Prevent system server dump stuck by pipe buffer full.

Symptom:
Watchdog timeout during dumping db info.

Root Cause:
When the caller is system server, this invocation is not IPC
that means it is not asynchronous, it will need writer has
written all data to finish. But pipe has 16*4KB buffer limit,
if no reader consumes the data, it will keep waiting.

Solution:
Check if caller is system server, then use another thread to write
so reader could consume the data in buffer.

Change-Id: I4bf80fd645cc9396f51ffc0eb27fb895756c1dcf

1 files changed, 17 insertions, 2 deletions

diff --git a/core/java/android/app/ActivityThread.java b/core/java/android/app/ActivityThread.java
index c931d79..36fdeb9 100644
--- a/core/java/android/app/ActivityThread.java
+++ b/core/java/android/app/ActivityThread.java
@@ -1061,8 +1061,7 @@ public final class ActivityThread {
             WindowManagerGlobal.getInstance().dumpGfxInfo(fd);
         }
 
-        @Override
-        public void dumpDbInfo(FileDescriptor fd, String[] args) {
+        private void dumpDatabaseInfo(FileDescriptor fd, String[] args) {
             PrintWriter pw = new FastPrintWriter(new FileOutputStream(fd));
             PrintWriterPrinter printer = new PrintWriterPrinter(pw);
             SQLiteDebug.dump(printer, args);
@@ -1070,6 +1069,22 @@ public final class ActivityThread {
         }
 
         @Override
+        public void dumpDbInfo(final FileDescriptor fd, final String[] args) {
+            if (mSystemThread) {
+                // Ensure this invocation is asynchronous to prevent
+                // writer waiting due to buffer cannot be consumed.
+                AsyncTask.THREAD_POOL_EXECUTOR.execute(new Runnable() {
+                    @Override
+                    public void run() {
+                        dumpDatabaseInfo(fd, args);
+                    }
+                });
+            } else {
+                dumpDatabaseInfo(fd, args);
+            }
+        }
+
+        @Override
         public void unstableProviderDied(IBinder provider) {
             sendMessage(H.UNSTABLE_PROVIDER_DIED, provider);
         }