org.springframework.boot.devtools.filewatch.SnapshotStateRepository Maven / Gradle / Ivy
/*
* Copyright 2012-2020 the original author or authors.
*
* 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
*
* https://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 org.springframework.boot.devtools.filewatch;
/**
* Repository used by {@link FileSystemWatcher} to save file/directory snapshots across
* restarts.
*
* @author Phillip Webb
* @since 2.4.0
*/
public interface SnapshotStateRepository {
/**
* A No-op {@link SnapshotStateRepository} that does not save state.
*/
SnapshotStateRepository NONE = new SnapshotStateRepository() {
@Override
public void save(Object state) {
}
@Override
public Object restore() {
return null;
}
};
/**
* A {@link SnapshotStateRepository} that uses a static instance to keep state across
* restarts.
*/
SnapshotStateRepository STATIC = StaticSnapshotStateRepository.INSTANCE;
/**
* Save the given state in the repository.
* @param state the state to save
*/
void save(Object state);
/**
* Restore any previously saved state.
* @return the previously saved state or {@code null}
*/
Object restore();
}