/*
* Copyright 2013-present Facebook, Inc.
*
* 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.facebook.buck.rules;
import java.io.IOException;
/**
* Object that has in-memory data structures that need to be populated as a result of executing its
* steps. An object that implements this interface will <em>always</em> have its internal data
* structures initialized through this interface, regardless of whether it was built locally or read
* from cache. This ensures that a rule is always in the same state once {@code isRuleBuilt()}
* returns {@code true}.
*
* <p>Objects that implement this interface should create getter methods that delegate to {@link
* BuildOutputInitializer#getBuildOutput()} to access the in-memory data structures rather than have
* clients invoke {@link BuildOutputInitializer#getBuildOutput()} directly. This ensures that all
* getters go through any protections provided by {@link BuildOutputInitializer#getBuildOutput()}.
*
* <p>
*/
public interface InitializableFromDisk<T> {
/**
* @param onDiskBuildInfo can be used to read metadata from disk to help initialize the rule.
* @return an object that has the in-memory data structures that need to be populated as a result
* of executing this object's steps.
*/
T initializeFromDisk(OnDiskBuildInfo onDiskBuildInfo) throws IOException;
BuildOutputInitializer<T> getBuildOutputInitializer();
}