refactor: start headless tasks for push and device sync the same way

The code that starts React Native for a headless JS task, when the process was woken without any UI, lived inside BulwarkPushJobService. The device sync adapters need the same start, so it moves to a shared HeadlessJs object, with a small startTask helper next to it. Push behaviour does not change: - onStartJob still calls the start code on the main thread, and the listener-then-ready-check order is the same code, moved verbatim - the task still starts from `UiThreadUtil.runOnUiThread`, its id is still recorded in that same UI-thread turn, and a refusal because the app came to the foreground still logs and finishes the job - the start code now returns React Native's start task, so a caller can notice a start that fails (a debug build with no Metro); the push job ignores it The helper documents that it must run on the main thread: the ReactHost is created on first use without a lock, so a background caller racing MainActivity could create a second one. Checked with `gradlew assembleDebug -PreactNativeArchitectures=x86_64`.
2026-11-02 00:06:23 +00:00 · 2026-09-27 01:19:17 +02:00
parent db07acc37c
commit 1f7acaf08a
2 changed files with 115 additions and 64 deletions
@@ -11,16 +11,11 @@ import android.os.Bundle
 import android.os.PersistableBundle
 import android.os.SystemClock
 import android.util.Log
-import com.facebook.react.ReactApplication
-import com.facebook.react.ReactInstanceEventListener
 import com.facebook.react.bridge.ReactContext
-import com.facebook.react.bridge.UiThreadUtil
-import com.facebook.react.internal.featureflags.ReactNativeNewArchitectureFeatureFlags
 import com.facebook.react.jstasks.HeadlessJsTaskConfig
 import com.facebook.react.jstasks.HeadlessJsTaskContext
 import com.facebook.react.jstasks.HeadlessJsTaskEventListener
 import java.util.concurrent.ConcurrentHashMap
-import java.util.concurrent.atomic.AtomicBoolean

 /**
 * Runs the BulwarkPushTask headless JS task from a JobScheduler job.
@@ -44,7 +39,8 @@ class BulwarkPushJobService : JobService(), HeadlessJsTaskEventListener {

    override fun onStartJob(params: JobParameters): Boolean {
        val config = BulwarkPushTaskService.taskConfig(Bundle(params.extras))
-        withReadyReactContext { startTask(it, config, params) }
+        // JobService callbacks run on the main thread, where HeadlessJs wants to be called.
+        HeadlessJs.withReadyReactContext(application) { startTask(it, config, params) }
        return true
    }

@@ -76,68 +72,17 @@ class BulwarkPushJobService : JobService(), HeadlessJsTaskEventListener {
            tasks.addTaskEventListener(this)
            taskContext = tasks
        }
-        UiThreadUtil.runOnUiThread {
-            try {
-                val taskId = tasks.startTask(config)
-                running[taskId] = RunningTask(params, SystemClock.elapsedRealtime())
-            } catch (e: IllegalStateException) {
+        HeadlessJs.startTask(
+            tasks,
+            config,
+            onStarted = { taskId -> running[taskId] = RunningTask(params, SystemClock.elapsedRealtime()) },
+            onRefused = { e ->
                // The app came to the foreground since the push arrived and
                // syncs on its own there.
                Log.i(TAG, "Push job ${params.jobId} skipped: ${e.message}")
                jobFinished(params, false)
-            }
-        }
-    }
-
-    /**
-     * Calls [onReady] once with a React context whose JS instance is up,
-     * starting React Native if the process was woken for this job.
-     *
-     * A context exists before its instance is ready, and a task started on
-     * it then never reaches JS (HeadlessJsTaskContext only logs "CatalystInstance
-     * not available" and waits for the timeout), which happened when several
-     * pushes arrived while the app was starting. So the listener goes in
-     * first and the ready check after it; whichever sees the ready instance
-     * first runs the task.
-     */
-    private fun withReadyReactContext(onReady: (ReactContext) -> Unit) {
-        val done = AtomicBoolean(false)
-        val runOnce = { context: ReactContext -> if (done.compareAndSet(false, true)) onReady(context) }
-        val app = application as ReactApplication
-        if (ReactNativeNewArchitectureFeatureFlags.enableBridgelessArchitecture()) {
-            val host = checkNotNull(app.reactHost) { "ReactHost is not initialized in New Architecture" }
-            val listener = object : ReactInstanceEventListener {
-                override fun onReactContextInitialized(context: ReactContext) {
-                    host.removeReactInstanceEventListener(this)
-                    runOnce(context)
-                }
-            }
-            host.addReactInstanceEventListener(listener)
-            val current = host.currentReactContext
-            if (current != null && current.hasActiveReactInstance()) {
-                host.removeReactInstanceEventListener(listener)
-                runOnce(current)
-            } else {
-                host.start()
-            }
-        } else {
-            @Suppress("DEPRECATION")
-            val manager = app.reactNativeHost.reactInstanceManager
-            val listener = object : ReactInstanceEventListener {
-                override fun onReactContextInitialized(context: ReactContext) {
-                    manager.removeReactInstanceEventListener(this)
-                    runOnce(context)
-                }
-            }
-            manager.addReactInstanceEventListener(listener)
-            val current = manager.currentReactContext
-            if (current != null && current.hasActiveReactInstance()) {
-                manager.removeReactInstanceEventListener(listener)
-                runOnce(current)
-            } else if (!manager.hasStartedCreatingInitialContext()) {
-                manager.createReactContextInBackground()
-            }
-        }
+            },
+        )
    }

