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Commit 670df0a2 authored by Garfield Tan's avatar Garfield Tan
Browse files

Wait until the thread is waiting before issuing next task 

The previous logic doesn't guarantee the persister queue treating the
second task as a new batch of tasks. Hence it isn't guaranteed to wait
pre-task delay before performing the second task.

Bug: 387899271
Test: atest --iterations 10 WmTests:PersisterQueueTests
Flag: EXEMPT test fix
Change-Id: Ia5a423a4f2c54d1e4931746d99e9fbb0974fe638
parent 01e0027b

services/core/java/com/android/server/wm/PersisterQueue.java

+28 −0
Original line number Diff line number Diff line
@@ -86,6 +86,34 @@ class PersisterQueue { 
        mLazyTaskWriterThread = new LazyTaskWriterThread("LazyTaskWriterThread");

    }



    /**

     * Busy wait until {@link #mLazyTaskWriterThread} is in {@link Thread.State#WAITING}, or

     * times out. This indicates the thread is waiting for new tasks to appear. If the wait

     * succeeds, this queue waits at least {@link #mPreTaskDelayMs} milliseconds before running the

     * next task.

     *

     * <p>This is for testing purposes only.

     *

     * @param timeoutMillis the maximum time of waiting in milliseconds

     * @return {@code true} if the thread is in {@link Thread.State#WAITING} at return

     */

    @VisibleForTesting

    boolean waitUntilWritingThreadIsWaiting(long timeoutMillis) {

        final long timeoutTime = SystemClock.uptimeMillis() + timeoutMillis;

        do {

            Thread.State state;

            synchronized (this) {

                state = mLazyTaskWriterThread.getState();

            }

            if (state == Thread.State.WAITING) {

                return true;

            }

            Thread.yield();

        } while (SystemClock.uptimeMillis() < timeoutTime);



        return false;

    }



    synchronized void startPersisting() {

        if (!mLazyTaskWriterThread.isAlive()) {

            mLazyTaskWriterThread.start();

services/tests/wmtests/src/com/android/server/wm/PersisterQueueTests.java

+6 −5
Original line number Diff line number Diff line
@@ -177,15 +177,16 @@ public class PersisterQueueTests { 
        assertTrue("Target didn't call callback enough times.",

                mListener.waitForAllExpectedCallbackDone(TIMEOUT_ALLOWANCE));



        // Wait until writing thread is waiting, which indicates the thread is waiting for new tasks

        // to appear.

        assertTrue("Failed to wait until the writing thread is waiting.",

                mTarget.waitUntilWritingThreadIsWaiting(TIMEOUT_ALLOWANCE));



        // Second item

        mFactory.setExpectedProcessedItemNumber(1);

        mListener.setExpectedOnPreProcessItemCallbackTimes(1);

        dispatchTime = SystemClock.uptimeMillis();

        // Synchronize on the instance to make sure we schedule the item after it starts to wait for

        // task indefinitely.

        synchronized (mTarget) {

        mTarget.addItem(mFactory.createItem(), false);

        }

        assertTrue("Target didn't process item enough times.",

                mFactory.waitForAllExpectedItemsProcessed(PRE_TASK_DELAY_MS + TIMEOUT_ALLOWANCE));

        assertEquals("Target didn't process all items.", 2, mFactory.getTotalProcessedItemCount());