Add ActionKeyContext to Action#getKey.

This key context can be used by actions to share partial key computations, for instance when computing MD5s for nested sets.

RELNOTES: None
PiperOrigin-RevId: 177359607

13 files changed, 148 insertions, 57 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/actions/AbstractAction.java b/src/main/java/com/google/devtools/build/lib/actions/AbstractAction.java
index d1d805fcd5..04f74585c2 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/AbstractAction.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/AbstractAction.java
@@ -295,16 +295,17 @@ public abstract class AbstractAction implements Action, SkylarkValue {
 
   /**
    * See the javadoc for {@link com.google.devtools.build.lib.actions.Action} and {@link
-   * com.google.devtools.build.lib.actions.ActionExecutionMetadata#getKey()} for the contract for
-   * {@link #computeKey()}.
+   * ActionExecutionMetadata#getKey(ActionKeyContext)} for the contract for {@link
+   * #computeKey(ActionKeyContext)}.
    */
-  protected abstract String computeKey() throws CommandLineExpansionException;
+  protected abstract String computeKey(ActionKeyContext actionKeyContext)
+      throws CommandLineExpansionException;
 
   @Override
-  public final synchronized String getKey() {
+  public final synchronized String getKey(ActionKeyContext actionKeyContext) {
     if (cachedKey == null) {
       try {
-        cachedKey = computeKey();
+        cachedKey = computeKey(actionKeyContext);
       } catch (CommandLineExpansionException e) {
         cachedKey = KEY_ERROR;
       }
@@ -481,12 +482,13 @@ public abstract class AbstractAction implements Action, SkylarkValue {
   }
 
   @Override
-  public ExtraActionInfo.Builder getExtraActionInfo() throws CommandLineExpansionException {
+  public ExtraActionInfo.Builder getExtraActionInfo(ActionKeyContext actionKeyContext)
+      throws CommandLineExpansionException {
     ActionOwner owner = getOwner();
     ExtraActionInfo.Builder result =
         ExtraActionInfo.newBuilder()
             .setOwner(owner.getLabel().toString())
-            .setId(getKey())
+            .setId(getKey(actionKeyContext))
             .setMnemonic(getMnemonic());
     Iterable<AspectDescriptor> aspectDescriptors = owner.getAspectDescriptors();
     AspectDescriptor lastAspect = null;
diff --git a/src/main/java/com/google/devtools/build/lib/actions/Action.java b/src/main/java/com/google/devtools/build/lib/actions/Action.java
index e1c1b35cff..217ce5d59d 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/Action.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/Action.java
@@ -192,5 +192,6 @@ public interface Action extends ActionExecutionMetadata, Describable {
    * <p>As this method is called from the ExtraAction, make sure it is ok to call this method from a
    * different thread than the one this action is executed on.
    */
-  ExtraActionInfo.Builder getExtraActionInfo() throws CommandLineExpansionException;
+  ExtraActionInfo.Builder getExtraActionInfo(ActionKeyContext actionKeyContext)
+      throws CommandLineExpansionException;
 }
diff --git a/src/main/java/com/google/devtools/build/lib/actions/ActionCacheChecker.java b/src/main/java/com/google/devtools/build/lib/actions/ActionCacheChecker.java
index 8a49c9c40c..8e4dc88a46 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/ActionCacheChecker.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/ActionCacheChecker.java
@@ -74,6 +74,7 @@ public class ActionCacheChecker {
   };
 
