docker/data-generator/src/main/java/org/apache/flink/playground/datagen/Throttler.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.flink.playground.datagen;

/** A data throttler that controls the rate at which data is written out to Kafka. */
final class Throttler {

  private final long throttleBatchSize;
  private final long nanosPerBatch;

  private long endOfNextBatchNanos;
  private int currentBatch;

  Throttler(long maxRecordsPerSecond) {
    if (maxRecordsPerSecond == -1) {
      // unlimited speed
      throttleBatchSize = -1;
      nanosPerBatch = 0;
      endOfNextBatchNanos = System.nanoTime() + nanosPerBatch;
      currentBatch = 0;
      return;
    }
    final float ratePerSubtask = (float) maxRecordsPerSecond;

    if (ratePerSubtask >= 10000) {
      // high rates: all throttling in intervals of 2ms
      throttleBatchSize = (int) ratePerSubtask / 500;
      nanosPerBatch = 2_000_000L;
    } else {
      throttleBatchSize = ((int) (ratePerSubtask / 20)) + 1;
      nanosPerBatch = ((int) (1_000_000_000L / ratePerSubtask)) * throttleBatchSize;
    }
    this.endOfNextBatchNanos = System.nanoTime() + nanosPerBatch;
    this.currentBatch = 0;
  }

  void throttle() throws InterruptedException {
    if (throttleBatchSize == -1) {
      return;
    }
    if (++currentBatch != throttleBatchSize) {
      return;
    }
    currentBatch = 0;

    final long now = System.nanoTime();
    final int millisRemaining = (int) ((endOfNextBatchNanos - now) / 1_000_000);

    if (millisRemaining > 0) {
      endOfNextBatchNanos += nanosPerBatch;
      Thread.sleep(millisRemaining);
    } else {
      endOfNextBatchNanos = now + nanosPerBatch;
    }
  }
}