Revert r1821526, r1821527, r1821534, r1821538, r1821539, r1821541, r1821605, r1821607, r1821608.

Instead of copying event/fdqueue.c code into existing mpm_unix.c, losing all
contributors (blame, since r105919...), will restart the series by svn-moving
event/fdqueue.[ch] to server/mpm_fdqueue.[ch] first.

The code is not really unix specific either, so this sounds better.



git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1821619 13f79535-47bb-0310-9956-ffa450edef68

9 files changed, 1064 insertions, 586 deletions

diff --git a/server/mpm/event/config3.m4 b/server/mpm/event/config3.m4
index b4dc5e38bc..e15f235314 100644
--- a/server/mpm/event/config3.m4
+++ b/server/mpm/event/config3.m4
@@ -8,7 +8,7 @@ if test "$ac_cv_serf" = yes ; then
 fi
 APACHE_SUBST(MOD_MPM_EVENT_LDADD)
 
-APACHE_MPM_MODULE(event, $enable_mpm_event, event.lo,[
+APACHE_MPM_MODULE(event, $enable_mpm_event, event.lo fdqueue.lo,[
     AC_CHECK_FUNCS(pthread_kill)
 ], , [\$(MOD_MPM_EVENT_LDADD)])
 
diff --git a/server/mpm/event/event.c b/server/mpm/event/event.c
index b272433aa1..5ac3e1b5e5 100644
--- a/server/mpm/event/event.c
+++ b/server/mpm/event/event.c
@@ -91,7 +91,7 @@
 #include "mpm_common.h"
 #include "ap_listen.h"
 #include "scoreboard.h"
-#include "mpm_unix.h"
+#include "fdqueue.h"
 #include "mpm_default.h"
 #include "http_vhost.h"
 #include "unixd.h"
@@ -219,8 +219,6 @@ static apr_pollfd_t *listener_pollfd;
  */
 static apr_pollset_t *event_pollset;
 
-typedef struct event_conn_state_t event_conn_state_t;
-
 /*
  * The chain of connections to be shutdown by a worker thread (deferred),
  * linked list updated atomically.
@@ -517,7 +515,7 @@ static void enable_listensocks(void)
                  apr_atomic_read32(&lingering_count),
                  apr_atomic_read32(&clogged_count),
                  apr_atomic_read32(&suspended_count),
-                 ap_queue_info_num_idlers(worker_queue_info));
+                 ap_queue_info_get_idlers(worker_queue_info));
     for (i = 0; i < num_listensocks; i++)
         apr_pollset_add(event_pollset, &listener_pollfd[i]);
     /*
@@ -534,7 +532,7 @@ static APR_INLINE apr_uint32_t listeners_disabled(void)
 
 static APR_INLINE int connections_above_limit(void)
 {
-    apr_uint32_t i_count = ap_queue_info_num_idlers(worker_queue_info);
+    apr_uint32_t i_count = ap_queue_info_get_idlers(worker_queue_info);
     if (i_count > 0) {
         apr_uint32_t c_count = apr_atomic_read32(&connection_count);
         apr_uint32_t l_count = apr_atomic_read32(&lingering_count);
@@ -2042,7 +2040,7 @@ static void * APR_THREAD_FUNC listener_thread(apr_thread_t * thd, void *dummy)
                                  apr_atomic_read32(&connection_count));
                     ap_log_error(APLOG_MARK, APLOG_TRACE1, 0, ap_server_conf,
                                  "Idle workers: %u",
-                                 ap_queue_info_num_idlers(worker_queue_info));
+                                 ap_queue_info_get_idlers(worker_queue_info));
                     workers_were_busy = 1;
                 }
                 else if (!listener_may_exit) {
@@ -2309,8 +2307,7 @@ static void *APR_THREAD_FUNC worker_thread(apr_thread_t * thd, void *dummy)
             break;
         }
 
-        rv = ap_queue_pop_something(worker_queue, &csd, (void **)&cs,
-                                    &ptrans, &te);
+        rv = ap_queue_pop_something(worker_queue, &csd, &cs, &ptrans, &te);
 
