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Commit 4c916509 authored by Lee Shombert's avatar Lee Shombert
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DisplayManagerService listens for frozen binder updates 

DisplayManagerService listens for frozen process updates via the
IBinder FrozenStateChangeCallback.  This avoids going through
ActivityManager and the associated locks.

The CallbackRecord implements the necessary listener.  Updates affect
the CallbackRecord state; if the state change requires any further
processing, a message is posted to the DisplayManager's message queue,
to avoid extra processing in the binder callback.

Flag: android.os.binder_frozen_state_change_callback
Flag: com.android.server.am.defer_display_events_when_frozen
Bug: 298055811
Test: atest
 * DisplayServiceTests
 * CtsDisplayTestCases
Change-Id: Ib816415422d75dcec218c3f0ae3699f34e5bf079
parent b6fdf4b4

core/java/android/os/BinderProxy.java

+6 −0
Original line number Diff line number Diff line
@@ -687,12 +687,18 @@ public final class BinderProxy implements IBinder { 
        return removeFrozenStateChangeCallbackNative(wrappedCallback);

    }



    public static boolean isFrozenStateChangeCallbackSupported() {

        return isFrozenStateChangeCallbackSupportedNative();

    }



    private native void addFrozenStateChangeCallbackNative(FrozenStateChangeCallback callback)

            throws RemoteException;



    private native boolean removeFrozenStateChangeCallbackNative(

            FrozenStateChangeCallback callback);



    private static native boolean isFrozenStateChangeCallbackSupportedNative();



    /**

     * Perform a dump on the remote object

     *

core/jni/android_util_Binder.cpp

+6 −0
Original line number Diff line number Diff line
@@ -1706,6 +1706,10 @@ static jboolean android_os_BinderProxy_removeFrozenStateChangeCallback(JNIEnv* e 
    return res;

}



static jboolean android_os_BinderProxy_frozenStateChangeCallbackSupported(JNIEnv*, jclass*) {

    return ProcessState::isDriverFeatureEnabled(ProcessState::DriverFeature::FREEZE_NOTIFICATION);

}



static void BinderProxy_destroy(void* rawNativeData)

{

    BinderProxyNativeData * nativeData = (BinderProxyNativeData *) rawNativeData;
@@ -1750,6 +1754,8 @@ static const JNINativeMethod gBinderProxyMethods[] = { 
        "(Landroid/os/IBinder$FrozenStateChangeCallback;)V", (void*)android_os_BinderProxy_addFrozenStateChangeCallback},

    {"removeFrozenStateChangeCallbackNative",

        "(Landroid/os/IBinder$FrozenStateChangeCallback;)Z", (void*)android_os_BinderProxy_removeFrozenStateChangeCallback},

    {"isFrozenStateChangeCallbackSupportedNative",

        "()Z", (void*)android_os_BinderProxy_frozenStateChangeCallbackSupported},

    {"getNativeFinalizer",  "()J", (void*)android_os_BinderProxy_getNativeFinalizer},

    {"getExtension",        "()Landroid/os/IBinder;", (void*)android_os_BinderProxy_getExtension},

};

services/core/java/com/android/server/display/DisplayManagerService.java

+40 −41
Original line number Diff line number Diff line
@@ -119,6 +119,7 @@ import android.os.Handler; 
import android.os.HandlerExecutor;

import android.os.IBinder;

import android.os.IBinder.DeathRecipient;

import android.os.IBinder.FrozenStateChangeCallback;

import android.os.IThermalService;

import android.os.Looper;

import android.os.Message;
@@ -272,6 +273,7 @@ public final class DisplayManagerService extends SystemService { 
    private static final int MSG_DELIVER_DISPLAY_EVENT_FRAME_RATE_OVERRIDE = 7;

    private static final int MSG_DELIVER_DISPLAY_GROUP_EVENT = 8;

    private static final int MSG_RECEIVED_DEVICE_STATE = 9;

    private static final int MSG_DISPATCH_PENDING_PROCESS_EVENTS = 10;

    private static final int[] EMPTY_ARRAY = new int[0];

    private static final HdrConversionMode HDR_CONVERSION_MODE_UNSUPPORTED = new HdrConversionMode(

