freeradius 多线程pool

 

1.thread_pool_manage

1.1  Loop over the thread pool, deleting exited threads.   状态 THREAD_EXITED

for (handle = thread_pool.head; handle; handle = next) {
		next = handle->next;

		/*
		 *	Maybe we've asked the thread to exit, and it
		 *	has agreed.
		 */
		if (handle->status == THREAD_EXITED) {
			pthread_join(handle->pthread_id, NULL);
			delete_thread(handle);

#ifdef HAVE_STDATOMIC_H
			CAS_DECR(thread_pool.exited_threads);
#else
			pthread_mutex_lock(&thread_pool.queue_mutex);
			thread_pool.exited_threads--;
			pthread_mutex_unlock(&thread_pool.queue_mutex);
#endif
		}
	}

1.2If there are too few spare threads.  Go create some more.  

/*
		 *	Create a number of spare threads.
		 */
		for (i = 0; i < total; i++) {
			handle = spawn_thread(now, 1);
			if (handle == NULL) {
				return;
			}
		}

1.3  If there are too many spare threads, delete one.   设置为 handle->status = THREAD_CANCELLED;

/*
		 *	Walk through the thread pool, deleting the
		 *	first idle thread we come across.
		 */
		for (handle = thread_pool.head; (handle != NULL) && (spare > 0) ; handle = next) {
			next = handle->next;

			/*
			 *	If the thread is not handling a
			 *	request, but still live, then tell it
			 *	to exit.
			 *
			 *	It will eventually wake up, and realize
			 *	it's been told to commit suicide.
			 */
			if ((handle->request == NULL) &&
			    (handle->status == THREAD_RUNNING)) {
				handle->status = THREAD_CANCELLED;
				/*
				 *	Post an extra semaphore, as a
				 *	signal to wake up, and exit.
				 */
				sem_post(&thread_pool.semaphore);
				spare--;
				break;
			}
		}

 

1.4Spawn a new thread, and place it in the thread pool.

static THREAD_HANDLE *spawn_thread(time_t now, int do_trigger)
{
	int rcode;
	THREAD_HANDLE *handle;

	/*
	 *	Ensure that we don't spawn too many threads.
	 */
	if (thread_pool.total_threads >= thread_pool.max_threads) {
		DEBUG2("Thread spawn failed.  Maximum number of threads (%d) already running.", thread_pool.max_threads);
		return NULL;
	}

	/*
	 *	Allocate a new thread handle.
	 */
	handle = (THREAD_HANDLE *) rad_malloc(sizeof(THREAD_HANDLE));
	memset(handle, 0, sizeof(THREAD_HANDLE));
	handle->prev = NULL;
	handle->next = NULL;
	handle->thread_num = thread_pool.max_thread_num++;
	handle->request_count = 0;
	handle->status = THREAD_RUNNING;
	handle->timestamp = time(NULL);

	/*
	 *	Create the thread joinable, so that it can be cleaned up
	 *	using pthread_join().
	 *
	 *	Note that the function returns non-zero on error, NOT
	 *	-1.  The return code is the error, and errno isn't set.
	 */
	rcode = pthread_create(&handle->pthread_id, 0, request_handler_thread, handle);
	if (rcode != 0) {
		free(handle);
		ERROR("Thread create failed: %s",
		       fr_syserror(rcode));
		return NULL;
	}

	/*
	 *	One more thread to go into the list.
	 */
	thread_pool.total_threads++;
	DEBUG2("Thread spawned new child %d. Total threads in pool: %d",
			handle->thread_num, thread_pool.total_threads);
	if (do_trigger) exec_trigger(NULL, NULL, "server.thread.start", true);

	/*
	 *	Add the thread handle to the tail of the thread pool list.
	 */
	if (thread_pool.tail) {
		thread_pool.tail->next = handle;
		handle->prev = thread_pool.tail;
		thread_pool.tail = handle;
	} else {
		rad_assert(thread_pool.head == NULL);
		thread_pool.head = thread_pool.tail = handle;
	}

	/*
	 *	Update the time we last spawned a thread.
	 */
	thread_pool.time_last_spawned = now;

	/*
	 * Fire trigger if maximum number of threads reached
	 */
	if (thread_pool.total_threads >= thread_pool.max_threads)
		exec_trigger(NULL, NULL, "server.thread.max_threads", true);

	/*
	 *	And return the new handle to the caller.
	 */
	return handle;
}

2、 The main thread handler for requests. Wait on the semaphore until we have it, and process the request.
 

static void *request_handler_thread(void *arg)
{
	THREAD_HANDLE *self = (THREAD_HANDLE *) arg;
	
	radlog_set_pthread_id(self->pthread_id);

	char tmpbuf[128];
	sprintf(tmpbuf, "request work%d", self->thread_num);
	INFO("start req hander thread:%s, tid:%d", tmpbuf, gettid());
	pthread_setname_np(pthread_self(), tmpbuf);

