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-rw-r--r--lib/pthreadpool/pthreadpool.c863
1 files changed, 863 insertions, 0 deletions
diff --git a/lib/pthreadpool/pthreadpool.c b/lib/pthreadpool/pthreadpool.c
new file mode 100644
index 0000000..cbabec9
--- /dev/null
+++ b/lib/pthreadpool/pthreadpool.c
@@ -0,0 +1,863 @@
+/*
+ * Unix SMB/CIFS implementation.
+ * thread pool implementation
+ * Copyright (C) Volker Lendecke 2009
+ *
+ * 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 <http://www.gnu.org/licenses/>.
+ */
+
+#include "replace.h"
+#include "system/time.h"
+#include "system/wait.h"
+#include "system/threads.h"
+#include "system/filesys.h"
+#include "pthreadpool.h"
+#include "lib/util/dlinklist.h"
+
+#ifdef NDEBUG
+#undef NDEBUG
+#endif
+
+#include <assert.h>
+
+struct pthreadpool_job {
+ int id;
+ void (*fn)(void *private_data);
+ void *private_data;
+};
+
+struct pthreadpool {
+ /*
+ * List pthreadpools for fork safety
+ */
+ struct pthreadpool *prev, *next;
+
+ /*
+ * Control access to this struct
+ */
+ pthread_mutex_t mutex;
+
+ /*
+ * Threads waiting for work do so here
+ */
+ pthread_cond_t condvar;
+
+ /*
+ * Array of jobs
+ */
+ size_t jobs_array_len;
+ struct pthreadpool_job *jobs;
+
+ size_t head;
+ size_t num_jobs;
+
+ /*
+ * Indicate job completion
+ */
+ int (*signal_fn)(int jobid,
+ void (*job_fn)(void *private_data),
+ void *job_fn_private_data,
+ void *private_data);
+ void *signal_fn_private_data;
+
+ /*
+ * indicator to worker threads to stop processing further jobs
+ * and exit.
+ */
+ bool stopped;
+
+ /*
+ * indicator to the last worker thread to free the pool
+ * resources.
+ */
+ bool destroyed;
+
+ /*
+ * maximum number of threads
+ * 0 means no real thread, only strict sync processing.
+ */
+ unsigned max_threads;
+
+ /*
+ * Number of threads
+ */
+ unsigned num_threads;
+
+ /*
+ * Number of idle threads
+ */
+ unsigned num_idle;
+
+ /*
+ * Condition variable indicating that helper threads should
+ * quickly go away making way for fork() without anybody
+ * waiting on pool->condvar.
+ */
+ pthread_cond_t *prefork_cond;
+
+ /*
+ * Waiting position for helper threads while fork is
+ * running. The forking thread will have locked it, and all
+ * idle helper threads will sit here until after the fork,
+ * where the forking thread will unlock it again.
