MFC r265689:

Import adapted OpenSolaris' thread pool API implementation.

The thread pool is used by libzfs to implement parallel disk scanning.
Without this change our dummy wrapper made `zpool import ZZZ` command to
scan all disks sequentially from the single thread when searching for pools.
This change makes it use two threads per CPU, same as in OpenSolaris.

On system with 200 HDDs this change reduces ZFS pool import time from 35
to 22 seconds.

3 files changed, 598 insertions, 30 deletions

diff --git a/cddl/compat/opensolaris/include/thread_pool.h b/cddl/compat/opensolaris/include/thread_pool.h
index 25ac55d..3bd23a6 100644
--- a/cddl/compat/opensolaris/include/thread_pool.h
+++ b/cddl/compat/opensolaris/include/thread_pool.h
@@ -1,39 +1,78 @@
-/*-
- * Copyright (c) 2010 Pawel Jakub Dawidek <pjd@FreeBSD.org>
- * All rights reserved.
+/*
+ * CDDL HEADER START
  *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
  *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
  *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+/*
  * $FreeBSD$
  */
 
-#ifndef _OPENSOLARIS_THREAD_POOL_H_
-#define _OPENSOLARIS_THREAD_POOL_H_
+#ifndef	_THREAD_POOL_H_
+#define	_THREAD_POOL_H_
+
+#pragma ident	"%Z%%M%	%I%	%E% SMI"
+
+#include <sys/types.h>
+#include <thread.h>
+#include <pthread.h>
+
+#ifdef	__cplusplus
+extern "C" {
+#endif
+
+typedef	struct tpool tpool_t;	/* opaque thread pool descriptor */
+
+#if defined(__STDC__)
+
+extern	tpool_t	*tpool_create(uint_t min_threads, uint_t max_threads,
+			uint_t linger, pthread_attr_t *attr);
+extern	int	tpool_dispatch(tpool_t *tpool,
+			void (*func)(void *), void *arg);
+extern	void	tpool_destroy(tpool_t *tpool);
+extern	void	tpool_abandon(tpool_t *tpool);
+extern	void	tpool_wait(tpool_t *tpool);
+extern	void	tpool_suspend(tpool_t *tpool);
+extern	int	tpool_suspended(tpool_t *tpool);
+extern	void	tpool_resume(tpool_t *tpool);
+extern	int	tpool_member(tpool_t *tpool);
+
+#else	/* Non ANSI */
+
+extern	tpool_t	*tpool_create();
+extern	int	tpool_dispatch();
+extern	void	tpool_destroy();
+extern	void	tpool_abandon();
+extern	void	tpool_wait();
+extern	void	tpool_suspend();
+extern	int	tpool_suspended();
+extern	void	tpool_resume();
+extern	int	tpool_member();
 
-typedef int tpool_t;
+#endif	/* __STDC__ */
 
-#define	tpool_create(a, b, c, d)	(0)
-#define	tpool_dispatch(pool, func, arg)	func(arg)
-#define	tpool_wait(pool)		do { } while (0)
-#define	tpool_destroy(pool)		do { } while (0)
+#ifdef	__cplusplus
+}
+#endif
 
