130 lines
4.1 KiB
C
130 lines
4.1 KiB
C
/*
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* Copyright (C) 2008 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <pthread.h>
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#include <semaphore.h>
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#include <errno.h>
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#include <stdio.h>
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#include <time.h>
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#include <string.h>
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#include <unistd.h>
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/* a simple semaphore test, using three threads
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*
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* a semaphore is initialized with a value of 1
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*
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* Thread 1, 2 and 3 start at the same time
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*
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* Thread 1 takes the semaphore, then sleeps for 2 seconds, then post the semaphore
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* Thread 2 sleeps for 1 second, then waits the semaphore, sleeps for 2 seconds, then post the semaphoe
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* Thread 3 sleeps 3 seconds, waits for the semaphore
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*/
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static sem_t semaphore;
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static void*
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_thread1( void* unused )
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{
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printf( "thread 1: waiting for semaphore\n" );
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if ( sem_wait( &semaphore ) < 0 ) {
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printf( "thread 1: could not wait for semaphore: %s\n", strerror(errno) );
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return NULL;
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}
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printf( "thread 1: got the semaphore ! sleeping for 2 seconds\n" );
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sleep( 2 );
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printf( "thread 1: awake !! posting semaphore\n" );
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if ( sem_post( &semaphore ) < 0 ) {
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printf( "thread 2: could not post semaphore: %s\n", strerror(errno) );
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}
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printf( "thread 1: quitting\n" );
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return NULL;
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}
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static void*
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_thread2( void* unused )
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{
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printf( "thread 2: sleeping for 1 second\n" );
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sleep(1);
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printf( "thread 2: awake !! waiting for semaphore\n" );
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if ( sem_wait( &semaphore ) < 0 ) {
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printf( "thread 2: could not wait for semaphore: %s\n", strerror(errno) );
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return NULL;
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}
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printf( "thread 2: got the semaphore ! sleeping for 2 seconds\n" );
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sleep( 2 );
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printf( "thread 2: awake !! posting semaphore\n" );
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if ( sem_post( &semaphore ) < 0 ) {
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printf( "thread 2: could not post semaphore: %s\n", strerror(errno) );
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}
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printf( "thread 2: quitting\n" );
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return NULL;
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}
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static void*
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_thread3( void* unused )
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{
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printf( "thread 3: sleeping for 3 seconds\n" );
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sleep(3);
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printf( "thread 3: awake !! waiting for semaphore\n" );
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if ( sem_wait( &semaphore ) < 0 ) {
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printf( "thread 3: could not wait for semaphore: %s\n", strerror(errno) );
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return NULL;
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}
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printf( "thread 3: got semaphore. quitting\n" );
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return NULL;
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}
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typedef void* (*thread_func)(void*);
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static const thread_func thread_routines[] =
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{
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&_thread1,
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&_thread2,
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&_thread3
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};
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int main( void )
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{
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pthread_t t[3];
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int nn;
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if ( sem_init( &semaphore, 0, 1 ) < 0 ) {
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printf( "could not initialize semaphore: %s\n", strerror(errno) );
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return -1;
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}
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for ( nn = 0; nn < 3; nn++ ) {
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if ( pthread_create( &t[nn], NULL, thread_routines[nn], NULL ) < 0 ) {
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printf("could not create thread %d: %s\n", nn+1, strerror(errno) );
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return -2;
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}
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}
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sleep( 5 );
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return 0;
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}
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