAsString(userProfile)
-
-        val preparedStatement = connection.prepareStatement(
-        "MERGE INTO userinfo (id, timestamp, data) KEY (id) " +
-            "VALUES (?, CURRENT_TIMESTAMP(), ? FORMAT JSON)"
-        )
-
-        preparedStatement.setString(1, userProfile.user.login)
-        preparedStatement.setString(2, json)
-
-        preparedStatement.execute()
-    }
-
     private fun generateUserProfile(username: String): UserProfile {
         val user = GhService.users.getUser(username)
         val repos = GhService.repos.getRepositories(username).filter { !it.isFork && it.size != 0 }
@@ -182,112 +94,8 @@ object UserService {
             repoStarCountDescriptions
         )
 
-        saveInCache(userProfile)
+        CacheService.saveInCache(userProfile)
 
         return userProfile;
     }
 }
-
-data class UserProfile(
-        val user: User,
-        val quarterCommitCount: Map<String, Int>,
-        val langRepoCount: Map<String, Int>,
-        val langStarCount: Map<String, Int>,
-        val langCommitCount: Map<String, Int>,
-        val repoCommitCount: Map<String, Int>,
-        val repoStarCount: Map<String, Int>,
-        val repoCommitCountDescriptions: Map<String, String?>,
-        val repoStarCountDescriptions: Map<String, String?>
-) : Serializable {
-    val timeStamp = Instant.now().toEpochMilli()
-
-    class Deserializer(valueClass: Class<*>?): StdDeserializer<UserProfile>(valueClass) {
-        constructor(): this(null)
-
-        override fun deserialize(jsonParser: JsonParser?, context: DeserializationContext?): UserProfile {
-            if (jsonParser == null || context == null) {
-                throw RuntimeException()
-            }
-
-            val userProfileNode: JsonNode = jsonParser.codec?.readTree(jsonParser) ?: throw RuntimeException()
-
-            val userNode = userProfileNode.get("user")
-            val user = User()
-            user.isHireable = userNode.booleanValue()
-            user.createdAt = Date(userNode.longValue())
-            user.collaborators = userNode.intValue()
-            user.diskUsage = userNode.intValue()
-            user.followers = userNode.intValue()
-            user.following = userNode.intValue()
-            user.id = userNode.intValue()
-            user.ownedPrivateRepos = userNode.intValue()
-            user.privateGists = userNode.intValue()
-            user.publicGists = userNode.intValue()
-            user.publicRepos = userNode.intValue()
-            user.totalPrivateRepos = userNode.intValue()
-            user.avatarUrl = userNode.textValue()
-            user.blog = userNode.textValue()
-            user.company = userNode.textValue()
-            user.email = userNode.textValue()
-            user.gravatarId = userNode.textValue()
-            user.htmlUrl = userNode.textValue()
-            user.location = userNode.textValue()
-            user.login = userNode.textValue()
-            user.name = userNode.textValue()
-            user.type = userNode.textValue()
-            user.url = userNode.textValue()
-
-            val planNode = userNode.get("plan")
-            user.plan = if (planNode.isNull) null else context.readValue(planNode.traverse(), UserPlan::class.java)
-
-            val quarterCommitCount: MutableMap<String, Int> = parseInt(userProfileNode.get("quarterCommitCount"))
-            val langRepoCount: MutableMap<String, Int> = parseInt(userProfileNode.get("langRepoCount"))
-            val langStarCount: MutableMap<String, Int> = parseInt(userProfileNode.get("langStarCount"))
-            val langCommitCount: MutableMap<String, Int> = parseInt(userProfileNode.get("langCommitCount"))
-            val repoCommitCount: MutableMap<String, Int> = parseInt(userProfileNode.get("repoCommitCount"))
-            val repoStarCount: MutableMap<String, Int> = parseInt(userProfileNode.get("repoStarCount"))
-            val repoCommitCountDescriptions: MutableMap<String, String?> = parseString(userProfileNode.get("repoCommitCountDescriptions"))
-            val repoStarCountDescriptions: MutableMap<String, String?> = parseString(userProfileNode.get("repoStarCountDescriptions"))
-
-            return UserProfile(
-                user,
-                quarterCommitCount,
-                langRepoCount,
-                langStarCount,
-                langCommitCount,
-                repoCommitCount,
-                repoStarCount,
-                repoCommitCountDescriptions,
-                repoStarCountDescriptions
-            )
-        }
-
-        private fun parseInt(jsonNode: JsonNode): MutableMap<String, Int> {
-            val map: MutableMap<String, Int> = mutableMapOf()
-            if (!jsonNode.isNull) {
-                val fieldNames = jsonNode.fieldNames()
-                while (fieldNames.hasNext()) {
-                    val key = fieldNames.next()
-                    val value = jsonNode[key].intValue()
-                    map[key] = value
-                }
-            }
-
-            return map
-        }
-
-        private fun parseString(jsonNode: JsonNode): MutableMap<String, String?> {
-            val map: MutableMap<String, String?> = mutableMapOf()
-            if (!jsonNode.isNull) {
-                val fieldNames = jsonNode.fieldNames()
-                while (fieldNames.hasNext()) {
-                    val key = fieldNames.next()
-                    val value = jsonNode[key].textValue()
-                    map[key] = value
-                }
-            }
-
-            return map
-        }
-    }
-}

From 8f5889b569faefb774c04750f3db67f3b5cc9b72 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Thu, 19 May 2022 11:43:46 +0900
Subject: [PATCH 04/33] Change UserProfile to be not Serializable

---
 src/main/kotlin/app/UserProfile.kt | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/main/kotlin/app/UserProfile.kt b/src/main/kotlin/app/UserProfile.kt
index a251ed4..855916d 100644
--- a/src/main/kotlin/app/UserProfile.kt
+++ b/src/main/kotlin/app/UserProfile.kt
@@ -6,7 +6,6 @@ import com.fasterxml.jackson.databind.JsonNode
 import com.fasterxml.jackson.databind.deser.std.StdDeserializer
 import org.eclipse.egit.github.core.User
 import org.eclipse.egit.github.core.UserPlan
-import java.io.Serializable
 import java.util.Date
 
 data class UserProfile(
@@ -19,7 +18,7 @@ data class UserProfile(
     val repoStarCount: Map<String, Int>,
     val repoCommitCountDescriptions: Map<String, String?>,
     val repoStarCountDescriptions: Map<String, String?>
-) : Serializable {
+) {
     class Deserializer(valueClass: Class<*>?): StdDeserializer<UserProfile>(valueClass) {
         constructor(): this(null)
 

From 8347ea6f7bc640a33a0591a6c6edfb1ca3007299 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Thu, 19 May 2022 11:46:46 +0900
Subject: [PATCH 05/33] Fix copy-paste errors.

---
 src/main/kotlin/app/UserProfile.kt | 46 +++++++++++++++---------------
 1 file changed, 23 insertions(+), 23 deletions(-)

diff --git a/src/main/kotlin/app/UserProfile.kt b/src/main/kotlin/app/UserProfile.kt
index 855916d..fad07f9 100644
--- a/src/main/kotlin/app/UserProfile.kt
+++ b/src/main/kotlin/app/UserProfile.kt
@@ -31,29 +31,29 @@ data class UserProfile(
 
             val userNode = userProfileNode.get("user")
             val user = User()
-            user.isHireable = userNode.booleanValue()
-            user.createdAt = Date(userNode.longValue())
-            user.collaborators = userNode.intValue()
-            user.diskUsage = userNode.intValue()
-            user.followers = userNode.intValue()
-            user.following = userNode.intValue()
-            user.id = userNode.intValue()
-            user.ownedPrivateRepos = userNode.intValue()
-            user.privateGists = userNode.intValue()
-            user.publicGists = userNode.intValue()
-            user.publicRepos = userNode.intValue()
-            user.totalPrivateRepos = userNode.intValue()
-            user.avatarUrl = userNode.textValue()
-            user.blog = userNode.textValue()
-            user.company = userNode.textValue()
-            user.email = userNode.textValue()
-            user.gravatarId = userNode.textValue()
-            user.htmlUrl = userNode.textValue()
-            user.location = userNode.textValue()
-            user.login = userNode.textValue()
-            user.name = userNode.textValue()
-            user.type = userNode.textValue()
-            user.url = userNode.textValue()
+            user.isHireable = userNode.get("hireable").booleanValue()
+            user.createdAt = Date(userNode.get("createdAt").longValue())
+            user.collaborators = userNode.get("collaborators").intValue()
+            user.diskUsage = userNode.get("diskUsage").intValue()
+            user.followers = userNode.get("followers").intValue()
+            user.following = userNode.get("following").intValue()
+            user.id = userNode.get("id").intValue()
+            user.ownedPrivateRepos = userNode.get("ownedPrivateRepos").intValue()
+            user.privateGists = userNode.get("privateGists").intValue()
+            user.publicGists = userNode.get("publicGists").intValue()
+            user.publicRepos = userNode.get("publicRepos").intValue()
+            user.totalPrivateRepos = userNode.get("totalPrivateRepos").intValue()
+            user.avatarUrl = userNode.get("avatarUrl").textValue()
+            user.blog = userNode.get("blog").textValue()
+            user.company = userNode.get("company").textValue()
+            user.email = userNode.get("email").textValue()
+            user.gravatarId = userNode.get("gravatarId").textValue()
+            user.htmlUrl = userNode.get("htmlUrl").textValue()
+            user.location = userNode.get("location").textValue()
+            user.login = userNode.get("login").textValue()
+            user.name = userNode.get("name").textValue()
+            user.type = userNode.get("type").textValue()
+            user.url = userNode.get("url").textValue()
 
             val planNode = userNode.get("plan")
             user.plan = if (planNode.isNull) null else context.readValue(planNode.traverse(), UserPlan::class.java)

From e487b1c15f5557b02a2f6a749a9b18323e551be4 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Fri, 20 May 2022 12:29:09 +0900
Subject: [PATCH 06/33] Replace Jackson with Gson which reduced boilerplate
 code by a bit.

