text: /* $OpenLDAP$ */
  /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
   *
   * Copyright 1998-2014 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/signal.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" /* Get the thread interface */
  #include "ldap_queue.h"
  #define LDAP_THREAD_POOL_IMPLEMENTATION
  #include "ldap_thr_debug.h"  /* May rename symbols defined below */
  
  #ifndef LDAP_THREAD_HAVE_TPOOL
  
  #ifndef CACHELINE
  #define CACHELINE	64
  #endif
  
  /* Thread-specific key with data and optional free function */
  typedef struct ldap_int_tpool_key_s {
  	void *ltk_key;
  	void *ltk_data;
  	ldap_pvt_thread_pool_keyfree_t *ltk_free;
  } ldap_int_tpool_key_t;
  
  /* Max number of thread-specific keys we store per thread.
   * We don't expect to use many...
   */
  #define	MAXKEYS	32
  
  /* 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) */
  
  /* pool->ltp_pause values */
  enum { NOT_PAUSED = 0, WANT_PAUSE = 1, PAUSED = 2 };
  
  /* Context: thread ID and thread-specific key/data pairs */
  typedef struct ldap_int_thread_userctx_s {
  	struct ldap_int_thread_poolq_s *ltu_pq;
  	ldap_pvt_thread_t ltu_id;
  	ldap_int_tpool_key_t ltu_key[MAXKEYS];
  } ldap_int_thread_userctx_t;
  
  
  /* Simple {thread ID -> context} hash table; key=ctx->ltu_id.
   * Protected by ldap_pvt_thread_pool_mutex except during pauses,
   * when it is read-only (used by pool_purgekey and pool_context).
   * Protected by ldap_pvt_thread_pool_mutex.
   */
  static struct {
  	ldap_int_thread_userctx_t *ctx;
  	/* ctx is valid when not NULL or DELETED_THREAD_CTX */
  #	define DELETED_THREAD_CTX (&ldap_int_main_thrctx + 1) /* dummy addr */
  } thread_keys[LDAP_MAXTHR];
  
  #define	TID_HASH(tid, hash) do { \
  	unsigned const char *ptr_ = (unsigned const char *)&(tid); \
  	unsigned i_; \
  	for (i_ = 0, (hash) = ptr_[0]; ++i_ < sizeof(tid);) \
  		(hash) += ((hash) << 5) ^ ptr_[i_]; \
  } while(0)
  
  
  /* Task for a thread to perform */
  typedef struct ldap_int_thread_task_s {
  	union {
  		LDAP_STAILQ_ENTRY(ldap_int_thread_task_s) q;
  		LDAP_SLIST_ENTRY(ldap_int_thread_task_s) l;
  	} ltt_next;
  	ldap_pvt_thread_start_t *ltt_start_routine;
  	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_poolq_s {
  	void *ltp_free;
  
  	struct ldap_int_thread_pool_s *ltp_pool;
  
  	/* protect members below */
  	ldap_pvt_thread_mutex_t ltp_mutex;
  
  	/* not paused and something to do for pool_<wrapper/pause/destroy>()
  	 * Used for normal pool operation, to synch between submitter and
  	 * worker threads. Not used for pauses. In normal operation multiple
  	 * queues can rendezvous without acquiring the main pool lock.
  	 */
  	ldap_pvt_thread_cond_t ltp_cond;
  
  	/* ltp_pause == 0 ? &ltp_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_int_tpool_plist_t ltp_pending_list;
  	LDAP_SLIST_HEAD(tcl, ldap_int_thread_task_s) ltp_free_list;
  
  	/* Max number of threads in this queue */
  	int ltp_max_count;
  
  	/* Max pending + paused + idle tasks, negated when ltp_finishing */
  	int ltp_max_pending;
  
  	int ltp_pending_count;		/* Pending + paused + idle tasks */
  	int ltp_active_count;		/* Active, not paused/idle tasks */
  	int ltp_open_count;			/* Number of threads, negated when ltp_pause */
  	int ltp_starting;			/* Currently starting threads */
  };
  
  struct ldap_int_thread_pool_s {
  	LDAP_STAILQ_ENTRY(ldap_int_thread_pool_s) ltp_next;
  
  	struct ldap_int_thread_poolq_s **ltp_wqs;
  
  	/* number of poolqs */
  	int ltp_numqs;
  
  	/* protect members below */
  	ldap_pvt_thread_mutex_t ltp_mutex;
  
  	/* paused and waiting for resume
  	 * When a pause is in effect all workers switch to waiting on
  	 * this cond instead of their per-queue cond.
  	 */
  	ldap_pvt_thread_cond_t ltp_cond;
  
  	/* ltp_active_queues < 1 && ltp_pause */
  	ldap_pvt_thread_cond_t ltp_pcond;
  
  	/* number of active queues */
  	int ltp_active_queues;
  
  	/* 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.
  	 */
  	volatile sig_atomic_t ltp_pause;
  
  	/* Max number of threads in pool */
  	int ltp_max_count;
  
  	/* Configured max number of threads in pool, 0 for default (LDAP_MAXTHR) */
  	int ltp_conf_max_count;
  
  	/* Max pending + paused + idle tasks, negated when ltp_finishing */
  	int ltp_max_pending;
  };
  
  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 =
  	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 );
  
  static ldap_pvt_thread_key_t	ldap_tpool_key;
  