   private final ActionCache actionCache;
+  private final ActionKeyContext actionKeyContext;
   private final Predicate<? super Action> executionFilter;
   private final ArtifactResolver artifactResolver;
   private final CacheConfig cacheConfig;
@@ -103,10 +104,12 @@ public class ActionCacheChecker {
   public ActionCacheChecker(
       ActionCache actionCache,
       ArtifactResolver artifactResolver,
+      ActionKeyContext actionKeyContext,
       Predicate<? super Action> executionFilter,
       @Nullable CacheConfig cacheConfig) {
     this.actionCache = actionCache;
     this.executionFilter = executionFilter;
+    this.actionKeyContext = actionKeyContext;
     this.artifactResolver = artifactResolver;
     this.cacheConfig =
         cacheConfig != null
@@ -303,7 +306,7 @@ public class ActionCacheChecker {
       reportChanged(handler, action);
       actionCache.accountMiss(MissReason.DIFFERENT_FILES);
       return true;
-    } else if (!entry.getActionKey().equals(action.getKey())) {
+    } else if (!entry.getActionKey().equals(action.getKey(actionKeyContext))) {
       reportCommand(handler, action);
       actionCache.accountMiss(MissReason.DIFFERENT_ACTION_KEY);
       return true;
@@ -356,7 +359,8 @@ public class ActionCacheChecker {
     }
     Map<String, String> usedClientEnv = computeUsedClientEnv(action, clientEnv);
     ActionCache.Entry entry =
-        new ActionCache.Entry(action.getKey(), usedClientEnv, action.discoversInputs());
+        new ActionCache.Entry(
+            action.getKey(actionKeyContext), usedClientEnv, action.discoversInputs());
     for (Artifact output : action.getOutputs()) {
       // Remove old records from the cache if they used different key.
       String execPath = output.getExecPathString();
diff --git a/src/main/java/com/google/devtools/build/lib/actions/ActionExecutionContext.java b/src/main/java/com/google/devtools/build/lib/actions/ActionExecutionContext.java
index fc8a6bfb47..f356559a86 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/ActionExecutionContext.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/ActionExecutionContext.java
@@ -43,6 +43,7 @@ public class ActionExecutionContext implements Closeable {
   private final Executor executor;
   private final ActionInputFileCache actionInputFileCache;
   private final ActionInputPrefetcher actionInputPrefetcher;
+  private final ActionKeyContext actionKeyContext;
   private final MetadataHandler metadataHandler;
   private final FileOutErr fileOutErr;
   private final ImmutableMap<String, String> clientEnv;
@@ -54,6 +55,7 @@ public class ActionExecutionContext implements Closeable {
       Executor executor,
       ActionInputFileCache actionInputFileCache,
       ActionInputPrefetcher actionInputPrefetcher,
+      ActionKeyContext actionKeyContext,
       MetadataHandler metadataHandler,
       FileOutErr fileOutErr,
       Map<String, String> clientEnv,
@@ -61,6 +63,7 @@ public class ActionExecutionContext implements Closeable {
       @Nullable SkyFunction.Environment env) {
     this.actionInputFileCache = actionInputFileCache;
     this.actionInputPrefetcher = actionInputPrefetcher;
+    this.actionKeyContext = actionKeyContext;
     this.metadataHandler = metadataHandler;
     this.fileOutErr = fileOutErr;
     this.clientEnv = ImmutableMap.copyOf(clientEnv);
@@ -73,6 +76,7 @@ public class ActionExecutionContext implements Closeable {
       Executor executor,
       ActionInputFileCache actionInputFileCache,
       ActionInputPrefetcher actionInputPrefetcher,
+      ActionKeyContext actionKeyContext,
       MetadataHandler metadataHandler,
       FileOutErr fileOutErr,
       Map<String, String> clientEnv,
@@ -81,6 +85,7 @@ public class ActionExecutionContext implements Closeable {
         executor,
         actionInputFileCache,
         actionInputPrefetcher,
+        actionKeyContext,
         metadataHandler,
         fileOutErr,
         clientEnv,
@@ -92,6 +97,7 @@ public class ActionExecutionContext implements Closeable {
       Executor executor,
       ActionInputFileCache actionInputFileCache,
       ActionInputPrefetcher actionInputPrefetcher,
+      ActionKeyContext actionKeyContext,
       MetadataHandler metadataHandler,
       FileOutErr fileOutErr,
       Map<String, String> clientEnv,
@@ -100,6 +106,7 @@ public class ActionExecutionContext implements Closeable {
         executor,
         actionInputFileCache,
         actionInputPrefetcher,
+        actionKeyContext,
         metadataHandler,
         fileOutErr,
         clientEnv,
@@ -216,6 +223,10 @@ public class ActionExecutionContext implements Closeable {
     return Preconditions.checkNotNull(env);
   }
 