---
 src/main/kotlin/app/CacheService.kt |  14 ++--
 src/main/kotlin/app/UserProfile.kt  | 116 +++++++++++-----------------
 2 files changed, 50 insertions(+), 80 deletions(-)

diff --git a/src/main/kotlin/app/CacheService.kt b/src/main/kotlin/app/CacheService.kt
index 2a3d6f1..3d0be4e 100644
--- a/src/main/kotlin/app/CacheService.kt
+++ b/src/main/kotlin/app/CacheService.kt
@@ -1,8 +1,7 @@
 package app
 
-import com.fasterxml.jackson.databind.module.SimpleModule
 import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
-import com.fasterxml.jackson.module.kotlin.readValue
+import com.google.gson.GsonBuilder
 import org.slf4j.LoggerFactory
 import java.sql.DriverManager
 import java.time.LocalDateTime
@@ -50,13 +49,12 @@ object CacheService {
 
                     log.debug("cache hit: {}", json)
 
-                    val simpleModule = SimpleModule()
-                    simpleModule.addDeserializer(UserProfile::class.java, UserProfile.Deserializer())
+                    val gson = GsonBuilder()
+                        .registerTypeAdapter(UserProfile::class.java, UserProfile.Deserializer())
+                        .serializeNulls()
+                        .create()
 
-                    val objectMapper = jacksonObjectMapper()
-                    objectMapper.registerModule(simpleModule)
-
-                    return objectMapper.readValue<UserProfile>(json)
+                    return gson.fromJson(json, UserProfile::class.java)
                 }
             }
         }
diff --git a/src/main/kotlin/app/UserProfile.kt b/src/main/kotlin/app/UserProfile.kt
index fad07f9..af0a44f 100644
--- a/src/main/kotlin/app/UserProfile.kt
+++ b/src/main/kotlin/app/UserProfile.kt
@@ -1,11 +1,12 @@
 package app
 
-import com.fasterxml.jackson.core.JsonParser
-import com.fasterxml.jackson.databind.DeserializationContext
-import com.fasterxml.jackson.databind.JsonNode
-import com.fasterxml.jackson.databind.deser.std.StdDeserializer
+import com.google.gson.JsonDeserializationContext
+import com.google.gson.JsonDeserializer
+import com.google.gson.JsonElement
+import com.google.gson.reflect.TypeToken
 import org.eclipse.egit.github.core.User
 import org.eclipse.egit.github.core.UserPlan
+import java.lang.reflect.Type
 import java.util.Date
 
 data class UserProfile(
@@ -19,53 +20,52 @@ data class UserProfile(
     val repoCommitCountDescriptions: Map<String, String?>,
     val repoStarCountDescriptions: Map<String, String?>
 ) {
-    class Deserializer(valueClass: Class<*>?): StdDeserializer<UserProfile>(valueClass) {
-        constructor(): this(null)
-
-        override fun deserialize(jsonParser: JsonParser?, context: DeserializationContext?): UserProfile {
-            if (jsonParser == null || context == null) {
+    class Deserializer: JsonDeserializer<UserProfile> {
+        override fun deserialize(jsonElement: JsonElement?, typeOfT: Type?, context: JsonDeserializationContext?): UserProfile {
+            if (jsonElement == null || context == null) {
                 throw RuntimeException()
             }
 
-            val userProfileNode: JsonNode = jsonParser.codec?.readTree(jsonParser) ?: throw RuntimeException()
+            val jsonObject = jsonElement.asJsonObject
 
-            val userNode = userProfileNode.get("user")
+            val userObject = jsonObject.getAsJsonObject("user")
             val user = User()
-            user.isHireable = userNode.get("hireable").booleanValue()
-            user.createdAt = Date(userNode.get("createdAt").longValue())
-            user.collaborators = userNode.get("collaborators").intValue()
-            user.diskUsage = userNode.get("diskUsage").intValue()
-            user.followers = userNode.get("followers").intValue()
-            user.following = userNode.get("following").intValue()
-            user.id = userNode.get("id").intValue()
-            user.ownedPrivateRepos = userNode.get("ownedPrivateRepos").intValue()
-            user.privateGists = userNode.get("privateGists").intValue()
-            user.publicGists = userNode.get("publicGists").intValue()
-            user.publicRepos = userNode.get("publicRepos").intValue()
-            user.totalPrivateRepos = userNode.get("totalPrivateRepos").intValue()
-            user.avatarUrl = userNode.get("avatarUrl").textValue()
-            user.blog = userNode.get("blog").textValue()
-            user.company = userNode.get("company").textValue()
-            user.email = userNode.get("email").textValue()
-            user.gravatarId = userNode.get("gravatarId").textValue()
-            user.htmlUrl = userNode.get("htmlUrl").textValue()
-            user.location = userNode.get("location").textValue()
-            user.login = userNode.get("login").textValue()
-            user.name = userNode.get("name").textValue()
-            user.type = userNode.get("type").textValue()
-            user.url = userNode.get("url").textValue()
+            user.isHireable = userObject.get("hireable").asBoolean
+            user.createdAt = Date(userObject.get("createdAt").asLong)
+            user.collaborators = userObject.get("collaborators").asInt
+            user.diskUsage = userObject.get("diskUsage").asInt
+            user.followers = userObject.get("followers").asInt
+            user.following = userObject.get("following").asInt
+            user.id = userObject.get("id").asInt
+            user.ownedPrivateRepos = userObject.get("ownedPrivateRepos").asInt
+            user.privateGists = userObject.get("privateGists").asInt
+            user.publicGists = userObject.get("publicGists").asInt
+            user.publicRepos = userObject.get("publicRepos").asInt
+            user.totalPrivateRepos = userObject.get("totalPrivateRepos").asInt
+            user.avatarUrl = if (userObject.get("avatarUrl").isJsonNull) null else userObject.get("avatarUrl").asString
+            user.blog = if (userObject.get("blog").isJsonNull) null else userObject.get("blog").asString
+            user.company = if (userObject.get("company").isJsonNull) null else userObject.get("company").asString
+            user.email = if (userObject.get("email").isJsonNull) null else userObject.get("email").asString
+            user.gravatarId = if (userObject.get("gravatarId").isJsonNull) null else userObject.get("gravatarId").asString
+            user.htmlUrl = if (userObject.get("htmlUrl").isJsonNull) null else userObject.get("htmlUrl").asString
+            user.location = if (userObject.get("location").isJsonNull) null else userObject.get("location").asString
+            user.login = if (userObject.get("login").isJsonNull) null else userObject.get("login").asString
+            user.name = if (userObject.get("name").isJsonNull) null else userObject.get("name").asString
+            user.type = if (userObject.get("type").isJsonNull) null else userObject.get("type").asString
+            user.url = if (userObject.get("url").isJsonNull) null else userObject.get("url").asString
+            user.plan = context.deserialize(userObject.get("plan"), UserPlan::class.java)
 
-            val planNode = userNode.get("plan")
-            user.plan = if (planNode.isNull) null else context.readValue(planNode.traverse(), UserPlan::class.java)
+            val mapType1 = object: TypeToken<Map<String, Int>>() {}.type
+            val mapType2 = object: TypeToken<Map<String, String?>>() {}.type
 
