- Rework event handling system so we don't use a full thread per

   connection, but instead only use threads for active requests.

4 files changed, 1074 insertions, 0 deletions

diff --git a/common/server-mainloop.c b/common/server-mainloop.c
new file mode 100644
index 0000000..c102b88
--- /dev/null
+++ b/common/server-mainloop.c
@@ -0,0 +1,583 @@
+/*
+ * Copyright (c) 2006, Stefan Walter
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *	 * Redistributions of source code must retain the above
+ *	   copyright notice, this list of conditions and the
+ *	   following disclaimer.
+ *	 * 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 names of contributors to this software may not be
+ *	   used to endorse or promote products derived from this
+ *	   software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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
+ * COPYRIGHT OWNER 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.
+ */
+
+#include "config.h"
+#include "server-mainloop.h"
+
+#include <sys/time.h>
+
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#ifdef HAVE_PTHREAD
+#include <pthread.h>
+#endif
+
+typedef struct _socket_callback {
+	int fd;
+	server_socket_callback callback;
+	void *arg;
+	int closed;
+
+	struct _socket_callback *next;
+} socket_callback;
+
+typedef struct _timer_callback {
+	struct timeval at;
+	struct timeval interval;
+	server_timer_callback callback;
+	void* arg;
+	int closed;
+
+	struct _timer_callback *next;
+} timer_callback;
+
+typedef struct _server_context {
+	int stopped;
+	fd_set read_fds;
+	fd_set write_fds;
+	int max_fd;
+	int revision;
+	socket_callback *callbacks;
+	timer_callback *timers;
+	int wakeup[2];
+#ifdef HAVE_PTHREAD
+	pthread_mutex_t mutex;
+#endif
+} server_context;
+
+#ifdef HAVE_PTHREAD
+#define LOCK() pthread_mutex_lock (&ctx.mutex)
+#define UNLOCK() pthread_mutex_unlock (&ctx.mutex)
+#else
+#define LOCK()
+#define UNLOCK()
+#endif
+
+/* Global context */
+static server_context ctx;
+
+static void
+timeval_add(struct timeval *t1, struct timeval *t2)
+{
+	assert (t1->tv_usec < 1000000);
+	assert (t2->tv_usec < 1000000);
+
+	t1->tv_sec += t2->tv_sec;
+	t1->tv_usec += t2->tv_usec;
+	if (t1->tv_usec >= 1000000) {
+		t1->tv_usec -= 1000000;
+		t1->tv_sec += 1;
+	}
+}
+
+static void
+timeval_subtract (struct timeval *t1, struct timeval *t2)
+{
+	assert (t1->tv_usec < 1000000);
+	assert (t2->tv_usec < 1000000);
+
+	t1->tv_sec -= t2->tv_sec;
+	if (t1->tv_usec < t2->tv_usec) {
+		t1->tv_usec += 1000000;
+		t1->tv_sec -= 1;
+	}
+	t1->tv_usec -= t2->tv_usec;
+}
+
+static int
+timeval_compare(struct timeval *t1, struct timeval *t2)
+{
+	assert (t1->tv_usec < 1000000);
+	assert (t2->tv_usec < 1000000);
+
+	if (t1->tv_sec > t2->tv_sec)
+		return 1;
+	else if (t1->tv_sec < t2->tv_sec)
+		return -1;
+	else {
+		if (t1->tv_usec > t2->tv_usec)
+			return 1;
+		else if (t1->tv_usec < t2->tv_usec)
+			return -1;
+		else
+			return 0;
+	}
+}
+
+#define timeval_empty(tv) \
+	((tv)->tv_sec == 0 && (tv)->tv_usec == 0)
+
+#define timeval_to_ms(tv) \
+	((((uint64_t)(tv).tv_sec) * 1000L) + (((uint64_t)(tv).tv_usec) / 1000L))
+
+#define timeval_dump(tv) \