+ */
+ pthread_mutex_t fork_mutex;
+};
+
+static pthread_mutex_t pthreadpools_mutex = PTHREAD_MUTEX_INITIALIZER;
+static struct pthreadpool *pthreadpools = NULL;
+static pthread_once_t pthreadpool_atfork_initialized = PTHREAD_ONCE_INIT;
+
+static void pthreadpool_prep_atfork(void);
+
+/*
+ * Initialize a thread pool
+ */
+
+int pthreadpool_init(unsigned max_threads, struct pthreadpool **presult,
+ int (*signal_fn)(int jobid,
+ void (*job_fn)(void *private_data),
+ void *job_fn_private_data,
+ void *private_data),
+ void *signal_fn_private_data)
+{
+ struct pthreadpool *pool;
+ int ret;
+
+ pool = (struct pthreadpool *)malloc(sizeof(struct pthreadpool));
+ if (pool == NULL) {
+ return ENOMEM;
+ }
+ pool->signal_fn = signal_fn;
+ pool->signal_fn_private_data = signal_fn_private_data;
+
+ pool->jobs_array_len = 4;
+ pool->jobs = calloc(
+ pool->jobs_array_len, sizeof(struct pthreadpool_job));
+
+ if (pool->jobs == NULL) {
+ free(pool);
+ return ENOMEM;
+ }
+
+ pool->head = pool->num_jobs = 0;
+
+ ret = pthread_mutex_init(&pool->mutex, NULL);
+ if (ret != 0) {
+ free(pool->jobs);
+ free(pool);
+ return ret;
+ }
+
+ ret = pthread_cond_init(&pool->condvar, NULL);
+ if (ret != 0) {
+ pthread_mutex_destroy(&pool->mutex);
+ free(pool->jobs);
+ free(pool);
+ return ret;
+ }
+
+ ret = pthread_mutex_init(&pool->fork_mutex, NULL);
+ if (ret != 0) {
+ pthread_cond_destroy(&pool->condvar);
+ pthread_mutex_destroy(&pool->mutex);
+ free(pool->jobs);
+ free(pool);
+ return ret;
+ }
+
+ pool->stopped = false;
+ pool->destroyed = false;
+ pool->num_threads = 0;
+ pool->max_threads = max_threads;
+ pool->num_idle = 0;
+ pool->prefork_cond = NULL;
+
+ ret = pthread_mutex_lock(&pthreadpools_mutex);
+ if (ret != 0) {
+ pthread_mutex_destroy(&pool->fork_mutex);
+ pthread_cond_destroy(&pool->condvar);
+ pthread_mutex_destroy(&pool->mutex);
+ free(pool->jobs);
+ free(pool);
+ return ret;
+ }
+ DLIST_ADD(pthreadpools, pool);
+
+ ret = pthread_mutex_unlock(&pthreadpools_mutex);
+ assert(ret == 0);
+
+ pthread_once(&pthreadpool_atfork_initialized, pthreadpool_prep_atfork);
+
+ *presult = pool;
+
+ return 0;
+}
+
+size_t pthreadpool_max_threads(struct pthreadpool *pool)
+{
+ if (pool->stopped) {
+ return 0;
+ }
+
+ return pool->max_threads;
+}
+
+size_t pthreadpool_queued_jobs(struct pthreadpool *pool)
+{
+ int res;
+ int unlock_res;
+ size_t ret;
+
+ if (pool->stopped) {
+ return 0;
+ }
+
+ res = pthread_mutex_lock(&pool->mutex);
+ if (res != 0) {
+ return res;
+ }
+
+ if (pool->stopped) {
+ unlock_res = pthread_mutex_unlock(&pool->mutex);
+ assert(unlock_res == 0);
+ return 0;
+ }
+
+ ret = pool->num_jobs;
+
+ unlock_res = pthread_mutex_unlock(&pool->mutex);
+ assert(unlock_res == 0);
+ return ret;
+}
+
+static void pthreadpool_prepare_pool(struct pthreadpool *pool)
+{
+ int ret;
+
+ ret = pthread_mutex_lock(&pool->fork_mutex);
+ assert(ret == 0);
+
+ ret = pthread_mutex_lock(&pool->mutex);
+ assert(ret == 0);
+
+ while (pool->num_idle != 0) {
+ unsigned num_idle = pool->num_idle;
+ pthread_cond_t prefork_cond;
+
+ ret = pthread_cond_init(&prefork_cond, NULL);
+ assert(ret == 0);
+
+ /*
+ * Push all idle threads off pool->condvar. In the
+ * child we can destroy the pool, which would result
+ * in undefined behaviour in the
+ * pthread_cond_destroy(pool->condvar). glibc just
+ * blocks here.
+ */
+ pool->prefork_cond = &prefork_cond;
+
+ ret = pthread_cond_signal(&pool->condvar);
+ assert(ret == 0);
+
+ while (pool->num_idle == num_idle) {
+ ret = pthread_cond_wait(&prefork_cond, &pool->mutex);
+ assert(ret == 0);
+ }
+
+ pool->prefork_cond = NULL;
+
+ ret = pthread_cond_destroy(&prefork_cond);
+ assert(ret == 0);
+ }
+
+ /*
+ * Probably it's well-defined somewhere: What happens to
+ * condvars after a fork? The rationale of pthread_atfork only
+ * writes about mutexes. So better be safe than sorry and
+ * destroy/reinit pool->condvar across a fork.