  /* Context of the main thread */
  static ldap_int_thread_userctx_t ldap_int_main_thrctx;
  
  int
  ldap_int_thread_pool_startup ( void )
  {
  	ldap_int_main_thrctx.ltu_id = ldap_pvt_thread_self();
  	ldap_pvt_thread_key_create( &ldap_tpool_key );
  	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_pvt_thread_pool_destroy)(&pool, 0); /* ignore thr_debug macro */
  	}
  	ldap_pvt_thread_mutex_destroy(&ldap_pvt_thread_pool_mutex);
  	ldap_pvt_thread_key_destroy( ldap_tpool_key );
  	return(0);
  }
  
  
  /* Create a thread pool */
  int
  ldap_pvt_thread_pool_init_q (
  	ldap_pvt_thread_pool_t *tpool,
  	int max_threads,
  	int max_pending,
  	int numqs )
  {
  	ldap_pvt_thread_pool_t pool;
  	struct ldap_int_thread_poolq_s *pq;
  	int i, rc, rem_thr, rem_pend;
  
  	/* multiple pools are currently not supported (ITS#4943) */
  	assert(!ldap_int_has_thread_pool);
  
  	if (! (0 <= max_threads && max_threads <= LDAP_MAXTHR))
  		max_threads = 0;
  	if (! (1 <= max_pending && max_pending <= MAX_PENDING))
  		max_pending = MAX_PENDING;
  
  	*tpool = NULL;
  	pool = (ldap_pvt_thread_pool_t) LDAP_CALLOC(1,
  		sizeof(struct ldap_int_thread_pool_s));
  
  	if (pool == NULL) return(-1);
  
  	pool->ltp_wqs = LDAP_MALLOC(numqs * sizeof(struct ldap_int_thread_poolq_s *));
  	if (pool->ltp_wqs == NULL) {
  		LDAP_FREE(pool);
  		return(-1);
  	}
  
  	for (i=0; i<numqs; i++) {
  		char *ptr = LDAP_CALLOC(1, sizeof(struct ldap_int_thread_poolq_s) + CACHELINE-1);
  		if (ptr == NULL) {
  			for (--i; i>=0; i--)
  				LDAP_FREE(pool->ltp_wqs[i]->ltp_free);
  			LDAP_FREE(pool->ltp_wqs);
  			LDAP_FREE(pool);
  			return(-1);
  		}
  		pool->ltp_wqs[i] = (struct ldap_int_thread_poolq_s *)(((size_t)ptr + CACHELINE-1) & ~(CACHELINE-1));
  		pool->ltp_wqs[i]->ltp_free = ptr;
  	}
  
  	pool->ltp_numqs = numqs;
  	pool->ltp_conf_max_count = max_threads;
  	if ( !max_threads )
  		max_threads = LDAP_MAXTHR;
  
  	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);
  
  	rem_thr = max_threads % numqs;
  	rem_pend = max_pending % numqs;
  	for ( i=0; i<numqs; i++ ) {
  		pq = pool->ltp_wqs[i];
  		pq->ltp_pool = pool;
  		rc = ldap_pvt_thread_mutex_init(&pq->ltp_mutex);
  		if (rc != 0)
  			return(rc);
  		rc = ldap_pvt_thread_cond_init(&pq->ltp_cond);
  		if (rc != 0)
  			return(rc);
  		LDAP_STAILQ_INIT(&pq->ltp_pending_list);
  		pq->ltp_work_list = &pq->ltp_pending_list;
  		LDAP_SLIST_INIT(&pq->ltp_free_list);
  
  		pq->ltp_max_count = max_threads / numqs;
  		if ( rem_thr ) {
  			pq->ltp_max_count++;
  			rem_thr--;
  		}
  		pq->ltp_max_pending = max_pending / numqs;
  		if ( rem_pend ) {
  			pq->ltp_max_pending++;
  			rem_pend--;
  		}
  	}
  
  	ldap_int_has_thread_pool = 1;
  
  	pool->ltp_max_count = max_threads;
  	pool->ltp_max_pending = max_pending;
  
  	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);
  
  	/* Start no threads just yet.  That can break if the process forks
  	 * later, as slapd does in order to daemonize.  On at least POSIX,
  	 * only the forking thread would survive in the child.  Yet fork()
  	 * can't unlock/clean up other threads' locks and data structures,
  	 * unless pthread_atfork() handlers have been set up to do so.
  	 */
  
  	*tpool = pool;
  	return(0);
  }
  
  int
  ldap_pvt_thread_pool_init (
  	ldap_pvt_thread_pool_t *tpool,
  	int max_threads,
  	int max_pending )
  {
  	return ldap_pvt_thread_pool_init_q( tpool, max_threads, max_pending, 1 );
  }
  
  static int
  ldap_int_poolq_hash(
  	struct ldap_int_thread_pool_s *pool,
  	void *arg )
  {
  	int i = 0, j;
  	unsigned char *ptr = (unsigned char *)&arg;
  	/* dumb hash of arg to choose a queue */
  	for (j=0; j<sizeof(arg); j++)
  		i += *ptr++;
  	i %= pool->ltp_numqs;
  	return i;
  }
  