+	(fprintf(stderr, "{ %d:%d }", (uint)((tv).tv_sec), (uint)((tv).tv_usec / 1000)))
+
+static int
+add_timer (int ms, int oneshot, server_timer_callback callback, void *arg)
+{
+	struct timeval interval;
+	timer_callback *cb;
+
+	assert (ms || oneshot);
+	assert (callback != NULL);
+
+	interval.tv_sec = ms / 1000;
+	interval.tv_usec = (ms % 1000) * 1000; /* into micro seconds */
+
+	cb = (timer_callback*)calloc (1, sizeof (*cb));
+	if(!cb) {
+		errno = ENOMEM;
+		return -1;
+	}
+
+	if (gettimeofday (&(cb->at), NULL) == -1) {
+		free(cb);
+		return -1;
+	}
+
+	timeval_add (&(cb->at), &interval);
+
+	if (oneshot)
+		memset (&(cb->interval), 0, sizeof (cb->interval));
+	else
+		memcpy (&(cb->interval), &interval, sizeof(cb->interval));
+
+	cb->callback = callback;
+	cb->arg = arg;
+
+	cb->next = ctx.timers;
+	ctx.timers = cb;
+	++ctx.revision;
+	server_wakeup ();
+
+	return 0;
+}
+
+static void
+remove_closed (void)
+{
+	timer_callback **tcb, *timcb;
+	socket_callback **scb, *sockcb;
+
+	for (tcb = &ctx.timers; *tcb; ) {
+		timcb = *tcb;
+		if (timcb->closed) {
+			*tcb = timcb->next;
+			free (timcb);
+			continue;
+		} else {
+			tcb = &timcb->next;
+		}
+	}
+
+	for (scb = &ctx.callbacks; *scb; ) {
+		sockcb = *scb;
+		if (sockcb->closed) {
+			*scb = sockcb->next;
+			free (sockcb);
+			continue;
+		} else {
+			scb = &sockcb->next;
+		}
+	}
+}
+
+int
+server_init (void)
+{
+	memset (&ctx, 0, sizeof (ctx));
+
+	if (pipe (ctx.wakeup) < 0)
+		return -1;
+
+	FD_ZERO (&ctx.read_fds);
+	FD_ZERO (&ctx.write_fds);
+
+	/* The wakeup descriptor */
+	FD_SET (ctx.wakeup[0], &ctx.read_fds);
+	fcntl (ctx.wakeup[0], F_SETFL, fcntl (ctx.wakeup[0], F_GETFL, 0) | O_NONBLOCK);
+
+	ctx.max_fd = ctx.wakeup[0] + 1;
+
+	ctx.stopped = 1;
+	ctx.callbacks = NULL;
+	ctx.timers = NULL;
+
+
+#ifdef HAVE_PTHREAD
+	{
+		int ret = pthread_mutex_init (&ctx.mutex, NULL);
+		if (ret != 0) {
+			errno = ret;
+			close (ctx.wakeup[0]);
+			close (ctx.wakeup[1]);
+			return -1;
+		}
+	}
+#endif
+
+	return 0;
+}
+
+void
+server_uninit (void)
+{
+	timer_callback *timcb;
+	timer_callback *timn;
+	socket_callback *sockcb;
+	socket_callback *sockn;
+
+	LOCK ();
+
+	for(timcb = ctx.timers; timcb; timcb = timn) {
+		timn = timcb->next;
+		free (timcb);
+	}
+
+	ctx.timers = NULL;
+
+	for(sockcb = ctx.callbacks; sockcb; sockcb = sockn) {
+		sockn = sockcb->next;
+		free (sockcb);
+	}
+
+	ctx.callbacks = NULL;
+
+	UNLOCK ();
+
+#ifdef HAVE_PTHREAD
+	pthread_mutex_destroy (&ctx.mutex);
+#endif
+}
+
+uint64_t
+server_get_time (void)
+{
+	struct timeval tv;
+	if (gettimeofday (&tv, NULL) == -1)
+		return 0L;
+	return timeval_to_ms (tv);
+}
+
+int
+server_run (void)
+{
+	char buffer[16];
+	struct timeval *timeout;
+	struct timeval tv, current;
+	timer_callback *timcb;
+	socket_callback *sockcb;
+	fd_set rfds, wfds;
+	int r, revision, max_fd;
+	int ret = 0;
+
+	/* For doing lock safe callbacks */
+	int type, fd;
+	server_socket_callback scb;
+	server_timer_callback tcb;
+	void *arg;
+
+	LOCK ();
+
+	/* No watches have been set */
+	assert (ctx.max_fd > -1);
+
+	ctx.stopped = 0;
+	ctx.revision = 0;
+
+	while (!ctx.stopped)  {
+