         if (rv != APR_SUCCESS) {
             /* We get APR_EOF during a graceful shutdown once all the
diff --git a/server/mpm/event/fdqueue.c b/server/mpm/event/fdqueue.c
new file mode 100644
index 0000000000..5b0192b2ee
--- /dev/null
+++ b/server/mpm/event/fdqueue.c
@@ -0,0 +1,524 @@
+/* Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "fdqueue.h"
+#include "apr_atomic.h"
+
+static const apr_uint32_t zero_pt = APR_UINT32_MAX/2;
+
+struct recycled_pool
+{
+    apr_pool_t *pool;
+    struct recycled_pool *next;
+};
+
+struct fd_queue_info_t
+{
+    apr_uint32_t volatile idlers; /**
+                                   * >= zero_pt: number of idle worker threads
+                                   * <  zero_pt: number of threads blocked,
+                                   *             waiting for an idle worker
+                                   */
+    apr_thread_mutex_t *idlers_mutex;
+    apr_thread_cond_t *wait_for_idler;
+    int terminated;
+    int max_idlers;
+    int max_recycled_pools;
+    apr_uint32_t recycled_pools_count;
+    struct recycled_pool *volatile recycled_pools;
+};
+
+static apr_status_t queue_info_cleanup(void *data_)
+{
+    fd_queue_info_t *qi = data_;
+    apr_thread_cond_destroy(qi->wait_for_idler);
+    apr_thread_mutex_destroy(qi->idlers_mutex);
+
+    /* Clean up any pools in the recycled list */
+    for (;;) {
+        struct recycled_pool *first_pool = qi->recycled_pools;
+        if (first_pool == NULL) {
+            break;
+        }
+        if (apr_atomic_casptr
+            ((void*) &(qi->recycled_pools), first_pool->next,
+             first_pool) == first_pool) {
+            apr_pool_destroy(first_pool->pool);
+        }
+    }
+
+    return APR_SUCCESS;
+}
+
+apr_status_t ap_queue_info_create(fd_queue_info_t ** queue_info,
+                                  apr_pool_t * pool, int max_idlers,
+                                  int max_recycled_pools)
+{
+    apr_status_t rv;
+    fd_queue_info_t *qi;
+
+    qi = apr_pcalloc(pool, sizeof(*qi));
+
+    rv = apr_thread_mutex_create(&qi->idlers_mutex, APR_THREAD_MUTEX_DEFAULT,
+                                 pool);
+    if (rv != APR_SUCCESS) {
+        return rv;
+    }
+    rv = apr_thread_cond_create(&qi->wait_for_idler, pool);
+    if (rv != APR_SUCCESS) {
+        return rv;
+    }
+    qi->recycled_pools = NULL;
+    qi->max_recycled_pools = max_recycled_pools;
+    qi->max_idlers = max_idlers;
+    qi->idlers = zero_pt;
+    apr_pool_cleanup_register(pool, qi, queue_info_cleanup,
+                              apr_pool_cleanup_null);
+
+    *queue_info = qi;
+
+    return APR_SUCCESS;
+}
+
+apr_status_t ap_queue_info_set_idle(fd_queue_info_t * queue_info,
+                                    apr_pool_t * pool_to_recycle)
+{
+    apr_status_t rv;
+
+    ap_push_pool(queue_info, pool_to_recycle);
+
+    /* If other threads are waiting on a worker, wake one up */
+    if (apr_atomic_inc32(&queue_info->idlers) < zero_pt) {
+        rv = apr_thread_mutex_lock(queue_info->idlers_mutex);
+        if (rv != APR_SUCCESS) {
+            AP_DEBUG_ASSERT(0);
+            return rv;
+        }
+        rv = apr_thread_cond_signal(queue_info->wait_for_idler);
+        if (rv != APR_SUCCESS) {
+            apr_thread_mutex_unlock(queue_info->idlers_mutex);
+            return rv;
+        }
+        rv = apr_thread_mutex_unlock(queue_info->idlers_mutex);
+        if (rv != APR_SUCCESS) {
+            return rv;
+        }
+    }
+
+    return APR_SUCCESS;
+}
+
+apr_status_t ap_queue_info_try_get_idler(fd_queue_info_t * queue_info)
+{
+    /* Don't block if there isn't any idle worker. */
+    for (;;) {
+        apr_uint32_t idlers = queue_info->idlers;
+        if (idlers <= zero_pt) {
+            return APR_EAGAIN;
+        }
+        if (apr_atomic_cas32(&queue_info->idlers, idlers - 1,
+                             idlers) == idlers) {
+            return APR_SUCCESS;
+        }
+    }
+}
+
+apr_status_t ap_queue_info_wait_for_idler(fd_queue_info_t * queue_info,
+                                          int *had_to_block)
+{
+    apr_status_t rv;
+
+    /* Block if there isn't any idle worker.
+     * apr_atomic_add32(x, -1) does the same as dec32(x), except
+     * that it returns the previous value (unlike dec32's bool).
+     */
+    if (apr_atomic_add32(&queue_info->idlers, -1) <= zero_pt) {
+        rv = apr_thread_mutex_lock(queue_info->idlers_mutex);
+        if (rv != APR_SUCCESS) {
+            AP_DEBUG_ASSERT(0);
+            apr_atomic_inc32(&(queue_info->idlers));    /* back out dec */
+            return rv;
+        }
+        /* Re-check the idle worker count to guard against a
+         * race condition.  Now that we're in the mutex-protected
+         * region, one of two things may have happened:
+         *   - If the idle worker count is still negative, the
+         *     workers are all still busy, so it's safe to
+         *     block on a condition variable.
+         *   - If the idle worker count is non-negative, then a
+         *     worker has become idle since the first check
+         *     of queue_info->idlers above.  It's possible
+         *     that the worker has also signaled the condition
+         *     variable--and if so, the listener missed it
+         *     because it wasn't yet blocked on the condition
+         *     variable.  But if the idle worker count is
+         *     now non-negative, it's safe for this function to
+         *     return immediately.
+         *
+         *     A "negative value" (relative to zero_pt) in
+         *     queue_info->idlers tells how many
+         *     threads are waiting on an idle worker.
+         */
+        if (queue_info->idlers < zero_pt) {
+            *had_to_block = 1;
+            rv = apr_thread_cond_wait(queue_info->wait_for_idler,
+                                      queue_info->idlers_mutex);
+            if (rv != APR_SUCCESS) {
+                apr_status_t rv2;
+                AP_DEBUG_ASSERT(0);
+                rv2 = apr_thread_mutex_unlock(queue_info->idlers_mutex);
+                if (rv2 != APR_SUCCESS) {
+                    return rv2;
+                }
+                return rv;
+            }
+        }
+        rv = apr_thread_mutex_unlock(queue_info->idlers_mutex);
+        if (rv != APR_SUCCESS) {
+            return rv;
+        }
+    }
+
+    if (queue_info->terminated) {
+        return APR_EOF;
+    }
+    else {
+        return APR_SUCCESS;
+    }
+}
+
+apr_uint32_t ap_queue_info_get_idlers(fd_queue_info_t * queue_info)
+{
+    apr_uint32_t val;
+    val = apr_atomic_read32(&queue_info->idlers);
+    if (val <= zero_pt)
+        return 0;
+    return val - zero_pt;
+}
+
+void ap_push_pool(fd_queue_info_t * queue_info,
+                                    apr_pool_t * pool_to_recycle)
+{
+    struct recycled_pool *new_recycle;
+    /* If we have been given a pool to recycle, atomically link
+     * it into the queue_info's list of recycled pools
+     */
+    if (!pool_to_recycle)
+        return;
+
+    if (queue_info->max_recycled_pools >= 0) {
+        apr_uint32_t cnt = apr_atomic_read32(&queue_info->recycled_pools_count);
+        if (cnt >= queue_info->max_recycled_pools) {
+            apr_pool_destroy(pool_to_recycle);
+            return;
+        }
+        apr_atomic_inc32(&queue_info->recycled_pools_count);
+    }
+
+    apr_pool_clear(pool_to_recycle);
+    new_recycle = (struct recycled_pool *) apr_palloc(pool_to_recycle,
+                                                      sizeof (*new_recycle));
+    new_recycle->pool = pool_to_recycle;
+    for (;;) {
+        /*
+         * Save queue_info->recycled_pool in local variable next because
+         * new_recycle->next can be changed after apr_atomic_casptr
+         * function call. For gory details see PR 44402.
+         */
+        struct recycled_pool *next = queue_info->recycled_pools;
+        new_recycle->next = next;
+        if (apr_atomic_casptr((void*) &(queue_info->recycled_pools),
+                              new_recycle, next) == next)
+            break;
+    }
+}
+
+void ap_pop_pool(apr_pool_t ** recycled_pool, fd_queue_info_t * queue_info)
+{
