diff --git a/idea-plugin/src/main/kotlin/com/itangcent/idea/plugin/utils/AbstractStorage.kt b/idea-plugin/src/main/kotlin/com/itangcent/idea/plugin/utils/AbstractStorage.kt
index 263222091..21df64bac 100644
--- a/idea-plugin/src/main/kotlin/com/itangcent/idea/plugin/utils/AbstractStorage.kt
+++ b/idea-plugin/src/main/kotlin/com/itangcent/idea/plugin/utils/AbstractStorage.kt
@@ -1,7 +1,12 @@
 package com.itangcent.idea.plugin.utils
 
 import com.itangcent.idea.plugin.utils.Storage.Companion.DEFAULT_GROUP
+import com.itangcent.idea.plugin.utils.Storage.Companion.NULL
+import java.util.*
 
+/**
+ * Abstract implementation of [Storage]
+ */
 abstract class AbstractStorage : Storage {
 
     override fun get(name: String?): Any? {
@@ -36,4 +41,93 @@ abstract class AbstractStorage : Storage {
         clear(DEFAULT_GROUP)
     }
 
+    override fun get(group: String?, name: String?): Any? {
+        return getCache(group ?: DEFAULT_GROUP)[name]
+    }
+
+    override fun set(group: String?, name: String?, value: Any?) {
+        useCache(group) { put(name ?: NULL, value) }
+    }
+
+    override fun pop(group: String?, name: String?): Any? {
+        return useQueue(group, name) { pollLast() }
+    }
+
+    override fun peek(group: String?, name: String?): Any? {
+        return useQueue(group, name) { peekLast() }
+    }
+
+    override fun push(group: String?, name: String?, value: Any?) {
+        useQueue(group, name) { addLast(value) }
+    }
+
+    override fun remove(group: String?, name: String) {
+        useCache(group) { remove(name) }
+    }
+
+    override fun keys(group: String?): Array<Any?> {
+        return getCache(group ?: DEFAULT_GROUP).keys.toTypedArray()
+    }
+
+    override fun clear(group: String?) {
+        useCache(group ?: DEFAULT_GROUP) { clear() }
+    }
+
+    /**
+     * Use cache and update cache
+     */
+    @Synchronized
+    private fun <T : Any> useCache(group: String?, action: MutableMap<String, Any?>.() -> T?): T? {
+        val cache = getCache(group ?: DEFAULT_GROUP)
+        try {
+            return cache.action()
+        } finally {
+            onUpdate(group, cache)
+        }
+    }
+
+    /**
+     * Use queue and update cache
+     */
+    @Synchronized
+    @Suppress("UNCHECKED_CAST")
+    private fun <T : Any> useQueue(group: String?, name: String?, action: LinkedList<Any?>.() -> T?): T? {
+        val cache = getCache(group ?: DEFAULT_GROUP)
+        var queue = cache[name ?: NULL]
+        try {
+            when (queue) {
+
+                is LinkedList<*> -> {
+                    return action(queue as LinkedList<Any?>)
+                }
+
+                is Collection<*> -> {
+                    queue = LinkedList<Any?>(queue)
+                    cache[name ?: NULL] = queue
+                    return action(queue)
+                }
+
+                else -> {
+                    queue = LinkedList<Any?>()
+                    cache[name ?: NULL] = queue
+                    return action(queue)
+                }
+            }
+        } finally {
+            if (queue is Collection<*> && queue.isEmpty()) {
+                cache.remove(name ?: NULL)
+            }
+            onUpdate(group, cache)
+        }
+    }
+
+    /**
+     * Get cache of specified group
+     */
+    protected abstract fun getCache(group: String): MutableMap<String, Any?>
+
+    /**
+     * called when cache is updated
+     */
+    protected abstract fun onUpdate(group: String?, cache: MutableMap<String, Any?>)
 }
\ No newline at end of file
diff --git a/idea-plugin/src/main/kotlin/com/itangcent/idea/plugin/utils/LocalStorage.kt b/idea-plugin/src/main/kotlin/com/itangcent/idea/plugin/utils/LocalStorage.kt
index 42b1123ef..7aa361af4 100755
--- a/idea-plugin/src/main/kotlin/com/itangcent/idea/plugin/utils/LocalStorage.kt
+++ b/idea-plugin/src/main/kotlin/com/itangcent/idea/plugin/utils/LocalStorage.kt
@@ -7,8 +7,11 @@ import com.itangcent.common.utils.KV
 import com.itangcent.idea.binder.DbBeanBinderFactory
 import com.itangcent.idea.plugin.utils.Storage.Companion.DEFAULT_GROUP
 import com.itangcent.intellij.file.LocalFileRepository
-import java.util.*
 
