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Commit 3f40ee59 authored by Mark Fasheh's avatar Mark Fasheh
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Add WaitState class for new MessageQueue 

This encapsulates our logic for manipulating an atomic bitfield.

WaitState can be a counter or a deadline.

When it's a counter, the bit WAIT_STATE_IS_COUNTER is set and
the lower 63 bits are used as a long.

When WaitState is a deadline, we reserve bit 62 to indicate a
sync barrier. The middle 42 bits are used for the millisecond
resolution timestamp and the remaining 20 bits are used as a
counter.

Test: atest android.os.WaitStateTest
Bug: 421623328
Flag: EXEMPT new data structure isn't used yet; usages will be flagged.
Change-Id: I9f1a49378ce4c2cfda0f50d4febc57b050e55aef
parent ab70951a

core/java/android/os/OWNERS

+1 −0
Original line number Diff line number Diff line
@@ -136,6 +136,7 @@ per-file HandlerThread.java = file:/MESSAGE_QUEUE_OWNERS 
per-file HandlerExecutor.java = file:/MESSAGE_QUEUE_OWNERS

per-file MessageHeap.java = file:/MESSAGE_QUEUE_OWNERS

per-file MessageStack.java = file:/MESSAGE_QUEUE_OWNERS

per-file WaitState.java = file:/MESSAGE_QUEUE_OWNERS



# Stats

per-file IStatsBootstrapAtomService.aidl = file:/services/core/java/com/android/server/stats/OWNERS

core/java/android/os/WaitState.java

0 → 100644
+68 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2025 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License athasEqualMessages

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */



package android.os;



/**

 * Encapsulates the waiting logic of DeliQueue/MessageQueue

 * @hide

 */

public final class WaitState {

    private static final long IS_COUNTER = 1L  << 63;

    private static final long HAS_SYNC_BARRIER = 1L << 62;

    private static final long MASK = ~(IS_COUNTER | HAS_SYNC_BARRIER);



    public static boolean isCounter(long state) {

        return (state & IS_COUNTER) != 0;

    }



    public static long getCount(long state) {

        return state & ~IS_COUNTER;

    }



    public static long incrementCounter(long state) {

        long count = getCount(state) + 1;

        return count | IS_COUNTER;

    }



    public static long initCounter() {

        return IS_COUNTER;

    }



    public static boolean hasSyncBarrier(long state) {

        return (state & HAS_SYNC_BARRIER) != 0;

    }



    private static final long COUNTER_BITS = 20;

    public static long getTSMillis(long state) {

        return (state & MASK) >>> COUNTER_BITS;

    }



    public static long incrementDeadline(long state) {

        long bits = state & ~MASK;

        long ts = state & MASK;

        return (ts + 1) | bits;

    }



    public static long composeDeadline(long deadlineMS, boolean syncBarrier) {

        long state = deadlineMS << COUNTER_BITS;

        if (syncBarrier) {

            state |= HAS_SYNC_BARRIER;

        }



        return state;

    }

}

core/tests/coretests/src/android/os/OWNERS

+1 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ per-file RemoteCallbackListTest.java = shayba@google.com 
per-file MessageQueueTest.java = file:/MESSAGE_QUEUE_OWNERS

per-file MessageHeapTest.java = file:/MESSAGE_QUEUE_OWNERS

per-file MessageStackTest.java = file:/MESSAGE_QUEUE_OWNERS

per-file WaitStateTest.java = file:/MESSAGE_QUEUE_OWNERS



# Perfetto SDK

per-file PerfettoTrace*Test.java = file:/PERFETTO_OWNERS

core/tests/coretests/src/android/os/WaitStateTest.java

0 → 100644
+80 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2025 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License athasEqualMessages

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */



package android.os;



import static org.junit.Assert.assertEquals;

import static org.junit.Assert.assertFalse;

import static org.junit.Assert.assertTrue;



import android.os.WaitState;



import android.util.Log;



import androidx.test.runner.AndroidJUnit4;



import org.junit.Test;

import org.junit.runner.RunWith;



@RunWith(AndroidJUnit4.class)

public final class WaitStateTest {

    private static final String TAG = "WaitStateTest";



    @Test

    public void testCountOperations() {

        long state = WaitState.initCounter();



        assertTrue(WaitState.isCounter(state));

        assertEquals(WaitState.getCount(state), 0);

        Log.d(TAG, "state = " + Long.toHexString(state));



        state = WaitState.incrementCounter(state);

        Log.d(TAG, "state = " + Long.toHexString(state));

        assertTrue(WaitState.isCounter(state));

        assertEquals(WaitState.getCount(state), 1);

        for (int i = 2; i < 10; i++) {

            state = WaitState.incrementCounter(state);

            assertEquals(WaitState.getCount(state), i);

            assertTrue(WaitState.isCounter(state));

        }

    }



    @Test

    public void testDeadlineOperations() {

        final long now = SystemClock.uptimeMillis();

        long state = WaitState.composeDeadline(now, false);

        assertFalse(WaitState.hasSyncBarrier(state));

        long tsMillis = WaitState.getTSMillis(state);

        assertEquals(tsMillis, now);



        state = WaitState.incrementDeadline(state);

        state = WaitState.incrementDeadline(state);

        tsMillis = WaitState.getTSMillis(state);

        assertEquals(tsMillis, now);





        /* Do the same but with sync barrier bit set */

        state = WaitState.composeDeadline(now, true);

        assertTrue(WaitState.hasSyncBarrier(state));

        tsMillis = WaitState.getTSMillis(state);

        assertEquals(tsMillis, now);



        state = WaitState.incrementDeadline(state);

        state = WaitState.incrementDeadline(state);

        tsMillis = WaitState.getTSMillis(state);

        assertEquals(tsMillis, now);

    }

}