+ */
+
+ ret = pthread_cond_destroy(&pool->condvar);
+ assert(ret == 0);
+}
+
+static void pthreadpool_prepare(void)
+{
+ int ret;
+ struct pthreadpool *pool;
+
+ ret = pthread_mutex_lock(&pthreadpools_mutex);
+ assert(ret == 0);
+
+ pool = pthreadpools;
+
+ while (pool != NULL) {
+ pthreadpool_prepare_pool(pool);
+ pool = pool->next;
+ }
+}
+
+static void pthreadpool_parent(void)
+{
+ int ret;
+ struct pthreadpool *pool;
+
+ for (pool = DLIST_TAIL(pthreadpools);
+ pool != NULL;
+ pool = DLIST_PREV(pool)) {
+ ret = pthread_cond_init(&pool->condvar, NULL);
+ assert(ret == 0);
+ ret = pthread_mutex_unlock(&pool->mutex);
+ assert(ret == 0);
+ ret = pthread_mutex_unlock(&pool->fork_mutex);
+ assert(ret == 0);
+ }
+
+ ret = pthread_mutex_unlock(&pthreadpools_mutex);
+ assert(ret == 0);
+}
+
+static void pthreadpool_child(void)
+{
+ int ret;
+ struct pthreadpool *pool;
+
+ for (pool = DLIST_TAIL(pthreadpools);
+ pool != NULL;
+ pool = DLIST_PREV(pool)) {
+
+ pool->num_threads = 0;
+ pool->num_idle = 0;
+ pool->head = 0;
+ pool->num_jobs = 0;
+ pool->stopped = true;
+
+ ret = pthread_cond_init(&pool->condvar, NULL);
+ assert(ret == 0);
+
+ ret = pthread_mutex_unlock(&pool->mutex);
+ assert(ret == 0);
+
+ ret = pthread_mutex_unlock(&pool->fork_mutex);
+ assert(ret == 0);
+ }
+
+ ret = pthread_mutex_unlock(&pthreadpools_mutex);
+ assert(ret == 0);
+}
+
+static void pthreadpool_prep_atfork(void)
+{
+ pthread_atfork(pthreadpool_prepare, pthreadpool_parent,
+ pthreadpool_child);
+}
+
+static int pthreadpool_free(struct pthreadpool *pool)
+{
+ int ret, ret1, ret2;
+
+ ret = pthread_mutex_lock(&pthreadpools_mutex);
+ if (ret != 0) {
+ return ret;
+ }
+ DLIST_REMOVE(pthreadpools, pool);
+ ret = pthread_mutex_unlock(&pthreadpools_mutex);
+ assert(ret == 0);
+
+ ret = pthread_mutex_lock(&pool->mutex);
+ assert(ret == 0);
+ ret = pthread_mutex_unlock(&pool->mutex);
+ assert(ret == 0);
+
+ ret = pthread_mutex_destroy(&pool->mutex);
+ ret1 = pthread_cond_destroy(&pool->condvar);
+ ret2 = pthread_mutex_destroy(&pool->fork_mutex);
+
+ if (ret != 0) {
+ return ret;
+ }
+ if (ret1 != 0) {
+ return ret1;
+ }
+ if (ret2 != 0) {
+ return ret2;
+ }
+
+ free(pool->jobs);
+ free(pool);
+
+ return 0;
+}
+
+/*
+ * Stop a thread pool. Wake up all idle threads for exit.
+ */
+
+static int pthreadpool_stop_locked(struct pthreadpool *pool)
+{
+ int ret;
+
+ pool->stopped = true;
+
+ if (pool->num_threads == 0) {
+ return 0;
+ }
+
+ /*
+ * We have active threads, tell them to finish.
+ */
+
+ ret = pthread_cond_broadcast(&pool->condvar);
+
+ return ret;
+}
+
+/*
+ * Stop a thread pool. Wake up all idle threads for exit.