+/**
+ * Implementation of [Storage] based on local file
+ * The [LocalStorage] can be accessed cross projects.
+ */
 @Singleton
 @ScriptTypeName("localStorage")
 class LocalStorage : AbstractStorage() {
@@ -16,115 +19,24 @@ class LocalStorage : AbstractStorage() {
     @Inject
     private val localFileRepository: LocalFileRepository? = null
 
-    private var dbBeanBinderFactory: DbBeanBinderFactory<KV<Any?, Any?>>? = null
-
-    private fun getDbBeanBinderFactory(): DbBeanBinderFactory<KV<Any?, Any?>> {
-        if (dbBeanBinderFactory == null) {
-            synchronized(this) {
-                dbBeanBinderFactory = DbBeanBinderFactory(localFileRepository!!.getOrCreateFile(".api.local.storage.v1.1.db").path)
-                { KV.create<Any?, Any?>() }
-            }
-        }
-        return this.dbBeanBinderFactory!!
-    }
-
-    override fun get(group: String?, name: String?): Any? {
-        return getDbBeanBinderFactory().getBeanBinder(group ?: DEFAULT_GROUP)
-                .tryRead()?.get(name)
-    }
-
-    override fun set(group: String?, name: String?, value: Any?) {
-        val beanBinder = getDbBeanBinderFactory().getBeanBinder(group ?: DEFAULT_GROUP)
-        val kv = beanBinder.read()
-        if (value == null) {
-            kv.remove(name)
-        } else {
-            kv[name] = value
-        }
-        beanBinder.save(kv)
-    }
-
-    override fun pop(group: String?, name: String?): Any? {
-        val beanBinder = getDbBeanBinderFactory().getBeanBinder(group ?: DEFAULT_GROUP)
-        val kv = beanBinder.read()
-        return tryQueue(kv, name)?.let {
-            val last = it.pollLast()
-            beanBinder.save(kv)
-            last
-        }
-    }
-
-    override fun peek(group: String?, name: String?): Any? {
-        val beanBinder = getDbBeanBinderFactory().getBeanBinder(group ?: DEFAULT_GROUP)
-        val kv = beanBinder.read()
-        return tryQueue(kv, name)?.peekLast()
+    private val dbBeanBinderFactory: DbBeanBinderFactory<KV<String, Any?>> by lazy {
+        DbBeanBinderFactory(localFileRepository!!.getOrCreateFile(".api.local.storage.v1.1.db").path)
+        { KV.create() }
     }
 
-    override fun push(group: String?, name: String?, value: Any?) {
-        val beanBinder = getDbBeanBinderFactory().getBeanBinder(group ?: DEFAULT_GROUP)
-        val kv = beanBinder.read()
-        val queue = queue(kv, name)
-        queue.addLast(value)
-        beanBinder.save(kv)
+    override fun clear(group: String?) {
+        dbBeanBinderFactory.deleteBinder(group ?: DEFAULT_GROUP)
     }
 
