Collect action cache hits, misses, and reasons for the misses.

As a bonus, this brings in a bunch of new unit tests for the
ActionCacheChecker.

RELNOTES: None.
PiperOrigin-RevId: 170059577

3 files changed, 482 insertions, 0 deletions

diff --git a/src/test/java/com/google/devtools/build/lib/actions/ActionCacheCheckerTest.java b/src/test/java/com/google/devtools/build/lib/actions/ActionCacheCheckerTest.java
new file mode 100644
index 0000000000..4da84f8923
--- /dev/null
+++ b/src/test/java/com/google/devtools/build/lib/actions/ActionCacheCheckerTest.java
@@ -0,0 +1,340 @@
+// 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 static com.google.common.truth.Truth.assertThat;
+
+import com.google.common.base.Predicates;
+import com.google.common.collect.ImmutableList;
+import com.google.devtools.build.lib.actions.ActionCacheChecker.Token;
+import com.google.devtools.build.lib.actions.cache.ActionCache;
+import com.google.devtools.build.lib.actions.cache.CompactPersistentActionCache;
+import com.google.devtools.build.lib.actions.cache.Md5Digest;
+import com.google.devtools.build.lib.actions.cache.Metadata;
+import com.google.devtools.build.lib.actions.cache.MetadataHandler;
+import com.google.devtools.build.lib.actions.cache.Protos.ActionCacheStatistics;
+import com.google.devtools.build.lib.actions.cache.Protos.ActionCacheStatistics.MissDetail;
+import com.google.devtools.build.lib.actions.cache.Protos.ActionCacheStatistics.MissReason;
+import com.google.devtools.build.lib.actions.util.ActionsTestUtil.FakeArtifactResolverBase;
+import com.google.devtools.build.lib.actions.util.ActionsTestUtil.FakeMetadataHandlerBase;
+import com.google.devtools.build.lib.actions.util.ActionsTestUtil.MissDetailsBuilder;
+import com.google.devtools.build.lib.actions.util.ActionsTestUtil.NullAction;
+import com.google.devtools.build.lib.clock.Clock;
+import com.google.devtools.build.lib.skyframe.FileArtifactValue;
+import com.google.devtools.build.lib.testutil.ManualClock;
+import com.google.devtools.build.lib.testutil.Scratch;
+import com.google.devtools.build.lib.vfs.FileSystem;
+import com.google.devtools.build.lib.vfs.FileSystemUtils;
+import com.google.devtools.build.lib.vfs.Path;
+import java.io.IOException;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public class ActionCacheCheckerTest {
+  private CorruptibleCompactPersistentActionCache cache;
+  private ActionCacheChecker cacheChecker;
+  private Set<Path> filesToDelete;
+
+  @Before
+  public void setupCache() throws Exception {
+    Scratch scratch = new Scratch();
+    Clock clock = new ManualClock();
+    ArtifactResolver artifactResolver = new FakeArtifactResolverBase();
+
+    cache = new CorruptibleCompactPersistentActionCache(scratch.resolve("/cache/test.dat"), clock);
+    cacheChecker = new ActionCacheChecker(cache, artifactResolver, Predicates.alwaysTrue(), null);
+  }
+
+  @Before
+  public void clearFilesToDeleteAfterTest() throws Exception {
+    filesToDelete = new HashSet<>();
+  }
+
+  @After
+  public void deleteFilesCreatedDuringTest() throws Exception {
+    for (Path path : filesToDelete) {
+      path.delete();
+    }
+  }
+
+  /** "Executes" the given action from the point of view of the cache's lifecycle. */
+  private void runAction(Action action) throws Exception {
+    runAction(action, new HashMap<>());
+  }
+
+  /**
+   * "Executes" the given action from the point of view of the cache's lifecycle with a custom
+   * client environment.
+   */
+  private void runAction(Action action, Map<String, String> clientEnv) throws Exception {
+    MetadataHandler metadataHandler = new FakeMetadataHandler();
+
+    for (Artifact artifact : action.getOutputs()) {
+      Path path = artifact.getPath();
+
+      // Record all action outputs as files to be deleted across tests to prevent cross-test
+      // pollution.  We need to do this on a path basis because we don't know upfront which file
+      // system they live in so we cannot just recreate the file system.  (E.g. all NullActions
+      // share an in-memory file system to hold dummy outputs.)
