1/*
2 * Copyright (C) 2012 Square, Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16package com.squareup.okhttp.internal.spdy;
17
18import java.util.concurrent.CountDownLatch;
19import java.util.concurrent.TimeUnit;
20
21/**
22 * A locally-originated ping.
23 */
24public final class Ping {
25  private final CountDownLatch latch = new CountDownLatch(1);
26  private long sent = -1;
27  private long received = -1;
28
29  Ping() {
30  }
31
32  void send() {
33    if (sent != -1) throw new IllegalStateException();
34    sent = System.nanoTime();
35  }
36
37  void receive() {
38    if (received != -1 || sent == -1) throw new IllegalStateException();
39    received = System.nanoTime();
40    latch.countDown();
41  }
42
43  void cancel() {
44    if (received != -1 || sent == -1) throw new IllegalStateException();
45    received = sent - 1;
46    latch.countDown();
47  }
48
49  /**
50   * Returns the round trip time for this ping in nanoseconds, waiting for the
51   * response to arrive if necessary. Returns -1 if the response was
52   * cancelled.
53   */
54  public long roundTripTime() throws InterruptedException {
55    latch.await();
56    return received - sent;
57  }
58
59  /**
60   * Returns the round trip time for this ping in nanoseconds, or -1 if the
61   * response was cancelled, or -2 if the timeout elapsed before the round
62   * trip completed.
63   */
64  public long roundTripTime(long timeout, TimeUnit unit) throws InterruptedException {
65    if (latch.await(timeout, unit)) {
66      return received - sent;
67    } else {
68      return -2;
69    }
70  }
71}
72