#include <stdio.h>
+#include <ac/signal.h>
#include <ac/stdarg.h>
#include <ac/stdlib.h>
#include <ac/string.h>
#ifndef LDAP_THREAD_HAVE_TPOOL
-typedef enum ldap_int_thread_pool_state_e {
- LDAP_INT_THREAD_POOL_RUNNING,
- LDAP_INT_THREAD_POOL_FINISHING,
- LDAP_INT_THREAD_POOL_STOPPING
-} ldap_int_thread_pool_state_t;
-
/* Thread-specific key with data and optional free function */
typedef struct ldap_int_tpool_key_s {
void *ltk_key;
/* Max number of threads */
#define LDAP_MAXTHR 1024 /* must be a power of 2 */
+/* (Theoretical) max number of pending requests */
+#define MAX_PENDING (INT_MAX/2) /* INT_MAX - (room to avoid overflow) */
+
/* Context: thread ID and thread-specific key/data pairs */
typedef struct ldap_int_thread_userctx_s {
ldap_pvt_thread_t ltu_id;
void *ltt_arg;
} ldap_int_thread_task_t;
+typedef LDAP_STAILQ_HEAD(tcq, ldap_int_thread_task_s) ldap_int_tpool_plist_t;
+
struct ldap_int_thread_pool_s {
LDAP_STAILQ_ENTRY(ldap_int_thread_pool_s) ltp_next;
/* ltp_active_count <= 1 && ltp_pause */
ldap_pvt_thread_cond_t ltp_pcond;
+ /* ltp_pause == 0 ? <p_pending_list : &empty_pending_list,
+ * maintaned to reduce work for pool_wrapper()
+ */
+ ldap_int_tpool_plist_t *ltp_work_list;
+
/* pending tasks, and unused task objects */
- LDAP_STAILQ_HEAD(tcq, ldap_int_thread_task_s) ltp_pending_list;
+ ldap_int_tpool_plist_t ltp_pending_list;
LDAP_SLIST_HEAD(tcl, ldap_int_thread_task_s) ltp_free_list;
- ldap_int_thread_pool_state_t ltp_state;
+ /* The pool is finishing, waiting for its threads to close.
+ * They close when ltp_pending_list is done. pool_submit()
+ * rejects new tasks. ltp_max_pending = -(its old value).
+ */
+ int ltp_finishing;
+
+ /* Some active task needs to be the sole active task.
+ * Atomic variable so ldap_pvt_thread_pool_pausing() can read it.
+ * Note: Pauses adjust ltp_<open_count/vary_open_count/work_list>,
+ * so pool_<submit/wrapper>() mostly can avoid testing ltp_pause.
+ */
+ volatile sig_atomic_t ltp_pause;
+
+ /* Max number of threads in pool, or 0 for default (LDAP_MAXTHR) */
+ int ltp_max_count;
- /* some active request needs to be the sole active request */
- int ltp_pause;
+ /* Max number of pending + paused requests, negated when ltp_finishing */
+ int ltp_max_pending;
- long ltp_max_count; /* max number of threads in pool, or 0 */
- long ltp_max_pending; /* max pending or paused requests, or 0 */
- long ltp_pending_count; /* pending or paused requests */
- long ltp_active_count; /* active, not paused requests */
- long ltp_open_count; /* number of threads */
- long ltp_starting; /* currenlty starting threads */
+ int ltp_pending_count; /* Pending or paused requests */
+ int ltp_active_count; /* Active, not paused requests */
+ int ltp_open_count; /* Number of threads, negated when ltp_pause */
+ int ltp_starting; /* Currenlty starting threads */
+
+ /* >0 if paused or we may open a thread, <0 if we should close a thread.
+ * Updated when ltp_<finishing/pause/max_count/open_count> change.
+ * Maintained to reduce the time ltp_mutex must be locked in
+ * ldap_pvt_thread_pool_<submit/wrapper>().
