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// 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 com.google.devtools.build.lib.events.ExtendedEventHandler;
import com.google.devtools.build.lib.vfs.Path;
/**
* An action which must know when it is skipped due to an action cache hit.
*
* Use should be rare, as the action graph is a functional model.
*/
public interface NotifyOnActionCacheHit extends Action {
/** A custom interface similar to {@link ActionExecutionContext}, but specific to cache hits. */
interface ActionCachedContext {
/**
* An event listener to report messages to. Errors that signal an action failure should use
* ActionExecutionException.
*/
ExtendedEventHandler getEventHandler();
/**
* Returns the execution root. This is the directory underneath which Blaze builds its entire
* output working tree, including the source symlink forest. All build actions are executed
* relative to this directory.
*/
Path getExecRoot();
/**
* Looks up and returns an action context implementation of the given interface type.
*/
<T extends ActionContext> T getContext(Class<? extends T> type);
}
/**
* Called when action has "cache hit", and therefore need not be executed. Returns false if there
* was a failure to record the action cache hit, and so the action must be executed.
*
* @param context the action context for a cache hit
*/
boolean actionCacheHit(ActionCachedContext context);
}