Improve latency of IME tracing

Improve latency of IME tracing by increasing the priority of the
tracing thread and adding the dump of the debugging information
at the beginning of the execution queue.

The Design Doc for IME tracing is found here: go/ime-tracing

Bug: 154348613
Test: start trace by calling "adb shell ime tracing start"
      end trace by calling "adb shell ime tracing stop"
      pull trace using "adb pull /data/misc/wmtrace/ime_trace.pb ime_trace.pb"
Change-Id: I153ccac6d8b93f86f3180b0a23240c6a63758ed6

2 files changed, 2 insertions, 2 deletions

diff --git a/core/java/android/inputmethodservice/IInputMethodWrapper.java b/core/java/android/inputmethodservice/IInputMethodWrapper.java
index 0512305e71a2..bb2357e24617 100644
--- a/core/java/android/inputmethodservice/IInputMethodWrapper.java
+++ b/core/java/android/inputmethodservice/IInputMethodWrapper.java
@@ -280,7 +280,7 @@ class IInputMethodWrapper extends IInputMethod.Stub
         }
 
         CountDownLatch latch = new CountDownLatch(1);
-        mCaller.executeOrSendMessage(mCaller.obtainMessageOOOO(DO_DUMP,
+        mCaller.getHandler().sendMessageAtFrontOfQueue(mCaller.obtainMessageOOOO(DO_DUMP,
                 fd, fout, args, latch));
         try {
             if (!latch.await(5, TimeUnit.SECONDS)) {
diff --git a/services/core/java/com/android/server/inputmethod/InputMethodManagerService.java b/services/core/java/com/android/server/inputmethod/InputMethodManagerService.java
index 9947ecd42e31..a738b035e8a4 100644
--- a/services/core/java/com/android/server/inputmethod/InputMethodManagerService.java
+++ b/services/core/java/com/android/server/inputmethod/InputMethodManagerService.java
@@ -1713,7 +1713,7 @@ public class InputMethodManagerService extends IInputMethodManager.Stub
                 mSettings, context);
         mMenuController = new InputMethodMenuController(this);
 
-        mTracingThread = new HandlerThread("android.tracing", Process.THREAD_PRIORITY_BACKGROUND);
+        mTracingThread = new HandlerThread("android.tracing", Process.THREAD_PRIORITY_FOREGROUND);
         mTracingThread.start();
     }