com.google.devtools.build.lib.runtime.CacheFileDigestsModule.java Source code

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Here is the source code for com.google.devtools.build.lib.runtime.CacheFileDigestsModule.java

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// Copyright 2017 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.runtime;

import com.google.common.cache.CacheStats;
import com.google.devtools.build.lib.actions.cache.DigestUtils;
import com.google.devtools.build.lib.buildtool.BuildRequest;
import com.google.devtools.build.lib.exec.ExecutionOptions;
import com.google.devtools.build.lib.exec.ExecutorBuilder;
import com.google.devtools.build.lib.util.Preconditions;
import java.util.logging.Logger;

/** Enables the caching of file digests in {@link DigestUtils}. */
public class CacheFileDigestsModule extends BlazeModule {

    private static final Logger log = Logger.getLogger(CacheFileDigestsModule.class.getName());

    /** Stats gathered at the beginning of a command, to compute deltas on completion. */
    private CacheStats stats;

    /**
     * Last known size of the cache. Changes to this value cause the cache to be reinitialized. null
     * if we don't know anything about the last value yet (i.e. before any command has been run).
     */
    private Long lastKnownCacheSize;

    public CacheFileDigestsModule() {
    }

    /**
     * Adds a line to the log with cache statistics.
     *
     * @param message message to prefix to the written line
     * @param stats the cache statistics to be logged
     */
    private static void logStats(String message, CacheStats stats) {
        log.info(message + ": hit count=" + stats.hitCount() + ", miss count=" + stats.missCount() + ", hit rate="
                + stats.hitRate() + ", eviction count=" + stats.evictionCount());
    }

    @Override
    public void executorInit(CommandEnvironment env, BuildRequest request, ExecutorBuilder builder) {
        super.executorInit(env, request, builder);

        ExecutionOptions options = request.getOptions(ExecutionOptions.class);
        if (lastKnownCacheSize == null || options.cacheSizeForComputedFileDigests != lastKnownCacheSize) {
            log.info("Reconfiguring cache with size=" + options.cacheSizeForComputedFileDigests);
            DigestUtils.configureCache(options.cacheSizeForComputedFileDigests);
            lastKnownCacheSize = options.cacheSizeForComputedFileDigests;
        }

        if (options.cacheSizeForComputedFileDigests == 0) {
            stats = null;
            log.info("Disabled cache");
        } else {
            stats = DigestUtils.getCacheStats();
            logStats("Accumulated cache stats before command", stats);
        }
    }

    @Override
    public void afterCommand() {
        super.afterCommand();

        if (stats != null) {
            CacheStats newStats = DigestUtils.getCacheStats();
            Preconditions.checkNotNull(newStats, "The cache is enabled so we must get some stats back");
            logStats("Accumulated cache stats after command", newStats);
            logStats("Cache stats for finished command", newStats.minus(stats));
            stats = null; // Silence stats until next command that uses the executor.
        }
    }
}