openldap/libraries/libldap_r/tpool.c
2001-12-31 06:46:03 +00:00

422 lines
11 KiB
C

/* $OpenLDAP$ */
/*
* 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 <ac/stdarg.h>
#include <ac/stdlib.h>
#include <ac/string.h>
#include <ac/time.h>
#include "ldap-int.h"
#include "ldap_pvt_thread.h"
#include "queue-compat.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_ctx_s {
union {
STAILQ_ENTRY(ldap_int_thread_ctx_s) q;
SLIST_ENTRY(ldap_int_thread_ctx_s) l;
} ltc_next;
void *(*ltc_start_routine)( void *);
void *ltc_arg;
} ldap_int_thread_ctx_t;
struct ldap_int_thread_pool_s {
STAILQ_ENTRY(ldap_int_thread_pool_s) ltp_next;
ldap_pvt_thread_mutex_t ltp_mutex;
ldap_pvt_thread_cond_t ltp_cond;
STAILQ_HEAD(tcq, ldap_int_thread_ctx_s) ltp_pending_list;
SLIST_HEAD(tcl, ldap_int_thread_ctx_s) ltp_free_list;
long ltp_state;
long ltp_max_count;
long ltp_max_pending;
long ltp_pending_count;
long ltp_active_count;
long ltp_open_count;
long ltp_starting;
};
static STAILQ_HEAD(tpq, ldap_int_thread_pool_s)
ldap_int_thread_pool_list =
STAILQ_HEAD_INITIALIZER(ldap_int_thread_pool_list);
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 );
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 )
{
ldap_int_thread_ctx_t *ctx;
struct ldap_int_thread_pool_s *pool;
while ((pool = STAILQ_FIRST(&ldap_int_thread_pool_list)) != NULL) {
STAILQ_REMOVE_HEAD(&ldap_int_thread_pool_list, ltp_next);
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_threads,
int max_pending )
{
ldap_pvt_thread_pool_t pool;
int rc;
*tpool = NULL;
pool = (ldap_pvt_thread_pool_t) LDAP_CALLOC(1,
sizeof(struct ldap_int_thread_pool_s));
if (pool == NULL) return(-1);
rc = ldap_pvt_thread_mutex_init(&pool->ltp_mutex);
if (rc != 0)
return(rc);
rc = ldap_pvt_thread_cond_init(&pool->ltp_cond);
if (rc != 0)
return(rc);
pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
pool->ltp_max_count = max_threads;
pool->ltp_max_pending = max_pending;
STAILQ_INIT(&pool->ltp_pending_list);
SLIST_INIT(&pool->ltp_free_list);
ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
STAILQ_INSERT_TAIL(&ldap_int_thread_pool_list, pool, ltp_next);
ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
#if 0
/* THIS WILL NOT WORK on some systems. If the process
* forks after starting a thread, there is no guarantee
* that the thread will survive the fork. For example,
* slapd forks in order to daemonize, and does so after
* calling ldap_pvt_thread_pool_init. On some systems,
* this initial thread does not run in the child process,
* but ltp_open_count == 1, so two things happen:
* 1) the first client connection fails, and 2) when
* slapd is kill'ed, it never terminates since it waits
* for all worker threads to exit. */
/* start up one thread, just so there is one. no need to
* lock the mutex right now, since no threads are running.
*/
pool->ltp_open_count++;
ldap_pvt_thread_t thr;
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);
STAILQ_REMOVE(ldap_int_thread_pool_list, pool,
ldap_int_thread_element_s, ltp_next);
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);
}
#endif
*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);
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);
return(-1);
}
ctx = SLIST_FIRST(&pool->ltp_free_list);
if (ctx) {
SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
} else {
ctx = (ldap_int_thread_ctx_t *) LDAP_MALLOC(
sizeof(ldap_int_thread_ctx_t));
if (ctx == NULL) {
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
return(-1);
}
}
ctx->ltc_start_routine = start_routine;
ctx->ltc_arg = arg;
pool->ltp_pending_count++;
STAILQ_INSERT_TAIL(&pool->ltp_pending_list, ctx, ltc_next.q);
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++;
pool->ltp_starting++;
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 );
ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
if (rc == 0) {
pool->ltp_starting--;
} else {
/* couldn't create thread. back out of
* ltp_open_count and check for even worse things.
*/
pool->ltp_open_count--;
pool->ltp_starting--;
if (pool->ltp_open_count == 0) {
/* no open threads at all?!?
*/
ldap_int_thread_ctx_t *ptr;
STAILQ_FOREACH(ptr, &pool->ltp_pending_list, ltc_next.q)
if (ptr == ctx) break;
if (ptr == ctx) {
/* no open threads, context not handled, so
* back out of ltp_pending_count, free the context,
* report the error.
*/
STAILQ_REMOVE(&pool->ltp_pending_list, ctx,
ldap_int_thread_ctx_s, ltc_next.q);
pool->ltp_pending_count++;
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
free(ctx);
return(-1);
}
}
/* there is another open thread, so this
* context will be handled eventually.
* continue on and signal that the context
* is waiting.
*/
}
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
}
return(0);
}
int
ldap_pvt_thread_pool_maxthreads ( ldap_pvt_thread_pool_t *tpool, int max_threads )
{
struct ldap_int_thread_pool_s *pool;
if (tpool == NULL)
return(-1);
pool = *tpool;
if (pool == NULL)
return(-1);
ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
pool->ltp_max_count = max_threads;
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
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, *pptr;
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);
STAILQ_FOREACH(pptr, &ldap_int_thread_pool_list, ltp_next)
if (pptr == pool) break;
if (pptr == pool)
STAILQ_REMOVE(&ldap_int_thread_pool_list, pool,
ldap_int_thread_pool_s, ltp_next);
ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
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;
waiting = pool->ltp_open_count;
/* 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);
}
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
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 = STAILQ_FIRST(&pool->ltp_pending_list)) != NULL)
{
STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
free(ctx);
}
while ((ctx = SLIST_FIRST(&pool->ltp_free_list)) != NULL)
{
SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
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 = STAILQ_FIRST(&pool->ltp_pending_list);
if (ctx) {
STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
} else {
if (pool->ltp_state == LDAP_INT_THREAD_POOL_FINISHING)
break;
if (pool->ltp_max_count > 0
&& pool->ltp_open_count > pool->ltp_max_count)
{
/* 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.
*/
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). the check
* should be like this:
* if (pool->ltp_open_count > 1 && pool->ltp_starting == 0)
* check timer, leave thread (break;)
*/
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);
SLIST_INSERT_HEAD(&pool->ltp_free_list, ctx, ltc_next.l);
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);
}
#endif /* LDAP_HAVE_THREAD_POOL */