+  public ActionKeyContext getActionKeyContext() {
+    return actionKeyContext;
+  }
+
   @Override
   public void close() throws IOException {
     fileOutErr.close();
@@ -230,6 +241,7 @@ public class ActionExecutionContext implements Closeable {
         executor,
         actionInputFileCache,
         actionInputPrefetcher,
+        actionKeyContext,
         metadataHandler,
         fileOutErr,
         clientEnv,
diff --git a/src/main/java/com/google/devtools/build/lib/actions/ActionExecutionMetadata.java b/src/main/java/com/google/devtools/build/lib/actions/ActionExecutionMetadata.java
index 7f4b569b13..ec94b6c72a 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/ActionExecutionMetadata.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/ActionExecutionMetadata.java
@@ -59,35 +59,36 @@ public interface ActionExecutionMetadata extends ActionAnalysisMetadata {
    * <p>Examples of changes that should affect the key are:
    *
    * <ul>
-   * <li>Changes to the BUILD file that materially affect the rule which gave rise to this Action.
-   * <li>Changes to the command-line options, environment, or other global configuration resources
-   *     which affect the behaviour of this kind of Action (other than changes to the names of the
-   *     input/output files, which are handled externally).
-   * <li>An upgrade to the build tools which changes the program logic of this kind of Action
-   *     (typically this is achieved by incorporating a UUID into the key, which is changed each
-   *     time the program logic of this action changes).
+   *   <li>Changes to the BUILD file that materially affect the rule which gave rise to this Action.
+   *   <li>Changes to the command-line options, environment, or other global configuration resources
+   *       which affect the behaviour of this kind of Action (other than changes to the names of the
+   *       input/output files, which are handled externally).
+   *   <li>An upgrade to the build tools which changes the program logic of this kind of Action
+   *       (typically this is achieved by incorporating a UUID into the key, which is changed each
+   *       time the program logic of this action changes).
    * </ul>
    */
-  String getKey();
+  String getKey(ActionKeyContext actionKeyContext);
 
   /**
-   * Returns a human-readable description of the inputs to {@link #getKey()}.
-   * Used in the output from '--explain', and in error messages for
-   * '--check_up_to_date' and '--check_tests_up_to_date'.
-   * May return null, meaning no extra information is available.
+   * Returns a human-readable description of the inputs to {@link #getKey(ActionKeyContext)}. Used
+   * in the output from '--explain', and in error messages for '--check_up_to_date' and
+   * '--check_tests_up_to_date'. May return null, meaning no extra information is available.
    *
    * <p>If the return value is non-null, for consistency it should be a multiline message of the
    * form:
+   *
    * <pre>
    *   <var>Summary</var>
    *     <var>Fieldname</var>: <var>value</var>
    *     <var>Fieldname</var>: <var>value</var>
    *     ...
    * </pre>
+   *
    * where each line after the first one is intended two spaces, and where any fields that might
    * contain newlines or other funny characters are escaped using {@link
-   * com.google.devtools.build.lib.shell.ShellUtils#shellEscape}.
-   * For example:
+   * com.google.devtools.build.lib.shell.ShellUtils#shellEscape}. For example:
+   *
    * <pre>
    *   Compiling foo.cc
    *     Command: /usr/bin/gcc
@@ -97,7 +98,8 @@ public interface ActionExecutionMetadata extends ActionAnalysisMetadata {
    *     Argument: foo.o
    * </pre>
    */
-  @Nullable String describeKey();
+  @Nullable
+  String describeKey();
 
   /**
    * Get the {@link RunfilesSupplier} providing runfiles needed by this action.
diff --git a/src/main/java/com/google/devtools/build/lib/actions/ActionKeyContext.java b/src/main/java/com/google/devtools/build/lib/actions/ActionKeyContext.java
new file mode 100644
index 0000000000..6ba29a7655
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/actions/ActionKeyContext.java
@@ -0,0 +1,41 @@
+// 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.actions;
+
+import com.google.devtools.build.lib.collect.nestedset.NestedSet;
+import com.google.devtools.build.lib.collect.nestedset.NestedSetFingerprintCache;
+import com.google.devtools.build.lib.util.Fingerprint;
+
+/** Contains state that aids in action key computation via {@link AbstractAction#computeKey}. */
+public class ActionKeyContext {
+  private static final class ArtifactNestedSetFingerprintCache
+      extends NestedSetFingerprintCache<Artifact> {
+    @Override
+    protected void addItemFingerprint(Fingerprint fingerprint, Artifact item) {
+      fingerprint.addPath(item.getExecPath());
+    }
+  }
+
+  private final ArtifactNestedSetFingerprintCache artifactNestedSetFingerprintCache =
+      new ArtifactNestedSetFingerprintCache();
+
+  public void addArtifactsToFingerprint(Fingerprint fingerprint, NestedSet<Artifact> artifacts) {
+    artifactNestedSetFingerprintCache.addNestedSetToFingerprint(fingerprint, artifacts);
+  }
+
+  public void clear() {
+    artifactNestedSetFingerprintCache.clear();
+  }
+}
diff --git a/src/main/java/com/google/devtools/build/lib/actions/ActionLookupValue.java b/src/main/java/com/google/devtools/build/lib/actions/ActionLookupValue.java
index bf6e3a0099..ffe650a19b 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/ActionLookupValue.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/ActionLookupValue.java
@@ -42,9 +42,9 @@ public class ActionLookupValue implements SkyValue {
   private final ImmutableMap<Artifact, Integer> generatingActionIndex;
 