  /* Submit a task to be performed by the thread pool */
  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;
  	struct ldap_int_thread_poolq_s *pq;
  	ldap_int_thread_task_t *task;
  	ldap_pvt_thread_t thr;
  	int i, j;
  
  	if (tpool == NULL)
  		return(-1);
  
  	pool = *tpool;
  
  	if (pool == NULL)
  		return(-1);
  
  	if ( pool->ltp_numqs > 1 )
  		i = ldap_int_poolq_hash( pool, arg );
  	else
  		i = 0;
  
  	j = i;
  	while(1) {
  		ldap_pvt_thread_mutex_lock(&pool->ltp_wqs[i]->ltp_mutex);
  		if (pool->ltp_wqs[i]->ltp_pending_count < pool->ltp_wqs[i]->ltp_max_pending) {
  			break;
  		}
  		ldap_pvt_thread_mutex_unlock(&pool->ltp_wqs[i]->ltp_mutex);
  		i++;
  		i %= pool->ltp_numqs;
  		if ( i == j )
  			return -1;
  	}
  
  	pq = pool->ltp_wqs[i];
  	task = LDAP_SLIST_FIRST(&pq->ltp_free_list);
  	if (task) {
  		LDAP_SLIST_REMOVE_HEAD(&pq->ltp_free_list, ltt_next.l);
  	} else {
  		task = (ldap_int_thread_task_t *) LDAP_MALLOC(sizeof(*task));
  		if (task == NULL)
  			goto failed;
  	}
  
  	task->ltt_start_routine = start_routine;
  	task->ltt_arg = arg;
  
  	pq->ltp_pending_count++;
  	LDAP_STAILQ_INSERT_TAIL(&pq->ltp_pending_list, task, ltt_next.q);
  
  	if (pool->ltp_pause)
  		goto done;
  
  	/* should we open (create) a thread? */
  	if (pq->ltp_open_count < pq->ltp_active_count+pq->ltp_pending_count &&
  		pq->ltp_open_count < pq->ltp_max_count)
  	{
  		pq->ltp_starting++;
  		pq->ltp_open_count++;
  
  		if (0 != ldap_pvt_thread_create(
  			&thr, 1, ldap_int_thread_pool_wrapper, pq))
  		{
  			/* couldn't create thread.  back out of
  			 * ltp_open_count and check for even worse things.
  			 */
  			pq->ltp_starting--;
  			pq->ltp_open_count--;
  
  			if (pq->ltp_open_count == 0) {
  				/* no open threads at all?!?
  				 */
  				ldap_int_thread_task_t *ptr;
  
  				/* let pool_destroy know there are no more threads */
  				ldap_pvt_thread_cond_signal(&pq->ltp_cond);
  
  				LDAP_STAILQ_FOREACH(ptr, &pq->ltp_pending_list, ltt_next.q)
  					if (ptr == task) break;
  				if (ptr == task) {
  					/* no open threads, task not handled, so
  					 * back out of ltp_pending_count, free the task,
  					 * report the error.
  					 */
  					pq->ltp_pending_count--;
  					LDAP_STAILQ_REMOVE(&pq->ltp_pending_list, task,
  						ldap_int_thread_task_s, ltt_next.q);
  					LDAP_SLIST_INSERT_HEAD(&pq->ltp_free_list, task,
  						ltt_next.l);
  					goto failed;
  				}
  			}
  			/* there is another open thread, so this
  			 * task will be handled eventually.
  			 */
  		}
  	}
  	ldap_pvt_thread_cond_signal(&pq->ltp_cond);
  
   done:
  	ldap_pvt_thread_mutex_unlock(&pq->ltp_mutex);
  	return(0);
  
   failed:
  	ldap_pvt_thread_mutex_unlock(&pq->ltp_mutex);
  	return(-1);
  }
  
  static void *
  no_task( void *ctx, void *arg )
  {
  	return NULL;
  }
  
  /* Cancel a pending task that was previously submitted.
   * Return 1 if the task was successfully cancelled, 0 if
   * not found, -1 for invalid parameters
   */
  int
  ldap_pvt_thread_pool_retract (
  	ldap_pvt_thread_pool_t *tpool,
  	ldap_pvt_thread_start_t *start_routine, void *arg )
  {
  	struct ldap_int_thread_pool_s *pool;
  	struct ldap_int_thread_poolq_s *pq;
  	ldap_int_thread_task_t *task;
  	int i;
  
  	if (tpool == NULL)
  		return(-1);
  
  	pool = *tpool;
  
  	if (pool == NULL)
  		return(-1);
  
  	i = ldap_int_poolq_hash( pool, arg );
  	pq = pool->ltp_wqs[i];
  
  	ldap_pvt_thread_mutex_lock(&pq->ltp_mutex);
  	LDAP_STAILQ_FOREACH(task, &pq->ltp_pending_list, ltt_next.q)
  		if (task->ltt_start_routine == start_routine &&
  			task->ltt_arg == arg) {
  			/* Could LDAP_STAILQ_REMOVE the task, but that
  			 * walks ltp_pending_list again to find it.
  			 */
  			task->ltt_start_routine = no_task;
  			task->ltt_arg = NULL;
  			break;
  		}
  	ldap_pvt_thread_mutex_unlock(&pq->ltp_mutex);
  	return task != NULL;
  }
  