+    /* Atomically pop a pool from the recycled list */
+
+    /* This function is safe only as long as it is single threaded because
+     * it reaches into the queue and accesses "next" which can change.
+     * We are OK today because it is only called from the listener thread.
+     * cas-based pushes do not have the same limitation - any number can
+     * happen concurrently with a single cas-based pop.
+     */
+
+    *recycled_pool = NULL;
+
+
+    /* Atomically pop a pool from the recycled list */
+    for (;;) {
+        struct recycled_pool *first_pool = queue_info->recycled_pools;
+        if (first_pool == NULL) {
+            break;
+        }
+        if (apr_atomic_casptr
+            ((void*) &(queue_info->recycled_pools),
+             first_pool->next, first_pool) == first_pool) {
+            *recycled_pool = first_pool->pool;
+            if (queue_info->max_recycled_pools >= 0)
+                apr_atomic_dec32(&queue_info->recycled_pools_count);
+            break;
+        }
+    }
+}
+
+void ap_free_idle_pools(fd_queue_info_t *queue_info)
+{
+    apr_pool_t *p;
+
+    queue_info->max_recycled_pools = 0;
+    do {
+        ap_pop_pool(&p, queue_info);
+        if (p != NULL)
+            apr_pool_destroy(p);
+    } while (p != NULL);
+}
+
+
+apr_status_t ap_queue_info_term(fd_queue_info_t * queue_info)
+{
+    apr_status_t rv;
+    rv = apr_thread_mutex_lock(queue_info->idlers_mutex);
+    if (rv != APR_SUCCESS) {
+        return rv;
+    }
+    queue_info->terminated = 1;
+    apr_thread_cond_broadcast(queue_info->wait_for_idler);
+    return apr_thread_mutex_unlock(queue_info->idlers_mutex);
+}
+
+/**
+ * Detects when the fd_queue_t is full. This utility function is expected
+ * to be called from within critical sections, and is not threadsafe.
+ */
+#define ap_queue_full(queue) ((queue)->nelts == (queue)->bounds)
+
+/**
+ * Detects when the fd_queue_t is empty. This utility function is expected
+ * to be called from within critical sections, and is not threadsafe.
+ */
+#define ap_queue_empty(queue) ((queue)->nelts == 0 && APR_RING_EMPTY(&queue->timers ,timer_event_t, link))
+
+/**
+ * Callback routine that is called to destroy this
+ * fd_queue_t when its pool is destroyed.
+ */
+static apr_status_t ap_queue_destroy(void *data)
+{
+    fd_queue_t *queue = data;
+
+    /* Ignore errors here, we can't do anything about them anyway.
+     * XXX: We should at least try to signal an error here, it is
+     * indicative of a programmer error. -aaron */
+    apr_thread_cond_destroy(queue->not_empty);
+    apr_thread_mutex_destroy(queue->one_big_mutex);
+
+    return APR_SUCCESS;
+}
+
+/**
+ * Initialize the fd_queue_t.
+ */
+apr_status_t ap_queue_init(fd_queue_t * queue, int queue_capacity,
+                           apr_pool_t * a)
+{
+    int i;
+    apr_status_t rv;
+
+    if ((rv = apr_thread_mutex_create(&queue->one_big_mutex,
+                                      APR_THREAD_MUTEX_DEFAULT,
+                                      a)) != APR_SUCCESS) {
+        return rv;
+    }
+    if ((rv = apr_thread_cond_create(&queue->not_empty, a)) != APR_SUCCESS) {
+        return rv;
+    }
+
+    APR_RING_INIT(&queue->timers, timer_event_t, link);
+
+    queue->data = apr_palloc(a, queue_capacity * sizeof(fd_queue_elem_t));
+    queue->bounds = queue_capacity;
+    queue->nelts = 0;
+    queue->in = 0;
+    queue->out = 0;
+
+    /* Set all the sockets in the queue to NULL */
+    for (i = 0; i < queue_capacity; ++i)
+        queue->data[i].sd = NULL;
+
+    apr_pool_cleanup_register(a, queue, ap_queue_destroy,
+                              apr_pool_cleanup_null);
+
+    return APR_SUCCESS;
+}
+
+/**
+ * Push a new socket onto the queue.
+ *
+ * precondition: ap_queue_info_wait_for_idler has already been called
+ *               to reserve an idle worker thread
+ */
+apr_status_t ap_queue_push(fd_queue_t * queue, apr_socket_t * sd,
+                           event_conn_state_t * ecs, apr_pool_t * p)
+{
+    fd_queue_elem_t *elem;
+    apr_status_t rv;
+
+    if ((rv = apr_thread_mutex_lock(queue->one_big_mutex)) != APR_SUCCESS) {
+        return rv;
+    }
+
+    AP_DEBUG_ASSERT(!queue->terminated);
+    AP_DEBUG_ASSERT(!ap_queue_full(queue));
+
+    elem = &queue->data[queue->in];
+    queue->in++;
+    if (queue->in >= queue->bounds)
+        queue->in -= queue->bounds;
+    elem->sd = sd;
+    elem->ecs = ecs;
+    elem->p = p;
+    queue->nelts++;
+
+    apr_thread_cond_signal(queue->not_empty);
+
+    if ((rv = apr_thread_mutex_unlock(queue->one_big_mutex)) != APR_SUCCESS) {
+        return rv;
+    }
+
+    return APR_SUCCESS;
+}
+
+apr_status_t ap_queue_push_timer(fd_queue_t * queue, timer_event_t *te)
+{
+    apr_status_t rv;
+
+    if ((rv = apr_thread_mutex_lock(queue->one_big_mutex)) != APR_SUCCESS) {
+        return rv;
+    }
+
+    AP_DEBUG_ASSERT(!queue->terminated);
+
+    APR_RING_INSERT_TAIL(&queue->timers, te, timer_event_t, link);
+
+    apr_thread_cond_signal(queue->not_empty);
+
+    if ((rv = apr_thread_mutex_unlock(queue->one_big_mutex)) != APR_SUCCESS) {
+        return rv;
+    }
+
+    return APR_SUCCESS;
+}
+
+/**
+ * Retrieves the next available socket from the queue. If there are no
+ * sockets available, it will block until one becomes available.
+ * Once retrieved, the socket is placed into the address specified by
+ * 'sd'.
+ */
+apr_status_t ap_queue_pop_something(fd_queue_t * queue, apr_socket_t ** sd,
+                                    event_conn_state_t ** ecs, apr_pool_t ** p,
+                                    timer_event_t ** te_out)
+{
+    fd_queue_elem_t *elem;
+    apr_status_t rv;
+
+    if ((rv = apr_thread_mutex_lock(queue->one_big_mutex)) != APR_SUCCESS) {
+        return rv;
+    }
+
+    /* Keep waiting until we wake up and find that the queue is not empty. */
+    if (ap_queue_empty(queue)) {
+        if (!queue->terminated) {
+            apr_thread_cond_wait(queue->not_empty, queue->one_big_mutex);
+        }
+        /* If we wake up and it's still empty, then we were interrupted */
+        if (ap_queue_empty(queue)) {
+            rv = apr_thread_mutex_unlock(queue->one_big_mutex);
+            if (rv != APR_SUCCESS) {
+                return rv;
+            }
+            if (queue->terminated) {
+                return APR_EOF; /* no more elements ever again */
+            }
+            else {
+                return APR_EINTR;
+            }
+        }
+    }
+
+    *te_out = NULL;
+
+    if (!APR_RING_EMPTY(&queue->timers, timer_event_t, link)) {
+        *te_out = APR_RING_FIRST(&queue->timers);
+        APR_RING_REMOVE(*te_out, link);
+    }
+    else {
+        elem = &queue->data[queue->out];
+        queue->out++;
+        if (queue->out >= queue->bounds)
+            queue->out -= queue->bounds;
+        queue->nelts--;
+        *sd = elem->sd;
+        *ecs = elem->ecs;
+        *p = elem->p;
+#ifdef AP_DEBUG
+        elem->sd = NULL;
+        elem->p = NULL;
+#endif /* AP_DEBUG */
+    }
+
+    rv = apr_thread_mutex_unlock(queue->one_big_mutex);
+    return rv;
+}
+
+static apr_status_t queue_interrupt(fd_queue_t *queue, int all, int term)
+{
+    apr_status_t rv;
+
+    if ((rv = apr_thread_mutex_lock(queue->one_big_mutex)) != APR_SUCCESS) {
+        return rv;
+    }
+    /* we must hold one_big_mutex when setting this... otherwise,
+     * we could end up setting it and waking everybody up just after a
+     * would-be popper checks it but right before they block
+     */
+    if (term) {
+        queue->terminated = 1;
+    }
+    if (all)
+        apr_thread_cond_broadcast(queue->not_empty);
+    else
+        apr_thread_cond_signal(queue->not_empty);
+    return apr_thread_mutex_unlock(queue->one_big_mutex);
+}
+
+apr_status_t ap_queue_interrupt_all(fd_queue_t * queue)
+{
+    return queue_interrupt(queue, 1, 0);
+}
+
+apr_status_t ap_queue_interrupt_one(fd_queue_t * queue)
+{
+    return queue_interrupt(queue, 0, 0);
+}
+
+apr_status_t ap_queue_term(fd_queue_t * queue)
+{
+    return queue_interrupt(queue, 1, 1);
+}
diff --git a/server/mpm_unix.h b/server/mpm/event/fdqueue.h
index 13c4aceaa2..df54217387 100644
--- a/server/mpm_unix.h
+++ b/server/mpm/event/fdqueue.h
@@ -15,43 +15,52 @@
  */
 
