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Commit 6e3dfe61 authored by Shai Barack's avatar Shai Barack
Browse files

[queuedwork] Avoid blocking on thread creation 

Never create a HandlerThread just to then see that its queue is empty.
Reduces exposure to priority inversions.

Bug: 263820216

Change-Id: Id8db19b56a690c4eae88386554fa060d40e0b012
parent c415ebcd

core/java/android/app/QueuedWork.java

+23 −11
Original line number Diff line number Diff line
@@ -113,6 +113,22 @@ public class QueuedWork { 
        }

    }



    /**

     * Remove all Messages from the Handler with the given code.

     *

     * This method intentionally avoids creating the Handler if it doesn't

     * already exist.

     */

    private static void handlerRemoveMessages(int what) {

        synchronized (sLock) {

            if (sHandler == null) {

                // Nothing to remove

                return;

            }

            getHandler().removeMessages(what);

        }

    }



    /**

     * Add a finisher-runnable to wait for {@link #queue asynchronously processed work}.

     *
@@ -156,17 +172,13 @@ public class QueuedWork { 
        long startTime = System.currentTimeMillis();

        boolean hadMessages = false;



        Handler handler = getHandler();



        synchronized (sLock) {

            if (handler.hasMessages(QueuedWorkHandler.MSG_RUN)) {

                // Delayed work will be processed at processPendingWork() below

                handler.removeMessages(QueuedWorkHandler.MSG_RUN);



            if (DEBUG) {

                    hadMessages = true;

                    Log.d(LOG_TAG, "waiting");

                hadMessages = getHandler().hasMessages(QueuedWorkHandler.MSG_RUN);

            }

            handlerRemoveMessages(QueuedWorkHandler.MSG_RUN);

            if (DEBUG && hadMessages) {

                Log.d(LOG_TAG, "waiting");

            }



            // We should not delay any work as this might delay the finishers
@@ -257,7 +269,7 @@ public class QueuedWork { 
                sWork = new LinkedList<>();



                // Remove all msg-s as all work will be processed now

                getHandler().removeMessages(QueuedWorkHandler.MSG_RUN);

                handlerRemoveMessages(QueuedWorkHandler.MSG_RUN);

            }



            if (work.size() > 0) {