test_semaphore.c revision e16cb84e2324f05334d18dcf5956f20f44262b62
1e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project/* 2e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * Copyright (C) 2008 The Android Open Source Project 3e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * All rights reserved. 4e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * 5e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * Redistribution and use in source and binary forms, with or without 6e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * modification, are permitted provided that the following conditions 7e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * are met: 8e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * * Redistributions of source code must retain the above copyright 9e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * notice, this list of conditions and the following disclaimer. 10e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * * Redistributions in binary form must reproduce the above copyright 11e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * notice, this list of conditions and the following disclaimer in 12e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * the documentation and/or other materials provided with the 13e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * distribution. 14e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * 15e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * SUCH DAMAGE. 27e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project */ 28e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project#include <pthread.h> 29e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project#include <semaphore.h> 30e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project#include <errno.h> 31e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project#include <stdio.h> 32e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project#include <time.h> 33e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project#include <string.h> 34e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project#include <unistd.h> 35e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project 36e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project/* a simple semaphore test, using three threads 37e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * 38e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * a semaphore is initialized with a value of 1 39e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * 40e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * Thread 1, 2 and 3 start at the same time 41e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * 42e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * Thread 1 takes the semaphore, then sleeps for 2 seconds, then post the semaphore 43e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * Thread 2 sleeps for 1 second, then waits the semaphore, sleeps for 2 seconds, then post the semaphoe 44e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project * Thread 3 sleeps 3 seconds, waits for the semaphore 45e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project */ 46e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project 47e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Projectstatic sem_t semaphore; 48e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project 49e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Projectstatic void* 50e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project_thread1( void* unused ) 51e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project{ 52e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project printf( "thread 1: waiting for semaphore\n" ); 53e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project if ( sem_wait( &semaphore ) < 0 ) { 54e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project printf( "thread 1: could not wait for semaphore: %s\n", strerror(errno) ); 55e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project return NULL; 56e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project } 57e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project printf( "thread 1: got the semaphore ! sleeping for 2 seconds\n" ); 58e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project sleep( 2 ); 59e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project printf( "thread 1: awake !! posting semaphore\n" ); 60e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project if ( sem_post( &semaphore ) < 0 ) { 61e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project printf( "thread 2: could not post semaphore: %s\n", strerror(errno) ); 62e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project } 63e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project printf( "thread 1: quitting\n" ); 64e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project return NULL; 65e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project} 66e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project 67e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Projectstatic void* 68e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project_thread2( void* unused ) 69e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project{ 70e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project printf( "thread 2: sleeping for 1 second\n" ); 71e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project sleep(1); 72e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project printf( "thread 2: awake !! waiting for semaphore\n" ); 73e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project if ( sem_wait( &semaphore ) < 0 ) { 74e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project printf( "thread 2: could not wait for semaphore: %s\n", strerror(errno) ); 75e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project return NULL; 76e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project } 77e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project printf( "thread 2: got the semaphore ! sleeping for 2 seconds\n" ); 78e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project sleep( 2 ); 79e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project printf( "thread 2: awake !! posting semaphore\n" ); 80e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project if ( sem_post( &semaphore ) < 0 ) { 81e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project printf( "thread 2: could not post semaphore: %s\n", strerror(errno) ); 82e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project } 83e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project printf( "thread 2: quitting\n" ); 84e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project return NULL; 85e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project} 86e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project 87e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project 88e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Projectstatic void* 89e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project_thread3( void* unused ) 90e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project{ 91e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project printf( "thread 3: sleeping for 3 seconds\n" ); 92e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project sleep(3); 93e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project printf( "thread 3: awake !! waiting for semaphore\n" ); 94e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project if ( sem_wait( &semaphore ) < 0 ) { 95e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project printf( "thread 3: could not wait for semaphore: %s\n", strerror(errno) ); 96e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project return NULL; 97e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project } 98e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project printf( "thread 3: got semaphore. quitting\n" ); 99e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project return NULL; 100e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project} 101e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project 102e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Projecttypedef void* (*thread_func)(void*); 103e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project 104e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Projectstatic const thread_func thread_routines[] = 105e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project{ 106e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project &_thread1, 107e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project &_thread2, 108e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project &_thread3 109e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project}; 110e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project 111e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Projectint main( void ) 112e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project{ 113e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project pthread_t t[3]; 114e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project int nn; 115e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project 116e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project if ( sem_init( &semaphore, 0, 1 ) < 0 ) { 117e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project printf( "could not initialize semaphore: %s\n", strerror(errno) ); 118e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project return -1; 119e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project } 120e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project 121e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project for ( nn = 0; nn < 3; nn++ ) { 122e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project if ( pthread_create( &t[nn], NULL, thread_routines[nn], NULL ) < 0 ) { 123e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project printf("could not create thread %d: %s\n", nn+1, strerror(errno) ); 124e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project return -2; 125e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project } 126e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project } 127e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project sleep( 5 ); 128e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project return 0; 129e16cb84e2324f05334d18dcf5956f20f44262b62The Android Open Source Project} 130