 /**
- * @file  mpm_unix.h
+ * @file  event/fdqueue.h
  * @brief fd queue declarations
  *
- * @defgroup APACHE_MPM Multi-Processing Modules
- * @ingroup  APACHE
+ * @addtogroup APACHE_MPM_EVENT
  * @{
  */
 
-#ifndef MPM_UNIX_H
-#define MPM_UNIX_H
-
-#ifndef WIN32
-
-#include <apr.h>
-#include <apr_ring.h>
-#include <apr_pools.h>
-#include <apr_network_io.h>
+#ifndef FDQUEUE_H
+#define FDQUEUE_H
+#include "httpd.h"
+#include <stdlib.h>
+#if APR_HAVE_UNISTD_H
+#include <unistd.h>
+#endif
 #include <apr_thread_mutex.h>
 #include <apr_thread_cond.h>
+#include <sys/types.h>
+#if APR_HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+#include <apr_errno.h>
 
 #include "ap_mpm.h"
 
-struct fd_queue_info_t; /* opaque */
-struct fd_queue_elem_t; /* opaque */
 typedef struct fd_queue_info_t fd_queue_info_t;
-typedef struct fd_queue_elem_t fd_queue_elem_t;
+typedef struct event_conn_state_t event_conn_state_t;
 
-apr_status_t ap_queue_info_create(fd_queue_info_t **queue_info,
-                                  apr_pool_t *pool, int max_idlers,
+apr_status_t ap_queue_info_create(fd_queue_info_t ** queue_info,
+                                  apr_pool_t * pool, int max_idlers,
                                   int max_recycled_pools);
-apr_status_t ap_queue_info_set_idle(fd_queue_info_t *queue_info,
-                                    apr_pool_t *pool_to_recycle);
-apr_status_t ap_queue_info_try_get_idler(fd_queue_info_t *queue_info);
-apr_status_t ap_queue_info_wait_for_idler(fd_queue_info_t *queue_info,
+apr_status_t ap_queue_info_set_idle(fd_queue_info_t * queue_info,
+                                    apr_pool_t * pool_to_recycle);
+apr_status_t ap_queue_info_try_get_idler(fd_queue_info_t * queue_info);
+apr_status_t ap_queue_info_wait_for_idler(fd_queue_info_t * queue_info,
                                           int *had_to_block);
-apr_uint32_t ap_queue_info_num_idlers(fd_queue_info_t *queue_info);
-apr_status_t ap_queue_info_term(fd_queue_info_t *queue_info);
+apr_status_t ap_queue_info_term(fd_queue_info_t * queue_info);
+apr_uint32_t ap_queue_info_get_idlers(fd_queue_info_t * queue_info);
+void ap_free_idle_pools(fd_queue_info_t *queue_info);
+
+struct fd_queue_elem_t
+{
+    apr_socket_t *sd;
+    apr_pool_t *p;
+    event_conn_state_t *ecs;
+};
+typedef struct fd_queue_elem_t fd_queue_elem_t;
 
 typedef struct timer_event_t timer_event_t;
 
