simplify device id stuff

Author: polbins

android/src/main/java/com/amplitude/android/Amplitude.kt

@@ -6,6 +6,7 @@ import com.amplitude.android.migration.MigrationManager
 import com.amplitude.android.plugins.AnalyticsConnectorIdentityPlugin
 import com.amplitude.android.plugins.AnalyticsConnectorPlugin
 import com.amplitude.android.plugins.AndroidContextPlugin
+import com.amplitude.android.plugins.AndroidContextPlugin.Companion.validDeviceId
 import com.amplitude.android.plugins.AndroidLifecyclePlugin
 import com.amplitude.android.plugins.AndroidNetworkConnectivityCheckerPlugin
 import com.amplitude.android.storage.AndroidStorageContextV3
@@ -96,7 +97,11 @@ open class Amplitude internal constructor(
         }
         androidContextPlugin = AndroidContextPlugin()
         add(androidContextPlugin)
-        setDeviceId(androidContextPlugin.generateDeviceId(forceNew = false))
+        val deviceId =
+            configuration.deviceId
+                ?: store.deviceId?.takeIf { validDeviceId(it, allowAppSetId = false) }
+                ?: androidContextPlugin.createDeviceId()
+        setDeviceId(deviceId)
         add(GetAmpliExtrasPlugin())
         add(AndroidLifecyclePlugin(activityLifecycleCallbacks))
         add(AnalyticsConnectorIdentityPlugin())
@@ -117,7 +122,7 @@ open class Amplitude internal constructor(
             logger.error("Cannot reset identity before Amplitude is initialized.")
             return this
         }
-        val newDeviceId = androidContextPlugin.generateDeviceId(forceNew = true)
+        val newDeviceId = configuration.deviceId ?: androidContextPlugin.createDeviceId()
         val newIdentity = Identity(userId = null, deviceId = newDeviceId)
         store.identity = newIdentity
         (timeline as Timeline).queueSetIdentity(newIdentity)

android/src/main/java/com/amplitude/android/plugins/AndroidContextPlugin.kt

@@ -30,27 +30,12 @@ open class AndroidContextPlugin : ContextPlugin() {
     }
 
     /**
-     * Generate a device ID using Android-specific logic.
-     * Priority: configuration -> store (if not forceNew) -> advertising ID -> app set ID -> random UUID
-     *
-     * @param forceNew If true, skip checking the store and generate a fresh deviceId
-     * @return the generated device ID (never null for Android)
+     * Create a device ID from available sources.
+     * Priority: advertising ID -> app set ID -> random UUID
      */
-    fun generateDeviceId(forceNew: Boolean = false): String {
+    internal fun createDeviceId(): String {
         val configuration = amplitude.configuration as Configuration
 
-        // Check configuration (always respected, even with forceNew)
-        configuration.deviceId?.let { return it }
-
-        // Check store (skip if forcing new)
-        if (!forceNew) {
-            amplitude.store.deviceId?.let { deviceId ->
-                if (validDeviceId(deviceId) && !deviceId.endsWith("S")) {
-                    return deviceId
-                }
-            }
-        }
-
         // Check advertising ID (if enabled and not per-install)
         if (!configuration.newDeviceIdPerInstall &&
             configuration.useAdvertisingIdForDeviceId &&
@@ -67,21 +52,25 @@ open class AndroidContextPlugin : ContextPlugin() {
         if (configuration.useAppSetIdForDeviceId) {
             contextProvider.appSetId?.let { appSetId ->
                 if (validDeviceId(appSetId)) {
-                    return "${appSetId}S"
+                    return "$appSetId$DEVICE_ID_SUFFIX_APP_SET_ID"
                 }
             }
         }
 
         // Generate random ID
-        return UUID.randomUUID().toString() + "R"
+        return UUID.randomUUID().toString() + DEVICE_ID_SUFFIX_RANDOM
     }
 
     @Deprecated(
         message = "Use generateDeviceId() instead. Amplitude now handles setting the deviceId.",
         replaceWith = ReplaceWith("generateDeviceId()"),
     )
     fun initializeDeviceId(configuration: Configuration) {
-        amplitude.setDeviceId(generateDeviceId(forceNew = false))
+        val deviceId =
+            configuration.deviceId
+                ?: amplitude.store.deviceId?.takeIf { validDeviceId(it, allowAppSetId = false) }
+                ?: createDeviceId()
+        amplitude.setDeviceId(deviceId)
     }
 