+ */
+
+int pthreadpool_stop(struct pthreadpool *pool)
+{
+ int ret, ret1;
+
+ ret = pthread_mutex_lock(&pool->mutex);
+ if (ret != 0) {
+ return ret;
+ }
+
+ if (!pool->stopped) {
+ ret = pthreadpool_stop_locked(pool);
+ }
+
+ ret1 = pthread_mutex_unlock(&pool->mutex);
+ assert(ret1 == 0);
+
+ return ret;
+}
+
+/*
+ * Destroy a thread pool. Wake up all idle threads for exit. The last
+ * one will free the pool.
+ */
+
+int pthreadpool_destroy(struct pthreadpool *pool)
+{
+ int ret, ret1;
+ bool free_it;
+
+ assert(!pool->destroyed);
+
+ ret = pthread_mutex_lock(&pool->mutex);
+ if (ret != 0) {
+ return ret;
+ }
+
+ pool->destroyed = true;
+
+ if (!pool->stopped) {
+ ret = pthreadpool_stop_locked(pool);
+ }
+
+ free_it = (pool->num_threads == 0);
+
+ ret1 = pthread_mutex_unlock(&pool->mutex);
+ assert(ret1 == 0);
+
+ if (free_it) {
+ pthreadpool_free(pool);
+ }
+
+ return ret;
+}
+/*
+ * Prepare for pthread_exit(), pool->mutex must be locked and will be
+ * unlocked here. This is a bit of a layering violation, but here we
+ * also take care of removing the pool if we're the last thread.
+ */
+static void pthreadpool_server_exit(struct pthreadpool *pool)
+{
+ int ret;
+ bool free_it;
+
+ pool->num_threads -= 1;
+
+ free_it = (pool->destroyed && (pool->num_threads == 0));
+
+ ret = pthread_mutex_unlock(&pool->mutex);
+ assert(ret == 0);
+
+ if (free_it) {
+ pthreadpool_free(pool);
+ }
+}
+
+static bool pthreadpool_get_job(struct pthreadpool *p,
+ struct pthreadpool_job *job)
+{
+ if (p->stopped) {
+ return false;
+ }
+
+ if (p->num_jobs == 0) {
+ return false;
+ }
+ *job = p->jobs[p->head];
+ p->head = (p->head+1) % p->jobs_array_len;
+ p->num_jobs -= 1;
+ return true;
+}
+
+static bool pthreadpool_put_job(struct pthreadpool *p,
+ int id,
+ void (*fn)(void *private_data),
+ void *private_data)
+{
+ struct pthreadpool_job *job;
+
+ if (p->num_jobs == p->jobs_array_len) {
+ struct pthreadpool_job *tmp;
+ size_t new_len = p->jobs_array_len * 2;
+
+ tmp = realloc(
+ p->jobs, sizeof(struct pthreadpool_job) * new_len);
+ if (tmp == NULL) {
+ return false;
+ }
+ p->jobs = tmp;
+
+ /*
+ * We just doubled the jobs array. The array implements a FIFO
+ * queue with a modulo-based wraparound, so we have to memcpy
+ * the jobs that are logically at the queue end but physically
+ * before the queue head into the reallocated area. The new
+ * space starts at the current jobs_array_len, and we have to
+ * copy everything before the current head job into the new
+ * area.
+ */
+ memcpy(&p->jobs[p->jobs_array_len], p->jobs,
+ sizeof(struct pthreadpool_job) * p->head);
+
+ p->jobs_array_len = new_len;
+ }
+
+ job = &p->jobs[(p->head + p->num_jobs) % p->jobs_array_len];
+ job->id = id;
+ job->fn = fn;
+ job->private_data = private_data;
+
+ p->num_jobs += 1;
+
+ return true;
+}
+
+static void pthreadpool_undo_put_job(struct pthreadpool *p)
+{
+ p->num_jobs -= 1;
+}
+
+static void *pthreadpool_server(void *arg)
+{
+ struct pthreadpool *pool = (struct pthreadpool *)arg;
+ int res;
+
+ res = pthread_mutex_lock(&pool->mutex);
+ if (res != 0) {
+ return NULL;
+ }
+
+ while (1) {
+ struct timespec ts;
+ struct pthreadpool_job job;
+
+ /*
+ * idle-wait at most 1 second. If nothing happens in that
+ * time, exit this thread.