  /* Set number of work queues in this pool. Should not be
   * more than the number of CPUs. */
  int
  ldap_pvt_thread_pool_queues(
  	ldap_pvt_thread_pool_t *tpool,
  	int numqs )
  {
  	struct ldap_int_thread_pool_s *pool;
  	struct ldap_int_thread_poolq_s *pq;
  	int i, rc, rem_thr, rem_pend;
  
  	if (numqs < 1 || tpool == NULL)
  		return(-1);
  
  	pool = *tpool;
  
  	if (pool == NULL)
  		return(-1);
  
  	if (numqs < pool->ltp_numqs) {
  		for (i=numqs; i<pool->ltp_numqs; i++)
  			pool->ltp_wqs[i]->ltp_max_count = 0;
  	} else if (numqs > pool->ltp_numqs) {
  		struct ldap_int_thread_poolq_s **wqs;
  		wqs = LDAP_REALLOC(pool->ltp_wqs, numqs * sizeof(struct ldap_int_thread_poolq_s *));
  		if (wqs == NULL)
  			return(-1);
  		pool->ltp_wqs = wqs;
  		for (i=pool->ltp_numqs; i<numqs; i++) {
  			char *ptr = LDAP_CALLOC(1, sizeof(struct ldap_int_thread_poolq_s) + CACHELINE-1);
  			if (ptr == NULL) {
  				for (; i<numqs; i++)
  					pool->ltp_wqs[i] = NULL;
  				return(-1);
  			}
  			pq = (struct ldap_int_thread_poolq_s *)(((size_t)ptr + CACHELINE-1) & ~(CACHELINE-1));
  			pq->ltp_free = ptr;
  			pool->ltp_wqs[i] = pq;
  			pq->ltp_pool = pool;
  			rc = ldap_pvt_thread_mutex_init(&pq->ltp_mutex);
  			if (rc != 0)
  				return(rc);
  			rc = ldap_pvt_thread_cond_init(&pq->ltp_cond);
  			if (rc != 0)
  				return(rc);
  			LDAP_STAILQ_INIT(&pq->ltp_pending_list);
  			pq->ltp_work_list = &pq->ltp_pending_list;
  			LDAP_SLIST_INIT(&pq->ltp_free_list);
  		}
  	}
  	rem_thr = pool->ltp_max_count % numqs;
  	rem_pend = pool->ltp_max_pending % numqs;
  	for ( i=0; i<numqs; i++ ) {
  		pq = pool->ltp_wqs[i];
  		pq->ltp_max_count = pool->ltp_max_count / numqs;
  		if ( rem_thr ) {
  			pq->ltp_max_count++;
  			rem_thr--;
  		}
  		pq->ltp_max_pending = pool->ltp_max_pending / numqs;
  		if ( rem_pend ) {
  			pq->ltp_max_pending++;
  			rem_pend--;
  		}
  	}
  	pool->ltp_numqs = numqs;
  	return 0;
  }
  
  /* Set max #threads.  value <= 0 means max supported #threads (LDAP_MAXTHR) */
  int
  ldap_pvt_thread_pool_maxthreads(
  	ldap_pvt_thread_pool_t *tpool,
  	int max_threads )
  {
  	struct ldap_int_thread_pool_s *pool;
  	struct ldap_int_thread_poolq_s *pq;
  	int remthr, i;
  
  	if (! (0 <= max_threads && max_threads <= LDAP_MAXTHR))
  		max_threads = 0;
  
  	if (tpool == NULL)
  		return(-1);
  
  	pool = *tpool;
  
  	if (pool == NULL)
  		return(-1);
  
  	pool->ltp_conf_max_count = max_threads;
  	if ( !max_threads )
  		max_threads = LDAP_MAXTHR;
  	pool->ltp_max_count = max_threads;
  
  	remthr = max_threads % pool->ltp_numqs;
  	max_threads /= pool->ltp_numqs;
  
  	for (i=0; i<pool->ltp_numqs; i++) {
  		pq = pool->ltp_wqs[i];
  		pq->ltp_max_count = max_threads;
  		if (remthr) {
  			pq->ltp_max_count++;
  			remthr--;
  		}
  	}
  	return(0);
  }
  
  /* Inspect the pool */
  int
  ldap_pvt_thread_pool_query(
  	ldap_pvt_thread_pool_t *tpool,
  	ldap_pvt_thread_pool_param_t param,
  	void *value )
  {
  	struct ldap_int_thread_pool_s	*pool;
  	int				count = -1;
  
  	if ( tpool == NULL || value == NULL ) {
  		return -1;
  	}
  
  	pool = *tpool;
  
  	if ( pool == NULL ) {
  		return 0;
  	}
  
  	switch ( param ) {
  	case LDAP_PVT_THREAD_POOL_PARAM_MAX:
  		count = pool->ltp_conf_max_count;
  		break;
  
  	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_PAUSING:
  		ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
  		count = (pool->ltp_pause != 0);
  		ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
  		break;
  
  	case LDAP_PVT_THREAD_POOL_PARAM_OPEN:
  	case LDAP_PVT_THREAD_POOL_PARAM_STARTING:
  	case LDAP_PVT_THREAD_POOL_PARAM_ACTIVE:
  	case LDAP_PVT_THREAD_POOL_PARAM_PENDING:
  	case LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD:
  		{
  			int i;
  			count = 0;
  			for (i=0; i<pool->ltp_numqs; i++) {
  				struct ldap_int_thread_poolq_s *pq = pool->ltp_wqs[i];
  				ldap_pvt_thread_mutex_lock(&pq->ltp_mutex);
  				switch(param) {
  					case LDAP_PVT_THREAD_POOL_PARAM_OPEN:
  						count += pq->ltp_open_count;
  						break;
  					case LDAP_PVT_THREAD_POOL_PARAM_STARTING:
  						count += pq->ltp_starting;
  						break;
  					case LDAP_PVT_THREAD_POOL_PARAM_ACTIVE:
  						count += pq->ltp_active_count;
  						break;
  					case LDAP_PVT_THREAD_POOL_PARAM_PENDING:
  						count += pq->ltp_pending_count;
  						break;
  					case LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD:
  						count += pq->ltp_pending_count + pq->ltp_active_count;
  						break;
  				}
  				ldap_pvt_thread_mutex_unlock(&pq->ltp_mutex);
  			}
  			if (count < 0)
  				count = -count;
  		}
  		break;
  