            HDR_CONVERSION_UNSUPPORTED);
@@ -286,7 +288,6 @@ public final class DisplayManagerService extends SystemService { 
    private InputManagerInternal mInputManagerInternal;

    private ActivityManagerInternal mActivityManagerInternal;

    private final UidImportanceListener mUidImportanceListener = new UidImportanceListener();

    private final DisplayFrozenProcessListener mDisplayFrozenProcessListener;



    @Nullable

    private IMediaProjectionManager mProjectionService;
@@ -630,7 +631,6 @@ public final class DisplayManagerService extends SystemService { 
        mFlags = injector.getFlags();

        mHandler = new DisplayManagerHandler(displayThreadLooper);

        mHandlerExecutor = new HandlerExecutor(mHandler);

        mDisplayFrozenProcessListener = new DisplayFrozenProcessListener();

        mUiHandler = UiThread.getHandler();

        mDisplayDeviceRepo = new DisplayDeviceRepository(mSyncRoot, mPersistentDataStore);

        mLogicalDisplayMapper = new LogicalDisplayMapper(mContext,
@@ -1165,31 +1165,11 @@ public final class DisplayManagerService extends SystemService { 
        }

    }



    private class DisplayFrozenProcessListener

            implements ActivityManagerInternal.FrozenProcessListener {

        public void onProcessFrozen(int pid) {

            synchronized (mSyncRoot) {

                CallbackRecord callback = mCallbacks.get(pid);

                if (callback == null) {

                    return;

                }

                callback.setFrozen(true);

            }

        }



        public void onProcessUnfrozen(int pid) {

            // First, see if there is a callback associated with this pid.  If there's no

            // callback, then there is nothing to do.

            CallbackRecord callback;

            synchronized (mSyncRoot) {

                callback = mCallbacks.get(pid);

                if (callback == null) {

                    return;

                }

                callback.setFrozen(false);

            }

            // Attempt to dispatch pending events if the process is coming out of frozen.

    private void dispatchPendingProcessEvents(@NonNull Object cb) {

        if (cb instanceof CallbackRecord callback) {

            callback.dispatchPending();

        } else {

            Slog.wtf(TAG, "not a callback: " + cb);

        }

    }
@@ -4048,6 +4028,9 @@ public final class DisplayManagerService extends SystemService { 
                    deliverDisplayGroupEvent(msg.arg1, msg.arg2);

                    break;



                case MSG_DISPATCH_PENDING_PROCESS_EVENTS:

                    dispatchPendingProcessEvents(msg.obj);

                    break;

            }

        }

    }
@@ -4115,7 +4098,7 @@ public final class DisplayManagerService extends SystemService { 
        }

    }



    private final class CallbackRecord implements DeathRecipient {

    private final class CallbackRecord implements DeathRecipient, FrozenStateChangeCallback {

        public final int mPid;

        public final int mUid;

        private final IDisplayManagerCallback mCallback;
@@ -4138,6 +4121,8 @@ public final class DisplayManagerService extends SystemService { 
        private boolean mCached;

        @GuardedBy("mCallback")

        private boolean mFrozen;

        @GuardedBy("mCallback")

        private boolean mAlive;



        CallbackRecord(int pid, int uid, @NonNull IDisplayManagerCallback callback,

                @InternalEventFlag long internalEventFlagsMask) {
@@ -4147,18 +4132,20 @@ public final class DisplayManagerService extends SystemService { 
            mInternalEventFlagsMask = new AtomicLong(internalEventFlagsMask);

            mCached = false;

            mFrozen = false;

            mAlive = true;



            if (deferDisplayEventsWhenFrozen()) {

                // Some CallbackRecords are registered very early in system boot, before

                // mActivityManagerInternal is initialized. If mActivityManagerInternal is null,

                // do not register the frozen process listener.  However, do verify that all such

                // registrations are for the self pid (which can never be frozen, so the frozen

                // process listener does not matter).

                if (mActivityManagerInternal != null) {

                    mActivityManagerInternal.addFrozenProcessListener(pid, mHandlerExecutor,

                            mDisplayFrozenProcessListener);

                } else if (Process.myPid() != pid) {

                    Slog.e(TAG, "DisplayListener registered too early");

                try {

                    callback.asBinder().addFrozenStateChangeCallback(this);

                } catch (UnsupportedOperationException e) {

                    // Ignore the exception.  The callback is not supported on this platform or on

                    // this binder.  The callback is never supported for local binders.  There is

                    // no error: the UID importance listener will still operate.  A log message is

                    // provided for debug.