-#endif	/* !_OPENSOLARIS_THREAD_POOL_H_ */
+#endif	/* _THREAD_POOL_H_ */
diff --git a/cddl/compat/opensolaris/misc/thread_pool.c b/cddl/compat/opensolaris/misc/thread_pool.c
new file mode 100644
index 0000000..a6a834f
--- /dev/null
+++ b/cddl/compat/opensolaris/misc/thread_pool.c
@@ -0,0 +1,430 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#pragma ident	"%Z%%M%	%I%	%E% SMI"
+
+#include <stdlib.h>
+#include <signal.h>
+#include <errno.h>
+#include "thread_pool_impl.h"
+
+typedef void (*_Voidfp)(void*); /* pointer to extern "C" function */
+
+static void
+delete_pool(tpool_t *tpool)
+{
+	tpool_job_t *job;
+
+	/*
+	 * There should be no pending jobs, but just in case...
+	 */
+	for (job = tpool->tp_head; job != NULL; job = tpool->tp_head) {
+		tpool->tp_head = job->tpj_next;
+		free(job);
+	}
+	(void) pthread_attr_destroy(&tpool->tp_attr);
+	free(tpool);
+}
+
+/*
+ * Worker thread is terminating.
+ */
+static void
+worker_cleanup(void *arg)
+{
+	tpool_t *tpool = arg;
+
+	if (--tpool->tp_current == 0 &&
+	    (tpool->tp_flags & (TP_DESTROY | TP_ABANDON))) {
+		if (tpool->tp_flags & TP_ABANDON) {
+			pthread_mutex_unlock(&tpool->tp_mutex);
+			delete_pool(tpool);
+			return;
+		}
+		if (tpool->tp_flags & TP_DESTROY)
+			(void) pthread_cond_broadcast(&tpool->tp_busycv);
+	}
+	pthread_mutex_unlock(&tpool->tp_mutex);
+}
+
+static void
+notify_waiters(tpool_t *tpool)
+{
+	if (tpool->tp_head == NULL && tpool->tp_active == NULL) {
+		tpool->tp_flags &= ~TP_WAIT;
+		(void) pthread_cond_broadcast(&tpool->tp_waitcv);
+	}
+}
+
+/*
+ * Called by a worker thread on return from a tpool_dispatch()d job.
+ */
+static void
+job_cleanup(void *arg)
+{
+	tpool_t *tpool = arg;
+	pthread_t my_tid = pthread_self();
+	tpool_active_t *activep;
+	tpool_active_t **activepp;
+
+	pthread_mutex_lock(&tpool->tp_mutex);
+	/* CSTYLED */
+	for (activepp = &tpool->tp_active;; activepp = &activep->tpa_next) {
+		activep = *activepp;
+		if (activep->tpa_tid == my_tid) {
+			*activepp = activep->tpa_next;
+			break;
+		}
+	}
+	if (tpool->tp_flags & TP_WAIT)
+		notify_waiters(tpool);
+}
+
+static void *
+tpool_worker(void *arg)
+{
+	tpool_t *tpool = (tpool_t *)arg;
+	int elapsed;
+	tpool_job_t *job;
+	void (*func)(void *);
+	tpool_active_t active;
+	sigset_t maskset;
+
+	pthread_mutex_lock(&tpool->tp_mutex);
+	pthread_cleanup_push(worker_cleanup, tpool);
+
+	/*
+	 * This is the worker's main loop.
+	 * It will only be left if a timeout or an error has occured.
+	 */
+	active.tpa_tid = pthread_self();
+	for (;;) {
+		elapsed = 0;
+		tpool->tp_idle++;
+		if (tpool->tp_flags & TP_WAIT)
+			notify_waiters(tpool);
+		while ((tpool->tp_head == NULL ||
+		    (tpool->tp_flags & TP_SUSPEND)) &&
+		    !(tpool->tp_flags & (TP_DESTROY | TP_ABANDON))) {
+			if (tpool->tp_current <= tpool->tp_minimum ||
+			    tpool->tp_linger == 0) {
+				(void) pthread_cond_wait(&tpool->tp_workcv,
+				    &tpool->tp_mutex);
+			} else {
+				struct timespec timeout;
+
+				clock_gettime(CLOCK_MONOTONIC, &timeout);
+				timeout.tv_sec += tpool->tp_linger;
+				if (pthread_cond_timedwait(&tpool->tp_workcv,
+				    &tpool->tp_mutex, &timeout) != 0) {
+					elapsed = 1;
+					break;
+				}
+			}
+		}
+		tpool->tp_idle--;
+		if (tpool->tp_flags & TP_DESTROY)
