| // Copyright 2021 The Bazel Authors. All rights reserved. |
| // |
| // 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.google.devtools.build.lib.dynamic; |
| |
| import static com.google.common.truth.Truth.assertThat; |
| |
| import org.junit.Test; |
| import org.junit.runner.RunWith; |
| import org.junit.runners.JUnit4; |
| |
| /** Tests for {@link ShrinkableSemaphore}. */ |
| @RunWith(JUnit4.class) |
| public class ShrinkableSemaphoreTest { |
| |
| @Test |
| public void testUpdateLoad_shrinksUnderLoad() { |
| ShrinkableSemaphore sem = new ShrinkableSemaphore(12, 30, 0.75); |
| assertThat(sem.availablePermits()).isEqualTo(12); |
| sem.updateLoad(0); |
| assertThat(sem.availablePermits()).isEqualTo(12); |
| sem.updateLoad(10); // 1/3 load * 0.75 factor = 1/12 reduction |
| assertThat(sem.availablePermits()).isEqualTo(11); |
| sem.updateLoad(20); |
| assertThat(sem.availablePermits()).isEqualTo(10); |
| sem.updateLoad(30); |
| assertThat(sem.availablePermits()).isEqualTo(9); |
| sem.updateLoad(4); |
| assertThat(sem.availablePermits()).isEqualTo(12); |
| } |
| |
| @Test |
| public void testUpdateLoad_shrinksProperlyWhenPermitsTaken() throws InterruptedException { |
| ShrinkableSemaphore sem = new ShrinkableSemaphore(12, 30, 0.5); |
| assertThat(sem.availablePermits()).isEqualTo(12); |
| sem.acquire(5); |
| sem.updateLoad(0); |
| assertThat(sem.availablePermits()).isEqualTo(7); |
| sem.updateLoad(10); // 1/3 load * 0.5 factor = 1/6 reduction, and 5 acquired |
| assertThat(sem.availablePermits()).isEqualTo(5); |
| sem.acquire(5); |
| assertThat(sem.availablePermits()).isEqualTo(0); |
| sem.updateLoad(20); // More permits temporarily taken than available |
| assertThat(sem.availablePermits()).isEqualTo(-2); |
| sem.release(); |
| assertThat(sem.availablePermits()).isEqualTo(-1); |
| sem.updateLoad(30); // Only 6 permits allowed under load, 9 still acquired |
| assertThat(sem.availablePermits()).isEqualTo(-3); |
| sem.updateLoad(10); // Now 10 permits allowed under load, 9 still acquired |
| assertThat(sem.availablePermits()).isEqualTo(1); |
| } |
| |
| @Test |
| public void testUpdateLoad_noShrinkWithZeroFactor() throws InterruptedException { |
| ShrinkableSemaphore sem = new ShrinkableSemaphore(12, 30, 0); |
| assertThat(sem.availablePermits()).isEqualTo(12); |
| sem.acquire(5); |
| sem.updateLoad(0); |
| assertThat(sem.availablePermits()).isEqualTo(7); |
| sem.updateLoad(30); |
| assertThat(sem.availablePermits()).isEqualTo(7); |
| sem.release(2); |
| assertThat(sem.availablePermits()).isEqualTo(9); |
| } |
| |
| @Test |
| public void testUpdateLoad_noShrinkBelowZero() { |
| ShrinkableSemaphore sem = new ShrinkableSemaphore(12, 30, 0.5); |
| assertThat(sem.availablePermits()).isEqualTo(12); |
| sem.updateLoad(60); |
| assertThat(sem.availablePermits()).isEqualTo(1); |
| sem.updateLoad(80); |
| assertThat(sem.availablePermits()).isEqualTo(1); |
| sem.updateLoad(40); |
| assertThat(sem.availablePermits()).isEqualTo(4); |
| } |
| } |