	/*
	 *	Loop forever, until told to exit.
	 */
	do {
		/*
		 *	Wait to be signalled.
		 */
		DEBUG2("Thread %d waiting to be assigned a request",
		       self->thread_num);
	re_wait:
		if (sem_wait(&thread_pool.semaphore) != 0) { // Wait to be signalled.
			/*
			 *	Interrupted system call.  Go back to
			 *	waiting, but DON'T print out any more
			 *	text.
			 */
			if ((errno == EINTR) || (errno == EAGAIN)) {
				DEBUG2("Re-wait %d", self->thread_num);
				goto re_wait;
			}
			ERROR("Thread %d failed waiting for semaphore: %s: Exiting\n",
			       self->thread_num, fr_syserror(errno));
			break;
		}

		DEBUG2("Thread %d got semaphore", self->thread_num);

#ifdef HAVE_OPENSSL_ERR_H
		/*
		 *	Clear the error queue for the current thread.
		 */
		ERR_clear_error();
#endif

		/*
		 *	The server is exiting.  Don't dequeue any
		 *	requests.
		 */
		if (thread_pool.stop_flag) break;

		/*
		 *	Try to grab a request from the queue.
		 *
		 *	It may be empty, in which case we fail
		 *	gracefully.
		 */
		if (!request_dequeue(&self->request)) continue;

		self->request->child_pid = self->pthread_id;
		self->request_count++;
		self->request->auth_sock_id = self->thread_num;

		DEBUG2("Thread %d handling request %d, (%d handled so far)",
		       self->thread_num, self->request->number,
		       self->request_count);
		self->request->process(self->request, FR_ACTION_RUN);
		self->request = NULL;

#ifdef HAVE_STDATOMIC_H
		CAS_DECR(thread_pool.active_threads);
#else
		/*
		 *	Update the active threads.
		 */
		pthread_mutex_lock(&thread_pool.queue_mutex);
		rad_assert(thread_pool.active_threads > 0);
		thread_pool.active_threads--;
		pthread_mutex_unlock(&thread_pool.queue_mutex);
#endif

		/*
		 *	If the thread has handled too many requests, then make it
		 *	exit.
		 */
		if ((thread_pool.max_requests_per_thread > 0) &&
		    (self->request_count >= thread_pool.max_requests_per_thread)) {
			DEBUG2("Thread %d handled too many requests",
			       self->thread_num);
			break;
		}
	} while (self->status != THREAD_CANCELLED);

OUT:
	DEBUG2("Thread %d exiting...", self->thread_num);

#ifdef HAVE_OPENSSL_ERR_H
	/*
	 *	If we linked with OpenSSL, the application
	 *	must remove the thread's error queue before
	 *	exiting to prevent memory leaks.
	 */
#if OPENSSL_VERSION_NUMBER < 0x10000000L
	ERR_remove_state(0);
#elif OPENSSL_VERSION_NUMBER < 0x10100000L || defined(LIBRESSL_VERSION_NUMBER)
	ERR_remove_thread_state(NULL);
#endif
#endif

#ifdef HAVE_STDATOMIC_H
	CAS_INCR(thread_pool.exited_threads);
#else
	pthread_mutex_lock(&thread_pool.queue_mutex);
	thread_pool.exited_threads++;
	pthread_mutex_unlock(&thread_pool.queue_mutex);
#endif

	/*
	 *  Do this as the LAST thing before exiting.
	 */
	self->request = NULL;
	self->status = THREAD_EXITED;
	exec_trigger(NULL, NULL, "server.thread.stop", true);

	return NULL;
}

/*
 *	Take a THREAD_HANDLE, delete it from the thread pool and
 *	free its resources.
 *
 *	This function is called ONLY from the main server thread,
 *	ONLY after the thread has exited.
 */
static void delete_thread(THREAD_HANDLE *handle)
{
	THREAD_HANDLE *prev;
	THREAD_HANDLE *next;

	rad_assert(handle->request == NULL);

	DEBUG2("Deleting thread %d", handle->thread_num);

	prev = handle->prev;
	next = handle->next;
	rad_assert(thread_pool.total_threads > 0);
	thread_pool.total_threads--;

	/*
	 *	Remove the handle from the list.
	 */
	if (prev == NULL) {
		rad_assert(thread_pool.head == handle);
		thread_pool.head = next;
	} else {
		prev->next = next;
	}

	if (next == NULL) {
		rad_assert(thread_pool.tail == handle);
		thread_pool.tail = prev;
	} else {
		next->prev = prev;
	}

	/*
	 *	Free the handle, now that it's no longer referencable.
	 */
	free(handle);
}