| /* |
| * Copyright 2022 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.previewview.internal.utils.futures; |
| |
| import androidx.annotation.NonNull; |
| import androidx.annotation.Nullable; |
| import androidx.annotation.RequiresApi; |
| import androidx.camera.previewview.internal.utils.Logger; |
| import androidx.core.util.Preconditions; |
| |
| import com.google.common.util.concurrent.ListenableFuture; |
| |
| import java.util.concurrent.Delayed; |
| import java.util.concurrent.ExecutionException; |
| import java.util.concurrent.Executor; |
| import java.util.concurrent.ScheduledFuture; |
| import java.util.concurrent.TimeUnit; |
| |
| /** |
| * An implementation of {@link ListenableFuture} which immediately contains a result. |
| * |
| * <p>This implementation is based off of the Guava ImmediateSuccessfulFuture class. |
| * @param <V> The type of the value stored in the future. |
| * |
| */ |
| @RequiresApi(21) // TODO(b/200306659): Remove and replace with annotation on package-info.java |
| abstract class ImmediateFuture<V> implements ListenableFuture<V> { |
| |
| private static final String TAG = "ImmediateFuture"; |
| |
| /** |
| * Returns a future that contains a null value. |
| * |
| * <p>This should be used any time a null value is needed as it uses a static ListenableFuture |
| * that contains null, and thus will not allocate. |
| */ |
| public static <V> ListenableFuture<V> nullFuture() { |
| @SuppressWarnings({"unchecked", "rawtypes"}) // Safe since null can be cast to any type |
| ListenableFuture<V> typedNull = (ListenableFuture) ImmediateSuccessfulFuture.NULL_FUTURE; |
| return typedNull; |
| } |
| |
| @Override |
| public void addListener(@NonNull Runnable listener, @NonNull Executor executor) { |
| Preconditions.checkNotNull(listener); |
| Preconditions.checkNotNull(executor); |
| |
| try { |
| executor.execute(listener); |
| } catch (RuntimeException e) { |
| // ListenableFuture does not throw runtime exceptions, so swallow the exception and |
| // log it here. |
| Logger.e(TAG, "Experienced RuntimeException while attempting to notify " + listener |
| + " on Executor " + executor, e); |
| } |
| |
| } |
| |
| @Override |
| public boolean cancel(boolean mayInterruptIfRunning) { |
| return false; |
| } |
| |
| @Override |
| public boolean isCancelled() { |
| return false; |
| } |
| |
| @Override |
| public boolean isDone() { |
| return true; |
| } |
| |
| @Override |
| @Nullable |
| public abstract V get() throws ExecutionException; |
| |
| @Override |
| @Nullable |
| public V get(long timeout, @NonNull TimeUnit unit) throws ExecutionException { |
| Preconditions.checkNotNull(unit); |
| return get(); |
| } |
| |
| static final class ImmediateSuccessfulFuture<V> extends ImmediateFuture<V> { |
| |
| static final ImmediateFuture<Object> NULL_FUTURE = |
| new ImmediateSuccessfulFuture<>(null); |
| |
| @Nullable |
| private final V mValue; |
| |
| ImmediateSuccessfulFuture(@Nullable V value) { |
| mValue = value; |
| } |
| |
| |
| @Nullable |
| @Override |
| public V get() { |
| return mValue; |
| } |
| |
| @NonNull |
| @Override |
| public String toString() { |
| // Behaviour analogous to AbstractResolvableFuture#toString(). |
| return super.toString() + "[status=SUCCESS, result=[" + mValue + "]]"; |
| } |
| } |
| |
| static class ImmediateFailedFuture<V> extends ImmediateFuture<V> { |
| |
| @NonNull |
| private final Throwable mCause; |
| |
| ImmediateFailedFuture(@NonNull Throwable cause) { |
| mCause = cause; |
| } |
| |
| @Nullable |
| @Override |
| public V get() throws ExecutionException { |
| throw new ExecutionException(mCause); |
| } |
| |
| @Override |
| @NonNull |
| public String toString() { |
| // Behaviour analogous to AbstractResolvableFuture#toString(). |
| return super.toString() + "[status=FAILURE, cause=[" + mCause + "]]"; |
| } |
| } |
| |
| static final class ImmediateFailedScheduledFuture<V> extends ImmediateFailedFuture<V> implements |
| ScheduledFuture<V> { |
| |
| ImmediateFailedScheduledFuture(@NonNull Throwable cause) { |
| super(cause); |
| } |
| |
| @Override |
| public long getDelay(@NonNull TimeUnit timeUnit) { |
| return 0; |
| } |
| |
| @Override |
| public int compareTo(@NonNull Delayed delayed) { |
| return -1; |
| } |
| } |
| } |