+ */
+
+ clock_gettime(CLOCK_REALTIME, &ts);
+ ts.tv_sec += 1;
+
+ while ((pool->num_jobs == 0) && !pool->stopped) {
+
+ pool->num_idle += 1;
+ res = pthread_cond_timedwait(
+ &pool->condvar, &pool->mutex, &ts);
+ pool->num_idle -= 1;
+
+ if (pool->prefork_cond != NULL) {
+ /*
+ * Me must allow fork() to continue
+ * without anybody waiting on
+ * &pool->condvar. Tell
+ * pthreadpool_prepare_pool that we
+ * got that message.
+ */
+
+ res = pthread_cond_signal(pool->prefork_cond);
+ assert(res == 0);
+
+ res = pthread_mutex_unlock(&pool->mutex);
+ assert(res == 0);
+
+ /*
+ * pthreadpool_prepare_pool has
+ * already locked this mutex across
+ * the fork. This makes us wait
+ * without sitting in a condvar.
+ */
+ res = pthread_mutex_lock(&pool->fork_mutex);
+ assert(res == 0);
+ res = pthread_mutex_unlock(&pool->fork_mutex);
+ assert(res == 0);
+
+ res = pthread_mutex_lock(&pool->mutex);
+ assert(res == 0);
+ }
+
+ if (res == ETIMEDOUT) {
+
+ if (pool->num_jobs == 0) {
+ /*
+ * we timed out and still no work for
+ * us. Exit.
+ */
+ pthreadpool_server_exit(pool);
+ return NULL;
+ }
+
+ break;
+ }
+ assert(res == 0);
+ }
+
+ if (pthreadpool_get_job(pool, &job)) {
+ int ret;
+
+ /*
+ * Do the work with the mutex unlocked
+ */
+
+ res = pthread_mutex_unlock(&pool->mutex);
+ assert(res == 0);
+
+ job.fn(job.private_data);
+
+ ret = pool->signal_fn(job.id,
+ job.fn, job.private_data,
+ pool->signal_fn_private_data);
+
+ res = pthread_mutex_lock(&pool->mutex);
+ assert(res == 0);
+
+ if (ret != 0) {
+ pthreadpool_server_exit(pool);
+ return NULL;
+ }
+ }
+
+ if (pool->stopped) {
+ /*
+ * we're asked to stop processing jobs, so exit
+ */
+ pthreadpool_server_exit(pool);
+ return NULL;
+ }
+ }
+}
+
+static int pthreadpool_create_thread(struct pthreadpool *pool)
+{
+ pthread_attr_t thread_attr;
+ pthread_t thread_id;
+ int res;
+ sigset_t mask, omask;
+
+ /*
+ * Create a new worker thread. It should not receive any signals.
+ */
+
+ sigfillset(&mask);
+
+ res = pthread_attr_init(&thread_attr);
+ if (res != 0) {
+ return res;
+ }
+
+ res = pthread_attr_setdetachstate(
+ &thread_attr, PTHREAD_CREATE_DETACHED);
+ if (res != 0) {
+ pthread_attr_destroy(&thread_attr);
+ return res;
+ }
+
+ res = pthread_sigmask(SIG_BLOCK, &mask, &omask);
+ if (res != 0) {
+ pthread_attr_destroy(&thread_attr);
+ return res;
+ }
+
+ res = pthread_create(&thread_id, &thread_attr, pthreadpool_server,
+ (void *)pool);
+
+ assert(pthread_sigmask(SIG_SETMASK, &omask, NULL) == 0);
+
+ pthread_attr_destroy(&thread_attr);
+
+ if (res == 0) {
+ pool->num_threads += 1;
+ }
+
+ return res;
+}
+
+int pthreadpool_add_job(struct pthreadpool *pool, int job_id,
+ void (*fn)(void *private_data), void *private_data)
+{
+ int res;
+ int unlock_res;
+
+ assert(!pool->destroyed);
+
+ res = pthread_mutex_lock(&pool->mutex);
+ if (res != 0) {
+ return res;
+ }
+
+ if (pool->stopped) {
+ /*
+ * Protect against the pool being shut down while
+ * trying to add a job
+ */
+ unlock_res = pthread_mutex_unlock(&pool->mutex);
+ assert(unlock_res == 0);
+ return EINVAL;
+ }
+
+ if (pool->max_threads == 0) {
+ unlock_res = pthread_mutex_unlock(&pool->mutex);
+ assert(unlock_res == 0);
+
+ /*
+ * If no thread are allowed we do strict sync processing.
