79 lines
1.6 KiB
C++
79 lines
1.6 KiB
C++
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#include <pthread.h>
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#include <stdio.h>
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int balance1 = 100000000;
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int balance2 = 100000000;
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pthread_mutex_t m1;
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pthread_mutex_t m2;
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void transfer1to2(int amount)
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{
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pthread_mutex_lock(&m1);
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pthread_mutex_lock(&m2);
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balance1 -= amount;
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balance2 += amount;
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pthread_mutex_unlock(&m1);
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pthread_mutex_unlock(&m2);
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}
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void transfer2to1( int amount )
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{
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pthread_mutex_lock(&m1);
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pthread_mutex_lock(&m2);
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balance2 -= amount;
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balance1 += amount;
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pthread_mutex_unlock(&m1);
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pthread_mutex_unlock(&m2);
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}
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void thr1(int number) {
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for (int i = 0; i < number; i++) {
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if ( i % 1000000 == 0 ) printf("transfer1to2 %d times\n", i);
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transfer1to2(100);
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}
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}
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void thr2(int number) {
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for (int i = 0; i < number; i++) {
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if ( i % 1000000 == 0 ) printf("transfer2to1 %d times\n", i);
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transfer2to1(100);
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}
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}
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int main( int argc, char ** argv )
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{
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int n = 10000000;
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pthread_t t1, t2;
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pthread_attr_t attr;
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pthread_attr_init( &attr );
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pthread_attr_setscope(&attr, PTHREAD_SCOPE_SYSTEM);
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pthread_mutex_init(&m1, NULL);
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pthread_mutex_init(&m2, NULL);
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// Create threads
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pthread_create( &t1, &attr, (void * (*)(void *)) thr1,
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(void *) 10000000);
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pthread_create( &t2, &attr, (void * (*)(void *)) thr2,
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(void *) 10000000);
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// Wait until threads are done
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pthread_join( t1, NULL );
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pthread_join( t2, NULL );
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if ( balance1 + balance2 != 200000000) {
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printf("\n****** Error. Final total is %d\n", balance1 + balance2 );
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printf("****** It should be %d\n", 200000000 );
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}
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else {
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printf("\n>>>>>> O.K. Final total is %d\n", balance1 + balance2);
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}
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}
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