+		/* Drain the wakeup if necessary */
+		while (read (ctx.wakeup[0], buffer, sizeof (buffer)) > 0);
+
+		/* Watch for the various fds */
+		memcpy (&rfds, &ctx.read_fds, sizeof (rfds));
+		memcpy (&wfds, &ctx.write_fds, sizeof (wfds));
+
+		/* Prepare for timers */
+		timeout = NULL;
+		if (gettimeofday (&current, NULL) == -1) {
+			ret = -1;
+			break;
+		}
+
+		/* Cycle through timers */
+		for (timcb = ctx.timers; timcb; timcb = timcb->next) {
+			assert (timcb->callback);
+
+			if (timcb->closed)
+				continue;
+
+			/* Call any timers that have already passed */
+			if (timeval_compare (&current, &timcb->at) >= 0) {
+
+				/* Do a lock safe callback */
+				tcb = timcb->callback;
+				arg = timcb->arg;
+
+				/* Convert to milliseconds, and make the call */
+				UNLOCK ();
+				r = (tcb) (timeval_to_ms (current), arg);
+				LOCK ();
+
+				/* Reset timer if so desired */
+				if (r == 1 && !timeval_empty (&timcb->interval)) {
+					timeval_add (&timcb->at, &timcb->interval);
+
+					/* If the time has already passed, just use current time */
+					if (timeval_compare (&(timcb->at), &current) <= 0)
+						memcpy (&(timcb->at), &current, sizeof (timcb->at));
+
+				/* Otherwise remove it. Either one shot, or returned 0 */
+				} else {
+					timcb->closed = 1;
+					continue;
+				}
+			}
+
+			/* Get soonest timer */
+			if (!timeout || timeval_compare (&timcb->at, timeout) < 0)
+				timeout = &timcb->at;
+		}
+
+		/* Convert to an offset */
+		if (timeout) {
+			memcpy (&tv, timeout, sizeof (tv));
+			timeout = &tv;
+			timeval_subtract (timeout, &current);
+		}
+
+		if (ctx.stopped)
+			continue;
+
+		remove_closed ();
+
+		/* No callbacks? No use continuing */
+		if (!ctx.callbacks && !ctx.timers)
+			break;
+
+		/* fprintf(stderr, "selecting with timeout: ");
+		   timeval_dump(timeout);
+		   fprintf(stderr, "\n"); */
+
+		/* We can see if changes happen while in select */
+		revision = ctx.revision;
+		max_fd = ctx.max_fd;
+
+		UNLOCK ();
+		r = select (max_fd, &rfds, &wfds, NULL, timeout);
+		LOCK ();
+
+		if (r < 0) {
+			/* Interrupted so try again, and possibly exit */
+			if (errno == EINTR)
+				continue;
+
+			if (errno == EBADF) {
+				if (ctx.revision != revision)
+					continue;
+				assert (0 && "bad file descriptor being watched");
+			}
+
+			/* Programmer errors */
+			assert (errno != EINVAL);
+			ret = -1;
+			break;
+		}
+
+		/* Timeout, just jump to timeout processing */
+		if(r == 0)
+			continue;
+
+		/* Process ready file descriptors */
+		for (sockcb = ctx.callbacks; sockcb; sockcb = sockcb->next) {
+			assert (sockcb->fd != -1);
+			if (sockcb->closed)
+				continue;
+
+			/* Call any that are set */
+			type = 0;
+			if (FD_ISSET (sockcb->fd, &rfds))
+				type = SERVER_READ;
+			if (FD_ISSET (sockcb->fd, &wfds))
+				type = SERVER_WRITE;
+
+			/* Lock safe callback */
+			if (type != 0) {
+				scb = sockcb->callback;
+				fd = sockcb->fd;
+				arg = sockcb->arg;
+
+				UNLOCK ();
+					(scb) (fd, type, arg);
+				LOCK ();
+			}
+		}
+	}
+
+	UNLOCK ();
+	return ret;
+}
+
+void
+server_wakeup (void)
+{
+	/*
+	 * This can be called from within arbitrary
+	 * locks, so be careful.
