openldap/libraries/libldap_r/tpool.c

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/* $OpenLDAP$ */
/*
* Copyright 1998-2000 The OpenLDAP Foundation, Redwood City, California, USA
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted only
* as authorized by the OpenLDAP Public License. A copy of this
* license is available at http://www.OpenLDAP.org/license.html or
* in file LICENSE in the top-level directory of the distribution.
*/
#include "portable.h"
#include <stdio.h>
#include <stdarg.h>
#include <ac/stdlib.h>
#include <ac/string.h>
#include <ac/time.h>
#include "ldap-int.h"
#include "ldap_pvt_thread.h"
#ifndef LDAP_THREAD_HAVE_TPOOL
enum ldap_int_thread_pool_state {
LDAP_INT_THREAD_POOL_RUNNING,
LDAP_INT_THREAD_POOL_FINISHING,
LDAP_INT_THREAD_POOL_STOPPING
};
typedef struct ldap_int_thread_list_element_s {
struct ldap_int_thread_list_element_s *next;
} ldap_int_thread_list_element_t, *ldap_int_thread_list_t;
struct ldap_int_thread_pool_s {
struct ldap_int_thread_pool_s *ltp_next;
ldap_pvt_thread_mutex_t ltp_mutex;
ldap_pvt_thread_cond_t ltp_cond;
ldap_int_thread_list_t ltp_pending_list;
long ltp_state;
long ltp_max_count;
long ltp_max_pending;
long ltp_pending_count;
long ltp_active_count;
long ltp_open_count;
};
typedef struct ldap_int_thread_ctx_s {
struct ldap_int_thread_ctx_s *ltc_next;
void *(*ltc_start_routine)( void *);
void *ltc_arg;
} ldap_int_thread_ctx_t;
static ldap_int_thread_list_t ldap_int_thread_pool_list = NULL;
static ldap_pvt_thread_mutex_t ldap_pvt_thread_pool_mutex;
static void *ldap_int_thread_pool_wrapper(
struct ldap_int_thread_pool_s *pool );
static void *ldap_int_thread_enlist( ldap_int_thread_list_t *list, void *elem );
static void *ldap_int_thread_delist( ldap_int_thread_list_t *list, void *elem );
static void *ldap_int_thread_onlist( ldap_int_thread_list_t *list, void *elem );
int
ldap_int_thread_pool_startup ( void )
{
return ldap_pvt_thread_mutex_init(&ldap_pvt_thread_pool_mutex);
}
int
ldap_int_thread_pool_shutdown ( void )
{
while (ldap_int_thread_pool_list != NULL) {
struct ldap_int_thread_pool_s *pool =
(struct ldap_int_thread_pool_s *) ldap_int_thread_pool_list;
ldap_pvt_thread_pool_destroy( &pool, 0);
}
ldap_pvt_thread_mutex_destroy(&ldap_pvt_thread_pool_mutex);
return(0);
}
int
ldap_pvt_thread_pool_init (
ldap_pvt_thread_pool_t *tpool,
int max_concurrency,
int max_pending )
{
int rc;
ldap_pvt_thread_pool_t pool;
ldap_pvt_thread_t thr;
*tpool = NULL;
pool = (ldap_pvt_thread_pool_t) LDAP_CALLOC(1,
sizeof(struct ldap_int_thread_pool_s));
if (pool == NULL) return(-1);
ldap_pvt_thread_mutex_init(&pool->ltp_mutex);
ldap_pvt_thread_cond_init(&pool->ltp_cond);
pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
pool->ltp_max_count = max_concurrency;
pool->ltp_max_pending = max_pending;
ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
ldap_int_thread_enlist(&ldap_int_thread_pool_list, pool);
ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
/* start up one thread, just so there is one */
pool->ltp_open_count++;
rc = ldap_pvt_thread_create( &thr, 1,
(void *) ldap_int_thread_pool_wrapper, pool );
if( rc != 0) {
/* couldn't start one? then don't start any */
ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
ldap_int_thread_delist(&ldap_int_thread_pool_list, pool);
ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
free(pool);
return(-1);
}
*tpool = pool;
return(0);
}
int
ldap_pvt_thread_pool_submit (
ldap_pvt_thread_pool_t *tpool,
void *(*start_routine)( void * ), void *arg )
{
struct ldap_int_thread_pool_s *pool;
ldap_int_thread_ctx_t *ctx;
int need_thread = 0;
ldap_pvt_thread_t thr;
if (tpool == NULL)
return(-1);
pool = *tpool;
if (pool == NULL)
return(-1);
ctx = (ldap_int_thread_ctx_t *) LDAP_CALLOC(1,
sizeof(ldap_int_thread_ctx_t));
if (ctx == NULL) return(-1);
ctx->ltc_start_routine = start_routine;
ctx->ltc_arg = arg;
ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
if (pool->ltp_state != LDAP_INT_THREAD_POOL_RUNNING
|| (pool->ltp_max_pending > 0
&& pool->ltp_pending_count >= pool->ltp_max_pending))
{
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
free(ctx);
return(-1);
}
pool->ltp_pending_count++;
ldap_int_thread_enlist(&pool->ltp_pending_list, ctx);
ldap_pvt_thread_cond_signal(&pool->ltp_cond);
if ((pool->ltp_open_count <= 0
|| pool->ltp_pending_count > 1
|| pool->ltp_open_count == pool->ltp_active_count)
&& (pool->ltp_max_count <= 0
|| pool->ltp_open_count < pool->ltp_max_count))
{
pool->ltp_open_count++;
need_thread = 1;
}
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
if (need_thread) {
int rc = ldap_pvt_thread_create( &thr, 1,
(void *)ldap_int_thread_pool_wrapper, pool );
if (rc != 0) {
/* couldn't create thread. back out of
* ltp_open_count and check for even worse things.
