Automatically trace messages on shared loopers.

There are a handful of looper threads in the system_process that
are shared by dozens of different internal services.  To help track
down what these operations are, tag the processing of each message
with a string that tries describing where it originated from: the
class name of the Handler, and the message number or class name of the
Runnable.

Bug: 28046299
Change-Id: I409ec43fea8daaae4fd70df05d4fed929a7249ae

1 files changed, 13 insertions, 1 deletions

diff --git a/core/java/android/os/Handler.java b/core/java/android/os/Handler.java
index 878b7a0e8e10..3c7c962eaa12 100644
--- a/core/java/android/os/Handler.java
+++ b/core/java/android/os/Handler.java
@@ -231,6 +231,18 @@ public class Handler {
         mAsynchronous = async;
     }
 
+    /** {@hide} */
+    public String getTraceName(Message message) {
+        final StringBuilder sb = new StringBuilder();
+        sb.append(getClass().getName()).append(": ");
+        if (message.callback != null) {
+            sb.append(message.callback.getClass().getName());
+        } else {
+            sb.append("#").append(message.what);
+        }
+        return sb.toString();
+    }
+
     /**
      * Returns a string representing the name of the specified message.
      * The default implementation will either return the class name of the
@@ -739,8 +751,8 @@ public class Handler {
         message.callback.run();
     }
 
-    final MessageQueue mQueue;
     final Looper mLooper;
+    final MessageQueue mQueue;
     final Callback mCallback;
     final boolean mAsynchronous;
     IMessenger mMessenger;