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SnapshotableAtomicRegister.java
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SnapshotableAtomicRegister.java
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/*
* Copyright (c) 2020, MicroRaft.
*
* 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 io.microraft.tutorial.atomicregister;
import java.util.List;
import java.util.function.Consumer;
import javax.annotation.Nonnull;
import io.microraft.statemachine.StateMachine;
/**
* Provides snapshotting logic for the atomic register state machine.
* <p>
* YOU CAN SEE THIS CLASS AT:
* <p>
* https://github.com/MicroRaft/MicroRaft/blob/master/microraft-tutorial/src/main/java/io/microraft/tutorial/atomicregister/SnapshotableAtomicRegister.java
*/
public class SnapshotableAtomicRegister extends OperableAtomicRegister implements StateMachine {
@Override
public void takeSnapshot(long commitIndex, Consumer<Object> snapshotChunkConsumer) {
// put the current value of the atomic register into a snapshot chunk.
snapshotChunkConsumer.accept(new AtomicRegisterSnapshotChunk(value));
}
@Override
public void installSnapshot(long commitIndex, @Nonnull List<Object> snapshotChunks) {
if (snapshotChunks.size() != 1) {
// takeSnapshot() method returns a single snapshot chunk.
throw new IllegalArgumentException(
"Invalid snapshot chunks: " + snapshotChunks + " at commit index: " + commitIndex);
}
// install the value of the atomic register from the snapshot chunk.
this.value = ((AtomicRegisterSnapshotChunk) snapshotChunks.get(0)).value;
}
private static class AtomicRegisterSnapshotChunk {
final Object value;
AtomicRegisterSnapshotChunk(Object value) {
this.value = value;
}
@Override
public String toString() {
return "AtomicRegisterSnapshotChunk{" + "value='" + value + '\'' + '}';
}
}
}