@@ -79,25 +88,21 @@ struct fd_queue_t
 };
 typedef struct fd_queue_t fd_queue_t;
 
-void ap_pop_pool(apr_pool_t **recycled_pool, fd_queue_info_t *queue_info);
-void ap_push_pool(fd_queue_info_t *queue_info, apr_pool_t *pool_to_recycle);
-void ap_free_idle_pools(fd_queue_info_t *queue_info);
+void ap_pop_pool(apr_pool_t ** recycled_pool, fd_queue_info_t * queue_info);
+void ap_push_pool(fd_queue_info_t * queue_info,
+                                    apr_pool_t * pool_to_recycle);
 
-apr_status_t ap_queue_init(fd_queue_t *queue, int queue_capacity,
-                           apr_pool_t *a);
-apr_status_t ap_queue_push(fd_queue_t *queue, apr_socket_t *sd,
-                           void *baton, apr_pool_t *p);
+apr_status_t ap_queue_init(fd_queue_t * queue, int queue_capacity,
+                           apr_pool_t * a);
+apr_status_t ap_queue_push(fd_queue_t * queue, apr_socket_t * sd,
+                           event_conn_state_t * ecs, apr_pool_t * p);
 apr_status_t ap_queue_push_timer(fd_queue_t *queue, timer_event_t *te);
-apr_status_t ap_queue_pop_something(fd_queue_t *queue, apr_socket_t **sd,
-                                    void **baton, apr_pool_t **p,
-                                    timer_event_t **te);
-#define      ap_queue_pop(q_, s_, p_) \
-                ap_queue_pop_something((q_), (s_), NULL, (p_), NULL)
-apr_status_t ap_queue_interrupt_all(fd_queue_t *queue);
-apr_status_t ap_queue_interrupt_one(fd_queue_t *queue);
-apr_status_t ap_queue_term(fd_queue_t *queue);
-
-#endif /* WIN32 */
+apr_status_t ap_queue_pop_something(fd_queue_t * queue, apr_socket_t ** sd,
+                                    event_conn_state_t ** ecs, apr_pool_t ** p,
+                                    timer_event_t ** te);
+apr_status_t ap_queue_interrupt_all(fd_queue_t * queue);
+apr_status_t ap_queue_interrupt_one(fd_queue_t * queue);
+apr_status_t ap_queue_term(fd_queue_t * queue);
 
-#endif /* MPM_UNIX_H */
+#endif /* FDQUEUE_H */
 /** @} */
diff --git a/server/mpm/worker/config3.m4 b/server/mpm/worker/config3.m4
index f21817a4a8..68d861f494 100644
--- a/server/mpm/worker/config3.m4
+++ b/server/mpm/worker/config3.m4
@@ -1,7 +1,7 @@
 APACHE_MPMPATH_INIT(worker)
 
 dnl ## XXX - Need a more thorough check of the proper flags to use
-APACHE_MPM_MODULE(worker, $enable_mpm_worker, worker.lo,[
+APACHE_MPM_MODULE(worker, $enable_mpm_worker, worker.lo fdqueue.lo,[
     AC_CHECK_FUNCS(pthread_kill)
 ])
 