+			break;
+		if (tpool->tp_flags & TP_ABANDON) {
+			/* can't abandon a suspended pool */
+			if (tpool->tp_flags & TP_SUSPEND) {
+				tpool->tp_flags &= ~TP_SUSPEND;
+				(void) pthread_cond_broadcast(&tpool->tp_workcv);
+			}
+			if (tpool->tp_head == NULL)
+				break;
+		}
+		if ((job = tpool->tp_head) != NULL &&
+		    !(tpool->tp_flags & TP_SUSPEND)) {
+			elapsed = 0;
+			func = job->tpj_func;
+			arg = job->tpj_arg;
+			tpool->tp_head = job->tpj_next;
+			if (job == tpool->tp_tail)
+				tpool->tp_tail = NULL;
+			tpool->tp_njobs--;
+			active.tpa_next = tpool->tp_active;
+			tpool->tp_active = &active;
+			pthread_mutex_unlock(&tpool->tp_mutex);
+			pthread_cleanup_push(job_cleanup, tpool);
+			free(job);
+			/*
+			 * Call the specified function.
+			 */
+			func(arg);
+			/*
+			 * We don't know what this thread has been doing,
+			 * so we reset its signal mask and cancellation
+			 * state back to the initial values.
+			 */
+			sigfillset(&maskset);
+			(void) pthread_sigmask(SIG_SETMASK, &maskset, NULL);
+			(void) pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED,
+			    NULL);
+			(void) pthread_setcancelstate(PTHREAD_CANCEL_ENABLE,
+			    NULL);
+			pthread_cleanup_pop(1);
+		}
+		if (elapsed && tpool->tp_current > tpool->tp_minimum) {
+			/*
+			 * We timed out and there is no work to be done
+			 * and the number of workers exceeds the minimum.
+			 * Exit now to reduce the size of the pool.
+			 */
+			break;
+		}
+	}
+	pthread_cleanup_pop(1);
+	return (arg);
+}
+
+/*
+ * Create a worker thread, with all signals blocked.
+ */
+static int
+create_worker(tpool_t *tpool)
+{
+	sigset_t maskset, oset;
+	pthread_t thread;
+	int error;
+
+	sigfillset(&maskset);
+	(void) pthread_sigmask(SIG_SETMASK, &maskset, &oset);
+	error = pthread_create(&thread, &tpool->tp_attr, tpool_worker, tpool);
+	(void) pthread_sigmask(SIG_SETMASK, &oset, NULL);
+	return (error);
+}
+
+tpool_t	*
+tpool_create(uint_t min_threads, uint_t max_threads, uint_t linger,
+	pthread_attr_t *attr)
+{
+	tpool_t	*tpool;
+	int error;
+
+	if (min_threads > max_threads || max_threads < 1) {
+		errno = EINVAL;
+		return (NULL);
+	}
+
+	tpool = malloc(sizeof (*tpool));
+	if (tpool == NULL) {
+		errno = ENOMEM;
+		return (NULL);
+	}
+	bzero(tpool, sizeof(*tpool));
+	(void) pthread_mutex_init(&tpool->tp_mutex, NULL);
+	(void) pthread_cond_init(&tpool->tp_busycv, NULL);
+	(void) pthread_cond_init(&tpool->tp_workcv, NULL);
+	(void) pthread_cond_init(&tpool->tp_waitcv, NULL);
+	tpool->tp_minimum = min_threads;
+	tpool->tp_maximum = max_threads;
+	tpool->tp_linger = linger;
+
+	/* make all pool threads be detached daemon threads */
+	(void) pthread_attr_init(&tpool->tp_attr);
+	(void) pthread_attr_setdetachstate(&tpool->tp_attr,
+	    PTHREAD_CREATE_DETACHED);
+
+	return (tpool);
+}
+
+/*
+ * Dispatch a work request to the thread pool.
+ * If there are idle workers, awaken one.
+ * Else, if the maximum number of workers has
+ * not been reached, spawn a new worker thread.
+ * Else just return with the job added to the queue.
+ */
+int
+tpool_dispatch(tpool_t *tpool, void (*func)(void *), void *arg)
+{
+	tpool_job_t *job;
+
+	if ((job = malloc(sizeof (*job))) == NULL)
+		return (-1);
+	bzero(job, sizeof(*job));
