openldap/libraries/libldap_r/tpool.c
2005-07-11 10:39:32 +00:00

664 lines
16 KiB
C

/* $OpenLDAP$ */
/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
*
* Copyright 1998-2005 The OpenLDAP Foundation.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted only as authorized by the OpenLDAP
* Public License.
*
* A copy of this license is available in file LICENSE in the
* top-level directory of the distribution or, alternatively, at
* <http://www.OpenLDAP.org/license.html>.
*/
#include "portable.h"
#include <stdio.h>
#include <ac/stdarg.h>
#include <ac/stdlib.h>
#include <ac/string.h>
#include <ac/time.h>
#include <ac/errno.h>
#include "ldap-int.h"
#include "ldap_pvt_thread.h"
#include "ldap_queue.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,
LDAP_INT_THREAD_POOL_PAUSING
};
typedef struct ldap_int_thread_key_s {
void *ltk_key;
void *ltk_data;
ldap_pvt_thread_pool_keyfree_t *ltk_free;
} ldap_int_thread_key_t;
/* Max number of thread-specific keys we store per thread.
* We don't expect to use many...
*/
#define MAXKEYS 32
#define LDAP_MAXTHR 1024 /* must be a power of 2 */
static ldap_pvt_thread_t tid_zero;
#ifdef HAVE_PTHREADS
#define TID_EQ(a,b) pthread_equal((a),(b))
#else
#define TID_EQ(a,b) ((a) == (b))
#endif
static struct {
ldap_pvt_thread_t id;
ldap_int_thread_key_t *ctx;
} thread_keys[LDAP_MAXTHR];
typedef struct ldap_int_thread_ctx_s {
union {
LDAP_STAILQ_ENTRY(ldap_int_thread_ctx_s) q;
LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) l;
LDAP_SLIST_ENTRY(ldap_int_thread_ctx_s) al;
} ltc_next;
ldap_pvt_thread_start_t *ltc_start_routine;
void *ltc_arg;
} ldap_int_thread_ctx_t;
struct ldap_int_thread_pool_s {
LDAP_STAILQ_ENTRY(ldap_int_thread_pool_s) ltp_next;
ldap_pvt_thread_mutex_t ltp_mutex;
ldap_pvt_thread_cond_t ltp_cond;
ldap_pvt_thread_cond_t ltp_pcond;
LDAP_STAILQ_HEAD(tcq, ldap_int_thread_ctx_s) ltp_pending_list;
LDAP_SLIST_HEAD(tcl, ldap_int_thread_ctx_s) ltp_free_list;
LDAP_SLIST_HEAD(tclq, ldap_int_thread_ctx_s) ltp_active_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 LDAP_STAILQ_HEAD(tpq, ldap_int_thread_pool_s)
ldap_int_thread_pool_list =
LDAP_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( void *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 )
{
struct ldap_int_thread_pool_s *pool;
while ((pool = LDAP_STAILQ_FIRST(&ldap_int_thread_pool_list)) != NULL) {
LDAP_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);
rc = ldap_pvt_thread_cond_init(&pool->ltp_pcond);
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;
LDAP_STAILQ_INIT(&pool->ltp_pending_list);
LDAP_SLIST_INIT(&pool->ltp_free_list);
LDAP_SLIST_INIT(&pool->ltp_active_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);
#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, 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_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);
ldap_pvt_thread_cond_destroy(&pool->ltp_pcond);
ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
LDAP_FREE(pool);
return(-1);
}
#endif
*tpool = pool;
return(0);
}
#define TID_HASH(tid, hash) do { int i; \
unsigned char *ptr = (unsigned char *)&(tid); \
for (i=0, hash=0; i<sizeof(tid); i++) hash += ptr[i]; } while(0)
int
ldap_pvt_thread_pool_submit (
ldap_pvt_thread_pool_t *tpool,
ldap_pvt_thread_start_t *start_routine, 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_state != LDAP_INT_THREAD_POOL_PAUSING)
|| (pool->ltp_max_pending > 0
&& pool->ltp_pending_count >= pool->ltp_max_pending))
{
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
return(-1);
}
ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list);
if (ctx) {
LDAP_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++;
LDAP_STAILQ_INSERT_TAIL(&pool->ltp_pending_list, ctx, ltc_next.q);
if (pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING) {
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
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))
{
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_mutex_lock(&pool->ltp_mutex);
rc = ldap_pvt_thread_create( &thr, 1,
ldap_int_thread_pool_wrapper, pool );
if (rc == 0) {
int hash;
pool->ltp_starting--;
/* assign this thread ID to a key slot; start
* at the thread ID itself (mod LDAP_MAXTHR) and
* look for an empty slot.
*/
TID_HASH(thr, hash);
for (rc = hash & (LDAP_MAXTHR-1);
!TID_EQ(thread_keys[rc].id, tid_zero);
rc = (rc+1) & (LDAP_MAXTHR-1));
thread_keys[rc].id = thr;
} 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;
LDAP_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.
