Adding upstream version 2.4.57+dfsg.upstream/2.4.57+dfsgupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1032 insertions, 0 deletions

diff --git a/libraries/libldap_r/tpool.c b/libraries/libldap_r/tpool.c
new file mode 100644
index 0000000..17cee3b
--- /dev/null
+++ b/libraries/libldap_r/tpool.c
@@ -0,0 +1,1032 @@
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 1998-2021 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
+
+/* 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 {
+	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 tpool->ltp_mutex during pauses.
+ */
+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_pool_s {
+	LDAP_STAILQ_ENTRY(ldap_int_thread_pool_s) ltp_next;
+
+	/* protect members below, and protect thread_keys[] during pauses */
+	ldap_pvt_thread_mutex_t ltp_mutex;
+
+	/* not paused and something to do for pool_<wrapper/pause/destroy>() */
+	ldap_pvt_thread_cond_t ltp_cond;
+
+	/* ltp_active_count <= 1 && ltp_pause */
+	ldap_pvt_thread_cond_t ltp_pcond;
+
+	/* 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;
+
+	/* 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.
+	 * Note: Pauses adjust ltp_<open_count/vary_open_count/work_list>,
+	 * so pool_<submit/wrapper>() mostly can avoid testing ltp_pause.
+	 */
+	volatile sig_atomic_t ltp_pause;
+
+	/* Max number of threads in pool, or 0 for default (LDAP_MAXTHR) */
+	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;			/* Currenlty starting threads */
+
+	/* >0 if paused or we may open a thread, <0 if we should close a thread.
+	 * Updated when ltp_<finishing/pause/max_count/open_count> change.
+	 * Maintained to reduce the time ltp_mutex must be locked in
+	 * ldap_pvt_thread_pool_<submit/wrapper>().
+	 */
+	int ltp_vary_open_count;
+#	define SET_VARY_OPEN_COUNT(pool)	\
+		((pool)->ltp_vary_open_count =	\
+		 (pool)->ltp_pause      ?  1 :	\
+		 (pool)->ltp_finishing  ? -1 :	\
+		 ((pool)->ltp_max_count ? (pool)->ltp_max_count : LDAP_MAXTHR) \
+		 - (pool)->ltp_open_count)
+};
+
+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 (
+	ldap_pvt_thread_pool_t *tpool,
+	int max_threads,
+	int max_pending )
+{
+	ldap_pvt_thread_pool_t pool;
+	int rc;
+
+	/* 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);
+
+	rc = ldap_pvt_thread_mutex_init(&pool->ltp_mutex);
+	if (rc != 0) {
+fail1:
+		LDAP_FREE(pool);
+		return(rc);
+	}
+	rc = ldap_pvt_thread_cond_init(&pool->ltp_cond);
+	if (rc != 0) {
+fail2:
+		ldap_pvt_thread_mutex_destroy(&pool->ltp_mutex);
+		goto fail1;
+	}
+	rc = ldap_pvt_thread_cond_init(&pool->ltp_pcond);
+	if (rc != 0) {
+		ldap_pvt_thread_cond_destroy(&pool->ltp_cond);
+		goto fail2;
+	}
+
+	ldap_int_has_thread_pool = 1;
+
+	pool->ltp_max_count = max_threads;
+	SET_VARY_OPEN_COUNT(pool);
+	pool->ltp_max_pending = max_pending;
+
+	LDAP_STAILQ_INIT(&pool->ltp_pending_list);
+	pool->ltp_work_list = &pool->ltp_pending_list;
+	LDAP_SLIST_INIT(&pool->ltp_free_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);
+
+	/* 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);
+}
+
+
+/* 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;
+	ldap_int_thread_task_t *task;
+	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_pending_count >= pool->ltp_max_pending)
+		goto failed;
+
+	task = LDAP_SLIST_FIRST(&pool->ltp_free_list);
+	if (task) {
+		LDAP_SLIST_REMOVE_HEAD(&pool->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;
+
+	pool->ltp_pending_count++;
+	LDAP_STAILQ_INSERT_TAIL(&pool->ltp_pending_list, task, ltt_next.q);
+
+	/* true if ltp_pause != 0 or we should open (create) a thread */
+	if (pool->ltp_vary_open_count > 0 &&
+		pool->ltp_open_count < pool->ltp_active_count+pool->ltp_pending_count)
+	{
+		if (pool->ltp_pause)
+			goto done;
+
+		pool->ltp_starting++;
+		pool->ltp_open_count++;
+		SET_VARY_OPEN_COUNT(pool);
+
+		if (0 != ldap_pvt_thread_create(
+			&thr, 1, ldap_int_thread_pool_wrapper, pool))
+		{
+			/* couldn't create thread.  back out of
+			 * ltp_open_count and check for even worse things.
