Merge pull request #70 from square/py/fix_crash

Fix 'lateinit property currentTrigger has not been initialized' on WIKO devices

papa-main-trace/api/papa-main-trace.api

@@ -21,6 +21,7 @@ public final class papa/MainThreadMessageSpy {
 	public final fun addTracer (Lpapa/MainThreadMessageSpy$Tracer;)V
 	public final fun getCurrentMessageAsString ()Ljava/lang/String;
 	public final fun getEnabled ()Z
+	public final fun isInMainThreadMessage ()Z
 	public final fun removeTracer (Lpapa/MainThreadMessageSpy$Tracer;)V
 	public final fun startSpyingMainThreadDispatching ()V
 	public final fun stopSpyingMainThreadDispatching ()V

papa-main-trace/src/main/java/papa/Handlers.kt

@@ -25,7 +25,7 @@ object Handlers {
    */
   fun onCurrentMainThreadMessageFinished(block: () -> Unit) {
     checkOnMainThread()
-    if (MainThreadMessageSpy.enabled) {
+    if (MainThreadMessageSpy.isInMainThreadMessage) {
       MainThreadMessageSpy.onCurrentMessageFinished(block)
     } else {
       mainThreadHandler.postAtFrontOfQueueAsync(block)

papa-main-trace/src/main/java/papa/MainThreadMessageSpy.kt

@@ -18,6 +18,15 @@ object MainThreadMessageSpy {
   var enabled = false
     private set
 
+  val isInMainThreadMessage: Boolean
+    get() = enabled && currentMessageAsString != null
+
+  /**
+   * Must be called only from the main thread.
+   * Null if [enabled] is false or if the code calling this (from the main thread) is running
+   * from outside the dispatching of a main thread message. For example,
+   * [MessageQueue.nativePollOnce] may invoke input event dispatching code directly.
+   */
   var currentMessageAsString: String? = null
     private set
     get() {
@@ -59,9 +68,18 @@ object MainThreadMessageSpy {
     // Looper can log to a printer before and after each message. We leverage this to surface the
     // beginning and end of every main thread message in system traces. This costs a few extra string
     // concatenations for each message handling.
-    // The printer is called before ('>>' prefix) and after ('<<' prefix) every message.
+
+    // Looper.mLogging is extracted to a local variable inside the message loop, and the same
+    // reference is used for before and after. We're setting Looper.mLogging in the middle of a
+    // message but won't get the "finish" callback because that local variable still references
+    // null at that point.
+    var before = true
     Looper.getMainLooper().setMessageLogging { messageAsString ->
-      val before = messageAsString.startsWith('>')
+      if (!enabled) {
+        // We still get called here for the last message finishing after we called
+        // stopSpyingMainThreadDispatching which called Looper.setMessageLogging(null)
+        return@setMessageLogging
+      }
       if (before) {
         currentMessageAsString = messageAsString
       }
@@ -71,6 +89,7 @@ object MainThreadMessageSpy {
       if (!before) {
         currentMessageAsString = null
       }
+      before = !before
     }
   }
 

papa/src/androidTest/java/papa/test/MainThreadMessageSpyTest.kt

@@ -1,6 +1,7 @@
 package papa.test
 
 import android.os.Build.VERSION
+import android.view.Choreographer
 import android.view.MotionEvent
 import android.widget.Button
 import androidx.test.core.app.ActivityScenario
@@ -78,6 +79,49 @@ class MainThreadMessageSpyTest {
       .inOrder()
   }
 
+  @Test fun inputEventDispatching_not_in_MainThread_Message() {
+    var spyEnabled: Boolean? = null
+    var isInMainThreadMessage: Boolean? = null
+    var currentMessageAsString: String? = null
+
+    val handledTap = CountDownLatch(1)
+    ActivityScenario.launch(TestActivity::class.java).use { scenario ->
+
+      val blockFrame = CountDownLatch(1)
+      val waitForFrame = CountDownLatch(1)
+      scenario.onActivity { activity ->
+        activity.setContentView(Button(activity).apply {
+          text = "Click Me"
+          setOnTouchListener { _, _ ->
+            spyEnabled = MainThreadMessageSpy.enabled
+            isInMainThreadMessage = MainThreadMessageSpy.isInMainThreadMessage
+            currentMessageAsString = MainThreadMessageSpy.currentMessageAsString
+            handledTap.countDown()
+            false
+          }
+        })
+        Choreographer.getInstance().postFrameCallback {
+          // unblock clicking code.
+          waitForFrame.countDown()
+          check(blockFrame.await(5, SECONDS))
+          // Giving a little time to enqueue the tap.
+          Thread.sleep(500)
+        }
+      }
+
+      check(waitForFrame.await(5, SECONDS))
+      // unblock frame, at this point tap should be enqueued and dequeued immediately, and not
+      // during a choreographer frame.
+      blockFrame.countDown()
+      onView(withText("Click Me")).location.sendTap()
+
+      check(handledTap.await(5, SECONDS))
+      assertThat(spyEnabled).isTrue()
+      assertThat(currentMessageAsString).isNull()
+      assertThat(isInMainThreadMessage).isFalse()
+    }
+  }
+
   @Test
   fun no_ConcurrentModificationException_when_iterating_after_onCurrentMessageFinished_removes_its_tracer() {
     runOnMainSync {

papa/src/main/java/papa/Choreographers.kt

@@ -10,7 +10,11 @@ object Choreographers {
   private val pendingRenderedCallbacks = mutableListOf<OnFrameRenderedListener>()
 
   private val isInChoreographerFrameMessage by mainThreadMessageScopedLazy {
-    "android.view.Choreographer\$FrameDisplayEventReceiver" in MainThreadMessageSpy.currentMessageAsString!!
+    if (MainThreadMessageSpy.isInMainThreadMessage) {
+      "android.view.Choreographer\$FrameDisplayEventReceiver" in MainThreadMessageSpy.currentMessageAsString!!
+    } else {
+      false
+    }
   }
 
   /**