+      filesToDelete.add(path);
+
+      if (!path.exists()) {
+        FileSystemUtils.writeContentAsLatin1(path, "");
+      }
+    }
+
+    Token token = cacheChecker.getTokenIfNeedToExecute(
+        action, null, clientEnv, null, metadataHandler);
+    if (token != null) {
+      // Real action execution would happen here.
+      cacheChecker.afterExecution(action, token, metadataHandler, clientEnv);
+    }
+  }
+
+  /** Ensures that the cache statistics match exactly the given values. */
+  private void assertStatistics(int hits, Iterable<MissDetail> misses) {
+    ActionCacheStatistics.Builder builder = ActionCacheStatistics.newBuilder();
+    cache.mergeIntoActionCacheStatistics(builder);
+    ActionCacheStatistics stats = builder.build();
+
+    assertThat(stats.getHits()).isEqualTo(hits);
+    assertThat(stats.getMissDetailsList()).containsExactlyElementsIn(misses);
+  }
+
+  private void doTestNotCached(Action action, MissReason missReason) throws Exception {
+    runAction(action);
+
+    assertStatistics(0, new MissDetailsBuilder().set(missReason, 1).build());
+  }
+
+  private void doTestCached(Action action, MissReason missReason) throws Exception {
+    int runs = 5;
+    for (int i = 0; i < runs; i++) {
+      runAction(action);
+    }
+
+    assertStatistics(runs - 1, new MissDetailsBuilder().set(missReason, 1).build());
+  }
+
+  private void doTestCorruptedCacheEntry(Action action) throws Exception {
+    cache.corruptAllEntries();
+    runAction(action);
+
+    assertStatistics(
+        0,
+        new MissDetailsBuilder().set(MissReason.CORRUPTED_CACHE_ENTRY, 1).build());
+  }
+
+  @Test
+  public void testNoActivity() throws Exception {
+    assertStatistics(0, new MissDetailsBuilder().build());
+  }
+
+  @Test
+  public void testNotCached() throws Exception {
+    doTestNotCached(new NullAction(), MissReason.NOT_CACHED);
+  }
+
+  @Test
+  public void testCached() throws Exception {
+    doTestCached(new NullAction(), MissReason.NOT_CACHED);
+  }
+
+  @Test
+  public void testCorruptedCacheEntry() throws Exception {
+    doTestCorruptedCacheEntry(new NullAction());
+  }
+
+  @Test
+  public void testDifferentActionKey() throws Exception {
+    Action action = new NullAction() {
+      @Override
+      protected String computeKey() {
+        return "key1";
+      }
+    };
+    runAction(action);
+    action = new NullAction() {
+      @Override
+      protected String computeKey() {
+        return "key2";
+      }
+    };
+    runAction(action);
+
+    assertStatistics(
+        0,
+        new MissDetailsBuilder()
+            .set(MissReason.DIFFERENT_ACTION_KEY, 1)
+            .set(MissReason.NOT_CACHED, 1)
+            .build());
+  }
+
+  @Test
+  public void testDifferentEnvironment() throws Exception {
+    Action action = new NullAction() {
+      @Override
+      public Iterable<String> getClientEnvironmentVariables() {
+        return ImmutableList.of("used-var");
+      }
+    };
+    Map<String, String> clientEnv = new HashMap<>();
+    clientEnv.put("unused-var", "1");
+    runAction(action, clientEnv);  // Not cached.
+    clientEnv.remove("unused-var");
+    runAction(action, clientEnv);  // Cache hit because we only modified uninteresting variables.
+    clientEnv.put("used-var", "2");
+    runAction(action, clientEnv);  // Cache miss because of different environment.
+    runAction(action, clientEnv);  // Cache hit because we did not change anything.
+
+    assertStatistics(
+        2,
+        new MissDetailsBuilder()
+            .set(MissReason.DIFFERENT_ENVIRONMENT, 1)
+            .set(MissReason.NOT_CACHED, 1)
+            .build());
+  }
+
+  @Test
+  public void testDifferentFiles() throws Exception {
+    Action action = new NullAction();
+    runAction(action);  // Not cached.
+    FileSystemUtils.writeContentAsLatin1(action.getPrimaryOutput().getPath(), "modified");
+    runAction(action);  // Cache miss because output files were modified.
+
+    assertStatistics(
+        0,
+        new MissDetailsBuilder()