-            val quarterCommitCount: MutableMap<String, Int> = parseInt(userProfileNode.get("quarterCommitCount"))
-            val langRepoCount: MutableMap<String, Int> = parseInt(userProfileNode.get("langRepoCount"))
-            val langStarCount: MutableMap<String, Int> = parseInt(userProfileNode.get("langStarCount"))
-            val langCommitCount: MutableMap<String, Int> = parseInt(userProfileNode.get("langCommitCount"))
-            val repoCommitCount: MutableMap<String, Int> = parseInt(userProfileNode.get("repoCommitCount"))
-            val repoStarCount: MutableMap<String, Int> = parseInt(userProfileNode.get("repoStarCount"))
-            val repoCommitCountDescriptions: MutableMap<String, String?> = parseString(userProfileNode.get("repoCommitCountDescriptions"))
-            val repoStarCountDescriptions: MutableMap<String, String?> = parseString(userProfileNode.get("repoStarCountDescriptions"))
+            val quarterCommitCount: Map<String, Int> = context.deserialize(jsonObject.get("quarterCommitCount"), mapType1)
+            val langRepoCount: Map<String, Int> = context.deserialize(jsonObject.get("langRepoCount"), mapType1)
+            val langStarCount: Map<String, Int> = context.deserialize(jsonObject.get("langStarCount"), mapType1)
+            val langCommitCount: Map<String, Int> = context.deserialize(jsonObject.get("langCommitCount"), mapType1)
+            val repoCommitCount: Map<String, Int> = context.deserialize(jsonObject.get("repoCommitCount"), mapType1)
+            val repoStarCount: Map<String, Int> = context.deserialize(jsonObject.get("repoStarCount"), mapType1)
+            val repoCommitCountDescriptions: Map<String, String?> = context.deserialize(jsonObject.get("repoCommitCountDescriptions"), mapType2)
+            val repoStarCountDescriptions: Map<String, String?> = context.deserialize(jsonObject.get("repoStarCountDescriptions"), mapType2)
 
             return UserProfile(
                 user,
@@ -79,33 +79,5 @@ data class UserProfile(
                 repoStarCountDescriptions
             )
         }
-
-        private fun parseInt(jsonNode: JsonNode): MutableMap<String, Int> {
-            val map: MutableMap<String, Int> = mutableMapOf()
-            if (!jsonNode.isNull) {
-                val fieldNames = jsonNode.fieldNames()
-                while (fieldNames.hasNext()) {
-                    val key = fieldNames.next()
-                    val value = jsonNode[key].intValue()
-                    map[key] = value
-                }
-            }
-
-            return map
-        }
-
-        private fun parseString(jsonNode: JsonNode): MutableMap<String, String?> {
-            val map: MutableMap<String, String?> = mutableMapOf()
-            if (!jsonNode.isNull) {
-                val fieldNames = jsonNode.fieldNames()
-                while (fieldNames.hasNext()) {
-                    val key = fieldNames.next()
-                    val value = jsonNode[key].textValue()
-                    map[key] = value
-                }
-            }
-
-            return map
-        }
     }
 }

From a5c85ce5d99a816234428b4b4a7f34b53dcf2216 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Fri, 20 May 2022 13:39:44 +0900
Subject: [PATCH 07/33] Introduce an extension function

---
 src/main/kotlin/app/UserProfile.kt | 30 +++++++++++++++++++-----------
 1 file changed, 19 insertions(+), 11 deletions(-)

diff --git a/src/main/kotlin/app/UserProfile.kt b/src/main/kotlin/app/UserProfile.kt
index af0a44f..8edfb15 100644
--- a/src/main/kotlin/app/UserProfile.kt
+++ b/src/main/kotlin/app/UserProfile.kt
@@ -42,17 +42,17 @@ data class UserProfile(
             user.publicGists = userObject.get("publicGists").asInt
             user.publicRepos = userObject.get("publicRepos").asInt
             user.totalPrivateRepos = userObject.get("totalPrivateRepos").asInt
-            user.avatarUrl = if (userObject.get("avatarUrl").isJsonNull) null else userObject.get("avatarUrl").asString
-            user.blog = if (userObject.get("blog").isJsonNull) null else userObject.get("blog").asString
-            user.company = if (userObject.get("company").isJsonNull) null else userObject.get("company").asString
-            user.email = if (userObject.get("email").isJsonNull) null else userObject.get("email").asString
-            user.gravatarId = if (userObject.get("gravatarId").isJsonNull) null else userObject.get("gravatarId").asString
-            user.htmlUrl = if (userObject.get("htmlUrl").isJsonNull) null else userObject.get("htmlUrl").asString
-            user.location = if (userObject.get("location").isJsonNull) null else userObject.get("location").asString
-            user.login = if (userObject.get("login").isJsonNull) null else userObject.get("login").asString
-            user.name = if (userObject.get("name").isJsonNull) null else userObject.get("name").asString
-            user.type = if (userObject.get("type").isJsonNull) null else userObject.get("type").asString
-            user.url = if (userObject.get("url").isJsonNull) null else userObject.get("url").asString
+            user.avatarUrl = userObject.get("avatarUrl").asStringOrNull()
+            user.blog = userObject.get("blog").asStringOrNull()
+            user.company = userObject.get("company").asStringOrNull()
+            user.email = userObject.get("email").asStringOrNull()
+            user.gravatarId = userObject.get("gravatarId").asStringOrNull()
+            user.htmlUrl = userObject.get("htmlUrl").asStringOrNull()
+            user.location = userObject.get("location").asStringOrNull()
+            user.login = userObject.get("login").asStringOrNull()
+            user.name = userObject.get("name").asStringOrNull()
+            user.type = userObject.get("type").asStringOrNull()
+            user.url = userObject.get("url").asStringOrNull()
             user.plan = context.deserialize(userObject.get("plan"), UserPlan::class.java)
 
             val mapType1 = object: TypeToken<Map<String, Int>>() {}.type
@@ -79,5 +79,13 @@ data class UserProfile(
                 repoStarCountDescriptions
             )
         }
+
+        private fun JsonElement.asStringOr(fallback: String?): String? {
+            return if (isJsonNull) fallback else asString
+        }
+
+        private fun JsonElement.asStringOrNull(): String? {
+            return asStringOr(null)
+        }
     }
 }

From bf5cdd595a4b1452e9b9235406b8e92930f441a5 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Fri, 20 May 2022 14:04:19 +0900
Subject: [PATCH 08/33] Remove unnecessary JsonDeserializer class.

Instead, I decided to use a simple TypeAdapter in order to deserialize number into java.util.Date.
---
 src/main/kotlin/app/CacheService.kt | 20 +++++++-
 src/main/kotlin/app/UserProfile.kt  | 78 +----------------------------
 2 files changed, 20 insertions(+), 78 deletions(-)

diff --git a/src/main/kotlin/app/CacheService.kt b/src/main/kotlin/app/CacheService.kt
index 3d0be4e..28cc21a 100644
--- a/src/main/kotlin/app/CacheService.kt
+++ b/src/main/kotlin/app/CacheService.kt
@@ -2,10 +2,14 @@ package app
 
 import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
 import com.google.gson.GsonBuilder
+import com.google.gson.TypeAdapter
+import com.google.gson.stream.JsonReader
+import com.google.gson.stream.JsonWriter
 import org.slf4j.LoggerFactory
 import java.sql.DriverManager
 import java.time.LocalDateTime
 import java.time.temporal.ChronoUnit
+import java.util.Date
 
 object CacheService {
     private const val urlToDb = "jdbc:h2:mem:userinfo"
@@ -50,7 +54,7 @@ object CacheService {
                     log.debug("cache hit: {}", json)
 
                     val gson = GsonBuilder()
-                        .registerTypeAdapter(UserProfile::class.java, UserProfile.Deserializer())
+                        .registerTypeAdapter(Date::class.java, DateTypeAdapter())
                         .serializeNulls()
                         .create()
 
@@ -81,4 +85,18 @@ object CacheService {
 
         preparedStatement.execute()
     }
+
+    private class DateTypeAdapter: TypeAdapter<Date>() {
+        override fun write(out: JsonWriter, value: Date?) {
+            if (value == null) {
+                out.nullValue()
+            } else {
+                out.value(value.time)
+            }
+        }
+
+        override fun read(`in`: JsonReader): Date {
+            return Date(`in`.nextLong())
+        }
+    }
 }
diff --git a/src/main/kotlin/app/UserProfile.kt b/src/main/kotlin/app/UserProfile.kt
index 8edfb15..96621ae 100644
--- a/src/main/kotlin/app/UserProfile.kt
+++ b/src/main/kotlin/app/UserProfile.kt
@@ -1,13 +1,6 @@
 package app
 
-import com.google.gson.JsonDeserializationContext
-import com.google.gson.JsonDeserializer
-import com.google.gson.JsonElement
-import com.google.gson.reflect.TypeToken
 import org.eclipse.egit.github.core.User
-import org.eclipse.egit.github.core.UserPlan
-import java.lang.reflect.Type
-import java.util.Date
 
