asyncCompareExchange

单HashKey数据的原子CAS操作。compareExchange的异步版本。

public static class CompareExchangeResult {
    /**
     * return value for CompareExchange
     *
     * @param setSucceed true if set value succeed.
     * @param actualValue return the actual value if set value failed; null means the actual value is not exist.
     */
    boolean setSucceed;
    byte[] actualValue;
}
 
public static interface CompareExchangeListener extends GenericFutureListener<Future<CompareExchangeResult>> {
    /**
     * This function will be called when listened asyncCompareExchange future is done.
     *
     * @param future the listened future
     * @throws Exception throw exception if any error occurs.
     *
     * Notice: User shouldn't do any operations that may block or time-consuming
     */
    @Override
    public void operationComplete(Future<CompareExchangeResult> future) throws Exception;
}
 
/**
 * atomically compare and exchange value by key, async version.
 * <p>
 * - if the original value for the key is equal to the expected value, then update it with the desired value,
 *   set CompareExchangeResult.setSucceed to true, and set CompareExchangeResult.actualValue to null because
 *   the actual value must be equal to the desired value.
 * - if the original value for the key is not exist or not equal to the expected value, then set
 *   CompareExchangeResult.setSucceed to false, and set the actual value in CompareExchangeResult.actualValue.
 * <p>
 * this method is very like the C++ function in {https://en.cppreference.com/w/cpp/atomic/atomic_compare_exchange}.
 *
 * @param hashKey       the hash key to compare and exchange.
 * @param sortKey       the sort key to compare and exchange.
 * @param expectedValue the value expected to be found for the key.
 * @param desiredValue  the desired value to set if the original value for the key is equal to the expected value.
 * @param ttlSeconds    time to live in seconds of the desired value, 0 means no ttl.
 * @param timeout       how long will the operation timeout in milliseconds.
 *                      if timeout > 0, it is a timeout value for current op,
 *                      else the timeout value in the configuration file will be used.
 * @return the future for current op
 * <p>
 * Future return:
 * On success: return CompareExchangeResult.
 * On failure: a throwable, which is an instance of PException
 * <p>
 * Thread safety:
 * All the listeners for the same table are guaranteed to be dispatched in the same thread, so all the
 * listeners for the same future are guaranteed to be executed as the same order as the listeners added.
 * But listeners for different tables are not guaranteed to be dispatched in the same thread.
 */
public Future<CompareExchangeResult> asyncCompareExchange(byte[] hashKey, byte[] sortKey,
                                                          byte[] expectedValue, byte[] desiredValue,
                                                          int ttlSeconds, int timeout/*ms*/);

注：

• 参数和返回值：参见同步接口compareExchange。