--- /dev/null
+/* $Id $ */
+
+/* timed_thread.c
+ * Author: Philip Kovacs
+ *
+ * Abstraction layer for timed threads
+ * */
+
+#include <pthread.h>
+#include <assert.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <time.h>
+#include "timed_thread.h"
+
+/* Abstraction layer for timed threads */
+
+/* private */
+struct _timed_thread
+{
+ pthread_t thread; /* thread itself */
+ pthread_attr_t thread_attr; /* thread attributes */
+ pthread_mutex_t cs_mutex; /* critical section mutex */
+ pthread_mutex_t runnable_mutex; /* only for the runnable_cond */
+ pthread_cond_t runnable_cond; /* used to time and stop the thread */
+ unsigned int interval_usecs; /* firing interval in microseconds */
+};
+
+/* linked list of created threadsa */
+typedef struct _timed_thread_list
+{
+ timed_thread *p_timed_thread;
+ timed_thread **addr_of_p_timed_thread;
+ struct _timed_thread_list *next;
+} timed_thread_node, timed_thread_list;
+
+static timed_thread_list *p_timed_thread_list_head = NULL;
+static timed_thread_list *p_timed_thread_list_tail = NULL;
+
+
+/* create a timed thread */
+timed_thread*
+timed_thread_create (void *(*start_routine)(void*), void *arg, unsigned int interval_usecs)
+{
+ timed_thread *p_timed_thread;
+
+ assert ((start_routine != NULL) && (interval_usecs >= MINIMUM_INTERVAL_USECS));
+
+ if ((p_timed_thread = calloc (sizeof(timed_thread), 1)) == 0)
+ return NULL;
+
+ /* init attributes, e.g. joinable thread */
+ pthread_attr_init (&p_timed_thread->thread_attr);
+ pthread_attr_setdetachstate (&p_timed_thread->thread_attr, PTHREAD_CREATE_JOINABLE);
+ /* init mutexes */
+ pthread_mutex_init (&p_timed_thread->cs_mutex, NULL);
+ pthread_mutex_init (&p_timed_thread->runnable_mutex, NULL);
+ /* init cond */
+ pthread_cond_init (&p_timed_thread->runnable_cond, NULL);
+
+ p_timed_thread->interval_usecs = interval_usecs;
+
+ /* create thread */
+ if (pthread_create (&p_timed_thread->thread, &p_timed_thread->thread_attr, start_routine, arg))
+ {
+ timed_thread_destroy (p_timed_thread, NULL);
+ return NULL;
+ }
+
+ return p_timed_thread;
+}
+
+
+/* destroy a timed thread.
+ * optional addr_of_p_timed_thread to set callers pointer to NULL as a convenience. */
+void
+timed_thread_destroy (timed_thread* p_timed_thread, timed_thread** addr_of_p_timed_thread)
+{
+ assert (p_timed_thread != NULL);
+ assert ((addr_of_p_timed_thread == NULL) || (*addr_of_p_timed_thread == p_timed_thread));
+
+ /* signal thread to stop */
+ pthread_mutex_lock (&p_timed_thread->runnable_mutex);
+ pthread_cond_signal (&p_timed_thread->runnable_cond);
+ pthread_mutex_unlock (&p_timed_thread->runnable_mutex);
+
+ /* join the terminating thread */
+ pthread_join (p_timed_thread->thread, NULL);
+
+ /* clean up */
+ pthread_attr_destroy (&p_timed_thread->thread_attr);
+ pthread_mutex_destroy (&p_timed_thread->cs_mutex);
+ pthread_mutex_destroy (&p_timed_thread->runnable_mutex);
+ pthread_cond_destroy (&p_timed_thread->runnable_cond);
+
+ free (p_timed_thread);
+ if (addr_of_p_timed_thread)
+ *addr_of_p_timed_thread = NULL;
+}
+
+
+/* lock a timed thread for critical section activity */
+int
+timed_thread_lock (timed_thread* p_timed_thread)
+{
+ assert (p_timed_thread != NULL);
+
+ return pthread_mutex_lock (&p_timed_thread->cs_mutex);
+}
+
+
+/* unlock a timed thread after critical section activity */
+int
+timed_thread_unlock (timed_thread* p_timed_thread)
+{
+ assert (p_timed_thread != NULL);
+
+ return pthread_mutex_unlock (&p_timed_thread->cs_mutex);
+}
+
+
+/* waits required interval for termination signal and returns 1 if got it, 0 otherwise */
+int
+timed_thread_test (timed_thread* p_timed_thread)
+{
+ struct timespec abstime, reltime;
+
