1 /*
2 * Copyright 2025 The Netty Project
3 *
4 * The Netty Project licenses this file to you under the Apache License,
5 * version 2.0 (the "License"); you may not use this file except in compliance
6 * with the License. You may obtain a copy of the License at:
7 *
8 * https://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, WITHOUT
12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13 * License for the specific language governing permissions and limitations
14 * under the License.
15 */
16 package io.netty.util.concurrent;
17
18 import java.util.concurrent.TimeUnit;
19
20 /**
21 * A nanosecond-based time source, e.g. {@link System#nanoTime()}.
22 */
23 public interface Ticker {
24 /**
25 * Returns the singleton {@link Ticker} that returns the values from the real system clock source.
26 * However, note that this is not the same as {@link System#nanoTime()} because we apply a fixed offset
27 * to the {@link System#nanoTime() nanoTime}.
28 */
29 static Ticker systemTicker() {
30 return SystemTicker.INSTANCE;
31 }
32
33 /**
34 * Returns a newly created mock {@link Ticker} that allows the caller control the flow of time.
35 * This can be useful when you test time-sensitive logic without waiting for too long or introducing
36 * flakiness due to non-deterministic nature of system clock.
37 */
38 static MockTicker newMockTicker() {
39 return new DefaultMockTicker();
40 }
41
42 /**
43 * The initial value used for delay and computations based upon a monotonic time source.
44 * @return initial value used for delay and computations based upon a monotonic time source.
45 */
46 long initialNanoTime();
47
48 /**
49 * The time elapsed since initialization of this class in nanoseconds. This may return a negative number just like
50 * {@link System#nanoTime()}.
51 */
52 long nanoTime();
53
54 /**
55 * Waits until the given amount of time goes by.
56 *
57 * @param delay the amount of delay.
58 * @param unit the {@link TimeUnit} of {@code delay}.
59 *
60 * @see Thread#sleep(long)
61 */
62 void sleep(long delay, TimeUnit unit) throws InterruptedException;
63
64 /**
65 * Waits until the given amount of time goes by.
66 *
67 * @param delayMillis the number of milliseconds.
68 *
69 * @see Thread#sleep(long)
70 */
71 default void sleepMillis(long delayMillis) throws InterruptedException {
72 sleep(delayMillis, TimeUnit.MILLISECONDS);
73 }
74 }