+            .set(MissReason.DIFFERENT_FILES, 1)
+            .set(MissReason.NOT_CACHED, 1)
+            .build());
+  }
+
+  @Test
+  public void testUnconditionalExecution() throws Exception {
+    Action action = new NullAction() {
+      @Override
+      public boolean executeUnconditionally() {
+        return true;
+      }
+
+      @Override
+      public boolean isVolatile() {
+        return true;
+      }
+    };
+
+    int runs = 5;
+    for (int i = 0; i < runs; i++) {
+      runAction(action);
+    }
+
+    assertStatistics(
+        0, new MissDetailsBuilder().set(MissReason.UNCONDITIONAL_EXECUTION, runs).build());
+  }
+
+  @Test
+  public void testMiddleman_NotCached() throws Exception {
+    doTestNotCached(new NullMiddlemanAction(), MissReason.DIFFERENT_DEPS);
+  }
+
+  @Test
+  public void testMiddleman_Cached() throws Exception {
+    doTestCached(new NullMiddlemanAction(), MissReason.DIFFERENT_DEPS);
+  }
+
+  @Test
+  public void testMiddleman_CorruptedCacheEntry() throws Exception {
+    doTestCorruptedCacheEntry(new NullMiddlemanAction());
+  }
+
+  @Test
+  public void testMiddleman_DifferentFiles() throws Exception {
+    Action action = new NullMiddlemanAction() {
+      @Override
+      public synchronized Iterable<Artifact> getInputs() {
+        FileSystem fileSystem = getPrimaryOutput().getPath().getFileSystem();
+        Path path = fileSystem.getPath("/input");
+        Root root = Root.asSourceRoot(fileSystem.getPath("/"));
+        return ImmutableList.of(new Artifact(path, root));
+      }
+    };
+    runAction(action);  // Not cached so recorded as different deps.
+    FileSystemUtils.writeContentAsLatin1(action.getPrimaryInput().getPath(), "modified");
+    runAction(action);  // Cache miss because input files were modified.
+    FileSystemUtils.writeContentAsLatin1(action.getPrimaryOutput().getPath(), "modified");
+    runAction(action);  // Outputs are not considered for middleman actions, so this is a cache hit.
+    runAction(action);  // Outputs are not considered for middleman actions, so this is a cache hit.
+
+    assertStatistics(
+        2,
+        new MissDetailsBuilder()
+            .set(MissReason.DIFFERENT_DEPS, 1)
+            .set(MissReason.DIFFERENT_FILES, 1)
+            .build());
+  }
+
+  /** A {@link CompactPersistentActionCache} that allows injecting corruption for testing. */
+  private static class CorruptibleCompactPersistentActionCache
+      extends CompactPersistentActionCache {
+    private boolean corrupted = false;
+
+    CorruptibleCompactPersistentActionCache(Path cacheRoot, Clock clock) throws IOException {
+      super(cacheRoot, clock);
+    }
+
+    void corruptAllEntries() {
+      corrupted = true;
+    }
+
+    @Override
+    public Entry get(String key) {
+      if (corrupted) {
+        return ActionCache.Entry.CORRUPTED;
+      } else {
+        return super.get(key);
+      }
+    }
+  }
+
+  /** A null middleman action. */
+  private static class NullMiddlemanAction extends NullAction {
+    @Override
+    public MiddlemanType getActionType() {
+      return MiddlemanType.RUNFILES_MIDDLEMAN;
+    }
+  }
+
+  /** A fake metadata handler that is able to obtain metadata from the file system. */
+  private static class FakeMetadataHandler extends FakeMetadataHandlerBase {
+    @Override
+    public Metadata getMetadata(Artifact artifact) throws IOException {
+      return FileArtifactValue.create(artifact);
+    }
+
+    @Override
+    public void setDigestForVirtualArtifact(Artifact artifact, Md5Digest md5Digest) {
+
+    }
+  }
+}
diff --git a/src/test/java/com/google/devtools/build/lib/actions/util/ActionCacheTestHelper.java b/src/test/java/com/google/devtools/build/lib/actions/util/ActionCacheTestHelper.java
index 1415c810ed..93fd34f15b 100644
--- a/src/test/java/com/google/devtools/build/lib/actions/util/ActionCacheTestHelper.java
+++ b/src/test/java/com/google/devtools/build/lib/actions/util/ActionCacheTestHelper.java
@@ -14,6 +14,8 @@
 package com.google.devtools.build.lib.actions.util;
 