 data class UserProfile(
     val user: User,
@@ -19,73 +12,4 @@ data class UserProfile(
     val repoStarCount: Map<String, Int>,
     val repoCommitCountDescriptions: Map<String, String?>,
     val repoStarCountDescriptions: Map<String, String?>
-) {
-    class Deserializer: JsonDeserializer<UserProfile> {
-        override fun deserialize(jsonElement: JsonElement?, typeOfT: Type?, context: JsonDeserializationContext?): UserProfile {
-            if (jsonElement == null || context == null) {
-                throw RuntimeException()
-            }
-
-            val jsonObject = jsonElement.asJsonObject
-
-            val userObject = jsonObject.getAsJsonObject("user")
-            val user = User()
-            user.isHireable = userObject.get("hireable").asBoolean
-            user.createdAt = Date(userObject.get("createdAt").asLong)
-            user.collaborators = userObject.get("collaborators").asInt
-            user.diskUsage = userObject.get("diskUsage").asInt
-            user.followers = userObject.get("followers").asInt
-            user.following = userObject.get("following").asInt
-            user.id = userObject.get("id").asInt
-            user.ownedPrivateRepos = userObject.get("ownedPrivateRepos").asInt
-            user.privateGists = userObject.get("privateGists").asInt
-            user.publicGists = userObject.get("publicGists").asInt
-            user.publicRepos = userObject.get("publicRepos").asInt
-            user.totalPrivateRepos = userObject.get("totalPrivateRepos").asInt
-            user.avatarUrl = userObject.get("avatarUrl").asStringOrNull()
-            user.blog = userObject.get("blog").asStringOrNull()
-            user.company = userObject.get("company").asStringOrNull()
-            user.email = userObject.get("email").asStringOrNull()
-            user.gravatarId = userObject.get("gravatarId").asStringOrNull()
-            user.htmlUrl = userObject.get("htmlUrl").asStringOrNull()
-            user.location = userObject.get("location").asStringOrNull()
-            user.login = userObject.get("login").asStringOrNull()
-            user.name = userObject.get("name").asStringOrNull()
-            user.type = userObject.get("type").asStringOrNull()
-            user.url = userObject.get("url").asStringOrNull()
-            user.plan = context.deserialize(userObject.get("plan"), UserPlan::class.java)
-
-            val mapType1 = object: TypeToken<Map<String, Int>>() {}.type
-            val mapType2 = object: TypeToken<Map<String, String?>>() {}.type
-
-            val quarterCommitCount: Map<String, Int> = context.deserialize(jsonObject.get("quarterCommitCount"), mapType1)
-            val langRepoCount: Map<String, Int> = context.deserialize(jsonObject.get("langRepoCount"), mapType1)
-            val langStarCount: Map<String, Int> = context.deserialize(jsonObject.get("langStarCount"), mapType1)
-            val langCommitCount: Map<String, Int> = context.deserialize(jsonObject.get("langCommitCount"), mapType1)
-            val repoCommitCount: Map<String, Int> = context.deserialize(jsonObject.get("repoCommitCount"), mapType1)
-            val repoStarCount: Map<String, Int> = context.deserialize(jsonObject.get("repoStarCount"), mapType1)
-            val repoCommitCountDescriptions: Map<String, String?> = context.deserialize(jsonObject.get("repoCommitCountDescriptions"), mapType2)
-            val repoStarCountDescriptions: Map<String, String?> = context.deserialize(jsonObject.get("repoStarCountDescriptions"), mapType2)
-
-            return UserProfile(
-                user,
-                quarterCommitCount,
-                langRepoCount,
-                langStarCount,
-                langCommitCount,
-                repoCommitCount,
-                repoStarCount,
-                repoCommitCountDescriptions,
-                repoStarCountDescriptions
-            )
-        }
-
-        private fun JsonElement.asStringOr(fallback: String?): String? {
-            return if (isJsonNull) fallback else asString
-        }
-
-        private fun JsonElement.asStringOrNull(): String? {
-            return asStringOr(null)
-        }
-    }
-}
+)

From 415d70c73fc7451a0799ea3ee41b5612f505dd10 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Fri, 20 May 2022 14:19:10 +0900
Subject: [PATCH 09/33] Switch back to Jackson as deserializer.

---
 src/main/kotlin/app/CacheService.kt | 34 ++++++++++++-----------------
 1 file changed, 14 insertions(+), 20 deletions(-)

diff --git a/src/main/kotlin/app/CacheService.kt b/src/main/kotlin/app/CacheService.kt
index 28cc21a..a987bb0 100644
--- a/src/main/kotlin/app/CacheService.kt
+++ b/src/main/kotlin/app/CacheService.kt
@@ -1,10 +1,11 @@
 package app
 
+import com.fasterxml.jackson.core.JsonParser
+import com.fasterxml.jackson.databind.DeserializationContext
+import com.fasterxml.jackson.databind.deser.std.StdDeserializer
+import com.fasterxml.jackson.databind.module.SimpleModule
 import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
-import com.google.gson.GsonBuilder
-import com.google.gson.TypeAdapter
-import com.google.gson.stream.JsonReader
-import com.google.gson.stream.JsonWriter
+import com.fasterxml.jackson.module.kotlin.readValue
 import org.slf4j.LoggerFactory
 import java.sql.DriverManager
 import java.time.LocalDateTime
@@ -53,12 +54,13 @@ object CacheService {
 
                     log.debug("cache hit: {}", json)
 
-                    val gson = GsonBuilder()
-                        .registerTypeAdapter(Date::class.java, DateTypeAdapter())
-                        .serializeNulls()
-                        .create()
+                    val simpleModule = SimpleModule()
+                    simpleModule.addDeserializer(Date::class.java, DateDeserializer())
 
-                    return gson.fromJson(json, UserProfile::class.java)
+                    val objectMapper = jacksonObjectMapper()
+                    objectMapper.registerModule(simpleModule)
+
+                    return objectMapper.readValue<UserProfile>(json)
                 }
             }
         }
@@ -86,17 +88,9 @@ object CacheService {
         preparedStatement.execute()
     }
 
-    private class DateTypeAdapter: TypeAdapter<Date>() {
-        override fun write(out: JsonWriter, value: Date?) {
-            if (value == null) {
-                out.nullValue()
-            } else {
-                out.value(value.time)
-            }
-        }
-
-        override fun read(`in`: JsonReader): Date {
-            return Date(`in`.nextLong())
+    private class DateDeserializer: StdDeserializer<Date>(Date::class.java) {
+        override fun deserialize(jsonParser: JsonParser, context: DeserializationContext): Date {
+            return Date(jsonParser.readValueAs(Long::class.java))
         }
     }
 }

From c97ffd7390f9e103153b6b9d7fc508298473d754 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Fri, 20 May 2022 14:19:31 +0900
Subject: [PATCH 10/33] Add warning suppression.

---
 src/main/kotlin/app/CacheService.kt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/main/kotlin/app/CacheService.kt b/src/main/kotlin/app/CacheService.kt
index a987bb0..ad763c3 100644
--- a/src/main/kotlin/app/CacheService.kt
+++ b/src/main/kotlin/app/CacheService.kt
@@ -1,3 +1,5 @@
+@file:Suppress("SqlResolve")
+
 package app
 
 import com.fasterxml.jackson.core.JsonParser

From 5a929a9945073fb3ea937d6c7d93c30a0212c43f Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Mon, 23 May 2022 09:36:57 +0900
Subject: [PATCH 11/33] Replace redundant creation of ObjectMapper.

---
 src/main/kotlin/app/CacheService.kt | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/src/main/kotlin/app/CacheService.kt b/src/main/kotlin/app/CacheService.kt
index ad763c3..4c22f0f 100644
--- a/src/main/kotlin/app/CacheService.kt
+++ b/src/main/kotlin/app/CacheService.kt
@@ -17,6 +17,8 @@ import java.util.Date
 object CacheService {
     private const val urlToDb = "jdbc:h2:mem:userinfo"
     private val log = LoggerFactory.getLogger(CacheService.javaClass)
+    private val objectMapper = jacksonObjectMapper()
+        .registerModule(SimpleModule().addDeserializer(Date::class.java, DateDeserializer()))
 
     private fun createTableIfAbsent() {
         val connection = DriverManager.getConnection(urlToDb)
@@ -56,12 +58,6 @@ object CacheService {
 
                     log.debug("cache hit: {}", json)
 
-                    val simpleModule = SimpleModule()
-                    simpleModule.addDeserializer(Date::class.java, DateDeserializer())
-
-                    val objectMapper = jacksonObjectMapper()
-                    objectMapper.registerModule(simpleModule)
-
                     return objectMapper.readValue<UserProfile>(json)
                 }
             }
@@ -77,7 +73,7 @@ object CacheService {
 
         createTableIfAbsent()
 
-        val json = jacksonObjectMapper().writeValueAsString(userProfile)
+        val json = objectMapper.writeValueAsString(userProfile)
 
         val preparedStatement = connection.prepareStatement(
             "MERGE INTO userinfo (id, timestamp, data) KEY (id) " +

From 2f599bba8a1a918bb6fa87b5a3cb606a04410ae2 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Mon, 23 May 2022 09:42:38 +0900
Subject: [PATCH 12/33] Replace LocalDateTime with Instant.

---
 src/main/kotlin/app/CacheService.kt | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/main/kotlin/app/CacheService.kt b/src/main/kotlin/app/CacheService.kt
index 4c22f0f..6fd1bc5 100644
--- a/src/main/kotlin/app/CacheService.kt
+++ b/src/main/kotlin/app/CacheService.kt
@@ -10,7 +10,7 @@ import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
 import com.fasterxml.jackson.module.kotlin.readValue
 import org.slf4j.LoggerFactory
 import java.sql.DriverManager
-import java.time.LocalDateTime
+import java.time.Instant
 import java.time.temporal.ChronoUnit
 import java.util.Date
 
@@ -51,8 +51,8 @@ object CacheService {
         result.use {
             // guaranteed to be at most one.
             if (it.next()) {
-                val timestamp = it.getTimestamp(1).toLocalDateTime()
-                val diffInHours = ChronoUnit.HOURS.between(timestamp, LocalDateTime.now())
+                val timestamp = it.getTimestamp(1).toInstant()
+                val diffInHours = ChronoUnit.HOURS.between(timestamp, Instant.now())
                 if (diffInHours <= 6) {
                     val json: String = it.getString(2)
 

From 8306d9210135a2ad5d876d22e4a51e43626a8b4a Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Mon, 23 May 2022 09:59:40 +0900
Subject: [PATCH 13/33] Prevent multiple invocations of generateUserProfile.