diff --git a/server/mpm/worker/fdqueue.c b/server/mpm/worker/fdqueue.c
new file mode 100644
index 0000000000..3cb131090a
--- /dev/null
+++ b/server/mpm/worker/fdqueue.c
@@ -0,0 +1,401 @@
+/* Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "fdqueue.h"
+#include "apr_atomic.h"
+
+typedef struct recycled_pool {
+    apr_pool_t *pool;
+    struct recycled_pool *next;
+} recycled_pool;
+
+struct fd_queue_info_t {
+    volatile apr_uint32_t idlers;
+    apr_thread_mutex_t *idlers_mutex;
+    apr_thread_cond_t *wait_for_idler;
+    int terminated;
+    int max_idlers;
+    recycled_pool  *recycled_pools;
+};
+
+static apr_status_t queue_info_cleanup(void *data_)
+{
+    fd_queue_info_t *qi = data_;
+    apr_thread_cond_destroy(qi->wait_for_idler);
+    apr_thread_mutex_destroy(qi->idlers_mutex);
+
+    /* Clean up any pools in the recycled list */
+    for (;;) {
+        struct recycled_pool *first_pool = qi->recycled_pools;
+        if (first_pool == NULL) {
+            break;
+        }
+        if (apr_atomic_casptr((void*)&(qi->recycled_pools), first_pool->next,
+                              first_pool) == first_pool) {
+            apr_pool_destroy(first_pool->pool);
+        }
+    }
+
+    return APR_SUCCESS;
+}
+
+apr_status_t ap_queue_info_create(fd_queue_info_t **queue_info,
+                                  apr_pool_t *pool, int max_idlers)
+{
+    apr_status_t rv;
+    fd_queue_info_t *qi;
+
+    qi = apr_pcalloc(pool, sizeof(*qi));
+
+    rv = apr_thread_mutex_create(&qi->idlers_mutex, APR_THREAD_MUTEX_DEFAULT,
+                                 pool);
+    if (rv != APR_SUCCESS) {
+        return rv;
+    }
+    rv = apr_thread_cond_create(&qi->wait_for_idler, pool);
+    if (rv != APR_SUCCESS) {
+        return rv;
+    }
+    qi->recycled_pools = NULL;
+    qi->max_idlers = max_idlers;
+    apr_pool_cleanup_register(pool, qi, queue_info_cleanup,
+                              apr_pool_cleanup_null);
+
+    *queue_info = qi;
+
+    return APR_SUCCESS;
+}
+
+apr_status_t ap_queue_info_set_idle(fd_queue_info_t *queue_info,
+                                    apr_pool_t *pool_to_recycle)
+{
+    apr_status_t rv;
+
+    /* If we have been given a pool to recycle, atomically link
+     * it into the queue_info's list of recycled pools
+     */
+    if (pool_to_recycle) {
+        struct recycled_pool *new_recycle;
+        new_recycle = (struct recycled_pool *)apr_palloc(pool_to_recycle,
+                                                         sizeof(*new_recycle));
+        new_recycle->pool = pool_to_recycle;
+        for (;;) {
+            /* Save queue_info->recycled_pool in local variable next because
+             * new_recycle->next can be changed after apr_atomic_casptr
+             * function call. For gory details see PR 44402.
+             */
+            struct recycled_pool *next = queue_info->recycled_pools;
+            new_recycle->next = next;
+            if (apr_atomic_casptr((void*)&(queue_info->recycled_pools),
+                                  new_recycle, next) == next) {
+                break;
+            }
+        }
+    }
+
+    /* If this thread makes the idle worker count nonzero,
+     * wake up the listener. */
+    if (apr_atomic_inc32(&queue_info->idlers) == 0) {
+        rv = apr_thread_mutex_lock(queue_info->idlers_mutex);
+        if (rv != APR_SUCCESS) {
+            return rv;
+        }
+        rv = apr_thread_cond_signal(queue_info->wait_for_idler);
+        if (rv != APR_SUCCESS) {
+            apr_thread_mutex_unlock(queue_info->idlers_mutex);
+            return rv;
+        }
+        rv = apr_thread_mutex_unlock(queue_info->idlers_mutex);
+        if (rv != APR_SUCCESS) {
+            return rv;
+        }
+    }
+
+    return APR_SUCCESS;
+}
+
+apr_status_t ap_queue_info_wait_for_idler(fd_queue_info_t *queue_info,
+                                          apr_pool_t **recycled_pool)
+{
+    apr_status_t rv;
+
+    *recycled_pool = NULL;
+
+    /* Block if the count of idle workers is zero */
+    if (queue_info->idlers == 0) {
+        rv = apr_thread_mutex_lock(queue_info->idlers_mutex);
+        if (rv != APR_SUCCESS) {
+            return rv;
+        }
+        /* Re-check the idle worker count to guard against a
+         * race condition.  Now that we're in the mutex-protected
+         * region, one of two things may have happened:
+         *   - If the idle worker count is still zero, the
+         *     workers are all still busy, so it's safe to
+         *     block on a condition variable, BUT
+         *     we need to check for idle worker count again
+         *     when we are signaled since it can happen that
+         *     we are signaled by a worker thread that went idle
+         *     but received a context switch before it could
+         *     tell us. If it does signal us later once it is on
+         *     CPU again there might be no idle worker left.
+         *     See
+         *     https://issues.apache.org/bugzilla/show_bug.cgi?id=45605#c4
+         *   - If the idle worker count is nonzero, then a
+         *     worker has become idle since the first check
+         *     of queue_info->idlers above.  It's possible
+         *     that the worker has also signaled the condition
+         *     variable--and if so, the listener missed it
+         *     because it wasn't yet blocked on the condition
+         *     variable.  But if the idle worker count is
+         *     now nonzero, it's safe for this function to
+         *     return immediately.
+         */
+        while (queue_info->idlers == 0) {
+            rv = apr_thread_cond_wait(queue_info->wait_for_idler,
+                                  queue_info->idlers_mutex);
+            if (rv != APR_SUCCESS) {
+                apr_status_t rv2;
+                rv2 = apr_thread_mutex_unlock(queue_info->idlers_mutex);
+                if (rv2 != APR_SUCCESS) {
+                    return rv2;
+                }
+                return rv;
+            }
+        }
+        rv = apr_thread_mutex_unlock(queue_info->idlers_mutex);
+        if (rv != APR_SUCCESS) {
+            return rv;
+        }
+    }
+
+    /* Atomically decrement the idle worker count */
+    apr_atomic_dec32(&(queue_info->idlers));
+
+    /* Atomically pop a pool from the recycled list */
+
+    /* This function is safe only as long as it is single threaded because
+     * it reaches into the queue and accesses "next" which can change.
+     * We are OK today because it is only called from the listener thread.
+     * cas-based pushes do not have the same limitation - any number can
+     * happen concurrently with a single cas-based pop.
+     */
+
+    for (;;) {
+        struct recycled_pool *first_pool = queue_info->recycled_pools;
+        if (first_pool == NULL) {
+            break;
+        }
+        if (apr_atomic_casptr((void*)&(queue_info->recycled_pools), first_pool->next,
+                              first_pool) == first_pool) {
+            *recycled_pool = first_pool->pool;
+            break;
+        }
+    }
+
+    if (queue_info->terminated) {
+        return APR_EOF;
+    }
+    else {
+        return APR_SUCCESS;
+    }
+}
+
+apr_status_t ap_queue_info_term(fd_queue_info_t *queue_info)
+{
+    apr_status_t rv;
+    rv = apr_thread_mutex_lock(queue_info->idlers_mutex);
+    if (rv != APR_SUCCESS) {
+        return rv;
+    }
+    queue_info->terminated = 1;
+    apr_thread_cond_broadcast(queue_info->wait_for_idler);
+    return apr_thread_mutex_unlock(queue_info->idlers_mutex);
+}
+
+/**