+	 */
+	int r = write (ctx.wakeup[1], "a", 1);
+	fprintf (stderr, "wakeup: %d\n", r);
+}
+
+void
+server_stop (void)
+{
+	/*
+	 * This could be called from a signal handler,
+	 * so it's not worth trying to lock.
+	 */
+	ctx.stopped = 1;
+	server_wakeup ();
+}
+
+int
+server_stopped (void)
+{
+	return ctx.stopped;
+}
+
+int
+server_watch (int fd, int type, server_socket_callback callback, void *arg)
+{
+	socket_callback *cb;
+	assert (type != 0);
+	assert (fd != -1);
+	assert (callback != NULL);
+
+	cb = (socket_callback*)calloc (sizeof(*cb), 1);
+	if(!cb) {
+		errno = ENOMEM;
+		return -1;
+	}
+
+	LOCK ();
+
+	cb->fd = fd;
+	cb->callback = callback;
+	cb->arg = arg;
+
+	cb->next = ctx.callbacks;
+	ctx.callbacks = cb;
+
+	if (type & SERVER_READ)
+		FD_SET (fd, &ctx.read_fds);
+	if (type & SERVER_WRITE)
+		FD_SET (fd, &ctx.write_fds);
+
+	if (fd >= ctx.max_fd)
+		ctx.max_fd = fd + 1;
+
+	++ctx.revision;
+	server_wakeup ();
+
+	UNLOCK ();
+
+	return 0;
+}
+
+void
+server_unwatch (int fd)
+{
+	socket_callback* cb;
+
+	assert (fd != -1);
+
+	LOCK ();
+
+	FD_CLR (fd, &ctx.read_fds);
+	FD_CLR (fd, &ctx.write_fds);
+
+	if (!ctx.callbacks)
+		goto done;
+
+	/* First in list */;
+	if (ctx.callbacks->fd == fd) {
+		ctx.callbacks->closed = 1;
+		goto done;
+	}
+
+	/* One ahead processing of rest */
+	for (cb = ctx.callbacks; cb->next; cb = cb->next) {
+		if (cb->next->fd == fd) {
+			cb->next->closed = 1;
+			goto done;
+		}
+	}
+
+done:
+	server_wakeup ();
+	++ctx.revision;
+	UNLOCK ();
+}
+
+int
+server_timer (int ms, server_timer_callback callback, void *arg)
+{
+	int ret;
+
+	LOCK ();
+	ret = add_timer (ms, 0, callback, arg);
+	UNLOCK ();
+
+	return ret;
+}
+
+int
+server_oneshot (int ms, server_timer_callback callback, void *arg)
+{
+	int ret;
+
+	LOCK ();
+	ret = add_timer (ms, 1, callback, arg);
+	UNLOCK ();
+
+	return ret;
+}
diff --git a/common/server-mainloop.h b/common/server-mainloop.h
new file mode 100644
index 0000000..a749653
--- /dev/null
+++ b/common/server-mainloop.h
@@ -0,0 +1,57 @@
+/*
+ * Copyright (c) 2006, Stefan Walter
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *     * Redistributions of source code must retain the above
+ *       copyright notice, this list of conditions and the
+ *       following disclaimer.
+ *     * 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 names of contributors to this software may not be
+ *       used to endorse or promote products derived from this
+ *       software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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
+ * COPYRIGHT OWNER 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.
+ */
+
+#ifndef __SERVER_MAINLOOP_H__
+#define __SERVER_MAINLOOP_H__
+
+#include <stdint.h>
+
+#define SERVER_READ       0x01
+#define SERVER_WRITE      0x02
+
+typedef void (*server_socket_callback) (int fd, int type, void* arg);
+typedef int (*server_timer_callback) (uint64_t when, void* arg);
+
+int     server_init (void);
+void    server_uninit (void);
+int     server_run (void);
+void    server_stop (void);
+int     server_stopped (void);
+int     server_watch (int fd, int type, server_socket_callback callback, void* arg);
+void    server_unwatch (int fd);
+void    server_wakeup (void);
+int     server_timer (int length, server_timer_callback callback, void* arg);
+int     server_oneshot (int length, server_timer_callback callback, void* arg);
+uint64_t server_get_time (void);
+
+#endif /* __SERVER_MAINLOOP_H__ */
diff --git a/common/tpool.c b/common/tpool.c
new file mode 100644
index 0000000..f980b86
--- /dev/null
+++ b/common/tpool.c
@@ -0,0 +1,398 @@
+/*
+ * HttpAuth
+ *
+ * Copyright (C) 2008 Stefan Walter
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details.