 import com.google.devtools.build.lib.actions.cache.ActionCache;
+import com.google.devtools.build.lib.actions.cache.Protos.ActionCacheStatistics;
+import com.google.devtools.build.lib.actions.cache.Protos.ActionCacheStatistics.MissReason;
 import java.io.PrintStream;
 
 /**
@@ -46,5 +48,17 @@ public class ActionCacheTestHelper {
 
         @Override
         public void dump(PrintStream out) {}
+
+        @Override
+        public void accountHit() {}
+
+        @Override
+        public void accountMiss(MissReason reason) {}
+
+        @Override
+        public void mergeIntoActionCacheStatistics(ActionCacheStatistics.Builder builder) {}
+
+        @Override
+        public void resetStatistics() {}
       };
 }
diff --git a/src/test/java/com/google/devtools/build/lib/actions/util/ActionsTestUtil.java b/src/test/java/com/google/devtools/build/lib/actions/util/ActionsTestUtil.java
index d1b796b5c0..2fc80f5bde 100644
--- a/src/test/java/com/google/devtools/build/lib/actions/util/ActionsTestUtil.java
+++ b/src/test/java/com/google/devtools/build/lib/actions/util/ActionsTestUtil.java
@@ -14,6 +14,7 @@
 package com.google.devtools.build.lib.actions.util;
 
 import static com.google.common.truth.Truth.assertThat;
+import static com.google.devtools.build.lib.util.Preconditions.checkArgument;
 