*/
ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
pool->ltp_open_count--;
if (pool->ltp_open_count == 0) {
/* no open threads at all?!? this will never happen
* because we always leave at least one thread open.
*/
if (ldap_int_thread_delist(&pool->ltp_pending_list, ctx)) {
/* no open threads, context not handled, so
* back out of ltp_pending_count, free the context,
* report the error.
*/
pool->ltp_pending_count++;
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
free(ctx);
return(-1);
}
}
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
/* there is another open thread, so this
* context will be handled eventually.
* continue on and signal that the context
* is waiting.
*/
}
}
return(0);
}
int
ldap_pvt_thread_pool_backload ( ldap_pvt_thread_pool_t *tpool )
{
struct ldap_int_thread_pool_s *pool;
int count;
if (tpool == NULL)
return(-1);
pool = *tpool;
if (pool == NULL)
return(0);
ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
count = pool->ltp_pending_count + pool->ltp_active_count;
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
return(count);
}
int
ldap_pvt_thread_pool_destroy ( ldap_pvt_thread_pool_t *tpool, int run_pending )
{
struct ldap_int_thread_pool_s *pool;
long waiting;
ldap_int_thread_ctx_t *ctx;
if (tpool == NULL)
return(-1);
pool = *tpool;
if (pool == NULL) return(-1);
ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
pool = ldap_int_thread_delist(&ldap_int_thread_pool_list, pool);
ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
if (pool == NULL) 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;
waiting = pool->ltp_open_count;
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
/* broadcast could be used here, but only after
* it is fixed in the NT thread implementation
*/
while (--waiting >= 0) {
ldap_pvt_thread_cond_signal(&pool->ltp_cond);
}
do {
ldap_pvt_thread_yield();
ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
waiting = pool->ltp_open_count;
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
} while (waiting > 0);
while (ctx = (ldap_int_thread_ctx_t *)ldap_int_thread_delist(
&pool->ltp_pending_list, NULL))
{
free(ctx);
}
ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
free(pool);
return(0);
}
static void *
ldap_int_thread_pool_wrapper (
struct ldap_int_thread_pool_s *pool )
{
ldap_int_thread_ctx_t *ctx;
if (pool == NULL)
return NULL;
ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
while (pool->ltp_state != LDAP_INT_THREAD_POOL_STOPPING) {
ctx = ldap_int_thread_delist(&pool->ltp_pending_list, NULL);
if (ctx == NULL) {
if (pool->ltp_state == LDAP_INT_THREAD_POOL_FINISHING)
break;
/* we could check an idle timer here, and let the
* thread die if it has been inactive for a while.
* only die if there are other open threads (i.e.,
* always have at least one thread open).
*/
if (pool->ltp_state == LDAP_INT_THREAD_POOL_RUNNING)
ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
continue;
}
pool->ltp_pending_count--;
pool->ltp_active_count++;
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
(ctx->ltc_start_routine)(ctx->ltc_arg);
free(ctx);
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);
pool->ltp_active_count--;
}
pool->ltp_open_count--;
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
ldap_pvt_thread_exit(NULL);
return(NULL);
}
static void *
ldap_int_thread_enlist( ldap_int_thread_list_t *list, void *elem )
{
ldap_int_thread_list_element_t *prev;
if (elem == NULL) return(NULL);
((ldap_int_thread_list_element_t *)elem)->next = NULL;
if (*list == NULL) {
*list = elem;
return(elem);
}
for (prev = *list ; prev->next != NULL; prev = prev->next) ;
prev->next = elem;
return(elem);
}
static void *
ldap_int_thread_delist( ldap_int_thread_list_t *list, void *elem )
{
ldap_int_thread_list_element_t *prev;
if (*list == NULL) return(NULL);
if (elem == NULL) elem = *list;
if (*list == elem) {
*list = ((ldap_int_thread_list_element_t *)elem)->next;
return(elem);
}
for (prev = *list ; prev->next != NULL; prev = prev->next) {
if (prev->next == elem) {
prev->next = ((ldap_int_thread_list_element_t *)elem)->next;
return(elem);
}
}
return(NULL);
}
static void *
ldap_int_thread_onlist( ldap_int_thread_list_t *list, void *elem )
{
ldap_int_thread_list_element_t *prev;
if (elem == NULL || *list == NULL) return(NULL);
for (prev = *list ; prev != NULL; prev = prev->next) {
if (prev == elem)
return(elem);
}
return(NULL);
}
#endif /* LDAP_HAVE_THREAD_POOL */