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Commit 3dfdc4c2 authored by wilsonshih's avatar wilsonshih
Browse files

Only cache low-resolution task snapshots in the system server.(5/N) 

This change reduces both heap and dma_buf usage in the system server by
replacing high-resolution snapshots in the cache with low-resolution:

1. After a low-resolution bitmap is created in the persist thread, a
new task snapshot object is created from it. This then replaces the
previous high-resolution snapshot in the snapshot cache.
2. When getTaskSnapshot is called with a low-resolution request, a
low-resolution snapshot is either retrieved or created from the latest
task snapshot (if it exists). This replaces the high-resolution
snapshot in the snapshot cache. By respect the request, this also
reduce the memory usage in the client process since the returned
snapshot is smaller than the high-resolution one.

To prevent duplicate tasks resulting from both scenarios (1 and 2),
the second put-to-cache task can be ignored if the convert already
occurred.

3. Support takeTaskSnapshot to return a low-resolution snapshot, which
will be useful when clients request a snapshot but specifically require
a lower-resolution version.

Flag: com.android.window.flags.reduce_task_snapshot_memory_usage
Flag: com.android.window.flags.respect_requested_task_snapshot_resolution
Bug: 238206323
Test: dumpsys window every time after a close task transition finish,
verify the resolution in task snapshot cache is low-resolution.
dump dmabuf everytime after a close task transition finish, verify the
dmabuf won't increase in system server.

Change-Id: I37ebbef4f75a86c952f8e633fdbc8aedaf5b3d69
parent d1b30acd

core/java/android/window/ITaskSnapshotManager.aidl

+3 −1
Original line number Diff line number Diff line
@@ -46,11 +46,13 @@ interface ITaskSnapshotManager { 
     *                    If it is true, the snapshot can be either real content or app-theme mode

     *                    depending on the attributes of app. Otherwise, the snapshot will be taken

     *                    with real content.

     * @param lowResolution Whether to get the new snapshot in low resolution.

     * @throws RemoteException

     * @return a graphic buffer representing a screenshot of a task, or {@code null} if no

     *         corresponding task can be found.

     */

    android.window.TaskSnapshot takeTaskSnapshot(int taskId, boolean updateCache);

    android.window.TaskSnapshot takeTaskSnapshot(int taskId, boolean updateCache,

            boolean lowResolution);



    void registerTaskSnapshotListener(in ITaskSnapshotListener listener);

    void unregisterTaskSnapshotListener(in ITaskSnapshotListener listener);

core/java/android/window/TaskSnapshot.java

+5 −1
Original line number Diff line number Diff line
@@ -101,13 +101,17 @@ public class TaskSnapshot implements Parcelable { 
    /** This snapshot object will be passing to external process. Keep the snapshot reference after

     * writeToParcel*/

    public static final int REFERENCE_WRITE_TO_PARCEL = 1 << 4;

    /** This snapshot object is being used to convert resolution . */

    public static final int REFERENCE_CONVERT_RESOLUTION = 1 << 5;



    @IntDef(flag = true, prefix = { "REFERENCE_" }, value = {

            REFERENCE_NONE,

            REFERENCE_BROADCAST,

            REFERENCE_CACHE,

            REFERENCE_PERSIST,

            REFERENCE_CONTENT_SUGGESTION,

            REFERENCE_WRITE_TO_PARCEL

            REFERENCE_WRITE_TO_PARCEL,

            REFERENCE_CONVERT_RESOLUTION

    })

    @Retention(RetentionPolicy.SOURCE)

    public @interface ReferenceFlags {}

core/java/android/window/TaskSnapshotManager.java

+23 −1
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ import android.util.Singleton; 
import android.util.SparseArray;



import com.android.internal.annotations.GuardedBy;

import com.android.window.flags.Flags;



import java.io.PrintWriter;

import java.lang.annotation.Retention;
@@ -146,9 +147,28 @@ public class TaskSnapshotManager { 
     *         corresponding task can be found.

     */

    public TaskSnapshot takeTaskSnapshot(int taskId, boolean updateCache) throws RemoteException {

        return takeTaskSnapshot(taskId, updateCache, false /* lowResolution */);

    }



    /**

     * Requests for a new snapshot to be taken for the task with the given id, storing it in the

     * task snapshot cache only if requested.

     *

     * @param taskId the id of the task to take a snapshot of

     * @param updateCache Whether to store the new snapshot in the system's task snapshot cache.

     *                    If it is true, the snapshot can be either real content or app-theme mode

     *                    depending on the attributes of app. Otherwise, the snapshot will be taken

     *                    with real content.

     * @param lowResolution Whether to get the new snapshot in low resolution.

     * @return a graphic buffer representing a screenshot of a task,  or {@code null} if no

     *         corresponding task can be found.

     */

    public TaskSnapshot takeTaskSnapshot(int taskId, boolean updateCache,

            boolean lowResolution) throws RemoteException {

        final TaskSnapshot t;

        try {

            t = ISnapshotManagerSingleton.get().takeTaskSnapshot(taskId, updateCache);

            t = ISnapshotManagerSingleton.get().takeTaskSnapshot(taskId, updateCache,

                    lowResolution);

        } catch (RemoteException r) {

            Log.e(TAG, "takeTaskSnapshot fail: " + r);

            throw r;
@@ -210,6 +230,8 @@ public class TaskSnapshotManager { 
        final boolean isLowRes = snapshot.isLowResolution();

        if (isLowRes) {

            return retrieveResolution == TaskSnapshotManager.RESOLUTION_LOW;

        } else if (Flags.respectRequestedTaskSnapshotResolution()) {

            return retrieveResolution == TaskSnapshotManager.RESOLUTION_HIGH;

        }

        return true;

    }

core/java/android/window/flags/windowing_frontend.aconfig

+10 −0
Original line number Diff line number Diff line
@@ -344,6 +344,16 @@ flag { 
    }

}



flag {

    name: "respect_requested_task_snapshot_resolution"

    namespace: "windowing_frontend"

    description: "Produce a task snapshot object that respects the requested resolution, and only cache low resolution snapshot in system server."

    bug: "238206323"

    metadata {

        purpose: PURPOSE_BUGFIX

    }

}



flag {

    name: "scramble_snapshot_file_name"

    namespace: "windowing_frontend"

packages/SystemUI/shared/src/com/android/systemui/shared/system/ActivityManagerWrapper.java

+24 −0
Original line number Diff line number Diff line
@@ -177,6 +177,30 @@ public class ActivityManagerWrapper { 
        }

    }



    /**

     * Requests for a new snapshot to be taken for the given task, stores it in the cache, and

     * returns a {@link ThumbnailData} with specific resolution as result.

     */

    @NonNull

    public ThumbnailData takeTaskThumbnail(int taskId, boolean lowResolution) {

        if (!com.android.window.flags.Flags.respectRequestedTaskSnapshotResolution()

                || !com.android.window.flags.Flags.reduceTaskSnapshotMemoryUsage()) {

            return takeTaskThumbnail(taskId);

        }

        TaskSnapshot snapshot = null;

        try {

            snapshot = TaskSnapshotManager.getInstance().takeTaskSnapshot(taskId,

                    true /* updateCache */, lowResolution);

        } catch (RemoteException e) {

            Log.w(TAG, "Failed to take task snapshot", e);

        }

        if (snapshot != null) {

            return ThumbnailData.fromSnapshot(snapshot);

        } else {

            return new ThumbnailData();

        }

    }



    /**

     * Removes the outdated snapshot of home task.

     *