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the
+ * Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+/*
+ * -------------------------------------------------------------------------
+ * Ideas from tpool.c - htun thread pool functions
+ * Copyright (C) 2002 Moshe Jacobson <moshe@runslinux.net>,
+ *                    Ola Nordström <ola@triblock.com>
+ * -------------------------------------------------------------------------
+ */
+
+/*
+ * most of the theory and implementation of the thread pool was taken
+ * from the o'reilly pthreads programming book.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <err.h>
+#include <string.h>
+#include <assert.h>
+#include <signal.h>
+
+#define __USE_GNU
+#include <pthread.h>
+
+#include "tpool.h"
+
+typedef struct _tpool_work {
+	void (*handler_routine)(void*);
+	void *arg;
+	struct _tpool_work *next;
+} tpool_work;
+
+typedef struct _tpool_thread {
+	pthread_t handle;
+	int is_active;
+	struct _tpool_thread *next;
+} tpool_thread;
+
+static int tpool_max_threads = 0;
+static int tpool_min_threads = 0;
+static int tpool_running_threads = 0;
+static int tpool_idle_threads = 0;
+static int tpool_zombie_threads = 0;
+static tpool_thread *tpool_thread_list = NULL;
+
+static int tpool_max_queue_size = 0;
+static int tpool_cur_queue_size = 0;
+static tpool_work *tpool_queue_head = NULL;
+static tpool_work *tpool_queue_tail = NULL;
+static pthread_mutex_t tpool_queue_lock;
+static pthread_cond_t tpool_queue_not_full;
+static pthread_cond_t tpool_queue_not_empty;
+static pthread_cond_t tpool_queue_empty;
+
+static int tpool_queue_closed = 0;
+static int tpool_shutdown = 0;
+static int tpool_initialized = 0;
+
+#define PTHREQ(x) do { \
+	int r = (x); \
+	if (r != 0) { \
+		fprintf (stderr, "fatal: '%s' failed: %s", #x, strerror (r)); \
+		assert (0 && "" #x); \
+	} } while (0)
+
+static void*
+tpool_thread_func (void *data)
+{
+	tpool_thread *thread = (tpool_thread*)data;
+	tpool_work *work;
+	int stop = 0;
+	sigset_t set;
+
+	/* We handle these signals on the main thread */
+	sigemptyset (&set);
+	sigaddset (&set, SIGINT);
+	sigaddset (&set, SIGTERM);
+	pthread_sigmask (SIG_BLOCK, &set, NULL);
+
+	assert (thread);
+	assert (tpool_initialized);
+
+	PTHREQ (pthread_mutex_lock (&tpool_queue_lock));
+
+	assert (thread->is_active);
+	++tpool_running_threads;
+	++tpool_idle_threads;
+
+	while (!tpool_shutdown && !stop) {
+
+		/* No work to do? */
+		while (tpool_cur_queue_size == 0 && !tpool_shutdown && !stop) {
+
+			/* Too many idle threads? */
+			if (tpool_running_threads > tpool_min_threads) {
+				stop = 1;
+				break;
+			}
+
+			/*
+			 * Sleep until there is work, while asleep the queue_lock
+			 * is relinquished
+			 */
+			PTHREQ (pthread_cond_wait (&tpool_queue_not_empty, &tpool_queue_lock));
+		}
+
+		/* Are we shutting down? */
+		if (stop || tpool_shutdown)
+			break;
+
+		/* Pop the work off the queue */
+		work = tpool_queue_head;
+		tpool_cur_queue_size--;
+		if (tpool_cur_queue_size == 0)
+			tpool_queue_head = tpool_queue_tail = NULL;
+		else
+			tpool_queue_head = work->next;
+
+		/* Broadcast queue state to anyone who's waiting */
+		if (tpool_cur_queue_size < tpool_max_queue_size)
+			PTHREQ (pthread_cond_broadcast (&tpool_queue_not_full));
+		if (tpool_cur_queue_size == 0)
+			PTHREQ (pthread_cond_signal (&tpool_queue_empty));
+
+		--tpool_idle_threads;
+		assert (tpool_idle_threads >= 0);
+
+		/* Unlock the queue lock while processing */
+		PTHREQ (pthread_mutex_unlock (&tpool_queue_lock));
+
+			/* Perform the work */
+			(work->handler_routine) (work->arg);
+			free (work);
+
+		PTHREQ (pthread_mutex_lock (&tpool_queue_lock));
+
+		++tpool_idle_threads;