  	case LDAP_PVT_THREAD_POOL_PARAM_ACTIVE_MAX:
  		break;
  
  	case LDAP_PVT_THREAD_POOL_PARAM_PENDING_MAX:
  		break;
  
  	case LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD_MAX:
  		break;
  
  	case LDAP_PVT_THREAD_POOL_PARAM_STATE:
  		if (pool->ltp_pause)
  			*((char **)value) = "pausing";
  		else if (!pool->ltp_finishing)
  			*((char **)value) = "running";
  		else {
  			int i;
  			for (i=0; i<pool->ltp_numqs; i++)
  				if (pool->ltp_wqs[i]->ltp_pending_count) break;
  			if (i<pool->ltp_numqs)
  				*((char **)value) = "finishing";
  			else
  				*((char **)value) = "stopping";
  		}
  		break;
  
  	case LDAP_PVT_THREAD_POOL_PARAM_UNKNOWN:
  		break;
  	}
  
  	if ( count > -1 ) {
  		*((int *)value) = count;
  	}
  
  	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 != 0);
  	}
  
  	return rc;
  }
  
  /*
   * wrapper for ldap_pvt_thread_pool_query(), left around
   * for backwards compatibility
   */
  int
  ldap_pvt_thread_pool_backload ( ldap_pvt_thread_pool_t *tpool )
  {
  	int	rc, count;
  
  	rc = ldap_pvt_thread_pool_query( tpool,
  		LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD, (void *)&count );
  
  	if ( rc == 0 ) {
  		return count;
  	}
  
  	return rc;
  }
  
  /* Destroy the pool after making its threads finish */
  int
  ldap_pvt_thread_pool_destroy ( ldap_pvt_thread_pool_t *tpool, int run_pending )
  {
  	struct ldap_int_thread_pool_s *pool, *pptr;
  	struct ldap_int_thread_poolq_s *pq;
  	ldap_int_thread_task_t *task;
  	int i;
  
  	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_finishing = 1;
  	if (pool->ltp_max_pending > 0)
  		pool->ltp_max_pending = -pool->ltp_max_pending;
  
  	ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
  	ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
  
  	for (i=0; i<pool->ltp_numqs; i++) {
  		pq = pool->ltp_wqs[i];
  		ldap_pvt_thread_mutex_lock(&pq->ltp_mutex);
  		if (pq->ltp_max_pending > 0)
  			pq->ltp_max_pending = -pq->ltp_max_pending;
  		if (!run_pending) {
  			while ((task = LDAP_STAILQ_FIRST(&pq->ltp_pending_list)) != NULL) {
  				LDAP_STAILQ_REMOVE_HEAD(&pq->ltp_pending_list, ltt_next.q);
  				LDAP_FREE(task);
  			}
  			pq->ltp_pending_count = 0;
  		}
  
  		while (pq->ltp_open_count) {
  			ldap_pvt_thread_cond_broadcast(&pq->ltp_cond);
  			ldap_pvt_thread_cond_wait(&pq->ltp_cond, &pq->ltp_mutex);
  		}
  
  		while ((task = LDAP_SLIST_FIRST(&pq->ltp_free_list)) != NULL)
  		{
  			LDAP_SLIST_REMOVE_HEAD(&pq->ltp_free_list, ltt_next.l);
  			LDAP_FREE(task);
  		}
  		ldap_pvt_thread_mutex_unlock(&pq->ltp_mutex);
  		ldap_pvt_thread_cond_destroy(&pq->ltp_cond);
  		ldap_pvt_thread_mutex_destroy(&pq->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);
  	for (i=0; i<pool->ltp_numqs; i++) {
  		pq = pool->ltp_wqs[i];
  		if (pq->ltp_free) {
  			LDAP_FREE(pq->ltp_free);
  		}
  	}
  	LDAP_FREE(pool->ltp_wqs);
  	LDAP_FREE(pool);
  	*tpool = NULL;
  	ldap_int_has_thread_pool = 0;
  	return(0);
  }
  
  /* Thread loop.  Accept and handle submitted tasks. */
  static void *
  ldap_int_thread_pool_wrapper ( 
  	void *xpool )
  {
  	struct ldap_int_thread_poolq_s *pq = xpool;
  	struct ldap_int_thread_pool_s *pool = pq->ltp_pool;
  	ldap_int_thread_task_t *task;
  	ldap_int_tpool_plist_t *work_list;
  	ldap_int_thread_userctx_t ctx, *kctx;
  	unsigned i, keyslot, hash;
  	int pool_lock = 0, freeme = 0;
  
  	assert(pool != NULL);
  
  	for ( i=0; i<MAXKEYS; i++ ) {
  		ctx.ltu_key[i].ltk_key = NULL;
  	}
  
  	ctx.ltu_pq = pq;
  	ctx.ltu_id = ldap_pvt_thread_self();
  	TID_HASH(ctx.ltu_id, hash);
  
  	ldap_pvt_thread_key_setdata( ldap_tpool_key, &ctx );
  
  	if (pool->ltp_pause) {
  		ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
  		/* thread_keys[] is read-only when paused */
  		while (pool->ltp_pause)
  			ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
  		ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
  	}
  
