diff options
author | Eric Andersen <andersen@codepoet.org> | 2002-02-13 09:32:52 +0000 |
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committer | Eric Andersen <andersen@codepoet.org> | 2002-02-13 09:32:52 +0000 |
commit | 80e6061ac5deca193759b979d34906bfc9b857ef (patch) | |
tree | 51f5c410f9313c6892b50f27321b64db8cfbd737 /test/pthread/ex3.c | |
parent | 98cba6e7dd947aec0d4cf6e61f2f31318ac919e1 (diff) |
Several test suite updates. The testatexit, teston_exit, and
pthread tests were contributed by Stefan Soucek
Diffstat (limited to 'test/pthread/ex3.c')
-rw-r--r-- | test/pthread/ex3.c | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/test/pthread/ex3.c b/test/pthread/ex3.c new file mode 100644 index 000000000..8005200ef --- /dev/null +++ b/test/pthread/ex3.c @@ -0,0 +1,152 @@ +/* Multi-thread searching. + Illustrates: thread cancellation, cleanup handlers. */ + +#include <errno.h> +#include <stdio.h> +#include <unistd.h> +#include <stdlib.h> +#include <sys/types.h> +#include <pthread.h> + +/* Defines the number of searching threads */ +#define NUM_THREADS 5 + +/* Function prototypes */ +void *search(void *); +void print_it(void *); + +/* Global variables */ +pthread_t threads[NUM_THREADS]; +pthread_mutex_t lock; +int tries; +volatile int started; + +int main(int argc, char ** argv) +{ + int i; + int pid; + + /* create a number to search for */ + pid = getpid(); + printf("Searching for the number = %d...\n", pid); + + /* Initialize the mutex lock */ + pthread_mutex_init(&lock, NULL); + + /* Create the searching threads */ + for (started=0; started<NUM_THREADS; started++) + pthread_create(&threads[started], NULL, search, (void *)pid); + + /* Wait for (join) all the searching threads */ + for (i=0; i<NUM_THREADS; i++) + pthread_join(threads[i], NULL); + + printf("It took %d tries to find the number.\n", tries); + + /* Exit the program */ + return 0; +} + +/* This is the cleanup function that is called + when the threads are cancelled */ + +void print_it(void *arg) +{ + int *try = (int *) arg; + pthread_t tid; + + /* Get the calling thread's ID */ + tid = pthread_self(); + + /* Print where the thread was in its search when it was cancelled */ + printf("Thread %lx was canceled on its %d try.\n", tid, *try); +} + +/* This is the search routine that is executed in each thread */ + +void *search(void *arg) +{ + int num = (int) arg; + int i, j, ntries; + pthread_t tid; + + /* get the calling thread ID */ + tid = pthread_self(); + + /* use the thread ID to set the seed for the random number generator */ + /* Since srand and rand are not thread-safe, serialize with lock */ + + /* Try to lock the mutex lock -- + if locked, check to see if the thread has been cancelled + if not locked then continue */ + while (pthread_mutex_trylock(&lock) == EBUSY) + pthread_testcancel(); + + srand((int)tid); + i = rand() & 0xFFFFFF; + pthread_mutex_unlock(&lock); + ntries = 0; + + /* Set the cancellation parameters -- + - Enable thread cancellation + - Defer the action of the cancellation */ + + pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL); + pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED, NULL); + + while (started < NUM_THREADS) + sched_yield (); + + /* Push the cleanup routine (print_it) onto the thread + cleanup stack. This routine will be called when the + thread is cancelled. Also note that the pthread_cleanup_push + call must have a matching pthread_cleanup_pop call. The + push and pop calls MUST be at the same lexical level + within the code */ + + /* Pass address of `ntries' since the current value of `ntries' is not + the one we want to use in the cleanup function */ + + pthread_cleanup_push(print_it, (void *)&ntries); + + /* Loop forever */ + while (1) { + i = (i + 1) & 0xFFFFFF; + ntries++; + + /* Does the random number match the target number? */ + if (num == i) { + /* Try to lock the mutex lock -- + if locked, check to see if the thread has been cancelled + if not locked then continue */ + while (pthread_mutex_trylock(&lock) == EBUSY) + pthread_testcancel(); + + /* Set the global variable for the number of tries */ + tries = ntries; + printf("Thread %lx found the number!\n", tid); + + /* Cancel all the other threads */ + for (j=0; j<NUM_THREADS; j++) + if (threads[j] != tid) pthread_cancel(threads[j]); + + /* Break out of the while loop */ + break; + } + + /* Every 100 tries check to see if the thread has been cancelled. */ + if (ntries % 100 == 0) { + pthread_testcancel(); + } + } + + /* The only way we can get here is when the thread breaks out + of the while loop. In this case the thread that makes it here + has found the number we are looking for and does not need to run + the thread cleanup function. This is why the pthread_cleanup_pop + function is called with a 0 argument; this will pop the cleanup + function off the stack without executing it */ + + pthread_cleanup_pop(0); + return((void *)0); +} |