PriorityDataSource.java
/*
* Copyright (C) 2016 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.media3.datasource;
import android.net.Uri;
import androidx.annotation.Nullable;
import androidx.media3.common.PriorityTaskManager;
import androidx.media3.common.util.Assertions;
import androidx.media3.common.util.UnstableApi;
import java.io.IOException;
import java.util.List;
import java.util.Map;
/**
* A {@link DataSource} that can be used as part of a task registered with a {@link
* PriorityTaskManager}.
*
* <p>Calls to {@link #open(DataSpec)} and {@link #read(byte[], int, int)} are allowed to proceed
* only if there are no higher priority tasks registered to the {@link PriorityTaskManager}. If
* there exists a higher priority task then {@link PriorityTaskManager.PriorityTooLowException} is
* thrown.
*
* <p>Instances of this class are intended to be used as parts of (possibly larger) tasks that are
* registered with the {@link PriorityTaskManager}, and hence do <em>not</em> register as tasks
* themselves.
*/
@UnstableApi
public final class PriorityDataSource implements DataSource {
/** {@link DataSource.Factory} for {@link PriorityDataSource} instances. */
public static final class Factory implements DataSource.Factory {
private final DataSource.Factory upstreamFactory;
private final PriorityTaskManager priorityTaskManager;
private final int priority;
/**
* Creates an instance.
*
* @param upstreamFactory A {@link DataSource.Factory} that provides upstream {@link DataSource
* DataSources} for {@link PriorityDataSource} instances created by the factory.
* @param priorityTaskManager The {@link PriorityTaskManager} to which tasks using {@link
* PriorityDataSource} instances created by this factory will be registered.
* @param priority The priority of the tasks using {@link PriorityDataSource} instances created
* by this factory.
*/
public Factory(
DataSource.Factory upstreamFactory, PriorityTaskManager priorityTaskManager, int priority) {
this.upstreamFactory = upstreamFactory;
this.priorityTaskManager = priorityTaskManager;
this.priority = priority;
}
@Override
public PriorityDataSource createDataSource() {
return new PriorityDataSource(
upstreamFactory.createDataSource(), priorityTaskManager, priority);
}
}
private final DataSource upstream;
private final PriorityTaskManager priorityTaskManager;
private final int priority;
/**
* @param upstream The upstream {@link DataSource}.
* @param priorityTaskManager The priority manager to which the task is registered.
* @param priority The priority of the task.
*/
public PriorityDataSource(
DataSource upstream, PriorityTaskManager priorityTaskManager, int priority) {
this.upstream = Assertions.checkNotNull(upstream);
this.priorityTaskManager = Assertions.checkNotNull(priorityTaskManager);
this.priority = priority;
}
@Override
public void addTransferListener(TransferListener transferListener) {
Assertions.checkNotNull(transferListener);
upstream.addTransferListener(transferListener);
}
@Override
public long open(DataSpec dataSpec) throws IOException {
priorityTaskManager.proceedOrThrow(priority);
return upstream.open(dataSpec);
}
@Override
public int read(byte[] buffer, int offset, int length) throws IOException {
priorityTaskManager.proceedOrThrow(priority);
return upstream.read(buffer, offset, length);
}
@Override
@Nullable
public Uri getUri() {
return upstream.getUri();
}
@Override
public Map<String, List<String>> getResponseHeaders() {
return upstream.getResponseHeaders();
}
@Override
public void close() throws IOException {
upstream.close();
}
}