+ */
+ fn(private_data);
+ res = pool->signal_fn(job_id, fn, private_data,
+ pool->signal_fn_private_data);
+ return res;
+ }
+
+ /*
+ * Add job to the end of the queue
+ */
+ if (!pthreadpool_put_job(pool, job_id, fn, private_data)) {
+ unlock_res = pthread_mutex_unlock(&pool->mutex);
+ assert(unlock_res == 0);
+ return ENOMEM;
+ }
+
+ if (pool->num_idle > 0) {
+ /*
+ * We have idle threads, wake one.
+ */
+ res = pthread_cond_signal(&pool->condvar);
+ if (res != 0) {
+ pthreadpool_undo_put_job(pool);
+ }
+ unlock_res = pthread_mutex_unlock(&pool->mutex);
+ assert(unlock_res == 0);
+ return res;
+ }
+
+ if (pool->num_threads >= pool->max_threads) {
+ /*
+ * No more new threads, we just queue the request
+ */
+ unlock_res = pthread_mutex_unlock(&pool->mutex);
+ assert(unlock_res == 0);
+ return 0;
+ }
+
+ res = pthreadpool_create_thread(pool);
+ if (res == 0) {
+ unlock_res = pthread_mutex_unlock(&pool->mutex);
+ assert(unlock_res == 0);
+ return 0;
+ }
+
+ if (pool->num_threads != 0) {
+ /*
+ * At least one thread is still available, let
+ * that one run the queued job.
+ */
+ unlock_res = pthread_mutex_unlock(&pool->mutex);
+ assert(unlock_res == 0);
+ return 0;
+ }
+
+ pthreadpool_undo_put_job(pool);
+
+ unlock_res = pthread_mutex_unlock(&pool->mutex);
+ assert(unlock_res == 0);
+
+ return res;
+}
+
+size_t pthreadpool_cancel_job(struct pthreadpool *pool, int job_id,
+ void (*fn)(void *private_data), void *private_data)
+{
+ int res;
+ size_t i, j;
+ size_t num = 0;
+
+ assert(!pool->destroyed);
+
+ res = pthread_mutex_lock(&pool->mutex);
+ if (res != 0) {
+ return res;
+ }
+
+ for (i = 0, j = 0; i < pool->num_jobs; i++) {
+ size_t idx = (pool->head + i) % pool->jobs_array_len;
+ size_t new_idx = (pool->head + j) % pool->jobs_array_len;
+ struct pthreadpool_job *job = &pool->jobs[idx];
+
+ if ((job->private_data == private_data) &&
+ (job->id == job_id) &&
+ (job->fn == fn))
+ {
+ /*
+ * Just skip the entry.
+ */
+ num++;
+ continue;
+ }
+
+ /*
+ * If we already removed one or more jobs (so j will be smaller
+ * then i), we need to fill possible gaps in the logical list.
+ */
+ if (j < i) {
+ pool->jobs[new_idx] = *job;
+ }
+ j++;
+ }
+
+ pool->num_jobs -= num;
+
+ res = pthread_mutex_unlock(&pool->mutex);
+ assert(res == 0);
+
+ return num;
+}
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