| // Copyright 2019 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.actions; |
| |
| import com.google.devtools.build.lib.actions.Artifact.ArtifactExpander; |
| import com.google.devtools.build.lib.util.Fingerprint; |
| import javax.annotation.Nullable; |
| |
| /** |
| * An implementation of {@link ActionAnalysisMetadata} that caches its {@linkplain #getKey key} so |
| * that it is only computed once. |
| */ |
| public abstract class ActionKeyCacher implements ActionAnalysisMetadata { |
| |
| /** |
| * Integer embedded in every action key. |
| * |
| * <p>The purpose of this member and associated property is to allow to easily invalidate the |
| * action cache in case we want to mitigate bugs resulting with false-sharing. |
| */ |
| private static final int ACTION_KEY_UNIQUIFIER = |
| Integer.parseInt(System.getProperty("ACTION_KEY_UNIQUIFIER", "0")); |
| |
| @Nullable private volatile String cachedKey = null; |
| |
| @Override |
| public final String getKey( |
| ActionKeyContext actionKeyContext, @Nullable ArtifactExpander artifactExpander) |
| throws InterruptedException { |
| // Only cache the key when it is given all necessary information to compute a correct key. |
| // Practically, most of the benefit of the cache comes from execution, which does provide the |
| // artifactExpander. |
| if (artifactExpander == null) { |
| return computeActionKey(actionKeyContext, null); |
| } |
| |
| if (cachedKey == null) { |
| synchronized (this) { |
| if (cachedKey == null) { |
| cachedKey = computeActionKey(actionKeyContext, artifactExpander); |
| } |
| } |
| } |
| return cachedKey; |
| } |
| |
| private String computeActionKey( |
| ActionKeyContext actionKeyContext, @Nullable ArtifactExpander artifactExpander) |
| throws InterruptedException { |
| try { |
| Fingerprint fp = new Fingerprint(); |
| computeKey(actionKeyContext, artifactExpander, fp); |
| |
| // Add a bool indicating whether the execution platform was set. |
| fp.addBoolean(getExecutionPlatform() != null); |
| if (getExecutionPlatform() != null) { |
| // Add the execution platform information. |
| getExecutionPlatform().addTo(fp); |
| } |
| |
| fp.addStringMap(getExecProperties()); |
| fp.addInt(ACTION_KEY_UNIQUIFIER); |
| // Compute the actual key and store it. |
| return fp.hexDigestAndReset(); |
| } catch (CommandLineExpansionException e) { |
| return KEY_ERROR; |
| } |
| } |
| |
| /** |
| * See the javadoc for {@link Action} and {@link ActionAnalysisMetadata#getKey} for the contract |
| * of this method. |
| * |
| * <p>TODO(b/150305897): subtypes of this are not consistent about adding the UUID as stated in |
| * the ActionAnalysisMetadata. Perhaps ActionKeyCacher should just mandate subclasses provide a |
| * UUID and then add that UUID itself in getKey. |
| */ |
| protected abstract void computeKey( |
| ActionKeyContext actionKeyContext, |
| @Nullable ArtifactExpander artifactExpander, |
| Fingerprint fp) |
| throws CommandLineExpansionException, InterruptedException; |
| } |