Merge "Use WeakReference-s to cache Display instances in DisplayManager." into udc-dev (86a02228) · Commits · e / os / android_frameworks_base

core/java/android/hardware/display/DisplayManager.java

+63 −3

Original line number	Diff line number	Diff line
		@@ -51,9 +51,11 @@ import android.view.Display;
		import android.view.Surface;

		import com.android.internal.R;
		import com.android.internal.annotations.GuardedBy;

		import java.lang.annotation.Retention;
		import java.lang.annotation.RetentionPolicy;
		import java.lang.ref.WeakReference;
		import java.util.ArrayList;
		import java.util.List;
		import java.util.concurrent.Executor;
		@@ -81,8 +83,10 @@ public final class DisplayManager {
		private final DisplayManagerGlobal mGlobal;

		private final Object mLock = new Object();
		private final SparseArray<Display> mDisplays = new SparseArray<Display>();
		@GuardedBy("mLock")
		private final WeakDisplayCache mDisplayCache = new WeakDisplayCache();

		@GuardedBy("mLock")
		private final ArrayList<Display> mTempDisplays = new ArrayList<Display>();

		/**
		@@ -684,6 +688,7 @@ public final class DisplayManager {
		}
		}

		@GuardedBy("mLock")
		private void addAllDisplaysLocked(ArrayList<Display> displays, int[] displayIds) {
		for (int i = 0; i < displayIds.length; i++) {
		Display display = getOrCreateDisplayLocked(displayIds[i], true /assumeValid/);
		@@ -693,6 +698,7 @@ public final class DisplayManager {
		}
		}

		@GuardedBy("mLock")
		private void addDisplaysLocked(
		ArrayList<Display> displays, int[] displayIds, int matchType, int flagMask) {
		for (int displayId : displayIds) {
		@@ -709,8 +715,9 @@ public final class DisplayManager {
		}
		}

		@GuardedBy("mLock")
		private Display getOrCreateDisplayLocked(int displayId, boolean assumeValid) {
		Display display = mDisplays.get(displayId);
		Display display = mDisplayCache.get(displayId);
		if (display == null) {
		// TODO: We cannot currently provide any override configurations for metrics on displays
		// other than the display the context is associated with.
		@@ -719,7 +726,7 @@ public final class DisplayManager {

		display = mGlobal.getCompatibleDisplay(displayId, resources);
		if (display != null) {
		mDisplays.put(displayId, display);
		mDisplayCache.put(display);
		}
		} else if (!assumeValid && !display.isValid()) {
		display = null;
		@@ -1767,4 +1774,57 @@ public final class DisplayManager {
		*/
		String KEY_BRIGHTNESS_THROTTLING_DATA = "brightness_throttling_data";
		}

		/**
		* Helper class to maintain cache of weak references to Display instances.
		*
		* Note this class is not thread-safe, so external synchronization is needed if accessed
		* concurrently.
		*/
		private static final class WeakDisplayCache {
		private final SparseArray<WeakReference<Display>> mDisplayCache = new SparseArray<>();

		/**
		* Return cached {@link Display} instance for the provided display id.
		*
		* @param displayId - display id of the requested {@link Display} instance.
		* @return cached {@link Display} instance or null
		*/
		Display get(int displayId) {
		WeakReference<Display> wrDisplay = mDisplayCache.get(displayId);
		if (wrDisplay == null) {
		return null;
		}
		return wrDisplay.get();
		}

		/**
		* Insert new {@link Display} instance in the cache. This replaced the previously cached
		* {@link Display} instance, if there's already one with the same display id.
		*
		* @param display - Display instance to cache.
		*/
		void put(Display display) {
		removeStaleEntries();
		mDisplayCache.put(display.getDisplayId(), new WeakReference<>(display));
		}

		/**
		* Evict gc-ed entries from the cache.
		*/
		private void removeStaleEntries() {
		ArrayList<Integer> staleEntriesIndices = new ArrayList();
		for (int i = 0; i < mDisplayCache.size(); i++) {
		if (mDisplayCache.valueAt(i).get() == null) {
		staleEntriesIndices.add(i);
		}
		}

		for (int i = 0; i < staleEntriesIndices.size(); i++) {
		// removeAt call to SparseArray doesn't compact the underlying array
		// so the indices stay valid even after removal.
		mDisplayCache.removeAt(staleEntriesIndices.get(i));
		}
		}
		}
		}