   private static Actions.GeneratingActions filterSharedActionsAndThrowRuntimeIfConflict(
-      List<ActionAnalysisMetadata> actions) {
+      ActionKeyContext actionKeyContext, List<ActionAnalysisMetadata> actions) {
     try {
-      return Actions.filterSharedActionsAndThrowActionConflict(actions);
+      return Actions.filterSharedActionsAndThrowActionConflict(actionKeyContext, actions);
     } catch (ActionConflictException e) {
       // Programming bug.
       throw new IllegalStateException(e);
@@ -53,12 +53,19 @@ public class ActionLookupValue implements SkyValue {
 
   @VisibleForTesting
   public ActionLookupValue(
-      List<ActionAnalysisMetadata> actions, boolean removeActionsAfterEvaluation) {
-    this(filterSharedActionsAndThrowRuntimeIfConflict(actions), removeActionsAfterEvaluation);
+      ActionKeyContext actionKeyContext,
+      List<ActionAnalysisMetadata> actions,
+      boolean removeActionsAfterEvaluation) {
+    this(
+        filterSharedActionsAndThrowRuntimeIfConflict(actionKeyContext, actions),
+        removeActionsAfterEvaluation);
   }
 
-  protected ActionLookupValue(ActionAnalysisMetadata action, boolean removeActionAfterEvaluation) {
-    this(ImmutableList.of(action), removeActionAfterEvaluation);
+  protected ActionLookupValue(
+      ActionKeyContext actionKeyContext,
+      ActionAnalysisMetadata action,
+      boolean removeActionAfterEvaluation) {
+    this(actionKeyContext, ImmutableList.of(action), removeActionAfterEvaluation);
   }
 
   protected ActionLookupValue(
diff --git a/src/main/java/com/google/devtools/build/lib/actions/Actions.java b/src/main/java/com/google/devtools/build/lib/actions/Actions.java
index 4acd7fefd7..91438261c7 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/Actions.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/Actions.java
@@ -54,7 +54,8 @@ public final class Actions {
    * <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(ActionAnalysisMetadata a, ActionAnalysisMetadata b) {
+  public static boolean canBeShared(
+      ActionKeyContext actionKeyContext, ActionAnalysisMetadata a, ActionAnalysisMetadata b) {
     if (!a.getMnemonic().equals(b.getMnemonic())) {
       return false;
     }
@@ -66,7 +67,7 @@ public final class Actions {
 
     Action actionA = (Action) a;
     Action actionB = (Action) b;
-    if (!actionA.getKey().equals(actionB.getKey())) {
+    if (!actionA.getKey(actionKeyContext).equals(actionB.getKey(actionKeyContext))) {
       return false;
     }
     // Don't bother to check input and output counts first; the expected result for these tests is
@@ -89,10 +90,11 @@ public final class Actions {
    *     of indirection.
    * @throws ActionConflictException iff there are two actions generate the same output
    */
-  public static GeneratingActions findAndThrowActionConflict(List<ActionAnalysisMetadata> actions)
+  public static GeneratingActions findAndThrowActionConflict(
+      ActionKeyContext actionKeyContext, List<ActionAnalysisMetadata> actions)
       throws ActionConflictException {
     return Actions.maybeFilterSharedActionsAndThrowIfConflict(
-        actions, /*allowSharedAction=*/ false);
+        actionKeyContext, actions, /*allowSharedAction=*/ false);
   }
 
   /**
@@ -106,13 +108,16 @@ public final class Actions {
    *     output
    */
   public static GeneratingActions filterSharedActionsAndThrowActionConflict(
-      List<ActionAnalysisMetadata> actions) throws ActionConflictException {
+      ActionKeyContext actionKeyContext, List<ActionAnalysisMetadata> actions)
+      throws ActionConflictException {
     return Actions.maybeFilterSharedActionsAndThrowIfConflict(
-        actions, /*allowSharedAction=*/ true);
+        actionKeyContext, actions, /*allowSharedAction=*/ true);
   }
 