  	/* find a key slot to give this thread ID and store a
  	 * pointer to our keys there; start at the thread ID
  	 * itself (mod LDAP_MAXTHR) and look for an empty slot.
  	 */
  	ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
  	for (keyslot = hash & (LDAP_MAXTHR-1);
  		(kctx = thread_keys[keyslot].ctx) && kctx != DELETED_THREAD_CTX;
  		keyslot = (keyslot+1) & (LDAP_MAXTHR-1));
  	thread_keys[keyslot].ctx = &ctx;
  	ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
  
  	ldap_pvt_thread_mutex_lock(&pq->ltp_mutex);
  	pq->ltp_starting--;
  	pq->ltp_active_count++;
  
  	for (;;) {
  		work_list = pq->ltp_work_list; /* help the compiler a bit */
  		task = LDAP_STAILQ_FIRST(work_list);
  		if (task == NULL) {	/* paused or no pending tasks */
  			if (--(pq->ltp_active_count) < 1) {
  				if (pool->ltp_pause) {
  					ldap_pvt_thread_mutex_unlock(&pq->ltp_mutex);
  					ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
  					pool_lock = 1;
  					if (--(pool->ltp_active_queues) < 1) {
  						/* Notify pool_pause it is the sole active thread. */
  						ldap_pvt_thread_cond_signal(&pool->ltp_pcond);
  					}
  				}
  			}
  
  			do {
  				if (pool->ltp_finishing || pq->ltp_open_count > pq->ltp_max_count) {
  					/* Not paused, and either finishing or too many
  					 * threads running (can happen if ltp_max_count
  					 * was reduced).  Let this thread die.
  					 */
  					goto done;
  				}
  
  				/* 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, wait if ltp_pause, leave thread;
  				 *
  				 * Just use pthread_cond_timedwait() if we want to
  				 * check idle time.
  				 */
  				if (pool_lock) {
  					ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
  					if (!pool->ltp_pause) {
  						ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
  						ldap_pvt_thread_mutex_lock(&pq->ltp_mutex);
  						pool_lock = 0;
  					}
  				} else
  					ldap_pvt_thread_cond_wait(&pq->ltp_cond, &pq->ltp_mutex);
  
  				work_list = pq->ltp_work_list;
  				task = LDAP_STAILQ_FIRST(work_list);
  			} while (task == NULL);
  
  			if (pool_lock) {
  				ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
  				ldap_pvt_thread_mutex_lock(&pq->ltp_mutex);
  				pool_lock = 0;
  			}
  			pq->ltp_active_count++;
  		}
  
  		LDAP_STAILQ_REMOVE_HEAD(work_list, ltt_next.q);
  		pq->ltp_pending_count--;
  		ldap_pvt_thread_mutex_unlock(&pq->ltp_mutex);
  
  		task->ltt_start_routine(&ctx, task->ltt_arg);
  
  		ldap_pvt_thread_mutex_lock(&pq->ltp_mutex);
  		LDAP_SLIST_INSERT_HEAD(&pq->ltp_free_list, task, ltt_next.l);
  	}
   done:
  
  	ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
  
  	/* The pool_mutex lock protects ctx->ltu_key from pool_purgekey()
  	 * during this call, since it prevents new pauses. */
  	ldap_pvt_thread_pool_context_reset(&ctx);
  
  	thread_keys[keyslot].ctx = DELETED_THREAD_CTX;
  	ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
  
  	pq->ltp_open_count--;
  	if (pq->ltp_open_count == 0) {
  		if (pool->ltp_finishing)
  			/* let pool_destroy know we're all done */
  			ldap_pvt_thread_cond_signal(&pq->ltp_cond);
  		else
  			freeme = 1;
  	}
  
  	if (pool_lock)
  		ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
  	else
  		ldap_pvt_thread_mutex_unlock(&pq->ltp_mutex);
  
  	if (freeme) {
  		ldap_pvt_thread_cond_destroy(&pq->ltp_cond);
  		ldap_pvt_thread_mutex_destroy(&pq->ltp_mutex);
  		LDAP_FREE(pq->ltp_free);
  		pq->ltp_free = NULL;
  	}
  	ldap_pvt_thread_exit(NULL);
  	return(NULL);
  }
  
  /* Arguments > ltp_pause to handle_pause(,PAUSE_ARG()).  arg=PAUSE_ARG
   * ensures (arg-ltp_pause) sets GO_* at need and keeps DO_PAUSE/GO_*.
   */
  #define GO_IDLE		8
  #define GO_UNIDLE	16
  #define CHECK_PAUSE	32	/* if ltp_pause: GO_IDLE; wait; GO_UNIDLE */
  #define DO_PAUSE	64	/* CHECK_PAUSE; pause the pool */
  #define PAUSE_ARG(a) \
  		((a) | ((a) & (GO_IDLE|GO_UNIDLE) ? GO_IDLE-1 : CHECK_PAUSE))
  
  static int
  handle_pause( ldap_pvt_thread_pool_t *tpool, int pause_type )
  {
  	struct ldap_int_thread_pool_s *pool;
  	struct ldap_int_thread_poolq_s *pq;
  	int ret = 0, pause, max_ltp_pause;
  
  	if (tpool == NULL)
  		return(-1);
  
  	pool = *tpool;
  
  	if (pool == NULL)
  		return(0);
  
  	if (pause_type == CHECK_PAUSE && !pool->ltp_pause)
  		return(0);
  
  	{
  		ldap_int_thread_userctx_t *ctx = ldap_pvt_thread_pool_context();
  		pq = ctx->ltu_pq;
  	}
  
  	/* Let pool_unidle() ignore requests for new pauses */
  	max_ltp_pause = pause_type==PAUSE_ARG(GO_UNIDLE) ? WANT_PAUSE : NOT_PAUSED;
  
