/*
 * 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.lucene.store;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;
import org.apache.lucene.store.RateLimiter.SimpleRateLimiter;
import org.apache.lucene.tests.util.LuceneTestCase;
import org.apache.lucene.tests.util.TestUtil;
import org.apache.lucene.util.ThreadInterruptedException;

/** Simple testcase for RateLimiter.SimpleRateLimiter */
public final class TestRateLimiter extends LuceneTestCase {

  // LUCENE-6075
  public void testOverflowInt() throws Exception {
    Thread t =
        new Thread() {
          @Override
          public void run() {
            expectThrows(
                ThreadInterruptedException.class,
                () -> {
                  new SimpleRateLimiter(1)
                      .pause((long) (1.5 * Integer.MAX_VALUE * 1024 * 1024 / 1000));
                });
          }
        };
    t.start();
    Thread.sleep(10);
    t.interrupt();
  }

  public void testThreads() throws Exception {

    double targetMBPerSec = 10.0 + 20 * random().nextDouble();
    final SimpleRateLimiter limiter = new SimpleRateLimiter(targetMBPerSec);

    final CountDownLatch startingGun = new CountDownLatch(1);

    Thread[] threads = new Thread[TestUtil.nextInt(random(), 3, 6)];
    final AtomicLong totBytes = new AtomicLong();
    for (int i = 0; i < threads.length; i++) {
      threads[i] =
          new Thread() {
            @Override
            public void run() {
              try {
                startingGun.await();
              } catch (InterruptedException ie) {
                throw new ThreadInterruptedException(ie);
              }
              long bytesSinceLastPause = 0;
              for (int i = 0; i < 500; i++) {
                long numBytes = TestUtil.nextInt(random(), 1000, 10000);
                totBytes.addAndGet(numBytes);
                bytesSinceLastPause += numBytes;
                if (bytesSinceLastPause > limiter.getMinPauseCheckBytes()) {
                  limiter.pause(bytesSinceLastPause);
                  bytesSinceLastPause = 0;
                }
              }
            }
          };
      threads[i].start();
    }

    long startNS = System.nanoTime();
    startingGun.countDown();
    for (Thread thread : threads) {
      thread.join();
    }
    long endNS = System.nanoTime();
    double actualMBPerSec =
        (totBytes.get() / 1024. / 1024.)
            / ((endNS - startNS) / (double) TimeUnit.SECONDS.toNanos(1));

    // TODO: this may false trip .... could be we can only assert that it never exceeds the max, so
    // slow jenkins doesn't trip:
    double ratio = actualMBPerSec / targetMBPerSec;

    // Only enforce that it wasn't too fast; if machine is bogged down (can't schedule threads /
    // sleep properly) then it may falsely be too slow:
    assumeTrue(
        "actualMBPerSec=" + actualMBPerSec + " targetMBPerSec=" + targetMBPerSec, 0.9 <= ratio);
    assertTrue(
        "targetMBPerSec=" + targetMBPerSec + " actualMBPerSec=" + actualMBPerSec, ratio <= 1.1);
  }
}