---
 src/main/kotlin/app/UserService.kt | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/main/kotlin/app/UserService.kt b/src/main/kotlin/app/UserService.kt
index 0b32f3e..2bdc27d 100644
--- a/src/main/kotlin/app/UserService.kt
+++ b/src/main/kotlin/app/UserService.kt
@@ -32,7 +32,9 @@ object UserService {
     }
 
     fun getUserProfile(username: String): UserProfile {
-        return (CacheService.lookUpInCache(username) ?: generateUserProfile(username))
+        synchronized(username) {
+            return (CacheService.lookUpInCache(username) ?: generateUserProfile(username))
+        }
     }
 
     private fun hasStarredRepo(username: String): Boolean {

From 07071889e2d3488200746a314bc6efed83c5c982 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Mon, 23 May 2022 10:28:44 +0900
Subject: [PATCH 14/33] Cache by lazy.

---
 src/main/kotlin/app/UserService.kt | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/main/kotlin/app/UserService.kt b/src/main/kotlin/app/UserService.kt
index 2bdc27d..1b565f1 100644
--- a/src/main/kotlin/app/UserService.kt
+++ b/src/main/kotlin/app/UserService.kt
@@ -25,8 +25,9 @@ object UserService {
     fun canLoadUser(user: String): Boolean {
         val remainingRequests by lazy { GhService.remainingRequests }
         val hasFreeRemainingRequests by lazy { remainingRequests > (freeRequestCutoff ?: remainingRequests) }
+        val userCache by lazy { CacheService.lookUpInCache(user) }
         return Config.unrestricted()
-                || (CacheService.lookUpInCache(user) != null)
+                || (userCache != null)
                 || hasFreeRemainingRequests
                 || (remainingRequests > 0 && hasStarredRepo(user))
     }

From caaa0973bfd645d877f07aabd2d12c4360844d91 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Mon, 23 May 2022 11:04:11 +0900
Subject: [PATCH 15/33] Remove unnecessary JSON deserialization from
 lookUpInCache.

---
 src/main/kotlin/app/CacheService.kt | 10 ++++++++--
 src/main/kotlin/app/UserService.kt  |  2 +-
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/main/kotlin/app/CacheService.kt b/src/main/kotlin/app/CacheService.kt
index 6fd1bc5..25fad85 100644
--- a/src/main/kotlin/app/CacheService.kt
+++ b/src/main/kotlin/app/CacheService.kt
@@ -33,7 +33,7 @@ object CacheService {
         )
     }
 
-    fun lookUpInCache(username: String): UserProfile? {
+    fun lookUpInCache(username: String): String? {
         val connection = DriverManager.getConnection(urlToDb)
 
         createTableIfAbsent()
@@ -58,7 +58,7 @@ object CacheService {
 
                     log.debug("cache hit: {}", json)
 
-                    return objectMapper.readValue<UserProfile>(json)
+                    return json
                 }
             }
         }
@@ -68,6 +68,12 @@ object CacheService {
         return null
     }
 
+    fun getUserFromCache(username: String): UserProfile? {
+        val json = lookUpInCache(username) ?: return null
+
+        return objectMapper.readValue<UserProfile>(json)
+    }
+
     fun saveInCache(userProfile: UserProfile) {
         val connection = DriverManager.getConnection(urlToDb)
 
diff --git a/src/main/kotlin/app/UserService.kt b/src/main/kotlin/app/UserService.kt
index 1b565f1..8821e0b 100644
--- a/src/main/kotlin/app/UserService.kt
+++ b/src/main/kotlin/app/UserService.kt
@@ -34,7 +34,7 @@ object UserService {
 
     fun getUserProfile(username: String): UserProfile {
         synchronized(username) {
-            return (CacheService.lookUpInCache(username) ?: generateUserProfile(username))
+            return (CacheService.getUserFromCache(username) ?: generateUserProfile(username))
         }
     }
 

From c06acf592e6020844c4a4ea41c890c17b516e963 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Mon, 23 May 2022 11:10:00 +0900
Subject: [PATCH 16/33] Prevent NPE.

---
 src/main/kotlin/app/CacheService.kt | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/main/kotlin/app/CacheService.kt b/src/main/kotlin/app/CacheService.kt
index 25fad85..a4595e2 100644
--- a/src/main/kotlin/app/CacheService.kt
+++ b/src/main/kotlin/app/CacheService.kt
@@ -54,9 +54,10 @@ object CacheService {
                 val timestamp = it.getTimestamp(1).toInstant()
                 val diffInHours = ChronoUnit.HOURS.between(timestamp, Instant.now())
                 if (diffInHours <= 6) {
-                    val json: String = it.getString(2)
-
-                    log.debug("cache hit: {}", json)
+                    val json: String? = it.getString(2)
+                    if (json != null) {
+                        log.debug("cache hit: {}", json)
+                    }
 
                     return json
                 }

From 494ed41b81e8fcbab3155e87aad97f5355ade8d9 Mon Sep 17 00:00:00 2001
From: Attacktive <66462458+Attacktive@users.noreply.github.com>
Date: Mon, 23 May 2022 16:30:30 +0900
Subject: [PATCH 17/33] Update src/main/kotlin/app/CacheService.kt

Co-authored-by: Sidd <iProdigy@users.noreply.github.com>
---
 src/main/kotlin/app/CacheService.kt | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/src/main/kotlin/app/CacheService.kt b/src/main/kotlin/app/CacheService.kt
index a4595e2..7a4093b 100644
--- a/src/main/kotlin/app/CacheService.kt
+++ b/src/main/kotlin/app/CacheService.kt
@@ -69,11 +69,7 @@ object CacheService {
         return null
     }
 
-    fun getUserFromCache(username: String): UserProfile? {
-        val json = lookUpInCache(username) ?: return null
-
-        return objectMapper.readValue<UserProfile>(json)
-    }
+    fun getUserFromCache(username: String) = lookUpInCache(username)?.let { json -> objectMapper.readValue<UserProfile>(json) }
 
     fun saveInCache(userProfile: UserProfile) {
         val connection = DriverManager.getConnection(urlToDb)

From a0f11e707bd45f0b2b364a1308215aca644aeeaf Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Mon, 23 May 2022 16:31:12 +0900
Subject: [PATCH 18/33] Revert "Prevent multiple invocations of
 generateUserProfile."

This reverts commit 8306d921
---
 src/main/kotlin/app/UserService.kt | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/src/main/kotlin/app/UserService.kt b/src/main/kotlin/app/UserService.kt
index 8821e0b..f7f3a7d 100644
--- a/src/main/kotlin/app/UserService.kt
+++ b/src/main/kotlin/app/UserService.kt
@@ -33,9 +33,7 @@ object UserService {
     }
 
     fun getUserProfile(username: String): UserProfile {
-        synchronized(username) {
-            return (CacheService.getUserFromCache(username) ?: generateUserProfile(username))
-        }
+        return (CacheService.getUserFromCache(username) ?: generateUserProfile(username))
     }
 
     private fun hasStarredRepo(username: String): Boolean {

From 34acc07a5659c8749142866cf3e185242840b876 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Mon, 23 May 2022 16:36:42 +0900
Subject: [PATCH 19/33] Remove unnecessary custom deserializer.

---
 src/main/kotlin/app/CacheService.kt | 12 ------------
 1 file changed, 12 deletions(-)

diff --git a/src/main/kotlin/app/CacheService.kt b/src/main/kotlin/app/CacheService.kt
index 7a4093b..96e419d 100644
--- a/src/main/kotlin/app/CacheService.kt
+++ b/src/main/kotlin/app/CacheService.kt
@@ -2,23 +2,17 @@
 
 package app
 
-import com.fasterxml.jackson.core.JsonParser
-import com.fasterxml.jackson.databind.DeserializationContext
-import com.fasterxml.jackson.databind.deser.std.StdDeserializer
-import com.fasterxml.jackson.databind.module.SimpleModule
 import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
 import com.fasterxml.jackson.module.kotlin.readValue
 import org.slf4j.LoggerFactory
 import java.sql.DriverManager
 import java.time.Instant
 import java.time.temporal.ChronoUnit
-import java.util.Date
 
 object CacheService {
     private const val urlToDb = "jdbc:h2:mem:userinfo"
     private val log = LoggerFactory.getLogger(CacheService.javaClass)
     private val objectMapper = jacksonObjectMapper()
-        .registerModule(SimpleModule().addDeserializer(Date::class.java, DateDeserializer()))
 
     private fun createTableIfAbsent() {
         val connection = DriverManager.getConnection(urlToDb)
@@ -88,10 +82,4 @@ object CacheService {
 
         preparedStatement.execute()
     }
-
-    private class DateDeserializer: StdDeserializer<Date>(Date::class.java) {
-        override fun deserialize(jsonParser: JsonParser, context: DeserializationContext): Date {
-            return Date(jsonParser.readValueAs(Long::class.java))
-        }
-    }
 }