  	ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
  
  	pause = pool->ltp_pause;	/* NOT_PAUSED, WANT_PAUSE or PAUSED */
  
  	/* If ltp_pause and not GO_IDLE|GO_UNIDLE: Set GO_IDLE,GO_UNIDLE */
  	pause_type -= pause;
  
  	if (pause_type & GO_IDLE) {
  		int do_pool = 0;
  		ldap_pvt_thread_mutex_lock(&pq->ltp_mutex);
  		pq->ltp_pending_count++;
  		pq->ltp_active_count--;
  		if (pause && pq->ltp_active_count < 1) {
  			do_pool = 1;
  		}
  		ldap_pvt_thread_mutex_unlock(&pq->ltp_mutex);
  		if (do_pool) {
  			pool->ltp_active_queues--;
  			if (pool->ltp_active_queues < 1)
  			/* Tell the task waiting to DO_PAUSE it can proceed */
  				ldap_pvt_thread_cond_signal(&pool->ltp_pcond);
  		}
  	}
  
  	if (pause_type & GO_UNIDLE) {
  		/* Wait out pause if any, then cancel GO_IDLE */
  		if (pause > max_ltp_pause) {
  			ret = 1;
  			do {
  				ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
  			} while (pool->ltp_pause > max_ltp_pause);
  		}
  		ldap_pvt_thread_mutex_lock(&pq->ltp_mutex);
  		pq->ltp_pending_count--;
  		pq->ltp_active_count++;
  		ldap_pvt_thread_mutex_unlock(&pq->ltp_mutex);
  	}
  
  	if (pause_type & DO_PAUSE) {
  		int i, j;
  		/* Tell everyone else to pause or finish, then await that */
  		ret = 0;
  		assert(!pool->ltp_pause);
  		pool->ltp_pause = WANT_PAUSE;
  		pool->ltp_active_queues = 0;
  
  		for (i=0; i<pool->ltp_numqs; i++)
  			if (pool->ltp_wqs[i] == pq) break;
  
  		ldap_pvt_thread_mutex_lock(&pq->ltp_mutex);
  		/* temporarily remove ourself from active count */
  		pq->ltp_active_count--;
  
  		j=i;
  		do {
  			pq = pool->ltp_wqs[j];
  			if (j != i)
  				ldap_pvt_thread_mutex_lock(&pq->ltp_mutex);
  
  			/* Let ldap_pvt_thread_pool_submit() through to its ltp_pause test,
  			 * and do not finish threads in ldap_pvt_thread_pool_wrapper() */
  			pq->ltp_open_count = -pq->ltp_open_count;
  			/* Hide pending tasks from ldap_pvt_thread_pool_wrapper() */
  			pq->ltp_work_list = &empty_pending_list;
  
  			if (pq->ltp_active_count > 0)
  				pool->ltp_active_queues++;
  
  			ldap_pvt_thread_mutex_unlock(&pq->ltp_mutex);
  			if (pool->ltp_numqs > 1) {
  				j++;
  				j %= pool->ltp_numqs;
  			}
  		} while (j != i);
  
  		/* Wait for this task to become the sole active task */
  		while (pool->ltp_active_queues > 0)
  			ldap_pvt_thread_cond_wait(&pool->ltp_pcond, &pool->ltp_mutex);
  
  		/* restore us to active count */
  		pool->ltp_wqs[i]->ltp_active_count++;
  
  		assert(pool->ltp_pause == WANT_PAUSE);
  		pool->ltp_pause = PAUSED;
  	}
  	ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
  
  	return(ret);
  }
  
  /* Consider this task idle: It will not block pool_pause() in other tasks. */
  void
  ldap_pvt_thread_pool_idle( ldap_pvt_thread_pool_t *tpool )
  {
  	handle_pause(tpool, PAUSE_ARG(GO_IDLE));
  }
  
  /* Cancel pool_idle(). If the pool is paused, wait it out first. */
  void
  ldap_pvt_thread_pool_unidle( ldap_pvt_thread_pool_t *tpool )
  {
  	handle_pause(tpool, PAUSE_ARG(GO_UNIDLE));
  }
  
  /*
   * If a pause was requested, wait for it.  If several threads
   * are waiting to pause, let through one or more pauses.
   * The calling task must be active, not idle.
   * 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, PAUSE_ARG(CHECK_PAUSE));
  }
  
  /*
   * Pause the pool.  The calling task must be active, not idle.
   * Return when all other tasks are paused or idle.
   */
  int
  ldap_pvt_thread_pool_pause( ldap_pvt_thread_pool_t *tpool )
  {
  	return handle_pause(tpool, PAUSE_ARG(DO_PAUSE));
  }
  
  /* End a pause */
  int
  ldap_pvt_thread_pool_resume ( 
  	ldap_pvt_thread_pool_t *tpool )
  {
  	struct ldap_int_thread_pool_s *pool;
  	struct ldap_int_thread_poolq_s *pq;
  	int i;
  
  	if (tpool == NULL)
  		return(-1);
  
  	pool = *tpool;
  
  	if (pool == NULL)
  		return(0);
  
  	ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
  	assert(pool->ltp_pause == PAUSED);
  	pool->ltp_pause = 0;
  	for (i=0; i<pool->ltp_numqs; i++) {
  		pq = pool->ltp_wqs[i];
  		if (pq->ltp_open_count <= 0) /* true when paused, but be paranoid */
  			pq->ltp_open_count = -pq->ltp_open_count;
  		pq->ltp_work_list = &pq->ltp_pending_list;
  		ldap_pvt_thread_cond_broadcast(&pq->ltp_cond);
  	}
  	ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
  	ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
  	return(0);
  }
  