   private static GeneratingActions maybeFilterSharedActionsAndThrowIfConflict(
-      List<ActionAnalysisMetadata> actions, boolean allowSharedAction)
+      ActionKeyContext actionKeyContext,
+      List<ActionAnalysisMetadata> actions,
+      boolean allowSharedAction)
       throws ActionConflictException {
     Map<Artifact, Integer> generatingActions = new HashMap<>();
     int actionIndex = 0;
@@ -120,8 +125,10 @@ public final class Actions {
       for (Artifact artifact : action.getOutputs()) {
         Integer previousIndex = generatingActions.put(artifact, actionIndex);
         if (previousIndex != null && previousIndex != actionIndex) {
-          if (!allowSharedAction || !Actions.canBeShared(actions.get(previousIndex), action)) {
-            throw new ActionConflictException(artifact, actions.get(previousIndex), action);
+          if (!allowSharedAction
+              || !Actions.canBeShared(actionKeyContext, actions.get(previousIndex), action)) {
+            throw new ActionConflictException(
+                actionKeyContext, artifact, actions.get(previousIndex), action);
           }
         }
       }
diff --git a/src/main/java/com/google/devtools/build/lib/actions/BUILD b/src/main/java/com/google/devtools/build/lib/actions/BUILD
index f481e5f257..9b8d8bc600 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/BUILD
+++ b/src/main/java/com/google/devtools/build/lib/actions/BUILD
@@ -28,6 +28,7 @@ java_library(
         "//src/main/java/com/google/devtools/build/lib/causes",
         "//src/main/java/com/google/devtools/build/lib/collect",
         "//src/main/java/com/google/devtools/build/lib/collect/nestedset",
+        "//src/main/java/com/google/devtools/build/lib/collect/nestedset:fingerprint_cache",
         "//src/main/java/com/google/devtools/build/lib/concurrent",
         "//src/main/java/com/google/devtools/build/lib/profiler",
         "//src/main/java/com/google/devtools/build/lib/shell",
diff --git a/src/main/java/com/google/devtools/build/lib/actions/FailAction.java b/src/main/java/com/google/devtools/build/lib/actions/FailAction.java
index 7f217409c8..86c22e0855 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/FailAction.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/FailAction.java
@@ -45,7 +45,7 @@ public final class FailAction extends AbstractAction {
   }
 
   @Override
-  protected String computeKey() {
+  protected String computeKey(ActionKeyContext actionKeyContext) {
     return GUID;
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/actions/MapBasedActionGraph.java b/src/main/java/com/google/devtools/build/lib/actions/MapBasedActionGraph.java
index 9b27881aa6..f35f963bf7 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/MapBasedActionGraph.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/MapBasedActionGraph.java
@@ -23,9 +23,14 @@ import javax.annotation.concurrent.ThreadSafe;
  */
 @ThreadSafe
 public final class MapBasedActionGraph implements MutableActionGraph {
+  private final ActionKeyContext actionKeyContext;
   private final ConcurrentMultimapWithHeadElement<Artifact, ActionAnalysisMetadata>
       generatingActionMap = new ConcurrentMultimapWithHeadElement<>();
 
+  public MapBasedActionGraph(ActionKeyContext actionKeyContext) {
+    this.actionKeyContext = actionKeyContext;
+  }
+
   @Override
   @Nullable
   public ActionAnalysisMetadata getGeneratingAction(Artifact artifact) {
@@ -36,10 +41,11 @@ public final class MapBasedActionGraph implements MutableActionGraph {
   public void registerAction(ActionAnalysisMetadata action) throws ActionConflictException {
     for (Artifact artifact : action.getOutputs()) {
       ActionAnalysisMetadata previousAction = generatingActionMap.putAndGet(artifact, action);
-      if (previousAction != null && previousAction != action
-          && !Actions.canBeShared(action, previousAction)) {
+      if (previousAction != null
+          && previousAction != action
+          && !Actions.canBeShared(actionKeyContext, action, previousAction)) {
         generatingActionMap.remove(artifact, action);
-        throw new ActionConflictException(artifact, previousAction, action);
+        throw new ActionConflictException(actionKeyContext, artifact, previousAction, action);
       }
     }
   }
@@ -49,9 +55,13 @@ public final class MapBasedActionGraph implements MutableActionGraph {
     for (Artifact artifact : action.getOutputs()) {
       generatingActionMap.remove(artifact, action);
       ActionAnalysisMetadata otherAction = generatingActionMap.get(artifact);
-      Preconditions.checkState(otherAction == null
-          || (otherAction != action && Actions.canBeShared(action, otherAction)),
-          "%s %s", action, otherAction);
+      Preconditions.checkState(
+          otherAction == null
+              || (otherAction != action
+                  && Actions.canBeShared(actionKeyContext, action, otherAction)),
+          "%s %s",
+          action,
+          otherAction);
     }
   }
 
diff --git a/src/main/java/com/google/devtools/build/lib/actions/MiddlemanAction.java b/src/main/java/com/google/devtools/build/lib/actions/MiddlemanAction.java
index f0c5972c6a..787f05248d 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/MiddlemanAction.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/MiddlemanAction.java
@@ -56,7 +56,7 @@ public final class MiddlemanAction extends AbstractAction {
   }
 