+ */
+ int ltp_vary_open_count;
+# define SET_VARY_OPEN_COUNT(pool) \
+ ((pool)->ltp_vary_open_count = \
+ (pool)->ltp_pause ? 1 : \
+ (pool)->ltp_finishing ? -1 : \
+ ((pool)->ltp_max_count ? (pool)->ltp_max_count : LDAP_MAXTHR) \
+ - (pool)->ltp_open_count)
};
+static ldap_int_tpool_plist_t empty_pending_list =
+ LDAP_STAILQ_HEAD_INITIALIZER(empty_pending_list);
+
static int ldap_int_has_thread_pool = 0;
static LDAP_STAILQ_HEAD(tpq, ldap_int_thread_pool_s)
ldap_int_thread_pool_list =
if (! (0 <= max_threads && max_threads <= LDAP_MAXTHR))
max_threads = 0;
- if (max_pending < 0)
- max_pending = 0;
+ if (! (1 <= max_pending && max_pending <= MAX_PENDING))
+ max_pending = MAX_PENDING;
*tpool = NULL;
pool = (ldap_pvt_thread_pool_t) LDAP_CALLOC(1,
return(rc);
ldap_int_has_thread_pool = 1;
- pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
+
pool->ltp_max_count = max_threads;
+ SET_VARY_OPEN_COUNT(pool);
pool->ltp_max_pending = max_pending;
+
LDAP_STAILQ_INIT(&pool->ltp_pending_list);
+ pool->ltp_work_list = &pool->ltp_pending_list;
LDAP_SLIST_INIT(&pool->ltp_free_list);
+
ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
LDAP_STAILQ_INSERT_TAIL(&ldap_int_thread_pool_list, pool, ltp_next);
ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
* lock the mutex right now, since no threads are running.
*/
pool->ltp_open_count++;
+ SET_VARY_OPEN_COUNT(pool);
ldap_pvt_thread_t thr;
rc = ldap_pvt_thread_create( &thr, 1, ldap_int_thread_pool_wrapper, pool );
return(-1);
ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
- if (pool->ltp_state != LDAP_INT_THREAD_POOL_RUNNING
- || (pool->ltp_max_pending
- && pool->ltp_pending_count >= pool->ltp_max_pending))
- {
- ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
- return(-1);
- }
+
+ if (pool->ltp_pending_count >= pool->ltp_max_pending)
+ goto failed;
task = LDAP_SLIST_FIRST(&pool->ltp_free_list);
if (task) {
LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltt_next.l);
} else {
task = (ldap_int_thread_task_t *) LDAP_MALLOC(sizeof(*task));
- if (task == NULL) {
- ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
- return(-1);
- }
+ if (task == NULL)
+ goto failed;
}
task->ltt_start_routine = start_routine;
pool->ltp_pending_count++;
LDAP_STAILQ_INSERT_TAIL(&pool->ltp_pending_list, task, ltt_next.q);
- if (pool->ltp_pause) {
- ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
- return(0);
- }
- ldap_pvt_thread_cond_signal(&pool->ltp_cond);
- if (pool->ltp_open_count < pool->ltp_active_count + pool->ltp_pending_count
- && (pool->ltp_open_count <
- (pool->ltp_max_count ? pool->ltp_max_count : LDAP_MAXTHR)))
+
+ /* true if ltp_pause != 0 or we should open (create) a thread */
+ if (pool->ltp_vary_open_count > 0 &&
+ pool->ltp_open_count < pool->ltp_active_count+pool->ltp_pending_count)
{
- pool->ltp_open_count++;
+ if (pool->ltp_pause)
+ goto done;
+
pool->ltp_starting++;
+ pool->ltp_open_count++;
+ SET_VARY_OPEN_COUNT(pool);
+
if (0 != ldap_pvt_thread_create(
&thr, 1, ldap_int_thread_pool_wrapper, pool))
{
*/
pool->ltp_starting--;
pool->ltp_open_count--;
+ SET_VARY_OPEN_COUNT(pool);
+
if (pool->ltp_open_count == 0) {
/* no open threads at all?!?
*/
* back out of ltp_pending_count, free the task,
* report the error.
*/
+ pool->ltp_pending_count--;
LDAP_STAILQ_REMOVE(&pool->ltp_pending_list, task,
ldap_int_thread_task_s, ltt_next.q);
- pool->ltp_pending_count--;
- ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
- LDAP_FREE(task);
- return(-1);
+ LDAP_SLIST_INSERT_HEAD(&pool->ltp_free_list, task,
+ ltt_next.l);
+ goto failed;
}
}
/* there is another open thread, so this
* task will be handled eventually.
- * continue on, we have signalled that
- * the task is waiting.
