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// Copyright 2015 The Bazel Authors. All rights reserved.
//
// 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 com.google.devtools.build.lib.skyframe;
import com.google.common.collect.ImmutableList;
import com.google.devtools.build.lib.cmdline.PackageIdentifier;
import com.google.devtools.build.lib.concurrent.ParallelVisitor.UnusedException;
import com.google.devtools.build.lib.concurrent.ThreadSafeBatchCallback;
import com.google.devtools.build.lib.concurrent.ThreadSafety.ThreadSafe;
import com.google.devtools.build.lib.pkgcache.RecursivePackageProvider;
import javax.annotation.concurrent.GuardedBy;
/**
* A callback for {@link RecursivePackageProvider#streamPackagesUnderDirectory} that buffers the
* PackageIdentifiers it receives into fixed-size batches that it delivers to a supplied {@code
* ThreadSafeBatchCallback<PackageIdentifier, RuntimeException>}.
*
* <p>The final batch delivered to the delegate callback may be smaller than the fixed size; the
* callback must be {@link #close() closed} to deliver this final batch.
*/
@ThreadSafe
public class PackageIdentifierBatchingCallback
implements ThreadSafeBatchCallback<PackageIdentifier, UnusedException>, AutoCloseable {
private final ThreadSafeBatchCallback<PackageIdentifier, UnusedException> batchResults;
private final int batchSize;
@GuardedBy("this")
private ImmutableList.Builder<PackageIdentifier> packageIdentifiers;
@GuardedBy("this")
private int bufferedPackageIds;
public PackageIdentifierBatchingCallback(
ThreadSafeBatchCallback<PackageIdentifier, UnusedException> batchResults, int batchSize) {
this.batchResults = batchResults;
this.batchSize = batchSize;
reset();
}
@Override
public synchronized void process(Iterable<PackageIdentifier> partialResult)
throws InterruptedException {
for (PackageIdentifier path : partialResult) {
packageIdentifiers.add(path);
bufferedPackageIds++;
if (bufferedPackageIds >= this.batchSize) {
flush();
}
}
}
@Override
public synchronized void close() throws InterruptedException {
flush();
}
@GuardedBy("this")
private void flush() throws InterruptedException {
if (bufferedPackageIds > 0) {
batchResults.process(packageIdentifiers.build());
reset();
}
}
@GuardedBy("this")
private void reset() {
packageIdentifiers = ImmutableList.builderWithExpectedSize(batchSize);
bufferedPackageIds = 0;
}
}