   @Override
-  protected String computeKey() {
+  protected String computeKey(ActionKeyContext actionKeyContext) {
     // TODO(bazel-team): Need to take middlemanType into account here.
     // Only the set of inputs matters, and the dependency checker is
     // responsible for considering those.
diff --git a/src/main/java/com/google/devtools/build/lib/actions/MutableActionGraph.java b/src/main/java/com/google/devtools/build/lib/actions/MutableActionGraph.java
index 1b1955a5e5..24a74ad28c 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/MutableActionGraph.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/MutableActionGraph.java
@@ -61,15 +61,19 @@ public interface MutableActionGraph extends ActionGraph {
    * about the artifact for which the conflict is found, and data about the two conflicting actions
    * and their owners.
    */
-  public static final class ActionConflictException extends Exception {
+  final class ActionConflictException extends Exception {
 
+    private final ActionKeyContext actionKeyContext;
     private final Artifact artifact;
     private final ActionAnalysisMetadata previousAction;
     private final ActionAnalysisMetadata attemptedAction;
     
     private static final int MAX_DIFF_ARTIFACTS_TO_REPORT = 5;
 
-    public ActionConflictException(Artifact artifact, ActionAnalysisMetadata previousAction,
+    public ActionConflictException(
+        ActionKeyContext actionKeyContext,
+        Artifact artifact,
+        ActionAnalysisMetadata previousAction,
         ActionAnalysisMetadata attemptedAction) {
       super(
           String.format(
@@ -77,6 +81,7 @@ public interface MutableActionGraph extends ActionGraph {
               artifact.prettyPrint(),
               previousAction.prettyPrint(),
               attemptedAction.prettyPrint()));
+      this.actionKeyContext = actionKeyContext;
       this.artifact = artifact;
       this.previousAction = previousAction;
       this.attemptedAction = attemptedAction;
@@ -91,7 +96,7 @@ public interface MutableActionGraph extends ActionGraph {
           "file '"
               + artifact.prettyPrint()
               + "' is generated by these conflicting actions:\n"
-              + suffix(attemptedAction, previousAction);
+              + suffix(actionKeyContext, attemptedAction, previousAction);
       eventListener.handle(Event.error(msg));
     }
 
@@ -143,14 +148,13 @@ public interface MutableActionGraph extends ActionGraph {
       }
     }
 
-    private static String getKey(ActionAnalysisMetadata action) {
-      return action instanceof Action
-          ? ((Action) action).getKey()
-          : null;
+    private static String getKey(ActionKeyContext actionKeyContext, ActionAnalysisMetadata action) {
+      return action instanceof Action ? ((Action) action).getKey(actionKeyContext) : null;
     }
 
     // See also Actions.canBeShared()
-    private static String suffix(ActionAnalysisMetadata a, ActionAnalysisMetadata b) {
+    private static String suffix(
+        ActionKeyContext actionKeyContext, ActionAnalysisMetadata a, ActionAnalysisMetadata b) {
       // Note: the error message reveals to users the names of intermediate files that are not
       // documented in the BUILD language.  This error-reporting logic is rather elaborate but it
       // does help to diagnose some tricky situations.
@@ -167,7 +171,7 @@ public interface MutableActionGraph extends ActionGraph {
       addStringDetail(sb, "Configuration", aNull ? null : aOwner.getConfigurationChecksum(),
           bNull ? null : bOwner.getConfigurationChecksum());
       addStringDetail(sb, "Mnemonic", a.getMnemonic(), b.getMnemonic());
-      addStringDetail(sb, "Action key", getKey(a), getKey(b));
+      addStringDetail(sb, "Action key", getKey(actionKeyContext, a), getKey(actionKeyContext, b));
 
       if ((a instanceof ActionExecutionMetadata) && (b instanceof ActionExecutionMetadata)) {
         addStringDetail(