+	}
+
+	--tpool_idle_threads;
+	--tpool_running_threads;
+	++tpool_zombie_threads;
+	thread->is_active = 0;
+	assert (tpool_running_threads >= 0);
+	assert (tpool_idle_threads >= 0);
+
+	PTHREQ (pthread_mutex_unlock (&tpool_queue_lock));
+
+	/* So we can double check the result code */
+	return thread;
+}
+
+static void
+free_pool_stuff (void)
+{
+	tpool_work *work;
+
+	if (!tpool_initialized)
+		return;
+
+	/* No threads should be running at this point */
+	assert (!tpool_thread_list);
+
+	/* Clean up memory */
+	while (tpool_queue_head != NULL) {
+		work = tpool_queue_head;
+		tpool_queue_head = tpool_queue_head->next;
+		free (work);
+	}
+
+	pthread_cond_destroy (&tpool_queue_not_full);
+	pthread_cond_destroy (&tpool_queue_not_empty);
+	pthread_cond_destroy (&tpool_queue_empty);
+	pthread_mutex_destroy (&tpool_queue_lock);
+
+	tpool_initialized = 0;
+}
+
+int
+tpool_init (int max_threads, int min_threads, int max_queued)
+{
+	assert (!tpool_initialized);
+
+	/* set the desired thread pool values */
+	tpool_max_threads = max_threads;
+	tpool_running_threads = 0;
+	tpool_idle_threads = 0;
+	tpool_zombie_threads = 0;
+	tpool_min_threads = min_threads;
+
+	/* initialize the work queue */
+	tpool_max_queue_size = max_queued;
+	tpool_cur_queue_size = 0;
+	tpool_queue_head = NULL;
+	tpool_queue_tail = NULL;
+	tpool_queue_closed = 0;
+	tpool_shutdown = 0;
+
+	/* create the mutexs and cond vars */
+	PTHREQ (pthread_mutex_init (&tpool_queue_lock, NULL));
+	PTHREQ (pthread_cond_init (&tpool_queue_not_empty, NULL));
+	PTHREQ (pthread_cond_init (&tpool_queue_not_full, NULL));
+	PTHREQ (pthread_cond_init (&tpool_queue_empty, NULL));
+
+	tpool_initialized = 1;
+	return 0;
+}
+
+static void
+join_pool_threads (int all)
+{
+	tpool_thread *thread, **spot;
+	void *exit_code;
+
+	/* Should be called from within the lock */
+
+	for (spot = &tpool_thread_list, thread = *spot;
+	     thread && (all || tpool_zombie_threads > 0); ) {
+
+		assert (thread->handle);
+
+		if (all || !thread->is_active) {
+			if (!thread->is_active)
+				--tpool_zombie_threads;
+
+			/* Join the thread */
+			PTHREQ (pthread_join (thread->handle, &exit_code));
+			assert (exit_code == thread);
+
+			/* Remove and get the next in list */
+			*spot = thread->next;
+			free (thread);
+
+		} else {
+			/* Just get the next in list */
+			spot = &thread->next;
+		}
+
+		thread = *spot;
+	}
+}
+
+int
+tpool_add_work (void (*routine)(void*), void *arg)
+{
+	tpool_work *work;
+	tpool_thread *thread;
+	int r, ret = -1;
+
+	assert (tpool_initialized);
+
+	PTHREQ (pthread_mutex_lock (&tpool_queue_lock));
+
+	/* Join any old threads */
+	join_pool_threads (0);
+
+	/* Should have found all of these above */
+	assert (tpool_zombie_threads == 0);
+
+	/* Are we closed for business? */
+	if (tpool_shutdown || tpool_queue_closed) {
+		errno = ECANCELED;
+		goto done;
+	}
+
+	/* No idle threads to run this work? */
+	if (!tpool_idle_threads) {
+
+		/* See if we can start another thread */
+		if (tpool_max_threads <= 0 ||
+		    tpool_running_threads < tpool_max_threads) {
+
+			/* The thread context */
+			thread = calloc (1, sizeof (tpool_thread));
+			if (thread == NULL) {
+				errno = ENOMEM;
+				goto done;
+			}
+
+			/* Start the thread */
+			thread->is_active = 1;
+			r = pthread_create (&thread->handle, NULL, tpool_thread_func, (void*)thread);
+			if (r != 0) {
+				errno = r;
+				free (thread);
+				goto done;
+			}
+
+			/* Add the new thread to the list */
+			thread->next = tpool_thread_list;
+			tpool_thread_list = thread;
+		}
+	}
+
+	/*
+	 * If the queue is full, yield this thread, and see if
+	 * another processes something out of the queue.
