| // Copyright 2014 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 static java.util.concurrent.TimeUnit.MINUTES; |
| |
| import com.google.common.base.Preconditions; |
| import com.google.common.collect.ImmutableList; |
| import com.google.common.collect.ImmutableMap; |
| import com.google.common.collect.Iterators; |
| import com.google.common.escape.Escaper; |
| import com.google.common.escape.Escapers; |
| import com.google.common.flogger.GoogleLogger; |
| import com.google.devtools.build.lib.cmdline.Label; |
| import com.google.devtools.build.lib.skyframe.SkyframeAwareAction; |
| import com.google.devtools.build.lib.vfs.OsPathPolicy; |
| import com.google.devtools.build.lib.vfs.PathFragment; |
| import java.util.Arrays; |
| import java.util.Collection; |
| import java.util.Comparator; |
| import java.util.HashMap; |
| import java.util.Iterator; |
| import java.util.LinkedHashMap; |
| import java.util.Map; |
| import java.util.Optional; |
| |
| /** Utility class for actions. */ |
| public final class Actions { |
| private static final GoogleLogger logger = GoogleLogger.forEnclosingClass(); |
| |
| private static final Escaper PATH_ESCAPER = |
| Escapers.builder() |
| .addEscape('_', "_U") |
| .addEscape('/', "_S") |
| .addEscape('\\', "_B") |
| .addEscape(':', "_C") |
| .addEscape('@', "_A") |
| .build(); |
| |
| private Actions() {} |
| |
| /** |
| * Determines whether the given action needs to depend on the build ID. |
| * |
| * <p>Such actions are not shareable across servers. |
| */ |
| public static boolean dependsOnBuildId(ActionAnalysisMetadata action) { |
| // Volatile build actions may need to execute even if none of their known inputs have changed. |
| // Depending on the build ID ensures that these actions have a chance to execute. |
| // SkyframeAwareActions do not need to depend on the build ID because their volatility is due to |
| // their dependence on Skyframe nodes that are not captured in the action cache. Any changes to |
| // those nodes will cause this action to be rerun, so a build ID dependency is unnecessary. |
| if (!(action instanceof Action)) { |
| return false; |
| } |
| if (action instanceof NotifyOnActionCacheHit) { |
| return true; |
| } |
| return ((Action) action).isVolatile() && !(action instanceof SkyframeAwareAction); |
| } |
| |
| /** |
| * Checks if the two actions are equivalent. This method exists to support sharing actions between |
| * configured targets for cases where there is no canonical target that could own the action. In |
| * the action graph construction this case shows up as two actions generating the same output |
| * file. |
| * |
| * <p>This method implements an equivalence relationship across actions, based on the action |
| * class, the key, and the list of inputs and outputs. |
| */ |
| public static boolean canBeShared( |
| ActionKeyContext actionKeyContext, ActionAnalysisMetadata a, ActionAnalysisMetadata b) |
| throws InterruptedException { |
| return a.isShareable() |
| && b.isShareable() |
| && a.getMnemonic().equals(b.getMnemonic()) |
| // Non-Actions cannot be shared. |
| && a instanceof Action |
| && b instanceof Action |
| && a.getKey(actionKeyContext, /*artifactExpander=*/ null) |
| .equals(b.getKey(actionKeyContext, /*artifactExpander=*/ null)) |
| && artifactsEqualWithoutOwner( |
| a.getMandatoryInputs().toList(), b.getMandatoryInputs().toList()) |
| && artifactsEqualWithoutOwner(a.getOutputs(), b.getOutputs()); |
| } |
| |
| /** |
| * Checks whether provided actions are equivalent and adds a log line in case we may be overly |
| * permissive in the result. Returned result is the same as for {@link |
| * #canBeShared(ActionKeyContext, ActionAnalysisMetadata, ActionAnalysisMetadata)}. |
| * |
| * <p>TODO(b/160181927): Remove the logging once we move shared actions detection to execution |
| * phase. |
| */ |
| static boolean canBeSharedLogForPotentialFalsePositives( |
| ActionKeyContext actionKeyContext, |
| ActionAnalysisMetadata actionA, |