     @Deprecated(
@@ -187,11 +176,33 @@ open class AndroidContextPlugin : ContextPlugin() {
         const val PLATFORM = "Android"
         const val SDK_LIBRARY = "amplitude-analytics-android"
         const val SDK_VERSION = BuildConfig.AMPLITUDE_VERSION
+
+        /**
+         * Device ID suffix indicating the ID was derived from App Set ID.
+         *
+         * When a stored device ID ends with this suffix, [createDeviceId] will attempt
+         * to regenerate it to potentially upgrade to a better identifier (e.g., advertising ID
+         * if the user later grants permission).
+         */
+        private const val DEVICE_ID_SUFFIX_APP_SET_ID = "S"
+
+        /**
+         * Device ID suffix indicating the ID is a randomly generated UUID.
+         */
+        private const val DEVICE_ID_SUFFIX_RANDOM = "R"
+
         private val INVALID_DEVICE_IDS =
             setOf("", "9774d56d682e549c", "unknown", "000000000000000", "Android", "DEFACE", "00000000-0000-0000-0000-000000000000")
 
-        fun validDeviceId(deviceId: String): Boolean {
-            return !(deviceId.isEmpty() || INVALID_DEVICE_IDS.contains(deviceId))
+        fun validDeviceId(
+            deviceId: String,
+            allowAppSetId: Boolean = true,
+        ): Boolean {
+            return when {
+                deviceId.isEmpty() || INVALID_DEVICE_IDS.contains(deviceId) -> false
+                !allowAppSetId && deviceId.endsWith(DEVICE_ID_SUFFIX_APP_SET_ID) -> false
+                else -> true
+            }
         }
     }
 }

core/src/main/java/com/amplitude/core/Amplitude.kt

@@ -163,9 +163,8 @@ open class Amplitude(
         EventBridgeContainer.getInstance(
             configuration.instanceName,
         ).eventBridge.setEventReceiver(EventChannel.EVENT, AnalyticsEventReceiver(this))
-        val contextPlugin = ContextPlugin()
-        add(contextPlugin)
-        contextPlugin.generateDeviceId()?.let { setDeviceId(it) }
+        configuration.deviceId?.let { setDeviceId(it) }
+        add(ContextPlugin())
         add(GetAmpliExtrasPlugin())
         add(AmplitudeDestination())
     }

core/src/main/java/com/amplitude/core/State.kt

@@ -60,12 +60,13 @@ class State {
     /**
      * Notify observers about identity change. Called outside the lock.
      */
-    private fun notifyObservers(changeInfo: IdentityChangeInfo) = with(changeInfo) {
-        plugins.forEach { plugin ->
-            if (userIdChanged) plugin.onUserIdChanged(changeInfo.newIdentity.userId)
-            if (deviceIdChanged) plugin.onDeviceIdChanged(changeInfo.newIdentity.deviceId)
+    private fun notifyObservers(changeInfo: IdentityChangeInfo) =
+        with(changeInfo) {
+            plugins.forEach { plugin ->
+                if (userIdChanged) plugin.onUserIdChanged(changeInfo.newIdentity.userId)
+                if (deviceIdChanged) plugin.onDeviceIdChanged(changeInfo.newIdentity.deviceId)
+            }
         }
-    }
 
     private data class IdentityChangeInfo(
         val newIdentity: Identity,

core/src/main/java/com/amplitude/core/platform/plugins/ContextPlugin.kt

@@ -10,16 +10,6 @@ open class ContextPlugin : Plugin {
     override val type: Plugin.Type = Plugin.Type.Before
     override lateinit var amplitude: Amplitude
 
-    /**
-     * Generate a device ID based on platform-specific logic.
-     * Subclasses can override to provide platform-specific generation (e.g., advertising ID).
-     *
-     * @return the generated device ID, or null if no deviceId is configured
-     */
-    open fun generateDeviceId(): String? {
-        return amplitude.configuration.deviceId
-    }
-
     override fun execute(event: BaseEvent): BaseEvent? {
         applyContextData(event)
         return event