+ * Detects when the fd_queue_t is full. This utility function is expected
+ * to be called from within critical sections, and is not threadsafe.
+ */
+#define ap_queue_full(queue) ((queue)->nelts == (queue)->bounds)
+
+/**
+ * Detects when the fd_queue_t is empty. This utility function is expected
+ * to be called from within critical sections, and is not threadsafe.
+ */
+#define ap_queue_empty(queue) ((queue)->nelts == 0)
+
+/**
+ * Callback routine that is called to destroy this
+ * fd_queue_t when its pool is destroyed.
+ */
+static apr_status_t ap_queue_destroy(void *data)
+{
+    fd_queue_t *queue = data;
+
+    /* Ignore errors here, we can't do anything about them anyway.
+     * XXX: We should at least try to signal an error here, it is
+     * indicative of a programmer error. -aaron */
+    apr_thread_cond_destroy(queue->not_empty);
+    apr_thread_mutex_destroy(queue->one_big_mutex);
+
+    return APR_SUCCESS;
+}
+
+/**
+ * Initialize the fd_queue_t.
+ */
+apr_status_t ap_queue_init(fd_queue_t *queue, int queue_capacity, apr_pool_t *a)
+{
+    int i;
+    apr_status_t rv;
+
+    if ((rv = apr_thread_mutex_create(&queue->one_big_mutex,
+                                      APR_THREAD_MUTEX_DEFAULT, a)) != APR_SUCCESS) {
+        return rv;
+    }
+    if ((rv = apr_thread_cond_create(&queue->not_empty, a)) != APR_SUCCESS) {
+        return rv;
+    }
+
+    queue->data = apr_palloc(a, queue_capacity * sizeof(fd_queue_elem_t));
+    queue->bounds = queue_capacity;
+    queue->nelts = 0;
+    queue->in = 0;
+    queue->out = 0;
+
+    /* Set all the sockets in the queue to NULL */
+    for (i = 0; i < queue_capacity; ++i)
+        queue->data[i].sd = NULL;
+
+    apr_pool_cleanup_register(a, queue, ap_queue_destroy, apr_pool_cleanup_null);
+
+    return APR_SUCCESS;
+}
+
+/**
+ * Push a new socket onto the queue.
+ *
+ * precondition: ap_queue_info_wait_for_idler has already been called
+ *               to reserve an idle worker thread
+ */
+apr_status_t ap_queue_push(fd_queue_t *queue, apr_socket_t *sd, apr_pool_t *p)
+{
+    fd_queue_elem_t *elem;
+    apr_status_t rv;
+
+    if ((rv = apr_thread_mutex_lock(queue->one_big_mutex)) != APR_SUCCESS) {
+        return rv;
+    }
+
+    AP_DEBUG_ASSERT(!queue->terminated);
+    AP_DEBUG_ASSERT(!ap_queue_full(queue));
+
+    elem = &queue->data[queue->in];
+    queue->in++;
+    if (queue->in >= queue->bounds)
+        queue->in -= queue->bounds;
+    elem->sd = sd;
+    elem->p = p;
+    queue->nelts++;
+
+    apr_thread_cond_signal(queue->not_empty);
+
+    if ((rv = apr_thread_mutex_unlock(queue->one_big_mutex)) != APR_SUCCESS) {
+        return rv;
+    }
+
+    return APR_SUCCESS;
+}
+
+/**
+ * Retrieves the next available socket from the queue. If there are no
+ * sockets available, it will block until one becomes available.
+ * Once retrieved, the socket is placed into the address specified by
+ * 'sd'.
+ */
+apr_status_t ap_queue_pop(fd_queue_t *queue, apr_socket_t **sd, apr_pool_t **p)
+{
+    fd_queue_elem_t *elem;
+    apr_status_t rv;
+
+    if ((rv = apr_thread_mutex_lock(queue->one_big_mutex)) != APR_SUCCESS) {
+        return rv;
+    }
+
+    /* Keep waiting until we wake up and find that the queue is not empty. */
+    if (ap_queue_empty(queue)) {
+        if (!queue->terminated) {
+            apr_thread_cond_wait(queue->not_empty, queue->one_big_mutex);
+        }
+        /* If we wake up and it's still empty, then we were interrupted */
+        if (ap_queue_empty(queue)) {
+            rv = apr_thread_mutex_unlock(queue->one_big_mutex);
+            if (rv != APR_SUCCESS) {
+                return rv;
+            }
+            if (queue->terminated) {
+                return APR_EOF; /* no more elements ever again */
+            }
+            else {
+                return APR_EINTR;
+            }
+        }
+    }
+
+    elem = &queue->data[queue->out];
+    queue->out++;
+    if (queue->out >= queue->bounds)
+        queue->out -= queue->bounds;
+    queue->nelts--;
+    *sd = elem->sd;
+    *p = elem->p;
+#ifdef AP_DEBUG
+    elem->sd = NULL;
+    elem->p = NULL;
+#endif /* AP_DEBUG */
+
+    rv = apr_thread_mutex_unlock(queue->one_big_mutex);
+    return rv;
+}
+
+static apr_status_t queue_interrupt_all(fd_queue_t *queue, int term)
+{
+    apr_status_t rv;
+
+    if ((rv = apr_thread_mutex_lock(queue->one_big_mutex)) != APR_SUCCESS) {
+        return rv;
+    }
+    /* we must hold one_big_mutex when setting this... otherwise,
+     * we could end up setting it and waking everybody up just after a
+     * would-be popper checks it but right before they block
+     */
+    if (term) {
+        queue->terminated = 1;
+    }
+    apr_thread_cond_broadcast(queue->not_empty);
+    return apr_thread_mutex_unlock(queue->one_big_mutex);
+}
+
+apr_status_t ap_queue_interrupt_all(fd_queue_t *queue)
+{
+    return queue_interrupt_all(queue, 0);
+}
+
+apr_status_t ap_queue_term(fd_queue_t *queue)
+{
+    return queue_interrupt_all(queue, 1);
+}
diff --git a/server/mpm/worker/fdqueue.h b/server/mpm/worker/fdqueue.h
new file mode 100644
index 0000000000..1d48a1a826
--- /dev/null
+++ b/server/mpm/worker/fdqueue.h
@@ -0,0 +1,75 @@
+/* Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * @file  worker/fdqueue.h
+ * @brief fd queue declarations
+ *
+ * @addtogroup APACHE_MPM_WORKER
+ * @{
+ */
+
+#ifndef FDQUEUE_H
+#define FDQUEUE_H
+#include "httpd.h"
+#include <stdlib.h>
+#if APR_HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+#include <apr_thread_mutex.h>
+#include <apr_thread_cond.h>
+#include <sys/types.h>
+#if APR_HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+#include <apr_errno.h>
+
+typedef struct fd_queue_info_t fd_queue_info_t;
+
+apr_status_t ap_queue_info_create(fd_queue_info_t **queue_info,
+                                  apr_pool_t *pool, int max_idlers);
+apr_status_t ap_queue_info_set_idle(fd_queue_info_t *queue_info,
+                                    apr_pool_t *pool_to_recycle);
+apr_status_t ap_queue_info_wait_for_idler(fd_queue_info_t *queue_info,
+                                          apr_pool_t **recycled_pool);
+apr_status_t ap_queue_info_term(fd_queue_info_t *queue_info);
+
+struct fd_queue_elem_t {
+    apr_socket_t      *sd;
+    apr_pool_t        *p;
+};
+typedef struct fd_queue_elem_t fd_queue_elem_t;
+
+struct fd_queue_t {
+    fd_queue_elem_t    *data;
+    unsigned int       nelts;
+    unsigned int       bounds;
+    unsigned int       in;
+    unsigned int       out;
+    apr_thread_mutex_t *one_big_mutex;
+    apr_thread_cond_t  *not_empty;
+    int                 terminated;
+};
+typedef struct fd_queue_t fd_queue_t;
+
+apr_status_t ap_queue_init(fd_queue_t *queue, int queue_capacity, apr_pool_t *a);
+apr_status_t ap_queue_push(fd_queue_t *queue, apr_socket_t *sd, apr_pool_t *p);
+apr_status_t ap_queue_pop(fd_queue_t *queue, apr_socket_t **sd, apr_pool_t **p);
+apr_status_t ap_queue_interrupt_all(fd_queue_t *queue);
+apr_status_t ap_queue_term(fd_queue_t *queue);
+
+#endif /* FDQUEUE_H */
+/** @} */
diff --git a/server/mpm/worker/worker.c b/server/mpm/worker/worker.c
index 64b3916b46..9d72f90a46 100644
--- a/server/mpm/worker/worker.c
+++ b/server/mpm/worker/worker.c
@@ -64,7 +64,7 @@
 #include "mpm_common.h"
 #include "ap_listen.h"
 #include "scoreboard.h"
-#include "mpm_unix.h"
+#include "fdqueue.h"
 #include "mpm_default.h"
 #include "util_mutex.h"
 #include "unixd.h"
@@ -597,7 +597,11 @@ static void * APR_THREAD_FUNC listener_thread(apr_thread_t *thd, void * dummy)
         if (listener_may_exit) break;
 