| ActionAnalysisMetadata actionB) |
| throws InterruptedException { |
| if (!canBeShared(actionKeyContext, actionA, actionB)) { |
| return false; |
| } |
| Optional<Artifact> treeArtifactInput = |
| actionA.getMandatoryInputs().toList().stream().filter(Artifact::isTreeArtifact).findFirst(); |
| treeArtifactInput.ifPresent( |
| treeArtifact -> |
| logger.atInfo().atMostEvery(5, MINUTES).log( |
| "Shared action: %s has a tree artifact input: %s -- shared actions" |
| + " detection is overly permissive in this case and may allow" |
| + " sharing of different actions", |
| actionA, treeArtifact)); |
| return true; |
| } |
| |
| private static boolean artifactsEqualWithoutOwner( |
| Collection<Artifact> collection1, Collection<Artifact> collection2) { |
| if (collection1.size() != collection2.size()) { |
| return false; |
| } |
| Iterator<Artifact> iterator1 = collection1.iterator(); |
| Iterator<Artifact> iterator2 = collection2.iterator(); |
| while (iterator1.hasNext()) { |
| Artifact artifact1 = iterator1.next(); |
| Artifact artifact2 = iterator2.next(); |
| if (!artifact1.equalsWithoutOwner(artifact2)) { |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| /** |
| * Assigns generating action keys to artifacts, and finds action conflicts. An action conflict |
| * happens if two actions generate the same output artifact. Shared actions are not allowed. See |
| * {@link #canBeShared} for details. |
| * |
| * @param actions a list of actions to check for action conflict. |
| * @throws ActionConflictException iff there are two actions generate the same output |
| */ |
| public static void assignOwnersAndThrowIfConflict( |
| ActionKeyContext actionKeyContext, |
| ImmutableList<ActionAnalysisMetadata> actions, |
| ActionLookupKey actionLookupKey) |
| throws ActionConflictException, InterruptedException, ArtifactGeneratedByOtherRuleException { |
| assignOwnersAndThrowIfConflictMaybeToleratingSharedActions( |
| actionKeyContext, actions, actionLookupKey, /* allowSharedAction= */ false); |
| } |
| |
| /** |
| * Assigns generating action keys to artifacts and finds action conflicts. An action conflict |
| * happens if two actions generate the same output artifact. Shared actions are tolerated. See |
| * {@link #canBeShared} for details. Should be called by a configured target/aspect on the actions |
| * it owns. Should not be used for "global" checks of multiple configured targets: use {@link |
| * #findArtifactPrefixConflicts} for that. |
| * |
| * @param actions a list of actions to check for action conflicts, all generated by the same |
| * configured target/aspect. |
| * @throws ActionConflictException iff there are two unshareable actions generating the same |
| * output |
| */ |
| public static void assignOwnersAndThrowIfConflictToleratingSharedActions( |
| ActionKeyContext actionKeyContext, |
| ImmutableList<ActionAnalysisMetadata> actions, |
| ActionLookupKey actionLookupKey) |
| throws ActionConflictException, InterruptedException, ArtifactGeneratedByOtherRuleException { |
| assignOwnersAndThrowIfConflictMaybeToleratingSharedActions( |
| actionKeyContext, actions, actionLookupKey, /* allowSharedAction= */ true); |
| } |
| |
| private static void verifyGeneratingActionKeys( |
| Artifact.DerivedArtifact output, |
| ActionLookupData otherKey, |
| boolean allowSharedAction, |
| ActionKeyContext actionKeyContext, |
| ImmutableList<ActionAnalysisMetadata> actions) |
| throws ActionConflictException, InterruptedException { |
| ActionLookupData firstKey = output.getGeneratingActionKey(); |
| Preconditions.checkState( |
| firstKey.getActionLookupKey().equals(otherKey.getActionLookupKey()), |
| "Mismatched lookup keys? %s %s %s", |
| output, |
| firstKey, |
| otherKey); |
| int actionIndex = firstKey.getActionIndex(); |
| int otherIndex = otherKey.getActionIndex(); |
| if (actionIndex != otherIndex |
| && (!allowSharedAction |
| || !Actions.canBeSharedLogForPotentialFalsePositives( |
| actionKeyContext, actions.get(actionIndex), actions.get(otherIndex)))) { |