From 899a28f534b3056ea00f878a3e36a6a2f8f0d262 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Mon, 23 May 2022 17:50:20 +0900
Subject: [PATCH 20/33] Rename function.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

UserService#lookUpInCache → selectJsonFromDb
---
 src/main/kotlin/app/CacheService.kt | 4 ++--
 src/main/kotlin/app/UserService.kt  | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/main/kotlin/app/CacheService.kt b/src/main/kotlin/app/CacheService.kt
index 96e419d..4cdf331 100644
--- a/src/main/kotlin/app/CacheService.kt
+++ b/src/main/kotlin/app/CacheService.kt
@@ -27,7 +27,7 @@ object CacheService {
         )
     }
 
-    fun lookUpInCache(username: String): String? {
+    fun selectJsonFromDb(username: String): String? {
         val connection = DriverManager.getConnection(urlToDb)
 
         createTableIfAbsent()
@@ -63,7 +63,7 @@ object CacheService {
         return null
     }
 
-    fun getUserFromCache(username: String) = lookUpInCache(username)?.let { json -> objectMapper.readValue<UserProfile>(json) }
+    fun getUserFromCache(username: String) = selectJsonFromDb(username)?.let { json -> objectMapper.readValue<UserProfile>(json) }
 
     fun saveInCache(userProfile: UserProfile) {
         val connection = DriverManager.getConnection(urlToDb)
diff --git a/src/main/kotlin/app/UserService.kt b/src/main/kotlin/app/UserService.kt
index f7f3a7d..f15e390 100644
--- a/src/main/kotlin/app/UserService.kt
+++ b/src/main/kotlin/app/UserService.kt
@@ -25,7 +25,7 @@ object UserService {
     fun canLoadUser(user: String): Boolean {
         val remainingRequests by lazy { GhService.remainingRequests }
         val hasFreeRemainingRequests by lazy { remainingRequests > (freeRequestCutoff ?: remainingRequests) }
-        val userCache by lazy { CacheService.lookUpInCache(user) }
+        val userCache by lazy { CacheService.selectJsonFromDb(user) }
         return Config.unrestricted()
                 || (userCache != null)
                 || hasFreeRemainingRequests

From 1d04b350a914585197fd3103acb0fdd8c40e9567 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Mon, 23 May 2022 19:34:10 +0900
Subject: [PATCH 21/33] Reduce invocations of CacheService#selectJsonFromDb.

---
 src/main/kotlin/app/CacheService.kt |  2 +-
 src/main/kotlin/app/Main.kt         |  7 +++++--
 src/main/kotlin/app/UserService.kt  | 27 +++++++++++++++++++++++----
 3 files changed, 29 insertions(+), 7 deletions(-)

diff --git a/src/main/kotlin/app/CacheService.kt b/src/main/kotlin/app/CacheService.kt
index 4cdf331..7109f80 100644
--- a/src/main/kotlin/app/CacheService.kt
+++ b/src/main/kotlin/app/CacheService.kt
@@ -63,7 +63,7 @@ object CacheService {
         return null
     }
 
-    fun getUserFromCache(username: String) = selectJsonFromDb(username)?.let { json -> objectMapper.readValue<UserProfile>(json) }
+    fun getUserFromJson(json: String) = objectMapper.readValue<UserProfile>(json)
 
     fun saveInCache(userProfile: UserProfile) {
         val connection = DriverManager.getConnection(urlToDb)
diff --git a/src/main/kotlin/app/Main.kt b/src/main/kotlin/app/Main.kt
index f7255c5..4d8006d 100644
--- a/src/main/kotlin/app/Main.kt
+++ b/src/main/kotlin/app/Main.kt
@@ -46,8 +46,11 @@ fun main() {
         get("/api/user/{user}") { ctx ->
             val user = ctx.pathParam("user")
             if (!UserService.userExists(user)) throw NotFoundResponse()
-            if (!UserService.canLoadUser(user)) throw BadRequestResponse("Can't load user")
-            ctx.json(UserService.getUserProfile(user))
+            try {
+                ctx.json(UserService.getUserIfCanLoad(user))
+            } catch (exception: UserService.UserNotLoadableException) {
+                throw BadRequestResponse(exception.message.toString())
+            }
         }
         get("/search", VueComponent("search-view"))
         get("/user/{user}", VueComponent("user-view"))
diff --git a/src/main/kotlin/app/UserService.kt b/src/main/kotlin/app/UserService.kt
index f15e390..a72f77d 100644
--- a/src/main/kotlin/app/UserService.kt
+++ b/src/main/kotlin/app/UserService.kt
@@ -25,15 +25,32 @@ object UserService {
     fun canLoadUser(user: String): Boolean {
         val remainingRequests by lazy { GhService.remainingRequests }
         val hasFreeRemainingRequests by lazy { remainingRequests > (freeRequestCutoff ?: remainingRequests) }
-        val userCache by lazy { CacheService.selectJsonFromDb(user) }
+        val userCacheJson by lazy { CacheService.selectJsonFromDb(user) }
         return Config.unrestricted()
-                || (userCache != null)
+                || (userCacheJson != null)
                 || hasFreeRemainingRequests
                 || (remainingRequests > 0 && hasStarredRepo(user))
     }
 
-    fun getUserProfile(username: String): UserProfile {
-        return (CacheService.getUserFromCache(username) ?: generateUserProfile(username))
+    fun getUserIfCanLoad(username: String): UserProfile {
+        val remainingRequests by lazy { GhService.remainingRequests }
+        val hasFreeRemainingRequests by lazy { remainingRequests > (freeRequestCutoff ?: remainingRequests) }
+        val userCacheJson by lazy { CacheService.selectJsonFromDb(username) }
+
+        val canLoadUser = Config.unrestricted()
+            || (userCacheJson != null)
+            || hasFreeRemainingRequests
+            || (remainingRequests > 0 && hasStarredRepo(username))
+
+        if (canLoadUser) {
+            return if (userCacheJson == null) {
+                generateUserProfile(username)
+            } else {
+                CacheService.getUserFromJson(userCacheJson!!)
+            }
+        }
+
+        throw UserNotLoadableException()
     }
 
     private fun hasStarredRepo(username: String): Boolean {
@@ -99,4 +116,6 @@ object UserService {
 
         return userProfile;
     }
+
+    class UserNotLoadableException: RuntimeException("Can't load user")
 }

From b072c879978123ce891860a2a1e766e57e1aa602 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Mon, 23 May 2022 19:44:22 +0900
Subject: [PATCH 22/33] Extract functions from duplicate code.

---
 src/main/kotlin/app/UserService.kt | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/src/main/kotlin/app/UserService.kt b/src/main/kotlin/app/UserService.kt
index a72f77d..12f158d 100644
--- a/src/main/kotlin/app/UserService.kt
+++ b/src/main/kotlin/app/UserService.kt
@@ -22,25 +22,23 @@ object UserService {
         false
     }
 
+    private fun remainingRequests(): Int = GhService.remainingRequests
+    private fun hasFreeRemainingRequests(): Boolean = remainingRequests() > (freeRequestCutoff ?: remainingRequests())
+
     fun canLoadUser(user: String): Boolean {
-        val remainingRequests by lazy { GhService.remainingRequests }
-        val hasFreeRemainingRequests by lazy { remainingRequests > (freeRequestCutoff ?: remainingRequests) }
         val userCacheJson by lazy { CacheService.selectJsonFromDb(user) }
         return Config.unrestricted()
-                || (userCacheJson != null)
-                || hasFreeRemainingRequests
-                || (remainingRequests > 0 && hasStarredRepo(user))
+            || (userCacheJson != null)
+            || lazy { hasFreeRemainingRequests() }.value
+            || (lazy { remainingRequests() }.value > 0 && hasStarredRepo(user))
     }
 
     fun getUserIfCanLoad(username: String): UserProfile {
-        val remainingRequests by lazy { GhService.remainingRequests }
-        val hasFreeRemainingRequests by lazy { remainingRequests > (freeRequestCutoff ?: remainingRequests) }
         val userCacheJson by lazy { CacheService.selectJsonFromDb(username) }
-
         val canLoadUser = Config.unrestricted()
             || (userCacheJson != null)
-            || hasFreeRemainingRequests
-            || (remainingRequests > 0 && hasStarredRepo(username))
+            || lazy { hasFreeRemainingRequests() }.value
+            || (lazy { remainingRequests() }.value > 0 && hasStarredRepo(username))
 
         if (canLoadUser) {
             return if (userCacheJson == null) {

From 80154a0026af05c2e7266c94d5bc03e9853ba1f7 Mon Sep 17 00:00:00 2001
From: Attacktive <66462458+Attacktive@users.noreply.github.com>
Date: Tue, 24 May 2022 10:45:17 +0900
Subject: [PATCH 23/33] Update src/main/kotlin/app/CacheService.kt

Co-authored-by: Sidd <iProdigy@users.noreply.github.com>
---
 src/main/kotlin/app/CacheService.kt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/kotlin/app/CacheService.kt b/src/main/kotlin/app/CacheService.kt
index 7109f80..1b23bc3 100644
--- a/src/main/kotlin/app/CacheService.kt
+++ b/src/main/kotlin/app/CacheService.kt
@@ -39,7 +39,7 @@ object CacheService {
             "FROM userinfo " +
             "WHERE id = ?"
         )
-        preparedStatement.setString(1, username)
+        preparedStatement.setString(1, username.lowercase())
 
         val result = preparedStatement.executeQuery()
         result.use {

From 8e15906592d21995b2e07d2c378b0a7ff34a1790 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Tue, 24 May 2022 10:46:23 +0900
Subject: [PATCH 24/33] Remove unnecessary class UserNotLoadableException.