+ assert (p_timed_thread != NULL);
+
+ /* get the absolute time in the future we stop waiting for condition to signal */
+ clock_gettime (CLOCK_REALTIME, &abstime);
+ /* seconds portion of the microseconds interval */
+ reltime.tv_sec = (time_t)(p_timed_thread->interval_usecs / 1000000);
+ /* remaining microseconds convert to nanoseconds */
+ reltime.tv_nsec = (long)((p_timed_thread->interval_usecs % 1000000) * 1000);
+ /* absolute future time */
+ abstime.tv_sec += reltime.tv_sec;
+ abstime.tv_nsec += reltime.tv_nsec;
+
+ /* wait until future time for runnable_cond to signal */
+ if (pthread_cond_timedwait (&p_timed_thread->runnable_cond,
+ &p_timed_thread->runnable_mutex,
+ &abstime) != ETIMEDOUT)
+ {
+ /* runnable_cond was signalled or some error occured */
+ pthread_mutex_unlock (&p_timed_thread->runnable_mutex);
+ /* tell caller to exit */
+ return 1;
+ }
+
+ /* tell caller not to exit yet */
+ return 0;
+}
+
+
+/* exit a timed thread */
+void
+timed_thread_exit (timed_thread* p_timed_thread)
+{
+ assert (p_timed_thread != NULL);
+
+ pthread_exit (NULL);
+}
+
+
+/* register a timed thread for future destruction via timed_thread_destroy_registered_threads() */
+int
+timed_thread_register (timed_thread* p_timed_thread, timed_thread** addr_of_p_timed_thread)
+{
+ timed_thread_node *p_node;
+
+ assert (p_timed_thread != NULL);
+ assert ((addr_of_p_timed_thread == NULL) || (*addr_of_p_timed_thread == p_timed_thread));
+
+ if ((p_node = calloc (sizeof (timed_thread_node), 1)) == 0)
+ return 0;
+
+ p_node->p_timed_thread = p_timed_thread;
+ p_node->addr_of_p_timed_thread = addr_of_p_timed_thread;
+ p_node->next = NULL;
+
+ if (!p_timed_thread_list_tail)
+ {
+ /* first node of empty list */
+ p_timed_thread_list_tail = p_node;
+ p_timed_thread_list_head = p_node;
+ }
+ else
+ {
+ /* add node to tail of non-empty list */
+ p_timed_thread_list_tail->next = p_node;
+ p_timed_thread_list_tail = p_node;
+ }
+
+ return 0;
+}
+
+
+/* destroy all registered timed threads */
+void
+timed_thread_destroy_registered_threads (void)
+{
+ timed_thread_node *p_node, *p_next;
+
+ for (p_node=p_timed_thread_list_head;
+ p_node;
+ p_node=p_next)
+ {
+ p_next = p_node->next;
+ timed_thread_destroy (p_node->p_timed_thread, p_node->addr_of_p_timed_thread);
+ free (p_node);
+ }
+
+ p_timed_thread_list_head = NULL;
+ p_timed_thread_list_tail = NULL;
+}
+
--- /dev/null
+/* $Id $ */
+
+/* timed_thread.h
+ * Author: Philip Kovacs
+ *
+ * Abstraction layer for timed threads
+ * */
+
+
+#define MINIMUM_INTERVAL_USECS 50000 /* 50000 microseconds = 50 ms = 0.05 sec */
+
+/* opaque structure for clients */
+typedef struct _timed_thread timed_thread;
+
+/* create a timed thread */
+timed_thread* timed_thread_create (void *(*start_routine)(void*), void *arg, unsigned int interval_ms);
+
+/* destroy a timed thread */
+void timed_thread_destroy (timed_thread* p_timed_thread, timed_thread** addr_of_p_timed_thread);
+
+/* lock a timed thread for critical section activity */
+int timed_thread_lock (timed_thread* p_timed_thread);
+
+/* unlock a timed thread after critical section activity */
+int timed_thread_unlock (timed_thread* p_timed_thread);
+
+/* waits required interval for termination signal and returns 1 if got it, 0 otherwise */
+int timed_thread_test (timed_thread* p_timed_thread);
+
+/* exit a timed thread */
+void timed_thread_exit (timed_thread* p_timed_thread);
+
+/* register a timed thread for future destruction */
+int timed_thread_register (timed_thread* p_timed_thread, timed_thread** addr_of_p_timed_thread);
+
+/* destroy all registered timed threads */
+void timed_thread_destroy_registered_threads (void);
projects / monky / commitdiff