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/* Copyright (C) 2021 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include <assert.h>
#include <pthread.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include "libknot/libknot.h"
#include "knot/server/dthreads.h"
#include "knot/worker/pool.h"
/*!
* \brief Worker pool state.
*/
struct worker_pool {
dt_unit_t *threads;
pthread_mutex_t lock;
pthread_cond_t wake;
bool terminating; /*!< Is the pool terminating? .*/
bool suspended; /*!< Is execution temporarily suspended? .*/
int running; /*!< Number of running threads. */
worker_queue_t tasks;
};
/*!
* \brief Worker thread.
*
* The thread takes a task from the tasks queue and runs it, while checking
* if the dispatching of new tasks is allowed by the thread pool.
*
* An execution of a running thread cannot be enforced.
*
*/
static int worker_main(dthread_t *thread)
{
assert(thread);
worker_pool_t *pool = thread->data;
pthread_mutex_lock(&pool->lock);
for (;;) {
if (pool->terminating) {
break;
}
worker_task_t *task = NULL;
if (!pool->suspended) {
task = worker_queue_dequeue(&pool->tasks);
}
if (task == NULL) {
pthread_cond_wait(&pool->wake, &pool->lock);
continue;
}
assert(task->run);
pool->running += 1;
pthread_mutex_unlock(&pool->lock);
task->run(task);
pthread_mutex_lock(&pool->lock);
pool->running -= 1;
pthread_cond_broadcast(&pool->wake);
}
pthread_mutex_unlock(&pool->lock);
return KNOT_EOK;
}
/* -- public API ------------------------------------------------------------ */
worker_pool_t *worker_pool_create(unsigned threads)
{
worker_pool_t *pool = malloc(sizeof(worker_pool_t));
if (pool == NULL) {
return NULL;
}
memset(pool, 0, sizeof(worker_pool_t));
pool->threads = dt_create(threads, worker_main, NULL, pool);
if (pool->threads == NULL) {
goto fail;
}
if (pthread_mutex_init(&pool->lock, NULL) != 0) {
goto fail;
}
if (pthread_cond_init(&pool->wake, NULL) != 0) {
goto fail;
}
worker_queue_init(&pool->tasks);
return pool;
fail:
dt_delete(&pool->threads);
free(pool);
return NULL;
}
void worker_pool_destroy(worker_pool_t *pool)
{
if (!pool) {
return;
}
dt_delete(&pool->threads);
pthread_mutex_destroy(&pool->lock);
pthread_cond_destroy(&pool->wake);
worker_queue_deinit(&pool->tasks);
free(pool);
}
void worker_pool_start(worker_pool_t *pool)
{
if (!pool) {
return;
}
dt_start(pool->threads);
}
void worker_pool_stop(worker_pool_t *pool)
{
if (!pool) {
return;
}
pthread_mutex_lock(&pool->lock);
pool->terminating = true;
pthread_cond_broadcast(&pool->wake);
pthread_mutex_unlock(&pool->lock);
dt_stop(pool->threads);
}
void worker_pool_suspend(worker_pool_t *pool)
{
if (!pool) {
return;
}
pthread_mutex_lock(&pool->lock);
pool->suspended = true;
pthread_mutex_unlock(&pool->lock);
}
void worker_pool_resume(worker_pool_t *pool)
{
if (!pool) {
return;
}
pthread_mutex_lock(&pool->lock);
pool->suspended = false;
pthread_cond_broadcast(&pool->wake);
pthread_mutex_unlock(&pool->lock);
}
void worker_pool_join(worker_pool_t *pool)
{
if (!pool) {
return;
}
dt_join(pool->threads);
}
void worker_pool_wait_cb(worker_pool_t *pool, wait_callback_t cb)
{
if (!pool) {
return;
}
pthread_mutex_lock(&pool->lock);
while (!EMPTY_LIST(pool->tasks.list) || pool->running > 0) {
if (cb != NULL) {
cb(pool);
}
pthread_cond_wait(&pool->wake, &pool->lock);
}
pthread_mutex_unlock(&pool->lock);
}
void worker_pool_wait(worker_pool_t *pool)
{
worker_pool_wait_cb(pool, NULL);
}
void worker_pool_assign(worker_pool_t *pool, struct task *task)
{
if (!pool || !task) {
return;
}
pthread_mutex_lock(&pool->lock);
worker_queue_enqueue(&pool->tasks, task);
pthread_cond_signal(&pool->wake);
pthread_mutex_unlock(&pool->lock);
}
void worker_pool_clear(worker_pool_t *pool)
{
if (!pool) {
return;
}
pthread_mutex_lock(&pool->lock);
worker_queue_deinit(&pool->tasks);
worker_queue_init(&pool->tasks);
pthread_mutex_unlock(&pool->lock);
}
void worker_pool_status(worker_pool_t *pool, bool locked, int *running, int *queued)
{
if (!pool) {
*running = *queued = 0;
return;
}
if (!locked) {
pthread_mutex_lock(&pool->lock);
}
*running = pool->running;
*queued = worker_queue_length(&pool->tasks);
if (!locked) {
pthread_mutex_unlock(&pool->lock);
}
}
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