  /*
   * Get the key's data and optionally free function in the given context.
   */
  int ldap_pvt_thread_pool_getkey(
  	void *xctx,
  	void *key,
  	void **data,
  	ldap_pvt_thread_pool_keyfree_t **kfree )
  {
  	ldap_int_thread_userctx_t *ctx = xctx;
  	int i;
  
  	if ( !ctx || !key || !data ) return EINVAL;
  
  	for ( i=0; i<MAXKEYS && ctx->ltu_key[i].ltk_key; i++ ) {
  		if ( ctx->ltu_key[i].ltk_key == key ) {
  			*data = ctx->ltu_key[i].ltk_data;
  			if ( kfree ) *kfree = ctx->ltu_key[i].ltk_free;
  			return 0;
  		}
  	}
  	return ENOENT;
  }
  
  static void
  clear_key_idx( ldap_int_thread_userctx_t *ctx, int i )
  {
  	for ( ; i < MAXKEYS-1 && ctx->ltu_key[i+1].ltk_key; i++ )
  		ctx->ltu_key[i] = ctx->ltu_key[i+1];
  	ctx->ltu_key[i].ltk_key = NULL;
  }
  
  /*
   * Set or remove data for the key in the given context.
   * key can be any unique pointer.
   * kfree() is an optional function to free the data (but not the key):
   *   pool_context_reset() and pool_purgekey() call kfree(key, data),
   *   but pool_setkey() does not.  For pool_setkey() it is the caller's
   *   responsibility to free any existing data with the same key.
   *   kfree() must not call functions taking a tpool argument.
   */
  int ldap_pvt_thread_pool_setkey(
  	void *xctx,
  	void *key,
  	void *data,
  	ldap_pvt_thread_pool_keyfree_t *kfree,
  	void **olddatap,
  	ldap_pvt_thread_pool_keyfree_t **oldkfreep )
  {
  	ldap_int_thread_userctx_t *ctx = xctx;
  	int i, found;
  
  	if ( !ctx || !key ) return EINVAL;
  
  	for ( i=found=0; i<MAXKEYS; i++ ) {
  		if ( ctx->ltu_key[i].ltk_key == key ) {
  			found = 1;
  			break;
  		} else if ( !ctx->ltu_key[i].ltk_key ) {
  			break;
  		}
  	}
  
  	if ( olddatap ) {
  		if ( found ) {
  			*olddatap = ctx->ltu_key[i].ltk_data;
  		} else {
  			*olddatap = NULL;
  		}
  	}
  
  	if ( oldkfreep ) {
  		if ( found ) {
  			*oldkfreep = ctx->ltu_key[i].ltk_free;
  		} else {
  			*oldkfreep = 0;
  		}
  	}
  
  	if ( data || kfree ) {
  		if ( i>=MAXKEYS )
  			return ENOMEM;
  		ctx->ltu_key[i].ltk_key = key;
  		ctx->ltu_key[i].ltk_data = data;
  		ctx->ltu_key[i].ltk_free = kfree;
  	} else if ( found ) {
  		clear_key_idx( ctx, i );
  	}
  
  	return 0;
  }
  
  /* 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_userctx_t *ctx;
  
  	assert ( key != NULL );
  
  	ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
  	for ( i=0; i<LDAP_MAXTHR; i++ ) {
  		ctx = thread_keys[i].ctx;
  		if ( ctx && ctx != DELETED_THREAD_CTX ) {
  			for ( j=0; j<MAXKEYS && ctx->ltu_key[j].ltk_key; j++ ) {
  				if ( ctx->ltu_key[j].ltk_key == key ) {
  					if (ctx->ltu_key[j].ltk_free)
  						ctx->ltu_key[j].ltk_free( ctx->ltu_key[j].ltk_key,
  						ctx->ltu_key[j].ltk_data );
  					clear_key_idx( ctx, j );
  					break;
  				}
  			}
  		}
  	}
  	ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
  }
  
  /*
   * Find the context of the current thread.
   * 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
   * for the application to keep track of the thread context
   * handles itself.
   */
  void *ldap_pvt_thread_pool_context( )
  {
  	void *ctx = NULL;
  
  	ldap_pvt_thread_key_getdata( ldap_tpool_key, &ctx );
  	return ctx ? ctx : (void *) &ldap_int_main_thrctx;
  }
  
  /*
   * Free the context's keys.
   * Must not call functions taking a tpool argument (because this
   * thread already holds ltp_mutex when called from pool_wrapper()).
   */
  void ldap_pvt_thread_pool_context_reset( void *vctx )
  {
  	ldap_int_thread_userctx_t *ctx = vctx;
  	int i;
  
  	for ( i=MAXKEYS-1; i>=0; i--) {
  		if ( !ctx->ltu_key[i].ltk_key )
  			continue;
  		if ( ctx->ltu_key[i].ltk_free )
  			ctx->ltu_key[i].ltk_free( ctx->ltu_key[i].ltk_key,
  			ctx->ltu_key[i].ltk_data );
  		ctx->ltu_key[i].ltk_key = NULL;
  	}
  }
  
  ldap_pvt_thread_t ldap_pvt_thread_pool_tid( void *vctx )
  {
  	ldap_int_thread_userctx_t *ctx = vctx;
  
  	return ctx->ltu_id;
  }
  #endif /* LDAP_THREAD_HAVE_TPOOL */
  