spring-data-redis CompareAndSet 源码
spring-data-redis CompareAndSet 代码
文件路径：/src/main/java/org/springframework/data/redis/support/atomic/CompareAndSet.java
/*
* Copyright 2018-2022 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.data.redis.support.atomic;
import java.util.Collection;
import java.util.function.Consumer;
import java.util.function.Supplier;
import org.springframework.dao.DataAccessException;
import org.springframework.data.redis.core.RedisOperations;
import org.springframework.data.redis.core.SessionCallback;
import org.springframework.util.CollectionUtils;
/**
* Compare-and-set (CAS) operation using Redis Transactions ({@literal WATCH} and {@literal MULTI}) to atomically update
* the value at {@code key}.
* <p>
* The CAS block registers a {@literal WATCH} on the key holding the expected value which guarantees that changes after
* watching and comparing the key will rollback the transaction. The {@literal WATCH} is reset if the comparison fails.
*
* @author Mark Paluch
* @since 2.0.8
* @see RedisAtomicDouble
* @see RedisAtomicInteger
* @see RedisAtomicLong
*/
class CompareAndSet<T> implements SessionCallback<Boolean> {
private final Supplier<T> getter;
private final Consumer<T> setter;
private final Object key;
private final T expect;
private final T update;
CompareAndSet(Supplier<T> getter, Consumer<T> setter, Object key, T expect, T update) {
this.getter = getter;
this.setter = setter;
this.key = key;
this.expect = expect;
this.update = update;
}
@Override
@SuppressWarnings("unchecked")
public <K, V> Boolean execute(RedisOperations<K, V> operations) throws DataAccessException {
operations.watch((K) key);
if (expect.equals(getter.get())) {
operations.multi();
setter.accept(update);
if (updateSuccessful(operations.exec())) {
return true;
}
}
operations.unwatch();
return false;
}
private static boolean updateSuccessful(Collection<?> exec) {
return !CollectionUtils.isEmpty(exec);
}
}
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spring-data-redis RedisAtomicDouble 源码
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