Add a TrimmedConfigurationProgressReceiver.

This will be used to monitor Skyframe changes so that the trimming cache can be
updated accordingly.

Progress on #6524.

PiperOrigin-RevId: 244956343
diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/TrimmedConfigurationProgressReceiver.java b/src/main/java/com/google/devtools/build/lib/skyframe/TrimmedConfigurationProgressReceiver.java
new file mode 100644
index 0000000..6571bf5
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/TrimmedConfigurationProgressReceiver.java
@@ -0,0 +1,134 @@
+// 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.skyframe;
+
+import com.google.common.base.Preconditions;
+import com.google.devtools.build.lib.analysis.config.BuildOptions;
+import com.google.devtools.build.lib.cmdline.Label;
+import com.google.devtools.build.lib.skyframe.trimming.TrimmedConfigurationCache;
+import com.google.devtools.build.skyframe.EvaluationProgressReceiver.EvaluationState;
+import com.google.devtools.build.skyframe.EvaluationProgressReceiver.EvaluationSuccessState;
+import com.google.devtools.build.skyframe.EvaluationProgressReceiver.InvalidationState;
+import com.google.devtools.build.skyframe.EvaluationProgressReceiver.NullEvaluationProgressReceiver;
+import com.google.devtools.build.skyframe.SkyKey;
+import com.google.devtools.build.skyframe.SkyValue;
+import java.util.function.Supplier;
+import javax.annotation.Nullable;
+
+/**
+ * Skyframe progress receiver which keeps a {@link TrimmedConfigurationCache} in sync with Skyframe
+ * invalidations and revalidations.
+ */
+public final class TrimmedConfigurationProgressReceiver extends NullEvaluationProgressReceiver {
+
+  private final TrimmedConfigurationCache<SkyKey, Label, BuildOptions.OptionsDiffForReconstruction>
+      cache;
+
+  private boolean enabled = true;
+
+  public TrimmedConfigurationProgressReceiver(
+      TrimmedConfigurationCache<SkyKey, Label, BuildOptions.OptionsDiffForReconstruction> cache) {
+    this.cache = cache;
+  }
+
+  public static TrimmedConfigurationCache<SkyKey, Label, BuildOptions.OptionsDiffForReconstruction>
+      buildCache() {
+    return new TrimmedConfigurationCache<>(
+        TrimmedConfigurationProgressReceiver::extractLabel,
+        TrimmedConfigurationProgressReceiver::extractOptionsDiff,
+        BuildOptions.OptionsDiffForReconstruction::compareFragments);
+  }
+
+  public TrimmedConfigurationCache<SkyKey, Label, BuildOptions.OptionsDiffForReconstruction>
+      getCache() {
+    return this.cache;
+  }
+
+  public static Label extractLabel(SkyKey key) {
+    Preconditions.checkArgument(isKeyCacheable(key));
+    ConfiguredTargetKey configuredTargetKey = (ConfiguredTargetKey) key;
+    return configuredTargetKey.getLabel();
+  }
+
+  public static BuildOptions.OptionsDiffForReconstruction extractOptionsDiff(SkyKey key) {
+    Preconditions.checkArgument(isKeyCacheable(key));
+    ConfiguredTargetKey configuredTargetKey = (ConfiguredTargetKey) key;
+    BuildConfigurationValue.Key configurationKey = configuredTargetKey.getConfigurationKey();
+    return configurationKey.getOptionsDiff();
+  }
+
+  public static boolean isKeyCacheable(SkyKey key) {
+    if (!(key instanceof ConfiguredTargetKey)) {
+      // Only configured targets go in the cache.
+      // TODO(mstaib): add aspect support
+      return false;
+    }
+    ConfiguredTargetKey configuredTargetKey = (ConfiguredTargetKey) key;
+    if (configuredTargetKey.getConfigurationKey() == null) {
+      // Null-configured targets do not go in the cache.
+      return false;
+    }
+    return true;
+  }
+
+  public void activate() {
+    if (this.enabled) {
+      return;
+    }
+    this.enabled = true;
+  }
+
+  public void deactivate() {
+    if (!this.enabled) {
+      return;
+    }
+    this.enabled = false;
+    this.cache.clear();
+  }
+
+  @Override
+  public void invalidated(SkyKey key, InvalidationState state) {
+    if (!enabled || !isKeyCacheable(key)) {
+      return;
+    }
+    switch (state) {
+      case DIRTY:
+        cache.invalidate(key);
+        break;
+      case DELETED:
+        cache.remove(key);
+        break;
+    }
+  }
+
+  @Override
+  public void evaluated(
+      SkyKey key,
+      @Nullable SkyValue value,
+      Supplier<EvaluationSuccessState> evaluationSuccessState,
+      EvaluationState state) {
+    if (!enabled || !isKeyCacheable(key)) {
+      return;
+    }
+    switch (state) {
+      case BUILT:
+        // Do nothing; the evaluation would have handled putting itself (back) in the cache.
+        break;
+      case CLEAN:
+        cache.revalidate(key);
+        break;
+    }
+  }
+}