---
 src/main/kotlin/app/Main.kt        | 6 +-----
 src/main/kotlin/app/UserService.kt | 4 +---
 2 files changed, 2 insertions(+), 8 deletions(-)

diff --git a/src/main/kotlin/app/Main.kt b/src/main/kotlin/app/Main.kt
index 4d8006d..4caa77b 100644
--- a/src/main/kotlin/app/Main.kt
+++ b/src/main/kotlin/app/Main.kt
@@ -46,11 +46,7 @@ fun main() {
         get("/api/user/{user}") { ctx ->
             val user = ctx.pathParam("user")
             if (!UserService.userExists(user)) throw NotFoundResponse()
-            try {
-                ctx.json(UserService.getUserIfCanLoad(user))
-            } catch (exception: UserService.UserNotLoadableException) {
-                throw BadRequestResponse(exception.message.toString())
-            }
+            UserService.getUserIfCanLoad(user)?.let { ctx.json(it) } ?: throw BadRequestResponse("Can't load user")
         }
         get("/search", VueComponent("search-view"))
         get("/user/{user}", VueComponent("user-view"))
diff --git a/src/main/kotlin/app/UserService.kt b/src/main/kotlin/app/UserService.kt
index 12f158d..15f1cd0 100644
--- a/src/main/kotlin/app/UserService.kt
+++ b/src/main/kotlin/app/UserService.kt
@@ -48,7 +48,7 @@ object UserService {
             }
         }
 
-        throw UserNotLoadableException()
+        return null
     }
 
     private fun hasStarredRepo(username: String): Boolean {
@@ -114,6 +114,4 @@ object UserService {
 
         return userProfile;
     }
-
-    class UserNotLoadableException: RuntimeException("Can't load user")
 }

From 33d69948f54ccb5403500484a1eecefc569bc2a1 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Tue, 24 May 2022 10:46:42 +0900
Subject: [PATCH 25/33] Remove unnecessary lazy initialization.

---
 src/main/kotlin/app/UserService.kt | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/main/kotlin/app/UserService.kt b/src/main/kotlin/app/UserService.kt
index 15f1cd0..95ee30d 100644
--- a/src/main/kotlin/app/UserService.kt
+++ b/src/main/kotlin/app/UserService.kt
@@ -26,25 +26,25 @@ object UserService {
     private fun hasFreeRemainingRequests(): Boolean = remainingRequests() > (freeRequestCutoff ?: remainingRequests())
 
     fun canLoadUser(user: String): Boolean {
-        val userCacheJson by lazy { CacheService.selectJsonFromDb(user) }
+        val userCacheJson = CacheService.selectJsonFromDb(user)
         return Config.unrestricted()
             || (userCacheJson != null)
-            || lazy { hasFreeRemainingRequests() }.value
-            || (lazy { remainingRequests() }.value > 0 && hasStarredRepo(user))
+            || hasFreeRemainingRequests()
+            || (remainingRequests() > 0 && hasStarredRepo(user))
     }
 
-    fun getUserIfCanLoad(username: String): UserProfile {
-        val userCacheJson by lazy { CacheService.selectJsonFromDb(username) }
+    fun getUserIfCanLoad(username: String): UserProfile? {
+        val userCacheJson = CacheService.selectJsonFromDb(username)
         val canLoadUser = Config.unrestricted()
             || (userCacheJson != null)
-            || lazy { hasFreeRemainingRequests() }.value
-            || (lazy { remainingRequests() }.value > 0 && hasStarredRepo(username))
+            || hasFreeRemainingRequests()
+            || remainingRequests() > 0 && hasStarredRepo(username)
 
         if (canLoadUser) {
             return if (userCacheJson == null) {
                 generateUserProfile(username)
             } else {
-                CacheService.getUserFromJson(userCacheJson!!)
+                CacheService.getUserFromJson(userCacheJson)
             }
         }
 

From 797fcfdd04a4638040837b1479ed1f3e586d7767 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Tue, 24 May 2022 10:56:33 +0900
Subject: [PATCH 26/33] Change id values to lowercase in DB.

follow-up change to https://github.com/tipsy/profile-summary-for-github/pull/113/commits/80154a0026af05c2e7266c94d5bc03e9853ba1f7
---
 src/main/kotlin/app/CacheService.kt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/kotlin/app/CacheService.kt b/src/main/kotlin/app/CacheService.kt
index 1b23bc3..91379a3 100644
--- a/src/main/kotlin/app/CacheService.kt
+++ b/src/main/kotlin/app/CacheService.kt
@@ -77,7 +77,7 @@ object CacheService {
             "VALUES (?, CURRENT_TIMESTAMP(), ? FORMAT JSON)"
         )
 
-        preparedStatement.setString(1, userProfile.user.login)
+        preparedStatement.setString(1, userProfile.user.login.lowercase())
         preparedStatement.setString(2, json)
 
         preparedStatement.execute()

From 849c6e4557567260c768ef8c5ff6b6c08f3dcce1 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Tue, 24 May 2022 10:58:52 +0900
Subject: [PATCH 27/33] Change data type of `timestamp` from 'TIMESTAMP WITH
 TIME ZONE' to 'TIMESTAMP'.

---
 src/main/kotlin/app/CacheService.kt | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/main/kotlin/app/CacheService.kt b/src/main/kotlin/app/CacheService.kt
index 91379a3..afe0797 100644
--- a/src/main/kotlin/app/CacheService.kt
+++ b/src/main/kotlin/app/CacheService.kt
@@ -20,8 +20,8 @@ object CacheService {
 
         statement.execute(
             "CREATE TABLE IF NOT EXISTS userinfo (" +
-            "id VARCHAR2 PRIMARY KEY," +
-            "timestamp TIMESTAMP WITH TIME ZONE, " +
+            "id VARCHAR2 PRIMARY KEY, " +
+            "timestamp TIMESTAMP, " +
             "data JSON" +
             ")"
         )

From 290d2344a400aa7fcaff2efc05ed3c267d75e7d9 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Tue, 24 May 2022 11:28:03 +0900
Subject: [PATCH 28/33] Use HikariCP.

---
 pom.xml                                       |  5 +++++
 src/main/kotlin/app/CacheService.kt           |  9 ++++----
 .../kotlin/app/util/HikariCpDataSource.kt     | 22 +++++++++++++++++++
 3 files changed, 31 insertions(+), 5 deletions(-)
 create mode 100644 src/main/kotlin/app/util/HikariCpDataSource.kt

diff --git a/pom.xml b/pom.xml
index a3b7c9e..1bd16a4 100644
--- a/pom.xml
+++ b/pom.xml
@@ -64,6 +64,11 @@
             <version>2.1.212</version>
             <scope>runtime</scope>
         </dependency>
+        <dependency>
+            <groupId>com.zaxxer</groupId>
+            <artifactId>HikariCP</artifactId>
+            <version>4.0.3</version>
+        </dependency>
     </dependencies>
 
     <build>
diff --git a/src/main/kotlin/app/CacheService.kt b/src/main/kotlin/app/CacheService.kt
index afe0797..1e6deac 100644
--- a/src/main/kotlin/app/CacheService.kt
+++ b/src/main/kotlin/app/CacheService.kt
@@ -2,20 +2,19 @@
 
 package app
 
+import app.util.HikariCpDataSource
 import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
 import com.fasterxml.jackson.module.kotlin.readValue
 import org.slf4j.LoggerFactory
-import java.sql.DriverManager
 import java.time.Instant
 import java.time.temporal.ChronoUnit
 
 object CacheService {
-    private const val urlToDb = "jdbc:h2:mem:userinfo"
     private val log = LoggerFactory.getLogger(CacheService.javaClass)
     private val objectMapper = jacksonObjectMapper()
 
     private fun createTableIfAbsent() {
-        val connection = DriverManager.getConnection(urlToDb)
+        val connection = HikariCpDataSource.connection
         val statement = connection.createStatement()
 
         statement.execute(
@@ -28,7 +27,7 @@ object CacheService {
     }
 
     fun selectJsonFromDb(username: String): String? {
-        val connection = DriverManager.getConnection(urlToDb)
+        val connection = HikariCpDataSource.connection
 
         createTableIfAbsent()
 