+			 */
+			pool->ltp_starting--;
+			pool->ltp_open_count--;
+			SET_VARY_OPEN_COUNT(pool);
+
+			if (pool->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(&pool->ltp_cond);
+
+				LDAP_STAILQ_FOREACH(ptr, &pool->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.
+					 */
+					pool->ltp_pending_count--;
+					LDAP_STAILQ_REMOVE(&pool->ltp_pending_list, task,
+						ldap_int_thread_task_s, ltt_next.q);
+					LDAP_SLIST_INSERT_HEAD(&pool->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(&pool->ltp_cond);
+
+ done:
+	ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
+	return(0);
+
+ failed:
+	ldap_pvt_thread_mutex_unlock(&pool->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;
+	ldap_int_thread_task_t *task;
+
+	if (tpool == NULL)
+		return(-1);
+
+	pool = *tpool;
+
+	if (pool == NULL)
+		return(-1);
+
+	ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
+	LDAP_STAILQ_FOREACH(task, &pool->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(&pool->ltp_mutex);
+	return task != NULL;
+}
+
+/* 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;
+
+	if (! (0 <= max_threads && max_threads <= LDAP_MAXTHR))
+		max_threads = 0;
+
+	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;
+	SET_VARY_OPEN_COUNT(pool);
+
+	ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
+	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;
+	}
+
+	ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
+	switch ( param ) {
+	case LDAP_PVT_THREAD_POOL_PARAM_MAX:
+		count = pool->ltp_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_OPEN:
+		count = pool->ltp_open_count;
+		if (count < 0)
+			count = -count;
+		break;
+
+	case LDAP_PVT_THREAD_POOL_PARAM_STARTING:
+		count = pool->ltp_starting;
+		break;
+
+	case LDAP_PVT_THREAD_POOL_PARAM_ACTIVE:
+		count = pool->ltp_active_count;
+		break;
+
+	case LDAP_PVT_THREAD_POOL_PARAM_PAUSING:
+		count = (pool->ltp_pause != 0);
+		break;
+
+	case LDAP_PVT_THREAD_POOL_PARAM_PENDING:
+		count = pool->ltp_pending_count;
+		break;
+
+	case LDAP_PVT_THREAD_POOL_PARAM_BACKLOAD:
+		count = pool->ltp_pending_count + pool->ltp_active_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:
+		*((char **)value) =
+			pool->ltp_pause ? "pausing" :
+			!pool->ltp_finishing ? "running" :
+			pool->ltp_pending_count ? "finishing" : "stopping";
+		break;
+
+	case LDAP_PVT_THREAD_POOL_PARAM_UNKNOWN:
+		break;
+	}
+	ldap_pvt_thread_mutex_unlock( &pool->ltp_mutex );
+
+	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;
+	ldap_int_thread_task_t *task;
+
+	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;
+	SET_VARY_OPEN_COUNT(pool);
+	if (pool->ltp_max_pending > 0)
+		pool->ltp_max_pending = -pool->ltp_max_pending;
+
+	if (!run_pending) {
+		while ((task = LDAP_STAILQ_FIRST(&pool->ltp_pending_list)) != NULL) {
+			LDAP_STAILQ_REMOVE_HEAD(&pool->ltp_pending_list, ltt_next.q);
+			LDAP_FREE(task);
+		}
+		pool->ltp_pending_count = 0;
+	}
+
+	while (pool->ltp_open_count) {
+		if (!pool->ltp_pause)
+			ldap_pvt_thread_cond_broadcast(&pool->ltp_cond);
+		ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
+	}
+
+	while ((task = LDAP_SLIST_FIRST(&pool->ltp_free_list)) != NULL)
+	{
+		LDAP_SLIST_REMOVE_HEAD(&pool->ltp_free_list, ltt_next.l);
+		LDAP_FREE(task);
+	}
+
+	ldap_pvt_thread_mutex_unlock(&pool->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);
+	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_pool_s *pool = xpool;
+	ldap_int_thread_task_t *task;
+	ldap_int_tpool_plist_t *work_list;
+	ldap_int_thread_userctx_t ctx, *kctx;
+	unsigned i, keyslot, hash;
+
+	assert(pool != NULL);
+
+	for ( i=0; i<MAXKEYS; i++ ) {
+		ctx.ltu_key[i].ltk_key = NULL;
+	}
+
+	ctx.ltu_id = ldap_pvt_thread_self();
+	TID_HASH(ctx.ltu_id, hash);
+
+	ldap_pvt_thread_key_setdata( ldap_tpool_key, &ctx );
+
+	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);
+
+	/* 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);
+
+	pool->ltp_starting--;
+	pool->ltp_active_count++;
+
+	for (;;) {
+		work_list = pool->ltp_work_list; /* help the compiler a bit */
+		task = LDAP_STAILQ_FIRST(work_list);
+		if (task == NULL) {	/* paused or no pending tasks */
+			if (--(pool->ltp_active_count) < 2) {
+				/* Notify pool_pause it is the sole active thread. */
+				ldap_pvt_thread_cond_signal(&pool->ltp_pcond);
+			}
+
+			do {
+				if (pool->ltp_vary_open_count < 0) {
+					/* 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.