+	job->tpj_next = NULL;
+	job->tpj_func = func;
+	job->tpj_arg = arg;
+
+	pthread_mutex_lock(&tpool->tp_mutex);
+
+	if (tpool->tp_head == NULL)
+		tpool->tp_head = job;
+	else
+		tpool->tp_tail->tpj_next = job;
+	tpool->tp_tail = job;
+	tpool->tp_njobs++;
+
+	if (!(tpool->tp_flags & TP_SUSPEND)) {
+		if (tpool->tp_idle > 0)
+			(void) pthread_cond_signal(&tpool->tp_workcv);
+		else if (tpool->tp_current < tpool->tp_maximum &&
+		    create_worker(tpool) == 0)
+			tpool->tp_current++;
+	}
+
+	pthread_mutex_unlock(&tpool->tp_mutex);
+	return (0);
+}
+
+/*
+ * Assumes: by the time tpool_destroy() is called no one will use this
+ * thread pool in any way and no one will try to dispatch entries to it.
+ * Calling tpool_destroy() from a job in the pool will cause deadlock.
+ */
+void
+tpool_destroy(tpool_t *tpool)
+{
+	tpool_active_t *activep;
+
+	pthread_mutex_lock(&tpool->tp_mutex);
+	pthread_cleanup_push((_Voidfp)pthread_mutex_unlock, &tpool->tp_mutex);
+
+	/* mark the pool as being destroyed; wakeup idle workers */
+	tpool->tp_flags |= TP_DESTROY;
+	tpool->tp_flags &= ~TP_SUSPEND;
+	(void) pthread_cond_broadcast(&tpool->tp_workcv);
+
+	/* cancel all active workers */
+	for (activep = tpool->tp_active; activep; activep = activep->tpa_next)
+		(void) pthread_cancel(activep->tpa_tid);
+
+	/* wait for all active workers to finish */
+	while (tpool->tp_active != NULL) {
+		tpool->tp_flags |= TP_WAIT;
+		(void) pthread_cond_wait(&tpool->tp_waitcv, &tpool->tp_mutex);
+	}
+
+	/* the last worker to terminate will wake us up */
+	while (tpool->tp_current != 0)
+		(void) pthread_cond_wait(&tpool->tp_busycv, &tpool->tp_mutex);
+
+	pthread_cleanup_pop(1);	/* pthread_mutex_unlock(&tpool->tp_mutex); */
+	delete_pool(tpool);
+}
+
+/*
+ * Like tpool_destroy(), but don't cancel workers or wait for them to finish.
+ * The last worker to terminate will delete the pool.
+ */
+void
+tpool_abandon(tpool_t *tpool)
+{
+
+	pthread_mutex_lock(&tpool->tp_mutex);
+	if (tpool->tp_current == 0) {
+		/* no workers, just delete the pool */
+		pthread_mutex_unlock(&tpool->tp_mutex);
+		delete_pool(tpool);
+	} else {
+		/* wake up all workers, last one will delete the pool */
+		tpool->tp_flags |= TP_ABANDON;
+		tpool->tp_flags &= ~TP_SUSPEND;
+		(void) pthread_cond_broadcast(&tpool->tp_workcv);
+		pthread_mutex_unlock(&tpool->tp_mutex);
+	}
+}
+
+/*
+ * Wait for all jobs to complete.
+ * Calling tpool_wait() from a job in the pool will cause deadlock.
+ */
+void
+tpool_wait(tpool_t *tpool)
+{
+
+	pthread_mutex_lock(&tpool->tp_mutex);
+	pthread_cleanup_push((_Voidfp)pthread_mutex_unlock, &tpool->tp_mutex);
+	while (tpool->tp_head != NULL || tpool->tp_active != NULL) {
+		tpool->tp_flags |= TP_WAIT;
+		(void) pthread_cond_wait(&tpool->tp_waitcv, &tpool->tp_mutex);
+	}
+	pthread_cleanup_pop(1);	/* pthread_mutex_unlock(&tpool->tp_mutex); */
+}
+
+void
+tpool_suspend(tpool_t *tpool)
+{
+
+	pthread_mutex_lock(&tpool->tp_mutex);
+	tpool->tp_flags |= TP_SUSPEND;
+	pthread_mutex_unlock(&tpool->tp_mutex);
+}
+
+int
+tpool_suspended(tpool_t *tpool)
+{
+	int suspended;
+
+	pthread_mutex_lock(&tpool->tp_mutex);
+	suspended = (tpool->tp_flags & TP_SUSPEND) != 0;
+	pthread_mutex_unlock(&tpool->tp_mutex);
+
+	return (suspended);
+}
+
+void