-    @Suppress("UNCHECKED_CAST")
-    private fun queue(kv: KV<Any?, Any?>, name: String?): LinkedList<Any?> {
-        var queue = kv[name]
-        return when (queue) {
-            is LinkedList<*> -> {
-                queue as LinkedList<Any?>
-            }
-            //convert to linkedList
-            is List<*> -> {
-                val list = LinkedList(queue)
-                kv[name] = list
-                list
-            }
-            else -> {
-                queue = LinkedList<Any>()
-                kv[name ?: Storage.NULL] = queue
-                queue as LinkedList<Any?>
-            }
-        }
+    override fun getCache(group: String): MutableMap<String, Any?> {
+        return dbBeanBinderFactory.getBeanBinder(group).tryRead() ?: KV.create()
     }
 
-
-    @Suppress("UNCHECKED_CAST")
-    private fun tryQueue(kv: KV<Any?, Any?>, name: String?): LinkedList<Any?>? {
-        val v = kv[name] ?: return null
-        return when (v) {
-            is LinkedList<*> -> {
-                v as LinkedList<Any?>
-            }
-            //convert to linkedList
-            is List<*> -> {
-                val list = LinkedList(v)
-                kv[name] = list
-                list
-            }
-            else -> null
+    override fun onUpdate(group: String?, cache: MutableMap<String, Any?>) {
+        if (cache.isEmpty()) {
+            dbBeanBinderFactory.deleteBinder(group ?: DEFAULT_GROUP)
+        } else {
+            dbBeanBinderFactory.getBeanBinder(group ?: DEFAULT_GROUP).save(cache as KV<String, Any?>)
         }
     }
-
-
-    override fun remove(group: String?, name: String) {
-        val beanBinder = getDbBeanBinderFactory().getBeanBinder(group ?: DEFAULT_GROUP)
-        val kv = beanBinder.tryRead() ?: return
-        kv.remove(name)
-        beanBinder.save(kv)
-    }
-
-    override fun keys(group: String?): Array<Any?> {
-        return getDbBeanBinderFactory().getBeanBinder(group ?: DEFAULT_GROUP)
-                .tryRead()
-                ?.keys
-                ?.toTypedArray()
-                ?: emptyArray()
-    }
-
-    override fun clear(group: String?) {
-        getDbBeanBinderFactory().deleteBinder(group ?: DEFAULT_GROUP)
-    }
-
 }
diff --git a/idea-plugin/src/main/kotlin/com/itangcent/idea/plugin/utils/SessionStorage.kt b/idea-plugin/src/main/kotlin/com/itangcent/idea/plugin/utils/SessionStorage.kt
index b79b8a9a1..178e207e9 100755
--- a/idea-plugin/src/main/kotlin/com/itangcent/idea/plugin/utils/SessionStorage.kt
+++ b/idea-plugin/src/main/kotlin/com/itangcent/idea/plugin/utils/SessionStorage.kt
@@ -4,66 +4,27 @@ import com.google.inject.Singleton
 import com.itangcent.annotation.script.ScriptTypeName
 import com.itangcent.common.utils.KV
 import com.itangcent.common.utils.sub
-import com.itangcent.idea.plugin.utils.Storage.Companion.NULL
-import java.util.*
+import com.itangcent.idea.plugin.utils.Storage.Companion.DEFAULT_GROUP
 
+/**
+ * Implementation of [Storage] based on memory
+ * The [SessionStorage] can only be accessed in the current action.
+ */
 @Singleton
 @ScriptTypeName("session")
 class SessionStorage : AbstractStorage() {
 
-    private val localKV = ThreadLocal.withInitial {
-        KV.create<String, Any?>()
-    }
-
-    private val kv: KV<String, Any?>
-        get() = localKV.get()
-
-    override fun get(group: String?, name: String?): Any? {
-        return kv.sub(group ?: NULL)[name]
-    }
-
-    override fun set(group: String?, name: String?, value: Any?) {
-        kv.sub(group ?: NULL)[name ?: NULL] = value
-    }
-
-    override fun pop(group: String?, name: String?): Any? {
-        return tryQueue(group, name)?.pollLast()
-    }
-
-    override fun peek(group: String?, name: String?): Any? {
-        return tryQueue(group, name)?.peekLast()
-    }
+    private val kv: KV<String, Any?> by lazy { KV.create() }
 