 import com.google.common.base.Joiner;
 import com.google.common.base.Predicate;
@@ -29,6 +30,7 @@ import com.google.devtools.build.lib.actions.Action;
 import com.google.devtools.build.lib.actions.ActionAnalysisMetadata;
 import com.google.devtools.build.lib.actions.ActionExecutionContext;
 import com.google.devtools.build.lib.actions.ActionGraph;
+import com.google.devtools.build.lib.actions.ActionInput;
 import com.google.devtools.build.lib.actions.ActionInputHelper;
 import com.google.devtools.build.lib.actions.ActionInputPrefetcher;
 import com.google.devtools.build.lib.actions.ActionOwner;
@@ -36,15 +38,22 @@ import com.google.devtools.build.lib.actions.Artifact;
 import com.google.devtools.build.lib.actions.Artifact.ArtifactExpander;
 import com.google.devtools.build.lib.actions.Artifact.TreeFileArtifact;
 import com.google.devtools.build.lib.actions.ArtifactOwner;
+import com.google.devtools.build.lib.actions.ArtifactResolver;
 import com.google.devtools.build.lib.actions.Executor;
 import com.google.devtools.build.lib.actions.MutableActionGraph;
 import com.google.devtools.build.lib.actions.MutableActionGraph.ActionConflictException;
+import com.google.devtools.build.lib.actions.PackageRootResolver;
 import com.google.devtools.build.lib.actions.Root;
+import com.google.devtools.build.lib.actions.cache.Md5Digest;
+import com.google.devtools.build.lib.actions.cache.Metadata;
 import com.google.devtools.build.lib.actions.cache.MetadataHandler;
+import com.google.devtools.build.lib.actions.cache.Protos.ActionCacheStatistics.MissDetail;
+import com.google.devtools.build.lib.actions.cache.Protos.ActionCacheStatistics.MissReason;
 import com.google.devtools.build.lib.analysis.actions.CustomCommandLine;
 import com.google.devtools.build.lib.analysis.actions.SpawnActionTemplate;
 import com.google.devtools.build.lib.analysis.actions.SpawnActionTemplate.OutputPathMapper;
 import com.google.devtools.build.lib.cmdline.Label;
+import com.google.devtools.build.lib.cmdline.RepositoryName;
 import com.google.devtools.build.lib.events.EventHandler;
 import com.google.devtools.build.lib.events.ExtendedEventHandler;
 import com.google.devtools.build.lib.events.Reporter;
@@ -54,6 +63,7 @@ import com.google.devtools.build.lib.util.FileType;
 import com.google.devtools.build.lib.util.Preconditions;
 import com.google.devtools.build.lib.util.ResourceUsage;
 import com.google.devtools.build.lib.util.io.FileOutErr;
+import com.google.devtools.build.lib.vfs.FileStatus;
 import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.lib.vfs.PathFragment;
 import com.google.devtools.build.lib.vfs.inmemoryfs.InMemoryFileSystem;
@@ -65,9 +75,11 @@ import com.google.devtools.build.skyframe.SkyKey;
 import com.google.devtools.build.skyframe.SkyValue;
 import com.google.devtools.build.skyframe.ValueOrExceptionUtils;
 import com.google.devtools.build.skyframe.ValueOrUntypedException;
+import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.EnumMap;
 import java.util.HashMap;
 import java.util.LinkedHashSet;
 import java.util.LinkedList;
@@ -570,4 +582,120 @@ public final class ActionsTestUtil {
         })
         .build(NULL_ACTION_OWNER);
   }
+
+  /** Builder for a list of {@link MissDetail}s with defaults set to zero for all possible items. */
+  public static class MissDetailsBuilder {
+    private final Map<MissReason, Integer> details = new EnumMap<>(MissReason.class);
+
+    /** Constructs a new builder with all possible cache miss reasons set to zero counts. */
+    public MissDetailsBuilder() {
+      for (MissReason reason : MissReason.values()) {
+        if (reason == MissReason.UNRECOGNIZED) {
+          // The presence of this enum value is a protobuf artifact and not part of our metrics
+          // collection. Just skip it.
+          continue;
+        }
+        details.put(reason, 0);
+      }
+    }
+
+    /** Sets the count of the given miss reason to the given value. */
+    public MissDetailsBuilder set(MissReason reason, int count) {
+      checkArgument(details.containsKey(reason));
+      details.put(reason, count);
+      return this;
+    }
+
+    /** Constructs the list of {@link MissDetail}s. */
+    public Iterable<MissDetail> build() {
+      List<MissDetail> result = new ArrayList<>(details.size());
+      for (Map.Entry<MissReason, Integer> entry : details.entrySet()) {
+        MissDetail detail = MissDetail.newBuilder()
+            .setReason(entry.getKey())
+            .setCount(entry.getValue())
+            .build();
+        result.add(detail);
+      }
+      return result;
+    }
+  }
+
+  /**
+   * An {@link ArtifactResolver} all of whose operations throw an exception.
+   *
+   * <p>This is to be used as a base class by other test programs that need to implement only a
+   * few of the hooks required by the scenario under test.
+   */
+  public static class FakeArtifactResolverBase implements ArtifactResolver {
+    @Override
+    public Artifact getSourceArtifact(
+        PathFragment execPath, Root root, ArtifactOwner owner) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public Artifact getSourceArtifact(PathFragment execPath, Root root) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public Artifact resolveSourceArtifact(
+        PathFragment execPath, RepositoryName repositoryName) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public Map<PathFragment, Artifact> resolveSourceArtifacts(
+        Iterable<PathFragment> execPaths, PackageRootResolver resolver) {
+      throw new UnsupportedOperationException();
+    }
+  }
+
+  /**
+   * A {@link MetadataHandler} all of whose operations throw an exception.
+   *
+   * <p>This is to be used as a base class by other test programs that need to implement only a
+   * few of the hooks required by the scenario under test.
+   */
+  public static class FakeMetadataHandlerBase implements MetadataHandler {
+    @Override
+    public Metadata getMetadata(Artifact artifact) throws IOException {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void setDigestForVirtualArtifact(Artifact artifact, Md5Digest md5Digest) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void addExpandedTreeOutput(TreeFileArtifact output) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public Iterable<TreeFileArtifact> getExpandedOutputs(Artifact artifact) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void injectDigest(ActionInput output, FileStatus statNoFollow, byte[] digest) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public void markOmitted(ActionInput output) {
+      throw new UnsupportedOperationException();
+    }
+
+    @Override
+    public boolean artifactOmitted(Artifact artifact) {
+      return false;
+    }
+
+    @Override
+    public void discardOutputMetadata() {
+      throw new UnsupportedOperationException();
+    }
+  }
 }