@@ -66,7 +65,7 @@ object CacheService {
     fun getUserFromJson(json: String) = objectMapper.readValue<UserProfile>(json)
 
     fun saveInCache(userProfile: UserProfile) {
-        val connection = DriverManager.getConnection(urlToDb)
+        val connection = HikariCpDataSource.connection
 
         createTableIfAbsent()
 
diff --git a/src/main/kotlin/app/util/HikariCpDataSource.kt b/src/main/kotlin/app/util/HikariCpDataSource.kt
new file mode 100644
index 0000000..a3f6891
--- /dev/null
+++ b/src/main/kotlin/app/util/HikariCpDataSource.kt
@@ -0,0 +1,22 @@
+package app.util
+
+import com.zaxxer.hikari.HikariConfig
+import com.zaxxer.hikari.HikariDataSource
+import java.sql.Connection
+
+object HikariCpDataSource {
+    private const val urlToDb = "jdbc:h2:mem:userinfo"
+
+    private val config = HikariConfig()
+    private var hikariDataSource: HikariDataSource?
+
+    init {
+        config.jdbcUrl = urlToDb
+        config.addDataSourceProperty("cachePrepStmts", "true")
+        config.addDataSourceProperty("prepStmtCacheSize", "250")
+        config.addDataSourceProperty("prepStmtCacheSqlLimit", "2048")
+        hikariDataSource = HikariDataSource(config)
+    }
+
+    val connection: Connection get() = hikariDataSource!!.connection
+}

From afd125373b6f07887ff7816263172fd20f9c9026 Mon Sep 17 00:00:00 2001
From: Attacktive <66462458+Attacktive@users.noreply.github.com>
Date: Tue, 24 May 2022 12:16:06 +0900
Subject: [PATCH 29/33] Update src/main/kotlin/app/util/HikariCpDataSource.kt

Co-authored-by: Sidd <iProdigy@users.noreply.github.com>
---
 src/main/kotlin/app/util/HikariCpDataSource.kt | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/src/main/kotlin/app/util/HikariCpDataSource.kt b/src/main/kotlin/app/util/HikariCpDataSource.kt
index a3f6891..4c31d32 100644
--- a/src/main/kotlin/app/util/HikariCpDataSource.kt
+++ b/src/main/kotlin/app/util/HikariCpDataSource.kt
@@ -7,16 +7,14 @@ import java.sql.Connection
 object HikariCpDataSource {
     private const val urlToDb = "jdbc:h2:mem:userinfo"
 
-    private val config = HikariConfig()
-    private var hikariDataSource: HikariDataSource?
-
-    init {
-        config.jdbcUrl = urlToDb
-        config.addDataSourceProperty("cachePrepStmts", "true")
-        config.addDataSourceProperty("prepStmtCacheSize", "250")
-        config.addDataSourceProperty("prepStmtCacheSqlLimit", "2048")
-        hikariDataSource = HikariDataSource(config)
+    private val config = HikariConfig().apply {
+        jdbcUrl = urlToDb
+        addDataSourceProperty("cachePrepStmts", "true")
+        addDataSourceProperty("prepStmtCacheSize", "250")
+        addDataSourceProperty("prepStmtCacheSqlLimit", "2048")
     }
 
-    val connection: Connection get() = hikariDataSource!!.connection
+    private var hikariDataSource = HikariDataSource(config)
+
+    val connection: Connection get() = hikariDataSource.connection
 }

From aea86489ef743a02e52ffb2c09dfacdd37f3157e Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Mon, 30 May 2022 09:35:52 +0900
Subject: [PATCH 30/33] Replace string concatenation with multi-line string

---
 src/main/kotlin/app/CacheService.kt | 30 +++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/src/main/kotlin/app/CacheService.kt b/src/main/kotlin/app/CacheService.kt
index 1e6deac..2daf934 100644
--- a/src/main/kotlin/app/CacheService.kt
+++ b/src/main/kotlin/app/CacheService.kt
@@ -18,11 +18,13 @@ object CacheService {
         val statement = connection.createStatement()
 
         statement.execute(
-            "CREATE TABLE IF NOT EXISTS userinfo (" +
-            "id VARCHAR2 PRIMARY KEY, " +
-            "timestamp TIMESTAMP, " +
-            "data JSON" +
-            ")"
+            """
+            CREATE TABLE IF NOT EXISTS userinfo (
+            id VARCHAR2 PRIMARY KEY, 
+            timestamp TIMESTAMP, 
+            data JSON
+            )
+            """.trimIndent()
         )
     }
 
@@ -32,11 +34,13 @@ object CacheService {
         createTableIfAbsent()
 
         val preparedStatement = connection.prepareStatement(
-            "SELECT " +
-            "timestamp, " +
-            "data " +
-            "FROM userinfo " +
-            "WHERE id = ?"
+            """
+            SELECT 
+            timestamp, 
+            data 
+            FROM userinfo 
+            WHERE id = ?
+            """.trimIndent()
         )
         preparedStatement.setString(1, username.lowercase())
 
@@ -72,8 +76,10 @@ object CacheService {
         val json = objectMapper.writeValueAsString(userProfile)
 
         val preparedStatement = connection.prepareStatement(
-            "MERGE INTO userinfo (id, timestamp, data) KEY (id) " +
-            "VALUES (?, CURRENT_TIMESTAMP(), ? FORMAT JSON)"
+            """
+            MERGE INTO userinfo (id, timestamp, data) KEY (id) 
+            VALUES (?, CURRENT_TIMESTAMP(), ? FORMAT JSON)
+            """.trimIndent()
         )
 
         preparedStatement.setString(1, userProfile.user.login.lowercase())

From 1162a9e39cc2eec3992882d152551d2b437c4571 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Mon, 30 May 2022 09:42:33 +0900
Subject: [PATCH 31/33] Replace uses of magic numbers

---
 src/main/kotlin/app/CacheService.kt | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/main/kotlin/app/CacheService.kt b/src/main/kotlin/app/CacheService.kt
index 2daf934..c856c12 100644
--- a/src/main/kotlin/app/CacheService.kt
+++ b/src/main/kotlin/app/CacheService.kt
@@ -48,10 +48,10 @@ object CacheService {
         result.use {
             // guaranteed to be at most one.
             if (it.next()) {
-                val timestamp = it.getTimestamp(1).toInstant()
+                val timestamp = it.getTimestamp("timestamp").toInstant()
                 val diffInHours = ChronoUnit.HOURS.between(timestamp, Instant.now())
                 if (diffInHours <= 6) {
-                    val json: String? = it.getString(2)
+                    val json: String? = it.getString("data")
                     if (json != null) {
                         log.debug("cache hit: {}", json)
                     }

From 131228688dc8248a946f98a7c8067cbb6c6a65b0 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Mon, 30 May 2022 09:46:39 +0900
Subject: [PATCH 32/33] Remove intermediate local variable

---
 src/main/kotlin/app/CacheService.kt | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/main/kotlin/app/CacheService.kt b/src/main/kotlin/app/CacheService.kt
index c856c12..1523abd 100644
--- a/src/main/kotlin/app/CacheService.kt
+++ b/src/main/kotlin/app/CacheService.kt
@@ -14,8 +14,7 @@ object CacheService {
     private val objectMapper = jacksonObjectMapper()
 
     private fun createTableIfAbsent() {
-        val connection = HikariCpDataSource.connection
-        val statement = connection.createStatement()
+        val statement = HikariCpDataSource.connection.createStatement()
 
         statement.execute(
             """

From e9abd1979813e1c78dad544734dedc335df6a933 Mon Sep 17 00:00:00 2001
From: Attacktive <welcome.hell.dude@gmail.com>
Date: Mon, 30 May 2022 09:57:04 +0900
Subject: [PATCH 33/33] Make CacheService have `HikariCpDataSource.connection`
 as its field

---
 src/main/kotlin/app/CacheService.kt | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/src/main/kotlin/app/CacheService.kt b/src/main/kotlin/app/CacheService.kt
index 1523abd..e061f3d 100644
--- a/src/main/kotlin/app/CacheService.kt
+++ b/src/main/kotlin/app/CacheService.kt
@@ -12,9 +12,10 @@ import java.time.temporal.ChronoUnit
 object CacheService {
     private val log = LoggerFactory.getLogger(CacheService.javaClass)
     private val objectMapper = jacksonObjectMapper()
+    private val connection = HikariCpDataSource.connection
 
     private fun createTableIfAbsent() {
-        val statement = HikariCpDataSource.connection.createStatement()
+        val statement = connection.createStatement()
 
         statement.execute(
             """
@@ -28,8 +29,6 @@ object CacheService {
     }
 
     fun selectJsonFromDb(username: String): String? {
-        val connection = HikariCpDataSource.connection
-
         createTableIfAbsent()
 
         val preparedStatement = connection.prepareStatement(
@@ -68,8 +67,6 @@ object CacheService {
     fun getUserFromJson(json: String) = objectMapper.readValue<UserProfile>(json)
 
     fun saveInCache(userProfile: UserProfile) {
-        val connection = HikariCpDataSource.connection
-
         createTableIfAbsent()
 
         val json = objectMapper.writeValueAsString(userProfile)