-    override fun push(group: String?, name: String?, value: Any?) {
-        queue(group, name).addLast(value)
+    override fun getCache(group: String): MutableMap<String, Any?> {
+        return kv.sub(group)
     }
 
-    @Suppress("UNCHECKED_CAST")
-    private fun queue(group: String?, name: String?): LinkedList<Any?> {
-        val sub = kv.sub(group ?: NULL)
-        var queue = sub[name ?: NULL]
-        if (queue == null || queue !is LinkedList<*>) {
-            queue = LinkedList<Any>()
-            sub[name ?: NULL] = queue
+    override fun onUpdate(group: String?, cache: MutableMap<String, Any?>) {
+        if (cache.isEmpty()) {
+            kv.remove(group ?: DEFAULT_GROUP)
+        } else {
+            kv[group ?: DEFAULT_GROUP] = cache
         }
-        return queue as LinkedList<Any?>
-    }
-
-    @Suppress("UNCHECKED_CAST")
-    private fun tryQueue(group: String?, name: String?): LinkedList<Any?>? {
-        val sub = kv.sub(group ?: NULL)
-        return sub[name ?: NULL] as? LinkedList<Any?>
-    }
-
-    override fun remove(group: String?, name: String) {
-        kv.sub(group ?: NULL).remove(name)
-    }
-
-    override fun keys(group: String?): Array<Any?> {
-        return kv.sub(group ?: NULL).keys.toTypedArray()
-    }
-
-    override fun clear(group: String?) {
-        kv.remove(group)
     }
 }
diff --git a/idea-plugin/src/main/kotlin/com/itangcent/idea/plugin/utils/Storage.kt b/idea-plugin/src/main/kotlin/com/itangcent/idea/plugin/utils/Storage.kt
index 64bc79f0d..1b2aae4b8 100644
--- a/idea-plugin/src/main/kotlin/com/itangcent/idea/plugin/utils/Storage.kt
+++ b/idea-plugin/src/main/kotlin/com/itangcent/idea/plugin/utils/Storage.kt
@@ -1,5 +1,8 @@
 package com.itangcent.idea.plugin.utils
 
+/**
+ * The [Storage] provides a way to store data.
+ */
 interface Storage {
 
     fun get(name: String?): Any?
diff --git a/idea-plugin/src/test/kotlin/com/itangcent/idea/utils/JacksonUtilsTest.kt b/idea-plugin/src/test/kotlin/com/itangcent/idea/utils/JacksonUtilsTest.kt
index 03b140c28..299d8ac30 100644
--- a/idea-plugin/src/test/kotlin/com/itangcent/idea/utils/JacksonUtilsTest.kt
+++ b/idea-plugin/src/test/kotlin/com/itangcent/idea/utils/JacksonUtilsTest.kt
@@ -2,7 +2,6 @@ package com.itangcent.idea.utils
 
 import org.junit.jupiter.api.Assertions.*
 import org.junit.jupiter.api.Test
-import org.junit.jupiter.api.assertDoesNotThrow
 
 /**
  * Test case of [JacksonUtils]
@@ -41,13 +40,8 @@ internal class JacksonUtilsTest {
 
         assertEquals("java.lang.Object,[\"java.lang.Object\",{}]", JacksonUtils.toJson(Any()))
 
-        assertDoesNotThrow {
-            JacksonUtils.fromJson<Any>("java.lang.Object,[\"java.lang.Object\",{}]").let {
-                assertNotNull(it)
-                //todo: make it true
-                //assertEquals("java.lang.Object", it!!::class.java)
-            }
-        }
+
+        assertNotNull(JacksonUtils.fromJson<Any>("java.lang.Object,[\"java.lang.Object\",{}]"))
     }
 }