| throw ActionConflictException.create( |
| actionKeyContext, output, actions.get(actionIndex), actions.get(otherIndex)); |
| } |
| } |
| |
| /** |
| * Checks {@code actions} for conflicts and sets each artifact's generating action key. |
| * |
| * <p>Conflicts can happen in one of two ways: the same artifact can be the output of multiple |
| * unshareable actions (or shareable actions if {@code allowSharedAction} is false), or two |
| * artifacts with the same execPath can be the outputs of different unshareable actions. |
| */ |
| private static void assignOwnersAndThrowIfConflictMaybeToleratingSharedActions( |
| ActionKeyContext actionKeyContext, |
| ImmutableList<ActionAnalysisMetadata> actions, |
| ActionLookupKey actionLookupKey, |
| boolean allowSharedAction) |
| throws ActionConflictException, InterruptedException, ArtifactGeneratedByOtherRuleException { |
| Map<PathFragment, Artifact.DerivedArtifact> seenArtifacts = new HashMap<>(); |
| // Loop over the actions, looking at all outputs for conflicts. |
| int actionIndex = 0; |
| for (ActionAnalysisMetadata action : actions) { |
| ActionLookupData generatingActionKey = |
| dependsOnBuildId(action) |
| ? ActionLookupData.createUnshareable(actionLookupKey, actionIndex) |
| : ActionLookupData.create(actionLookupKey, actionIndex); |
| for (Artifact artifact : action.getOutputs()) { |
| Preconditions.checkState( |
| !artifact.isSourceArtifact(), |
| "Source in outputs: %s %s %s", |
| artifact, |
| generatingActionKey, |
| action); |
| Artifact.DerivedArtifact output = (Artifact.DerivedArtifact) artifact; |
| // Has an artifact with this execPath been seen before? |
| Artifact.DerivedArtifact equalOutput = |
| seenArtifacts.putIfAbsent(output.getExecPath(), output); |
| if (equalOutput != null) { |
| // Yes: assert that its generating action and this artifact's are compatible. |
| verifyGeneratingActionKeys( |
| equalOutput, |
| generatingActionKey, |
| allowSharedAction, |
| actionKeyContext, |
| actions); |
| } |
| // Was this output already seen, so it has a generating action key set? |
| if (!output.hasGeneratingActionKey()) { |
| // Common case: artifact hasn't been seen before. |
| output.setGeneratingActionKey(generatingActionKey); |
| } else { |
| ActionLookupData oldKey = output.getGeneratingActionKey(); |
| if (!actionLookupKey.equals(oldKey.getActionLookupKey())) { |
| // The rule is claiming to produce an output that one of its inputs produced. Silly! |
| throw new ArtifactGeneratedByOtherRuleException( |
| String.format( |
| "File '%s' is produced by %s but is already generated by rule %s", |
| output.prettyPrint(), |
| action.prettyPrint(), |
| oldKey.getActionLookupKey().getLabel())); |
| } |
| // Key is already set: verify that the generating action and this action are compatible. |
| verifyGeneratingActionKeys( |
| output, |
| generatingActionKey, |
| allowSharedAction, |
| actionKeyContext, |
| actions); |
| } |
| } |
| actionIndex++; |
| } |
| } |
| |
| private static final Comparator<Artifact> EXEC_PATH_PREFIX_COMPARATOR = |
| (lhs, rhs) -> { |
| // We need to use the OS path policy in case the OS is case insensitive. |
| OsPathPolicy os = OsPathPolicy.getFilePathOs(); |
| String str1 = lhs.getExecPathString(); |
| String str2 = rhs.getExecPathString(); |
| int len1 = str1.length(); |
| int len2 = str2.length(); |
| int n = Math.min(len1, len2); |
| for (int i = 0; i < n; ++i) { |
| char c1 = str1.charAt(i); |
| char c2 = str2.charAt(i); |
| int res = os.compare(c1, c2); |
| if (res != 0) { |
| if (c1 == PathFragment.SEPARATOR_CHAR) { |
| return -1; |
| } else if (c2 == PathFragment.SEPARATOR_CHAR) { |
| return 1; |
| } |
| return res; |
| } |
| } |
| return len1 - len2; |
| }; |
| |
| /** |
| * Finds Artifact prefix conflicts between generated artifacts. An artifact prefix conflict |
| * happens if one action generates an artifact whose path is a strict prefix of another artifact's |
| * path. Those two artifacts cannot exist simultaneously in the output tree. |