                    Slog.v(TAG, "FrozenStateChangeCallback not supported for pid " + mPid);

                } catch (RemoteException e) {

                    // This is unexpected.  Just give up.

                    throw new RuntimeException(e);

                }

            }
@@ -4183,7 +4170,7 @@ public final class DisplayManagerService extends SystemService { 
         */

        @GuardedBy("mCallback")

        private boolean hasPendingAndIsReadyLocked() {

            return isReadyLocked() && mPendingEvents != null && !mPendingEvents.isEmpty();

            return isReadyLocked() && mPendingEvents != null && !mPendingEvents.isEmpty() && mAlive;

        }



        /**
@@ -4191,7 +4178,7 @@ public final class DisplayManagerService extends SystemService { 
         * receive events and there are pending events to be delivered.

         * This is only used if {@link deferDisplayEventsWhenFrozen()} is true.

         */

        public boolean setFrozen(boolean frozen) {

        private boolean setFrozen(boolean frozen) {

            synchronized (mCallback) {

                mFrozen = frozen;

                return hasPendingAndIsReadyLocked();
@@ -4212,6 +4199,9 @@ public final class DisplayManagerService extends SystemService { 


        @Override

        public void binderDied() {

            synchronized (mCallback) {

                mAlive = false;

            }

            if (DEBUG || extraLogging(mPackageName)) {

                Slog.d(TAG, "Display listener for pid " + mPid + " died.");

            }
@@ -4222,6 +4212,14 @@ public final class DisplayManagerService extends SystemService { 
            onCallbackDied(this);

        }



        @Override

        public void onFrozenStateChanged(@NonNull IBinder who, int state) {

            if (setFrozen(state == FrozenStateChangeCallback.STATE_FROZEN)) {

                Message msg = mHandler.obtainMessage(MSG_DISPATCH_PENDING_PROCESS_EVENTS, this);

                mHandler.sendMessage(msg);

            }

        }



        /**

         * @return {@code false} if RemoteException happens; otherwise {@code true} for

         * success.  This returns true even if the event was deferred because the remote client is
@@ -4388,7 +4386,7 @@ public final class DisplayManagerService extends SystemService { 
        // This is only used if {@link deferDisplayEventsWhenFrozen()} is true.

        public boolean dispatchPending() {

            synchronized (mCallback) {

                if (mPendingEvents == null || mPendingEvents.isEmpty()) {

                if (mPendingEvents == null || mPendingEvents.isEmpty() || !mAlive) {

                    return true;

                }

                if (!isReadyLocked()) {
@@ -6060,6 +6058,7 @@ public final class DisplayManagerService extends SystemService { 
     * Return the value of the pause

     */

    private static boolean deferDisplayEventsWhenFrozen() {

        return com.android.server.am.Flags.deferDisplayEventsWhenFrozen();

        return android.os.Flags.binderFrozenStateChangeCallback()

                && com.android.server.am.Flags.deferDisplayEventsWhenFrozen();

    }

}

services/tests/displayservicetests/src/com/android/server/display/DisplayEventDeliveryTest.java

+7 −2
Original line number Diff line number Diff line
@@ -33,6 +33,7 @@ import android.content.Context; 
import android.content.Intent;

import android.hardware.display.DisplayManager;

import android.hardware.display.VirtualDisplay;

import android.os.BinderProxy;

import android.os.Handler;

import android.os.HandlerThread;

import android.os.Looper;
@@ -290,11 +291,15 @@ public class DisplayEventDeliveryTest { 
    }



    /**

     * Return true if the freezer is enabled on this platform.

     * Return true if the freezer is enabled on this platform and if freezer notifications are

     * supported.  It is not enough to test that the freezer notification feature is enabled

     * because some devices do not have the necessary kernel support.

     */

    private boolean isAppFreezerEnabled() {

        try {

            return mActivityManager.getService().isAppFreezerEnabled();

            return mActivityManager.getService().isAppFreezerEnabled()

                    && android.os.Flags.binderFrozenStateChangeCallback()

                    && BinderProxy.isFrozenStateChangeCallbackSupported();

        } catch (Exception e) {

            Log.e(TAG, "isAppFreezerEnabled() failed: " + e);

            return false;