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Commit 803254d0 authored by Lee Shombert's avatar Lee Shombert
Browse files

Fix concurrency issue in PropertyInvalidatedCache 

Bug: 253063488

Ensure the global lock is held while fetching the list of active
caches.  The global lock is necessary while the list is being fetched;
it is not necessary while each cache in the list is cleared.

Added a new test for PropertyInvalidatedCache.onTrimMemory().  This
test will not catch race conditions but does verify that
onTrimMemory() behaves as expected.

Test: atest
 * FrameworksCoreTests:PropertyInvalidatedCacheTests
Change-Id: I5022620cd4f2561179af709246a9bf149423143f
parent 03ffc41d

core/java/android/app/PropertyInvalidatedCache.java

+17 −2
Original line number Diff line number Diff line
@@ -1405,6 +1405,17 @@ public class PropertyInvalidatedCache<Query, Result> { 
        return isDisabled();

    }



    /**

     * Return the number of entries in the cache.  This is used for testing and has package-only

     * visibility.

     * @hide

     */

    public int size() {

        synchronized (mLock) {

            return mCache.size();

        }

    }



    /**

     * Returns a list of caches alive at the current time.

     */
@@ -1612,8 +1623,12 @@ public class PropertyInvalidatedCache<Query, Result> { 
     * @hide

     */

    public static void onTrimMemory() {

        for (PropertyInvalidatedCache pic : getActiveCaches()) {

            pic.clear();

        ArrayList<PropertyInvalidatedCache> activeCaches;

        synchronized (sGlobalLock) {

            activeCaches = getActiveCaches();

        }

        for (int i = 0; i < activeCaches.size(); i++) {

            activeCaches.get(i).clear();

        }

    }

}

core/tests/coretests/src/android/app/PropertyInvalidatedCacheTests.java

+16 −0
Original line number Diff line number Diff line
@@ -368,4 +368,20 @@ public class PropertyInvalidatedCacheTests { 
            PropertyInvalidatedCache.MODULE_BLUETOOTH, "getState");

        assertEquals(n1, "cache_key.bluetooth.get_state");

    }



    @Test

    public void testOnTrimMemory() {

        TestCache cache = new TestCache(MODULE, "trimMemoryTest");

        // The cache is not active until it has been invalidated once.

        cache.invalidateCache();

        // Populate the cache with six entries.

        for (int i = 0; i < 6; i++) {

            cache.query(i);

        }

        // The maximum number of entries in TestCache is 4, so even though six entries were

        // created, only four are retained.

        assertEquals(4, cache.size());

        PropertyInvalidatedCache.onTrimMemory();

        assertEquals(0, cache.size());

    }

}