+	 */
+	if (tpool_max_queue_size > 0 && tpool_cur_queue_size >= tpool_max_queue_size) {
+		PTHREQ (pthread_mutex_unlock (&tpool_queue_lock));
+		pthread_yield();
+		PTHREQ (pthread_mutex_lock (&tpool_queue_lock));
+	}
+
+	/* Are we closed for business? */
+	if (tpool_shutdown || tpool_queue_closed) {
+		errno = ECANCELED;
+		goto done;
+	}
+
+	/* Is the queue still full? */
+	if (tpool_max_queue_size > 0 && tpool_cur_queue_size >= tpool_max_queue_size) {
+		errno = EAGAIN;
+		goto done;
+	}
+
+	/* Allocate the work structure */
+	work = calloc (1, sizeof (tpool_work));
+	if (work == NULL) {
+		errno = ENOMEM;
+		goto done;
+	}
+
+	work->handler_routine = routine;
+	work->arg = arg;
+	work->next = NULL;
+
+	if (tpool_cur_queue_size == 0) {
+		tpool_queue_tail = tpool_queue_head = work;
+	} else {
+		tpool_queue_tail->next = work;
+		tpool_queue_tail = work;
+	}
+
+	PTHREQ (pthread_cond_broadcast (&tpool_queue_not_empty));
+	tpool_cur_queue_size++;
+	ret = 0;
+
+done:
+	PTHREQ (pthread_mutex_unlock (&tpool_queue_lock));
+	return ret;
+}
+
+int
+tpool_destroy (int finish)
+{
+	assert (tpool_initialized);
+
+	PTHREQ (pthread_mutex_lock (&tpool_queue_lock));
+
+	/* Can't have two places calling shutdown */
+	assert (!tpool_queue_closed && !tpool_shutdown);
+
+	/* close the queue to any new work */
+	tpool_queue_closed = 1;
+
+	/* if the finish flag is set, drain the queue */
+	if (finish) {
+		while (tpool_cur_queue_size != 0)
+			PTHREQ (pthread_cond_wait (&tpool_queue_empty, &tpool_queue_lock));
+	}
+
+	/* Set the shutdown flag */
+	tpool_shutdown = 1;
+
+	PTHREQ (pthread_mutex_unlock (&tpool_queue_lock));
+
+	/* wake up all workers to rechedk the shutdown flag */
+	PTHREQ (pthread_cond_broadcast (&tpool_queue_not_empty));
+	PTHREQ (pthread_cond_broadcast (&tpool_queue_not_full));
+
+	join_pool_threads (1);
+	free_pool_stuff ();
+
+	return 0;
+}
+
diff --git a/common/tpool.h b/common/tpool.h
new file mode 100644
index 0000000..ac5a3f4
--- /dev/null
+++ b/common/tpool.h
@@ -0,0 +1,36 @@
+/*
+ * HttpAuth
+ *
+ * Copyright (C) 2008 Stefan Walter
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details.
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the
+ * Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#ifndef _TPOOL_H_
+#define _TPOOL_H_
+
+typedef void (*tpool_routine) (void*);
+
+/* returns -1 if pool creation failed, 0 if succeeded */
+int tpool_init (int max_threads, int min_threads, int max_queued);
+
+/* returns -1 if failed (ie busy, closing etc...), 0 if succeeded */
+int tpool_add_work (tpool_routine routine, void *arg);
+
+/* cleanup and close. Must only be called once. Specify |finish| to drain queue */
+int tpool_destroy (int finish);
+
+#endif /* _TPOOL_H_ */