*/
LDAP_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);
LDAP_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);
LDAP_STAILQ_FOREACH(pptr, &ldap_int_thread_pool_list, ltp_next)
if (pptr == pool) break;
if (pptr == pool)
LDAP_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;
ldap_pvt_thread_cond_broadcast(&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 = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL)
{
LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltc_next.q);
LDAP_FREE(ctx);
}
while ((ctx = LDAP_SLIST_FIRST(&pool->ltp_free_list)) != NULL)
{
LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltc_next.l);
LDAP_FREE(ctx);
}
ldap_pvt_thread_cond_destroy(&pool->ltp_pcond);
ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
LDAP_FREE(pool);
return(0);
}
static void *
ldap_int_thread_pool_wrapper (
void *xpool )
{
struct ldap_int_thread_pool_s *pool = xpool;
ldap_int_thread_ctx_t *ctx;
ldap_int_thread_key_t ltc_key[MAXKEYS];
ldap_pvt_thread_t tid;
int i, keyslot, hash;
if (pool == NULL)
return NULL;
for ( i=0; i<MAXKEYS; i++ ) {
ltc_key[i].ltk_key = NULL;
}
tid = ldap_pvt_thread_self();
ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
/* store pointer to our keys */
TID_HASH(tid, hash);
for (i = hash & (LDAP_MAXTHR-1); !TID_EQ(thread_keys[i].id, tid);
i = (i+1) & (LDAP_MAXTHR-1));
thread_keys[i].ctx = ltc_key;
keyslot = i;
while (pool->ltp_state != LDAP_INT_THREAD_POOL_STOPPING) {
ctx = LDAP_STAILQ_FIRST(&pool->ltp_pending_list);
if (ctx) {
LDAP_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--;
LDAP_SLIST_INSERT_HEAD(&pool->ltp_active_list, ctx, ltc_next.al);
pool->ltp_active_count++;
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
ctx->ltc_start_routine(ltc_key, ctx->ltc_arg);
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_SLIST_INSERT_HEAD(&pool->ltp_free_list, ctx, ltc_next.l);
pool->ltp_active_count--;
if (pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING) {
if (pool->ltp_active_count < 2) {
ldap_pvt_thread_cond_signal(&pool->ltp_pcond);
}
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++ ) {
if (ltc_key[i].ltk_free)
ltc_key[i].ltk_free(
ltc_key[i].ltk_key,
ltc_key[i].ltk_data );
}
thread_keys[keyslot].ctx = NULL;
thread_keys[keyslot].id = tid_zero;
pool->ltp_open_count--;
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
ldap_pvt_thread_exit(NULL);
return(NULL);
}
int
ldap_pvt_thread_pool_pause (
ldap_pvt_thread_pool_t *tpool )
{
struct ldap_int_thread_pool_s *pool;
if (tpool == NULL)
return(-1);
pool = *tpool;
if (pool == NULL)
return(0);
ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
/* If someone else has already requested a pause, we have to wait */
if (pool->ltp_state == LDAP_INT_THREAD_POOL_PAUSING) {
pool->ltp_pending_count++;
pool->ltp_active_count--;
ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
pool->ltp_pending_count--;
pool->ltp_active_count++;
}
/* Wait for everyone else to finish */
pool->ltp_state = LDAP_INT_THREAD_POOL_PAUSING;
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);
}
int
ldap_pvt_thread_pool_resume (
ldap_pvt_thread_pool_t *tpool )
{
struct ldap_int_thread_pool_s *pool;
if (tpool == NULL)
return(-1);
pool = *tpool;
if (pool == NULL)
return(0);
ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
pool->ltp_state = LDAP_INT_THREAD_POOL_RUNNING;
ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
return(0);
}
int ldap_pvt_thread_pool_getkey(
void *xctx,
void *key,
void **data,
ldap_pvt_thread_pool_keyfree_t **kfree )
{
ldap_int_thread_key_t *ctx = xctx;
int i;
if ( !ctx || !data ) return EINVAL;
for ( i=0; i<MAXKEYS && ctx[i].ltk_key; i++ ) {
if ( ctx[i].ltk_key == key ) {
*data = ctx[i].ltk_data;
if ( kfree ) *kfree = ctx[i].ltk_free;
return 0;
}
}
return ENOENT;
}
int ldap_pvt_thread_pool_setkey(
void *xctx,
void *key,
void *data,
ldap_pvt_thread_pool_keyfree_t *kfree )
{
ldap_int_thread_key_t *ctx = xctx;
int i;
if ( !ctx || !key ) return EINVAL;
for ( i=0; i<MAXKEYS; i++ ) {
if ( !ctx[i].ltk_key || ctx[i].ltk_key == key ) {
ctx[i].ltk_key = key;
ctx[i].ltk_data = data;
ctx[i].ltk_free = kfree;
return 0;
}
}
return ENOMEM;
}
/* Free all elements with this key, no matter which thread they're in.
* May only be called while the pool is paused.
*/
void ldap_pvt_thread_pool_purgekey( void *key )
{
int i, j;
ldap_int_thread_key_t *ctx;
for ( i=0; i<LDAP_MAXTHR; i++ ) {
if ( thread_keys[i].ctx ) {
ctx = thread_keys[i].ctx;
for ( j=0; j<MAXKEYS; j++ ) {
if ( ctx[j].ltk_key == key ) {
if (ctx[j].ltk_free)
ctx[j].ltk_free( ctx[j].ltk_key, ctx[j].ltk_data );
ctx[j].ltk_key = NULL;
ctx[j].ltk_free = NULL;
break;
}
}
}
}
}
/*
* This is necessary if the caller does not have access to the
* thread context handle (for example, a slapd plugin calling
* slapi_search_internal()). No doubt it is more efficient to
* for the application to keep track of the thread context
* handles itself.
*/
void *ldap_pvt_thread_pool_context( )
{
ldap_pvt_thread_t tid;
int i, hash;
tid = ldap_pvt_thread_self();
TID_HASH( tid, hash );
for (i = hash & (LDAP_MAXTHR-1); !TID_EQ(thread_keys[i].id, tid_zero) &&
!TID_EQ(thread_keys[i].id, tid); i = (i+1) & (LDAP_MAXTHR-1));
return thread_keys[i].ctx;
}
#endif /* LDAP_THREAD_HAVE_TPOOL */