DeferrableSurfaces.java
/*
* Copyright 2019 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 at
*
* 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 androidx.camera.core.impl;
import android.view.Surface;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.RequiresApi;
import androidx.camera.core.impl.utils.futures.FutureCallback;
import androidx.camera.core.impl.utils.futures.Futures;
import androidx.concurrent.futures.CallbackToFutureAdapter;
import com.google.common.util.concurrent.ListenableFuture;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.Executor;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
/**
* Utility functions for manipulating {@link DeferrableSurface}.
*/
@RequiresApi(21) // TODO(b/200306659): Remove and replace with annotation on package-info.java
public final class DeferrableSurfaces {
private DeferrableSurfaces() {
}
/**
* Returns a {@link ListenableFuture} that get the List<Surface> result form
* {@link DeferrableSurface} collection.
*
* @param removeNullSurfaces If true remove all Surfaces that were not retrieved.
* @param timeout The task timeout value in milliseconds.
* @param executor The executor service to run the task.
* @param scheduledExecutorService The executor service to schedule the timeout event.
*/
@NonNull
public static ListenableFuture<List<Surface>> surfaceListWithTimeout(
@NonNull Collection<DeferrableSurface> deferrableSurfaces,
boolean removeNullSurfaces, long timeout, @NonNull Executor executor,
@NonNull ScheduledExecutorService scheduledExecutorService) {
List<ListenableFuture<Surface>> listenableFutureSurfaces = new ArrayList<>();
for (DeferrableSurface deferrableSurface : deferrableSurfaces) {
listenableFutureSurfaces.add(
Futures.nonCancellationPropagating(deferrableSurface.getSurface()));
}
return CallbackToFutureAdapter.getFuture(
completer -> {
ListenableFuture<List<Surface>> listenableFuture = Futures.successfulAsList(
listenableFutureSurfaces);
ScheduledFuture<?> scheduledFuture = scheduledExecutorService.schedule(() -> {
executor.execute(() -> {
if (!listenableFuture.isDone()) {
completer.setException(
new TimeoutException(
"Cannot complete surfaceList within " + timeout));
listenableFuture.cancel(true);
}
});
}, timeout, TimeUnit.MILLISECONDS);
// Cancel the listenableFuture if the outer task was cancelled, and the
// listenableFuture will cancel the scheduledFuture on its complete callback.
completer.addCancellationListener(() -> listenableFuture.cancel(true),
executor);
Futures.addCallback(listenableFuture,
new FutureCallback<List<Surface>>() {
@Override
public void onSuccess(@Nullable List<Surface> result) {
List<Surface> surfaces = new ArrayList<>(result);
if (removeNullSurfaces) {
surfaces.removeAll(Collections.singleton(null));
}
completer.set(surfaces);
scheduledFuture.cancel(true);
}
@Override
public void onFailure(@NonNull Throwable t) {
completer.set(
Collections.unmodifiableList(Collections.emptyList()));
scheduledFuture.cancel(true);
}
}, executor);
return "surfaceList";
});
}
/**
* Attempts to increment the usage count of all surfaces in the given surface list.
*
* <p>If any usage count fails to increment (due to the surface already being closed), then
* none of the surfaces in the list will have their usage count incremented.
*
* @param surfaceList The list of surfaces whose usage count should be incremented.
* @return {@code true} if all usage counts were successfully incremented, {@code false}
* otherwise.
*/
public static boolean tryIncrementAll(@NonNull List<DeferrableSurface> surfaceList) {
try {
incrementAll(surfaceList);
} catch (DeferrableSurface.SurfaceClosedException e) {
return false;
}
return true;
}
/**
* Attempts to increment the usage count of all surfaces in the given surface list.
*
* <p>If any usage count fails to increment (due to the surface already being closed), then
* none of the surfaces in the list will have their usage count incremented and an exception
* will be thrown.
*
* @param surfaceList The list of surfaces whose usage count should be incremented.
* @throws DeferrableSurface.SurfaceClosedException Containing the surface that failed to
* increment.
*/
public static void incrementAll(@NonNull List<DeferrableSurface> surfaceList)
throws DeferrableSurface.SurfaceClosedException {
if (!surfaceList.isEmpty()) {
int i = 0;
try {
do {
surfaceList.get(i).incrementUseCount();
// Successfully incremented.
i++;
} while (i < surfaceList.size());
} catch (DeferrableSurface.SurfaceClosedException e) {
// Didn't successfully increment all usages, decrement those which were incremented.
for (i = i - 1; i >= 0; --i) {
surfaceList.get(i).decrementUseCount();
}
// Rethrow the exception containing the surface that failed.
throw e;
}
}
}
/**
* Decrements the usage counts of every surface in the provided list.
*
* @param surfaceList The list of surfaces whose usage count should be decremented.
*/
public static void decrementAll(@NonNull List<DeferrableSurface> surfaceList) {
for (DeferrableSurface surface : surfaceList) {
surface.decrementUseCount();
}
}
}