| * |
| * @param actionGraph the {@link ActionGraph} to query for artifact conflicts |
| * @param artifacts all generated artifacts in the build |
| * @return An immutable map between actions that generated the conflicting artifacts and their |
| * associated {@link ActionConflictException} |
| */ |
| public static ImmutableMap<ActionAnalysisMetadata, ActionConflictException> |
| findArtifactPrefixConflicts(ActionGraph actionGraph, Collection<Artifact> artifacts) { |
| // No actions in graph -- currently happens only in tests. Special-cased because .next() call |
| // below is unconditional. |
| if (artifacts.isEmpty()) { |
| return ImmutableMap.of(); |
| } |
| |
| Artifact[] artifactArray = artifacts.toArray(new Artifact[0]); |
| Arrays.parallelSort(artifactArray, EXEC_PATH_PREFIX_COMPARATOR); |
| |
| // Keep deterministic ordering of bad actions. |
| Map<ActionAnalysisMetadata, ActionConflictException> badActions = new LinkedHashMap<>(); |
| Iterator<Artifact> iter = Iterators.forArray(artifactArray); |
| |
| // Report an error for every derived artifact which is a strict prefix of another. |
| // If x << y << z (where x << y means "y starts with x"), then we only report (x,y), (x,z), but |
| // not (y,z). |
| for (Artifact artifactJ = iter.next(); iter.hasNext(); ) { |
| // For each comparison, we have a prefix candidate (pathI) and a suffix candidate (pathJ). |
| // At the beginning of the loop, we set pathI to the last suffix candidate, since it has not |
| // yet been tested as a prefix candidate, and then set pathJ to the paths coming after pathI, |
| // until we come to one that does not contain pathI as a prefix. pathI is then verified not to |
| // be the prefix of any path, so we start the next run of the loop. |
| Artifact artifactI = artifactJ; |
| PathFragment pathI = artifactI.getExecPath(); |
| // Compare pathI to the paths coming after it. |
| while (iter.hasNext()) { |
| artifactJ = iter.next(); |
| PathFragment pathJ = artifactJ.getExecPath(); |
| // Check length first so that we only detect strict prefix conflicts. Equal exec paths are |
| // possible from shared actions. |
| if (pathJ.getPathString().length() > pathI.getPathString().length() |
| && pathJ.startsWith(pathI)) { |
| ActionAnalysisMetadata actionI = |
| Preconditions.checkNotNull(actionGraph.getGeneratingAction(artifactI), artifactI); |
| ActionAnalysisMetadata actionJ = |
| Preconditions.checkNotNull(actionGraph.getGeneratingAction(artifactJ), artifactJ); |
| ActionConflictException exception = |
| ActionConflictException.createPrefix(artifactI, artifactJ, actionI, actionJ); |
| badActions.put(actionI, exception); |
| badActions.put(actionJ, exception); |
| } else { // pathJ didn't have prefix pathI, so no conflict possible for pathI. |
| break; |
| } |
| } |
| } |
| return ImmutableMap.copyOf(badActions); |
| } |
| |
| /** |
| * Returns the escaped name for a given relative path as a string. This takes |
| * a short relative path and turns it into a string suitable for use as a |
| * filename. Invalid filename characters are escaped with an '_' + a single |
| * character token. |
| */ |
| public static String escapedPath(String path) { |
| return PATH_ESCAPER.escape(path); |
| } |
| |
| /** |
| * Returns a string that is usable as a unique path component for a label. It is guaranteed |
| * that no other label maps to this string. |
| */ |
| public static String escapeLabel(Label label) { |
| String path = label.getPackageName() + ":" + label.getName(); |
| if (!label.getRepository().isMain()) { |
| path = label.getRepository().getName() + "@" + path; |
| } |
| return PATH_ESCAPER.escape(path); |
| } |
| |
| /** |
| * Signals the rare case of a rule that claims to generate a file that was actually provided to it |
| * by one of its dependencies. |
| */ |
| public static class ArtifactGeneratedByOtherRuleException extends Exception { |
| private ArtifactGeneratedByOtherRuleException(String message) { |
| super(message); |
| } |
| } |
| } |
