https://github.com/datastax/java-driver/java-driver-core: A driver for Apache Cassandra(R) 2.1+ that works exclusively with the Cassandra Query Language version 3 (CQL3) and Cassandra's native protocol versions 3 and above.
  • Various (DataStax) 
/*
 * Copyright DataStax, 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.datastax.oss.driver.api.core.session.throttling;

import edu.umd.cs.findbugs.annotations.NonNull;
import java.io.Closeable;


Limits the number of concurrent requests executed by the driver. 
/** Limits the number of concurrent requests executed by the driver. */
public interface RequestThrottler extends Closeable {

  
Registers a new request to be throttled. The throttler will invoke Throttled.onThrottleReady(boolean) when the request is allowed to proceed. 
/**
   * Registers a new request to be throttled. The throttler will invoke {@link
   * Throttled#onThrottleReady(boolean)} when the request is allowed to proceed.
   */
  void register(@NonNull Throttled request);

  
Signals that a request has succeeded. This indicates to the throttler that another request
might be started.

/**
   * Signals that a request has succeeded. This indicates to the throttler that another request
   * might be started.
   */
  void signalSuccess(@NonNull Throttled request);

  
Signals that a request has failed. This indicates to the throttler that another request might
be started.

/**
   * Signals that a request has failed. This indicates to the throttler that another request might
   * be started.
   */
  void signalError(@NonNull Throttled request, @NonNull Throwable error);

  
Signals that a request has timed out. This indicates to the throttler that this request has
stopped (if it was running already), or that it doesn't need to be started in the future.

Note: requests are responsible for handling their own timeout. The throttler does not
perform time-based eviction on pending requests.

/**
   * Signals that a request has timed out. This indicates to the throttler that this request has
   * stopped (if it was running already), or that it doesn't need to be started in the future.
   *
   * <p>Note: requests are responsible for handling their own timeout. The throttler does not
   * perform time-based eviction on pending requests.
   */
  void signalTimeout(@NonNull Throttled request);
}