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// Copyright 2014 Google Inc. 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.skyframe;
import com.google.common.base.Preconditions;
import com.google.devtools.build.skyframe.GraphTester.ValueComputer;
import com.google.devtools.build.skyframe.ParallelEvaluator.SkyFunctionEnvironment;
import com.google.devtools.build.skyframe.SkyFunctionException.Transience;
import java.util.concurrent.CountDownLatch;
import javax.annotation.Nullable;
/**
* {@link ValueComputer} that can be chained together with others of its type to synchronize the
* order in which builders finish.
*/
final class ChainedFunction implements SkyFunction {
@Nullable private final SkyValue value;
@Nullable private final CountDownLatch notifyStart;
@Nullable private final CountDownLatch waitToFinish;
@Nullable private final CountDownLatch notifyFinish;
private final boolean waitForException;
private final Iterable<SkyKey> deps;
ChainedFunction(@Nullable CountDownLatch notifyStart, @Nullable CountDownLatch waitToFinish,
@Nullable CountDownLatch notifyFinish, boolean waitForException,
@Nullable SkyValue value, Iterable<SkyKey> deps) {
this.notifyStart = notifyStart;
this.waitToFinish = waitToFinish;
this.notifyFinish = notifyFinish;
this.waitForException = waitForException;
Preconditions.checkState(this.waitToFinish != null || !this.waitForException, value);
this.value = value;
this.deps = deps;
}
@Override
public SkyValue compute(SkyKey key, SkyFunction.Environment env) throws GenericFunctionException,
InterruptedException {
try {
if (notifyStart != null) {
notifyStart.countDown();
}
if (waitToFinish != null) {
TrackingAwaiter.INSTANCE.awaitLatchAndTrackExceptions(
waitToFinish, key + " timed out waiting to finish");
if (waitForException) {
SkyFunctionEnvironment skyEnv = (SkyFunctionEnvironment) env;
TrackingAwaiter.INSTANCE.awaitLatchAndTrackExceptions(
skyEnv.getExceptionLatchForTesting(), key + " timed out waiting for exception");
}
}
for (SkyKey dep : deps) {
env.getValue(dep);
}
if (value == null) {
throw new GenericFunctionException(new SomeErrorException("oops"),
Transience.PERSISTENT);
}
if (env.valuesMissing()) {
return null;
}
return value;
} finally {
if (notifyFinish != null) {
notifyFinish.countDown();
}
}
}
@Override
public String extractTag(SkyKey skyKey) {
throw new UnsupportedOperationException();
}
}
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