89 lines
2.8 KiB
C
89 lines
2.8 KiB
C
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//This program is demo for using pthreads with libev.
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//Try using Timeout values as large as 1.0 and as small as 0.000001
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//and notice the difference in the output
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//(c) 2009 debuguo
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//(c) 2013 enthusiasticgeek for stack overflow
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//Free to distribute and improve the code. Leave credits intact
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#include <ev.h>
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#include <stdio.h> // for puts
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#include <stdlib.h>
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#include <pthread.h>
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#include <stdbool.h>
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pthread_mutex_t lock;
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double timeout = 0.00001;
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ev_timer timeout_watcher;
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int timeout_count = 0;
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ev_async async_watcher;
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int async_count = 0;
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struct ev_loop* loop2;
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void* loop2thread(void* args)
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{
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printf("Inside loop 2"); // Here one could initiate another timeout watcher
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ev_loop(loop2, 0); // similar to the main loop - call it say timeout_cb1
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return NULL;
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}
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static void async_cb (EV_P_ ev_async *w, int revents)
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{
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//puts ("async ready");
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pthread_mutex_lock(&lock); //Don't forget locking
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++async_count;
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printf("async = %d, timeout = %d \n", async_count, timeout_count);
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pthread_mutex_unlock(&lock); //Don't forget unlocking
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}
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static void timeout_cb (EV_P_ ev_timer *w, int revents) // Timer callback function
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{
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//puts ("timeout");
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if (ev_async_pending(&async_watcher)==false) { //the event has not yet been processed (or even noted) by the event loop? (i.e. Is it serviced? If yes then proceed to)
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ev_async_send(loop2, &async_watcher); //Sends/signals/activates the given ev_async watcher, that is, feeds an EV_ASYNC event on the watcher into the event loop.
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}
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pthread_mutex_lock(&lock); //Don't forget locking
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++timeout_count;
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pthread_mutex_unlock(&lock); //Don't forget unlocking
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w->repeat = timeout;
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ev_timer_again(loop, &timeout_watcher); //Start the timer again.
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}
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int main (int argc, char** argv)
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{
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if (argc < 2) {
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puts("Timeout value missing.\n./demo <timeout>");
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return -1;
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}
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timeout = atof(argv[1]);
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struct ev_loop *loop = EV_DEFAULT; //or ev_default_loop (0);
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//Initialize pthread
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pthread_mutex_init(&lock, NULL);
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pthread_t thread;
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// This loop sits in the pthread
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loop2 = ev_loop_new(0);
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//This block is specifically used pre-empting thread (i.e. temporary interruption and suspension of a task, without asking for its cooperation, with the intention to resume that task later.)
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//This takes into account thread safety
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ev_async_init(&async_watcher, async_cb);
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ev_async_start(loop2, &async_watcher);
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pthread_create(&thread, NULL, loop2thread, NULL);
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ev_timer_init (&timeout_watcher, timeout_cb, timeout, 0.); // Non repeating timer. The timer starts repeating in the timeout callback function
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ev_timer_start (loop, &timeout_watcher);
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// now wait for events to arrive
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ev_loop(loop, 0);
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//Wait on threads for execution
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pthread_join(thread, NULL);
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pthread_mutex_destroy(&lock);
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return 0;
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}
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