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// Copyright 2021 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.bazel.bzlmod;
import static com.google.common.collect.ImmutableList.toImmutableList;
import static com.google.common.collect.ImmutableMap.toImmutableMap;
import com.google.common.collect.ImmutableTable;
import com.google.devtools.build.skyframe.SkyFunction;
import com.google.devtools.build.skyframe.SkyKey;
import com.google.devtools.build.skyframe.SkyValue;
import javax.annotation.Nullable;
/**
* A simple SkyFunction that takes the information needed by a {@link SingleExtensionEvalFunction}
* out of {@link BazelModuleResolutionValue} and stores it in a SkyValue.
*
* <p>The whole raison d'ĂȘtre of this function is to avoid unnecessary reruns of module extensions.
* Whenever any information in the whole dependency graph changes, {@link
* BazelModuleResolutionFunction} is rerun, producing a new {@link BazelModuleResolutionValue}. If
* {@link SingleExtensionEvalFunction} were to directly depend on {@link
* BazelModuleResolutionValue}, any such change would cause ALL module extensions to be rerun.
* Instead, by storing the input needed by a single {@link SingleExtensionEvalFunction}, we can rely
* on Skyframe's change pruning feature to make sure that we only rerun the module extension whose
* input data actually changed.
*/
public class SingleExtensionUsagesFunction implements SkyFunction {
@Override
@Nullable
public SkyValue compute(SkyKey skyKey, Environment env) throws InterruptedException {
BazelDepGraphValue bazelDepGraphValue =
(BazelDepGraphValue) env.getValue(BazelDepGraphValue.KEY);
if (bazelDepGraphValue == null) {
return null;
}
ModuleExtensionId id = (ModuleExtensionId) skyKey.argument();
ImmutableTable<ModuleExtensionId, ModuleKey, ModuleExtensionUsage> usagesTable =
bazelDepGraphValue.getExtensionUsagesTable();
return SingleExtensionUsagesValue.create(
usagesTable.row(id),
bazelDepGraphValue.getExtensionUniqueNames().get(id),
// Filter abridged modules down to only those that actually used this extension.
bazelDepGraphValue.getAbridgedModules().stream()
.filter(module -> usagesTable.contains(id, module.getKey()))
.collect(toImmutableList()),
// TODO(wyv): Maybe cache these mappings?
usagesTable.row(id).keySet().stream()
.collect(toImmutableMap(key -> key, bazelDepGraphValue::getFullRepoMapping)));
}
}