+				 */
+				ldap_pvt_thread_cond_wait(&pool->ltp_cond, &pool->ltp_mutex);
+
+				work_list = pool->ltp_work_list;
+				task = LDAP_STAILQ_FIRST(work_list);
+			} while (task == NULL);
+
+			pool->ltp_active_count++;
+		}
+
+		LDAP_STAILQ_REMOVE_HEAD(work_list, ltt_next.q);
+		pool->ltp_pending_count--;
+		ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
+
+		task->ltt_start_routine(&ctx, task->ltt_arg);
+
+		ldap_pvt_thread_mutex_lock(&pool->ltp_mutex);
+		LDAP_SLIST_INSERT_HEAD(&pool->ltp_free_list, task, ltt_next.l);
+	}
+ done:
+
+	assert(!pool->ltp_pause); /* thread_keys writable, ltp_open_count >= 0 */
+
+	/* The ltp_mutex lock protects ctx->ltu_key from pool_purgekey()
+	 * during this call, since it prevents new pauses. */
+	ldap_pvt_thread_pool_context_reset(&ctx);
+
+	ldap_pvt_thread_mutex_lock(&ldap_pvt_thread_pool_mutex);
+	thread_keys[keyslot].ctx = DELETED_THREAD_CTX;
+	ldap_pvt_thread_mutex_unlock(&ldap_pvt_thread_pool_mutex);
+
+	pool->ltp_open_count--;
+	SET_VARY_OPEN_COUNT(pool);
+	/* let pool_destroy know we're all done */
+	if (pool->ltp_open_count == 0)
+		ldap_pvt_thread_cond_signal(&pool->ltp_cond);
+
+	ldap_pvt_thread_mutex_unlock(&pool->ltp_mutex);
+
+	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;
+	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);
+
+	/* 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) {
+		pool->ltp_pending_count++;
+		pool->ltp_active_count--;
+		if (pause && pool->ltp_active_count < 2) {
+			/* 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);
+		}
+		pool->ltp_pending_count--;
+		pool->ltp_active_count++;
+	}
+
+	if (pause_type & DO_PAUSE) {
+		/* Tell everyone else to pause or finish, then await that */
+		ret = 0;
+		assert(!pool->ltp_pause);
+		pool->ltp_pause = WANT_PAUSE;
+		/* Let ldap_pvt_thread_pool_submit() through to its ltp_pause test,
+		 * and do not finish threads in ldap_pvt_thread_pool_wrapper() */
+		pool->ltp_open_count = -pool->ltp_open_count;
+		SET_VARY_OPEN_COUNT(pool);
+		/* Hide pending tasks from ldap_pvt_thread_pool_wrapper() */
+		pool->ltp_work_list = &empty_pending_list;
+		/* Wait for this task to become the sole active task */
+		while (pool->ltp_active_count > 1) {
+			ldap_pvt_thread_cond_wait(&pool->ltp_pcond, &pool->ltp_mutex);
+		}
+		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;
+
+	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;
+	if (pool->ltp_open_count <= 0) /* true when paused, but be paranoid */
+		pool->ltp_open_count = -pool->ltp_open_count;
+	SET_VARY_OPEN_COUNT(pool);
+	pool->ltp_work_list = &pool->ltp_pending_list;
+
+	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 );
+
+	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;
+				}
+			}
+		}
+	}
+}
+
+/*
+ * 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 */