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78 lines
1.8 KiB
78 lines
1.8 KiB
#include <stdio.h>
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#include <stdlib.h>
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#include <pthread.h>
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pthread_mutex_t count_mutex = PTHREAD_MUTEX_INITIALIZER;
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pthread_cond_t condition_var = PTHREAD_COND_INITIALIZER;
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void *functionCount1();
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void *functionCount2();
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int count = 0;
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#define COUNT_DONE 10
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#define COUNT_HALT1 3
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#define COUNT_HALT2 6
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main()
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{
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pthread_t thread1, thread2;
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pthread_create( &thread1, NULL, &functionCount1, NULL);
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pthread_create( &thread2, NULL, &functionCount2, NULL);
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pthread_join( thread1, NULL);
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pthread_join( thread2, NULL);
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printf("Final count: %d\n",count);
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exit(EXIT_SUCCESS);
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}
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// Write numbers 1-3 and 8-10 as permitted by functionCount2()
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void *functionCount1()
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{
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for(;;)
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{
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// Lock mutex and then wait for signal to relase mutex
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pthread_mutex_lock( &count_mutex );
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// Wait while functionCount2() operates on count
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// mutex unlocked if condition varialbe in functionCount2() signaled.
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pthread_cond_wait( &condition_var, &count_mutex );
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count++;
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printf("Counter value functionCount1: %d\n",count);
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pthread_mutex_unlock( &count_mutex );
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if(count >= COUNT_DONE) return(NULL);
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}
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}
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// Write numbers 4-7
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void *functionCount2()
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{
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for(;;)
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{
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pthread_mutex_lock( &count_mutex );
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if( count < COUNT_HALT1 || count > COUNT_HALT2 )
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{
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// Condition of if statement has been met.
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// Signal to free waiting thread by freeing the mutex.
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// Note: functionCount1() is now permitted to modify "count".
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pthread_cond_signal( &condition_var );
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}
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else
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{
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count++;
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printf("Counter value functionCount2: %d\n",count);
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}
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pthread_mutex_unlock( &count_mutex );
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if(count >= COUNT_DONE) return(NULL);
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}
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}
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