+tpool_resume(tpool_t *tpool)
+{
+	int excess;
+
+	pthread_mutex_lock(&tpool->tp_mutex);
+	if (!(tpool->tp_flags & TP_SUSPEND)) {
+		pthread_mutex_unlock(&tpool->tp_mutex);
+		return;
+	}
+	tpool->tp_flags &= ~TP_SUSPEND;
+	(void) pthread_cond_broadcast(&tpool->tp_workcv);
+	excess = tpool->tp_njobs - tpool->tp_idle;
+	while (excess-- > 0 && tpool->tp_current < tpool->tp_maximum) {
+		if (create_worker(tpool) != 0)
+			break;		/* pthread_create() failed */
+		tpool->tp_current++;
+	}
+	pthread_mutex_unlock(&tpool->tp_mutex);
+}
+
+int
+tpool_member(tpool_t *tpool)
+{
+	pthread_t my_tid = pthread_self();
+	tpool_active_t *activep;
+
+	pthread_mutex_lock(&tpool->tp_mutex);
+	for (activep = tpool->tp_active; activep; activep = activep->tpa_next) {
+		if (activep->tpa_tid == my_tid) {
+			pthread_mutex_unlock(&tpool->tp_mutex);
+			return (1);
+		}
+	}
+	pthread_mutex_unlock(&tpool->tp_mutex);
+	return (0);
+}
diff --git a/cddl/compat/opensolaris/misc/thread_pool_impl.h b/cddl/compat/opensolaris/misc/thread_pool_impl.h
new file mode 100644
index 0000000..bc98ac8
--- /dev/null
+++ b/cddl/compat/opensolaris/misc/thread_pool_impl.h
@@ -0,0 +1,99 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+
+/*
+ * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+/*
+ * $FreeBSD$
+ */
+
+#ifndef _THREAD_POOL_IMPL_H
+#define	_THREAD_POOL_IMPL_H
+
+#pragma ident	"%Z%%M%	%I%	%E% SMI"
+
+#include <thread_pool.h>
+
+#ifdef	__cplusplus
+extern "C" {
+#endif
+
+/*
+ * Thread pool implementation definitions.
+ * See <thread_pool.h> for interface declarations.
+ */
+
+/*
+ * FIFO queued job
+ */
+typedef struct tpool_job tpool_job_t;
+struct tpool_job {
+	tpool_job_t	*tpj_next;		/* list of jobs */
+	void		(*tpj_func)(void *);	/* function to call */
+	void		*tpj_arg;		/* its argument */
+};
+
+/*
+ * List of active threads, linked through their stacks.
+ */
+typedef struct tpool_active tpool_active_t;
+struct tpool_active {
+	tpool_active_t	*tpa_next;	/* list of active threads */
+	pthread_t	tpa_tid;	/* active thread id */
+};
+
+/*
+ * The thread pool.
+ */
+struct tpool {
+	tpool_t		*tp_forw;	/* circular list of all thread pools */
+	tpool_t		*tp_back;
+	mutex_t		tp_mutex;	/* protects the pool data */
+	cond_t		tp_busycv;	/* synchronization in tpool_dispatch */
+	cond_t		tp_workcv;	/* synchronization with workers */
+	cond_t		tp_waitcv;	/* synchronization in tpool_wait() */
+	tpool_active_t	*tp_active;	/* threads performing work */
+	tpool_job_t	*tp_head;	/* FIFO job queue */
+	tpool_job_t	*tp_tail;
+	pthread_attr_t	tp_attr;	/* attributes of the workers */
+	int		tp_flags;	/* see below */
+	uint_t		tp_linger;	/* seconds before idle workers exit */
+	int		tp_njobs;	/* number of jobs in job queue */
+	int		tp_minimum;	/* minimum number of worker threads */
+	int		tp_maximum;	/* maximum number of worker threads */
+	int		tp_current;	/* current number of worker threads */
+	int		tp_idle;	/* number of idle workers */
+};
+
+/* tp_flags */
+#define	TP_WAIT		0x01		/* waiting in tpool_wait() */
+#define	TP_SUSPEND	0x02		/* pool is being suspended */
+#define	TP_DESTROY	0x04		/* pool is being destroyed */
+#define	TP_ABANDON	0x08		/* pool is abandoned (auto-destroy) */
+
+#ifdef	__cplusplus
+}
+#endif
+
+#endif /* _THREAD_POOL_IMPL_H */