/* $OpenLDAP$ */
/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
*
- * Copyright 1998-2005 The OpenLDAP Foundation.
+ * Copyright 1998-2006 The OpenLDAP Foundation.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
return(0);
}
+typedef struct ldap_lazy_sem_t {
+ ldap_pvt_thread_mutex_t ls_mutex;
+ ldap_pvt_thread_cond_t ls_cond;
+ int ls_sem_value;
+ /*
+ * when more than ls_lazy_count number of resources
+ * becmoes available, the thread wating for the resources will
+ * be waken up in order to prevent frequent blocking/waking-up
+ */
+ unsigned int ls_lazy_count;
+ /*
+ * only one thread(listener) will wait on this semaphore
+ * using a flag instead of a list
+ */
+ int ls_wait;
+} ldap_lazy_sem_t;
+
+ldap_lazy_sem_t* thread_pool_sem = NULL;
+
+int
+ldap_lazy_sem_init( unsigned int value, unsigned int lazyness )
+{
+ thread_pool_sem = (ldap_lazy_sem_t*) LDAP_CALLOC(1,
+ sizeof( ldap_lazy_sem_t ));
+
+ if( thread_pool_sem == NULL ) return -1;
+
+ ldap_pvt_thread_mutex_init( &thread_pool_sem->ls_mutex );
+ ldap_pvt_thread_cond_init( &thread_pool_sem->ls_cond );
+ thread_pool_sem->ls_sem_value = value;
+ thread_pool_sem->ls_lazy_count = lazyness;
+ thread_pool_sem->ls_wait = 0;
+
+ return 0;
+}
+
+/* FIXME: move to some approprite header */
+int ldap_lazy_sem_dec( ldap_lazy_sem_t* ls );
+int ldap_lazy_sem_wait ( ldap_lazy_sem_t* ls );
+
+/*
+ * ldap_lazy_sem_wait is used if a caller is blockable(listener).
+ * Otherwise use ldap_lazy_sem_dec (worker)
+ */
+int
+ldap_lazy_sem_op_submit( ldap_lazy_sem_t* ls )
+{
+ if ( ls == NULL ) return -1;
+
+ /* only worker thread has its thread ctx */
+ if ( ldap_pvt_thread_pool_context() ) {
+ /* worker thread */
+ return ldap_lazy_sem_dec( ls );
+ } else {
+ /* listener */
+ return ldap_lazy_sem_wait( ls );
+ }
+}
+
+/*
+ * test if given semaphore's count is zero.
+ * If 0, the caller is blocked
+ * If not, the count is decremented.
+ */
+int
+ldap_lazy_sem_wait ( ldap_lazy_sem_t* ls )
+{
+ ldap_pvt_thread_mutex_lock( &ls->ls_mutex );
+
+lazy_sem_retry:
+ if ( ls->ls_sem_value <= 0 ) {
+ /* no more avaliable resources */
+ ls->ls_wait = 1;
+ ldap_pvt_thread_cond_wait( &ls->ls_cond, &ls->ls_mutex );
+ goto lazy_sem_retry;
+ } else {
+ /* avaliable resources */
+ ls->ls_sem_value--;
+ }
+
+ ldap_pvt_thread_mutex_unlock( &ls->ls_mutex );
+
+ return 0;
+}
+
+/*
+ * decrement the count without blocking
+ * even when the count becomes less than or equal to 0
+ */
+int
+ldap_lazy_sem_dec( ldap_lazy_sem_t* ls )
+{
+ ldap_pvt_thread_mutex_lock( &ls->ls_mutex );
+
+ ls->ls_sem_value--;
+
+ ldap_pvt_thread_mutex_unlock( &ls->ls_mutex );
+
+ return 0;
+}
+
+/*
+ * Increment the count by one and test if it is greater or
+ * equal to lazyness. If it is, wake up a blocked thread.
+ */
+int
+ldap_lazy_sem_post( ldap_lazy_sem_t* ls )
+{
+ if( ls == NULL ) return (-1);
+
+ ldap_pvt_thread_mutex_lock( &ls->ls_mutex );
+
+ ls->ls_sem_value++;
+ if ( ls->ls_wait ) {
+ if ( ls->ls_sem_value >= ls->ls_lazy_count ) {
+ ls->ls_wait = 0;
+ ldap_pvt_thread_cond_signal( &ls->ls_cond );
+ }
+ }
+
+ ldap_pvt_thread_mutex_unlock( &ls->ls_mutex );
+
+ return 0;
+}
+
int
ldap_pvt_thread_pool_init (
ldap_pvt_thread_pool_t *tpool,
return(0);
}
ldap_pvt_thread_cond_signal(&pool->ltp_cond);
- if ((pool->ltp_open_count <= 0
-#if 0
- || pool->ltp_pending_count > 1
-#endif
- || pool->ltp_open_count == pool->ltp_active_count)
- && (pool->ltp_max_count <= 0
- || pool->ltp_open_count < pool->ltp_max_count))
+ 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 <= 0 ))
{
pool->ltp_open_count++;
pool->ltp_starting++;
}
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
+#ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
+ ldap_lazy_sem_op_submit( thread_pool_sem );
+#endif
+
if (need_thread) {
int rc;
ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
LDAP_FREE(pool);
+#ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
+ if ( thread_pool_sem ) {
+ LDAP_FREE( thread_pool_sem );
+ }
+#endif
return(0);
}
* should be like this:
* if (pool->ltp_open_count > 1 && pool->ltp_starting == 0)
* check timer, leave thread (break;)
+ *
+ * Just use pthread_cond_timedwait if we want to
+ * check idle time.
*/
if (pool->ltp_state == LDAP_INT_THREAD_POOL_RUNNING
ctx->ltc_start_routine(ltc_key, ctx->ltc_arg);
+#ifdef LDAP_PVT_THREAD_POOL_SEM_LOAD_CONTROL
+ ldap_lazy_sem_post( thread_pool_sem );
+#endif
ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
LDAP_SLIST_REMOVE(&pool->ltp_active_list, ctx,
ldap_int_thread_ctx_s, ltc_next.al);
}
ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
}
- ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
-
- ldap_pvt_thread_yield();
-
- /* if we use an idle timer, here's
- * a good place to update it
- */
-
- ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
}
for ( i=0; i<MAXKEYS && ltc_key[i].ltk_key; i++ ) {
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