| #include <stdio.h>␍␊ |
| #include <time.h>␍␊ |
| #include <stdlib.h>␍␊ |
| ␍␊ |
| #define BUFFER_SIZE 10␍␊ |
| ␍␊ |
| #if !defined(true) && !defined(false)␍␊ |
| ␉#define true 1␍␊ |
| ␉#define false 0␍␊ |
| #endif␍␊ |
| ␍␊ |
| volatile int counter = -1;␍␊ |
| volatile int buffer[BUFFER_SIZE];␍␊ |
| ␍␊ |
| volatile int turn;␍␊ |
| volatile int flag[2];␍␊ |
| ␍␊ |
| void * produce(void* data) {␍␊ |
| ␉srand (time(NULL));␍␊ |
| ␉while (true)␍␊ |
| ␉{␍␊ |
| ␉␉flag[0] = true;␍␊ |
| ␉␉turn = 1;␍␊ |
| ␉␉while (flag[1] && turn == 1);␍␊ |
| ␉␉if (counter == BUFFER_SIZE - 1) // make sure the buffer doesn't overflow␍␊ |
| ␉␉{␍␊ |
| ␉␉␉flag[0] = false;␍␊ |
| ␉␉␉sleep(5);␍␊ |
| ␉␉␉continue;␍␊ |
| ␉␉}␍␊ |
| ␉␉␍␊ |
| ␉␉␍␊ |
| ␉␉buffer[counter + 1] = rand() % 20 + 1; // yes I know rand is not thread safe - I just need a way to demonstrate a producing/consuming problem - using the same number doesn't help.␍␊ |
| ␉␉printf("PRODUCER value = %i counter = %i\n", buffer[counter + 1], counter + 1);␍␊ |
| ␉␉counter++;␍␊ |
| ␉␉flag[0] = false;␍␊ |
| ␍␊ |
| ␉}␍␊ |
| }␍␊ |
| ␍␊ |
| void * consume(void* data) {␍␊ |
| ␉int i = 0;␍␊ |
| ␉while(true)␍␊ |
| ␉{␍␊ |
| ␉␉flag[1] = true;␍␊ |
| ␉␉turn = 0;␍␊ |
| ␉␉while (flag[0] && turn == 0);␍␊ |
| ␉␉if (counter == -1) // producer hasn't produced - make sure there is content to consume␍␊ |
| ␉␉{␍␊ |
| ␉␉␉flag[1] = false;␍␊ |
| ␉␉␉continue;␍␊ |
| ␉␉}␍␊ |
| ␉␉if (buffer[counter] == 0)␍␊ |
| ␉␉{␍␊ |
| ␉␉␉for(i = 0; i < BUFFER_SIZE; i++)␍␊ |
| ␉␉␉␉printf("%i\n", buffer[i]);␍␊ |
| ␉␉␉printf("Attempting to consume an element that was already consumed counter = %i\n", counter);␍␊ |
| ␉␉␉exit(1);␍␊ |
| ␉␉}␍␊ |
| ␉␉printf("CONSUMER value = %i counter = %i\n", buffer[counter], counter);␍␊ |
| ␉␉buffer[counter] = 0;␍␊ |
| ␉␉counter--;␍␊ |
| ␉␉flag[1] = false;␍␊ |
| ␉␉sleep(1);␍␊ |
| ␉}␍␊ |
| }␍␊ |
| ␍␊ |
| int main() {␍␊ |
| ␉int i;␍␊ |
| ␉pthread_t thread1, thread2;␍␊ |
| ␉int iret1, iret2;␍␊ |
| ␉for(i = 0; i < BUFFER_SIZE; i++)␍␊ |
| ␉␉buffer[i] = -1;␍␊ |
| ␉flag[0] = true;␍␊ |
| ␉flag[1] = true;␍␊ |
| ␉␍␊ |
| ␉iret1 = pthread_create( &thread1, NULL, produce, NULL);␍␊ |
| ␉iret2 = pthread_create( &thread2, NULL, consume, NULL);␍␊ |
| ␉␍␊ |
| ␉pthread_join( thread1, NULL);␍␊ |
| pthread_join( thread2, NULL);␍␊ |
| } |
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