allow anonymous uuid generation to be customizable

CHANGELOG.md

@@ -1,5 +1,7 @@
 ## Next
 
+- allow anonymous uuid generation to be customizable ([#132](https://github.com/PostHog/posthog-android/pull/132))
+
 ## 3.2.2 - 2024-05-21
 
 - chore: register to sdk console ([#131](https://github.com/PostHog/posthog-android/pull/131)) 
@@ -91,7 +93,7 @@
 
 ## 3.1.0 - 2024-01-08
 
-- chore: Add mutations support to Session Recording ([#72](https://github.com/PostHog/posthog-android/pull/72)) 
+- chore: Add mutations support to Session Recording ([#72](https://github.com/PostHog/posthog-android/pull/72))
 - chore: Session Recording as Experimental preview
   - Check out the [USAGE](https://github.com/PostHog/posthog-android/blob/main/USAGE.md#android-session-recording) guide.
 
@@ -192,15 +194,15 @@ Check out the [USAGE](https://github.com/PostHog/posthog-android/blob/main/USAGE
 
 ## 2.0.3 - 2023-01-30
 
-- Feature flags will be sent with payloads by default for capture and screen events. 
+- Feature flags will be sent with payloads by default for capture and screen events.
 
 ## 2.0.2 - 2023-02-21
 
-- Revert: Feature flags will be sent with payloads by default. Default Options will be properly applied 
+- Revert: Feature flags will be sent with payloads by default. Default Options will be properly applied
 
 ## 2.0.1 - 2023-01-30
 
-- Feature flags will be sent with payloads by default. Default Options will be properly applied 
+- Feature flags will be sent with payloads by default. Default Options will be properly applied
 
 ## 2.0.0 - 2022-08-29
 

posthog/api/posthog.api

@@ -60,8 +60,8 @@ public final class com/posthog/PostHog$Companion : com/posthog/PostHogInterface
 public class com/posthog/PostHogConfig {
 	public static final field Companion Lcom/posthog/PostHogConfig$Companion;
 	public static final field DEFAULT_HOST Ljava/lang/String;
-	public fun <init> (Ljava/lang/String;Ljava/lang/String;ZZZZIIIILcom/posthog/PostHogEncryption;Lcom/posthog/PostHogOnFeatureFlags;ZLcom/posthog/PostHogPropertiesSanitizer;)V
-	public synthetic fun <init> (Ljava/lang/String;Ljava/lang/String;ZZZZIIIILcom/posthog/PostHogEncryption;Lcom/posthog/PostHogOnFeatureFlags;ZLcom/posthog/PostHogPropertiesSanitizer;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
+	public fun <init> (Ljava/lang/String;Ljava/lang/String;ZZZZIIIILcom/posthog/PostHogEncryption;Lcom/posthog/PostHogOnFeatureFlags;ZLcom/posthog/PostHogPropertiesSanitizer;Lkotlin/jvm/functions/Function1;)V
+	public synthetic fun <init> (Ljava/lang/String;Ljava/lang/String;ZZZZIIIILcom/posthog/PostHogEncryption;Lcom/posthog/PostHogOnFeatureFlags;ZLcom/posthog/PostHogPropertiesSanitizer;Lkotlin/jvm/functions/Function1;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
 	public final fun addIntegration (Lcom/posthog/PostHogIntegration;)V
 	public final fun getApiKey ()Ljava/lang/String;
 	public final fun getCachePreferences ()Lcom/posthog/internal/PostHogPreferences;
@@ -71,6 +71,7 @@ public class com/posthog/PostHogConfig {
 	public final fun getEncryption ()Lcom/posthog/PostHogEncryption;
 	public final fun getFlushAt ()I
 	public final fun getFlushIntervalSeconds ()I
+	public final fun getGetAnonymousId ()Lkotlin/jvm/functions/Function1;
 	public final fun getHost ()Ljava/lang/String;
 	public final fun getIntegrations ()Ljava/util/List;
 	public final fun getLegacyStoragePrefix ()Ljava/lang/String;
@@ -98,6 +99,7 @@ public class com/posthog/PostHogConfig {
 	public final fun setEncryption (Lcom/posthog/PostHogEncryption;)V
 	public final fun setFlushAt (I)V
 	public final fun setFlushIntervalSeconds (I)V
+	public final fun setGetAnonymousId (Lkotlin/jvm/functions/Function1;)V
 	public final fun setLegacyStoragePrefix (Ljava/lang/String;)V
 	public final fun setLogger (Lcom/posthog/internal/PostHogLogger;)V
 	public final fun setMaxBatchSize (I)V

posthog/src/main/java/com/posthog/PostHog.kt

@@ -199,7 +199,10 @@ public class PostHog private constructor(
             synchronized(anonymousLock) {
                 anonymousId = getPreferences().getValue(ANONYMOUS_ID) as? String
                 if (anonymousId.isNullOrBlank()) {
-                    anonymousId = UUID.randomUUID().toString()
+                    var uuid = UUID.randomUUID()
+                    // when getAnonymousId method is available, pass-through the value for modification
+                    config?.getAnonymousId?.let { uuid = it(uuid) }
+                    anonymousId = uuid.toString()
                     this.anonymousId = anonymousId ?: ""
                 }
             }

posthog/src/main/java/com/posthog/PostHogConfig.kt

@@ -8,6 +8,7 @@ import com.posthog.internal.PostHogNetworkStatus
 import com.posthog.internal.PostHogPreferences
 import com.posthog.internal.PostHogPrintLogger
 import com.posthog.internal.PostHogSerializer
+import java.util.UUID
 
 /**
  * The SDK Config
@@ -94,6 +95,11 @@ public open class PostHogConfig(
      * The hook is called before the event is cached or sent over the wire
      */
     public var propertiesSanitizer: PostHogPropertiesSanitizer? = null,
+    /**
+     * Hook that allows for modification of the default mechanism for
+     * generating anonymous id (which as of now is just random UUID v4)
+     */
+    public var getAnonymousId: ((UUID) -> UUID) = { it },
 ) {
     // fix me: https://stackoverflow.com/questions/53866865/leaking-this-in-constructor-warning-should-apply-to-final-classes-as-well-as
     @PostHogInternal

posthog/src/test/java/com/posthog/PostHogTest.kt

@@ -10,11 +10,13 @@ import okhttp3.mockwebserver.MockResponse
 import org.junit.Rule
 import org.junit.rules.TemporaryFolder
 import java.io.File
+import java.util.UUID
 import java.util.concurrent.Executors
 import kotlin.test.AfterTest
 import kotlin.test.Test
 import kotlin.test.assertEquals
 import kotlin.test.assertFalse
+import kotlin.test.assertNotEquals
 import kotlin.test.assertNotNull
 import kotlin.test.assertNull
 import kotlin.test.assertTrue
@@ -852,6 +854,19 @@ internal class PostHogTest {
         sut.close()
     }
 
+    @Test
+    fun `allows for modification of the uuid generation mechanism`() {
+        val expected = UUID.randomUUID()
+        val config =
+            PostHogConfig(API_KEY, getAnonymousId = {
+                assertNotEquals(it, expected, "Expect two unique UUIDs")
+                expected
+            })
+        // now generate an event
+        val sut = PostHog.with(config)
+        assertEquals(expected.toString(), sut.distinctId(), "It should use the injected uuid instead")
+    }
+
     @Test
     fun `enables debug mode`() {
         val config = PostHogConfig(API_KEY)