*/
}
}
+ ldap_pvt_thread_cond_signal(&pool->ltp_cond);
+ done:
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
return(0);
+
+ failed:
+ ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
+ return(-1);
}
/* Set max #threads. value <= 0 means max supported #threads (LDAP_MAXTHR) */
return(-1);
ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
+
pool->ltp_max_count = max_threads;
+ SET_VARY_OPEN_COUNT(pool);
+
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
return(0);
}
case LDAP_PVT_THREAD_POOL_PARAM_MAX_PENDING:
count = pool->ltp_max_pending;
+ if (count < 0)
+ count = -count;
+ if (count == MAX_PENDING)
+ count = 0;
break;
case LDAP_PVT_THREAD_POOL_PARAM_OPEN:
count = pool->ltp_open_count;
+ if (count < 0)
+ count = -count;
break;
case LDAP_PVT_THREAD_POOL_PARAM_STARTING:
case LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD_MAX:
break;
- case LDAP_PVT_THREAD_POOL_PARAM_STATE: {
- static struct {
- char *name;
- ldap_int_thread_pool_state_t state;
- } str2state[] = {
- { "running", LDAP_INT_THREAD_POOL_RUNNING },
- { "finishing", LDAP_INT_THREAD_POOL_FINISHING },
- { "stopping", LDAP_INT_THREAD_POOL_STOPPING },
- { NULL }
- };
- int i;
-
- if ( pool->ltp_pause ) {
- *((char **)value) = "pausing";
- } else {
- for ( i = 0; str2state[ i ].name != NULL; i++ ) {
- if ( str2state[ i ].state == pool->ltp_state ) {
- break;
- }
- }
- *((char **)value) = str2state[ i ].name;
- }
- if ( *((char **)value) != NULL ) {
- count = -2;
- }
- } break;
+ case LDAP_PVT_THREAD_POOL_PARAM_STATE:
+ *((char **)value) =
+ pool->ltp_pause ? "pausing" :
+ !pool->ltp_finishing ? "running" :
+ pool->ltp_pending_count ? "finishing" : "stopping";
+ break;
case LDAP_PVT_THREAD_POOL_PARAM_UNKNOWN:
break;
return ( count == -1 ? -1 : 0 );
}
+/*
+ * true if pool is pausing; does not lock any mutex to check.
+ * 0 if not pause, 1 if pause, -1 if error or no pool.
+ */
+int
+ldap_pvt_thread_pool_pausing( ldap_pvt_thread_pool_t *tpool )
+{
+ int rc = -1;
+ struct ldap_int_thread_pool_s *pool;
+
+ if ( tpool != NULL && (pool = *tpool) != NULL ) {
+ rc = pool->ltp_pause;
+ }
+
+ return rc;
+}
+
/*
* wrapper for ldap_pvt_thread_pool_query(), left around
* for backwards compatibility
if (pool != pptr) return(-1);
ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
- pool->ltp_state = run_pending
- ? LDAP_INT_THREAD_POOL_FINISHING
- : LDAP_INT_THREAD_POOL_STOPPING;
+
+ pool->ltp_finishing = 1;
+ SET_VARY_OPEN_COUNT(pool);
+ if (pool->ltp_max_pending > 0)
+ pool->ltp_max_pending = -pool->ltp_max_pending;
+
+ if (!run_pending) {
+ while ((task = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL) {
+ LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltt_next.q);
+ LDAP_FREE(task);
+ }
+ pool->ltp_pending_count = 0;
+ }
while (pool->ltp_open_count) {
if (!pool->ltp_pause)
ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
}
- ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
-
- while ((task = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL)
- {
- LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltt_next.q);
- LDAP_FREE(task);
- }
while ((task = LDAP_SLIST_FIRST(&pool->ltp_free_list)) != NULL)
{
LDAP_FREE(task);
}
+ ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
ldap_pvt_thread_cond_destroy(&pool->ltp_pcond);
ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
{
struct ldap_int_thread_pool_s *pool = xpool;
ldap_int_thread_task_t *task;
+ ldap_int_tpool_plist_t *work_list;
ldap_int_thread_userctx_t ctx, *kctx;
unsigned i, keyslot, hash;
pool->ltp_starting--;
for (;;) {
- while (pool->ltp_pause)
- ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
-
- if (pool->ltp_state == LDAP_INT_THREAD_POOL_STOPPING)
- break;
-
- task = LDAP_STAILQ_FIRST(&pool->ltp_pending_list);
- if (task == NULL) {
- if (pool->ltp_state == LDAP_INT_THREAD_POOL_FINISHING)
- break;
-
- if (pool->ltp_open_count >
- (pool->ltp_max_count ? pool->ltp_max_count : LDAP_MAXTHR))
- {
- /* too many threads running (can happen if the
- * maximum threads value is set during ongoing
- * operation using ldap_pvt_thread_pool_maxthreads)
- * so let this thread die.