    companion object {
@@ -0,0 +1,106 @@
+package com.anonymous.bulwarkmobile
+
+import android.app.Application
+import androidx.annotation.MainThread
+import com.facebook.react.ReactApplication
+import com.facebook.react.ReactInstanceEventListener
+import com.facebook.react.bridge.ReactContext
+import com.facebook.react.bridge.UiThreadUtil
+import com.facebook.react.interfaces.TaskInterface
+import com.facebook.react.internal.featureflags.ReactNativeNewArchitectureFeatureFlags
+import com.facebook.react.jstasks.HeadlessJsTaskConfig
+import com.facebook.react.jstasks.HeadlessJsTaskContext
+import java.util.concurrent.atomic.AtomicBoolean
+
+/**
+ * Running a headless JS task without HeadlessJsTaskService: starting React
+ * Native when the process was woken without any UI, and starting the task on
+ * its context. Shared by the push job (BulwarkPushJobService) and the device
+ * sync adapters.
+ */
+object HeadlessJs {
+    /**
+     * Calls [onReady] once with a React context whose JS instance is up,
+     * starting React Native if the process was woken for this work.
+     *
+     * A context exists before its instance is ready, and a task started on
+     * it then never reaches JS (HeadlessJsTaskContext only logs "CatalystInstance
+     * not available" and waits for the timeout), which happened when several
+     * pushes arrived while the app was starting. So the listener goes in
+     * first and the ready check after it; whichever sees the ready instance
+     * first runs the task.
+     *
+     * Call it on the main thread; [onReady] runs there too. MainApplication
+     * creates the ReactHost on first use without a lock (ExpoReactHostFactory),
+     * so a background caller racing MainActivity could create a second one,
+     * with a second JS runtime.
+     *
+     * Returns React Native's start task when it had to be started, so a caller
+     * can notice a start that fails (a debug build with no Metro to load the
+     * bundle from), or null when the context was already up.
+     */
+    @MainThread
+    fun withReadyReactContext(app: Application, onReady: (ReactContext) -> Unit): TaskInterface<Void>? {
+        val done = AtomicBoolean(false)
+        val runOnce = { context: ReactContext -> if (done.compareAndSet(false, true)) onReady(context) }
+        val reactApp = app as ReactApplication
+        if (ReactNativeNewArchitectureFeatureFlags.enableBridgelessArchitecture()) {
+            val host = checkNotNull(reactApp.reactHost) { "ReactHost is not initialized in New Architecture" }
+            val listener = object : ReactInstanceEventListener {
+                override fun onReactContextInitialized(context: ReactContext) {
+                    host.removeReactInstanceEventListener(this)
+                    runOnce(context)
+                }
+            }
+            host.addReactInstanceEventListener(listener)
+            val current = host.currentReactContext
+            if (current != null && current.hasActiveReactInstance()) {
+                host.removeReactInstanceEventListener(listener)
+                runOnce(current)
+                return null
+            }
+            return host.start()
+        }
+        @Suppress("DEPRECATION")
+        val manager = reactApp.reactNativeHost.reactInstanceManager
+        val listener = object : ReactInstanceEventListener {
+            override fun onReactContextInitialized(context: ReactContext) {
+                manager.removeReactInstanceEventListener(this)
+                runOnce(context)
+            }
+        }
+        manager.addReactInstanceEventListener(listener)
+        val current = manager.currentReactContext
+        if (current != null && current.hasActiveReactInstance()) {
+            manager.removeReactInstanceEventListener(listener)
+            runOnce(current)
+        } else if (!manager.hasStartedCreatingInitialContext()) {
+            manager.createReactContextInBackground()
+        }
+        return null
+    }
+
+    /**
+     * Starts [config] on the UI thread, where HeadlessJsTaskContext wants it.
+     * [onStarted] gets the task id in that same UI-thread turn, so before any
+     * finish callback (HeadlessJsTaskContext posts those to the UI thread).
+     * [onRefused] gets the refusal when the context is resumed and [config]
+     * isn't allowed in the foreground.
+     */
+    fun startTask(
+        tasks: HeadlessJsTaskContext,
+        config: HeadlessJsTaskConfig,
+        onStarted: (taskId: Int) -> Unit,
+        onRefused: (IllegalStateException) -> Unit,
+    ) {
+        UiThreadUtil.runOnUiThread {
+            val taskId = try {
+                tasks.startTask(config)
+            } catch (e: IllegalStateException) {
+                onRefused(e)
+                return@runOnUiThread
+            }
+            onStarted(taskId)
+        }
+    }
+}