+ work_list = pool->ltp_work_list; /* help the compiler a bit */
+ task = LDAP_STAILQ_FIRST(work_list);
+ if (task == NULL) { /* paused or no pending tasks */
+ if (pool->ltp_vary_open_count < 0) {
+ /* not paused, and either finishing or too many
+ * threads running (can happen if ltp_max_count
+ * was reduced) so let this thread die.
*/
break;
}
* check idle time.
*/
- assert(pool->ltp_state == LDAP_INT_THREAD_POOL_RUNNING);
ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
continue;
}
- LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltt_next.q);
+ LDAP_STAILQ_REMOVE_HEAD(work_list, ltt_next.q);
pool->ltp_pending_count--;
pool->ltp_active_count++;
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
ldap_pvt_thread_cond_signal(&pool->ltp_pcond);
}
+ assert(!pool->ltp_pause); /* thread_keys writable, ltp_open_count >= 0 */
+
/* The ltp_mutex lock protects ctx->ltu_key from pool_purgekey()
* during this call, since it prevents new pauses. */
ldap_pvt_thread_pool_context_reset(&ctx);
ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
pool->ltp_open_count--;
+ SET_VARY_OPEN_COUNT(pool);
/* let pool_destroy know we're all done */
- if (pool->ltp_open_count < 1)
+ if (pool->ltp_open_count == 0)
ldap_pvt_thread_cond_signal(&pool->ltp_cond);
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
return(NULL);
}
-/* Pause the pool. Return when all other threads are paused. */
-int
-ldap_pvt_thread_pool_pause (
- ldap_pvt_thread_pool_t *tpool )
+static int
+handle_pause( ldap_pvt_thread_pool_t *tpool, int do_pause )
{
struct ldap_int_thread_pool_s *pool;
if (pool == NULL)
return(0);
+ if (! (do_pause || pool->ltp_pause))
+ return(0);
+
ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
/* If someone else has already requested a pause, we have to wait */
pool->ltp_active_count++;
}
- /* Wait for everyone else to pause or finish */
- pool->ltp_pause = 1;
- while (pool->ltp_active_count > 1) {
- ldap_pvt_thread_cond_wait(&pool->ltp_pcond, &pool->ltp_mutex);
+ if (do_pause) {
+ /* Wait for everyone else to pause or finish */
+ pool->ltp_pause = 1;
+ /* Let ldap_pvt_thread_pool_submit() through to its ltp_pause test,
+ * and do not finish threads in ldap_pvt_thread_pool_wrapper() */
+ pool->ltp_open_count = -pool->ltp_open_count;
+ SET_VARY_OPEN_COUNT(pool);
+ /* Hide pending tasks from ldap_pvt_thread_pool_wrapper() */
+ pool->ltp_work_list = &empty_pending_list;
+
+ while (pool->ltp_active_count > 1) {
+ ldap_pvt_thread_cond_wait(&pool->ltp_pcond, &pool->ltp_mutex);
+ }
}
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
- return(0);
+ return(!do_pause);
+}
+
+/*
+ * If a pause was requested, wait for it. If several threads
+ * are waiting to pause, let through one or more pauses.
+ * Return 1 if we waited, 0 if not, -1 at parameter error.
+ */
+int
+ldap_pvt_thread_pool_pausecheck( ldap_pvt_thread_pool_t *tpool )
+{
+ return handle_pause( tpool, 0 );
+}
+
+/* Pause the pool. Return when all other threads are paused. */
+int
+ldap_pvt_thread_pool_pause( ldap_pvt_thread_pool_t *tpool )
+{
+ return handle_pause( tpool, 1 );
}
/* End a pause */
return(0);
ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
+
+ assert(pool->ltp_pause);
pool->ltp_pause = 0;
- if (pool->ltp_state == LDAP_INT_THREAD_POOL_RUNNING)
+ if (pool->ltp_open_count <= 0) /* true when paused, but be paranoid */
+ pool->ltp_open_count = -pool->ltp_open_count;
+ SET_VARY_OPEN_COUNT(pool);
+ pool->ltp_work_list = &pool->ltp_pending_list;
+
+ if (!pool->ltp_finishing)
ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
+
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
return(0);
}
void *ctx = NULL;
ldap_pvt_thread_key_getdata( ldap_tpool_key, &ctx );
- return ctx ? ctx : &ldap_int_main_thrctx;
+ return ctx ? ctx : (void *) &ldap_int_main_thrctx;
}
/*
projects / openldap / commitdiff