         if (!have_idle_worker) {
-            rv = ap_queue_info_wait_for_idler(worker_queue_info, NULL);
+            /* the following pops a recycled ptrans pool off a stack
+             * if there is one, in addition to reserving a worker thread
+             */
+            rv = ap_queue_info_wait_for_idler(worker_queue_info,
+                                              &ptrans);
             if (APR_STATUS_IS_EOF(rv)) {
                 break; /* we've been signaled to die now */
             }
@@ -675,8 +679,6 @@ static void * APR_THREAD_FUNC listener_thread(apr_thread_t *thd, void * dummy)
         } /* if/else */
 
         if (!listener_may_exit) {
-            /* the following pops a recycled ptrans pool off a stack */
-            ap_pop_pool(&ptrans, worker_queue_info);
             if (ptrans == NULL) {
                 /* we can't use a recycled transaction pool this time.
                  * create a new transaction pool */
@@ -686,8 +688,8 @@ static void * APR_THREAD_FUNC listener_thread(apr_thread_t *thd, void * dummy)
                 apr_allocator_max_free_set(allocator, ap_max_mem_free);
                 apr_pool_create_ex(&ptrans, pconf, NULL, allocator);
                 apr_allocator_owner_set(allocator, ptrans);
-                apr_pool_tag(ptrans, "transaction");
             }
+            apr_pool_tag(ptrans, "transaction");
             rv = lr->accept_func(&csd, lr, ptrans);
             /* later we trash rv and rely on csd to indicate success/failure */
             AP_DEBUG_ASSERT(rv == APR_SUCCESS || !csd);
@@ -710,7 +712,7 @@ static void * APR_THREAD_FUNC listener_thread(apr_thread_t *thd, void * dummy)
                 accept_mutex_error("unlock", rv, process_slot);
             }
             if (csd != NULL) {
-                rv = ap_queue_push(worker_queue, csd, NULL, ptrans);
+                rv = ap_queue_push(worker_queue, csd, ptrans);
                 if (rv) {
                     /* trash the connection; we couldn't queue the connected
                      * socket to a worker
@@ -916,7 +918,7 @@ static void * APR_THREAD_FUNC start_threads(apr_thread_t *thd, void *dummy)
     }
 
     rv = ap_queue_info_create(&worker_queue_info, pchild,
-                              threads_per_child, -1);
+                              threads_per_child);
     if (rv != APR_SUCCESS) {
         ap_log_error(APLOG_MARK, APLOG_ALERT, rv, ap_server_conf, APLOGNO(03141)
                      "ap_queue_info_create() failed");
diff --git a/server/mpm_unix.c b/server/mpm_unix.c
index b76febece0..29bc3a2b00 100644
--- a/server/mpm_unix.c
+++ b/server/mpm_unix.c
@@ -27,8 +27,7 @@
 
 #ifndef WIN32
 
-#include "mpm_unix.h"
-
+#include "apr.h"
 #include "apr_thread_proc.h"
 #include "apr_signal.h"
 #include "apr_strings.h"
@@ -37,8 +36,6 @@
 #include "apr_getopt.h"
 #include "apr_optional.h"
 #include "apr_allocator.h"
-#include "apr_atomic.h"
-#include "apr_errno.h"
 
 #include "httpd.h"
 #include "http_config.h"
@@ -46,6 +43,7 @@
 #include "http_log.h"
 #include "http_main.h"
 #include "mpm_common.h"
+#include "ap_mpm.h"
 #include "ap_listen.h"
 #include "scoreboard.h"
 #include "util_mutex.h"
@@ -1106,528 +1104,4 @@ AP_DECLARE(apr_status_t) ap_fatal_signal_setup(server_rec *s,
     return APR_SUCCESS;
 }
 
-
-/* 
- * fdqueue code used by MPMs event and worker.
- * Not part of the API, so not AP_DECLARE()d.
- */
-
-static const apr_uint32_t zero_pt = APR_UINT32_MAX/2;
-
-struct recycled_pool
-{
-    apr_pool_t *pool;
-    struct recycled_pool *next;
-};
-
-struct fd_queue_info_t
-{
-    apr_uint32_t volatile idlers; /**
-                                   * >= zero_pt: number of idle worker threads
-                                   * <  zero_pt: number of threads blocked,
-                                   *             waiting for an idle worker
-                                   */
-    apr_thread_mutex_t *idlers_mutex;
-    apr_thread_cond_t *wait_for_idler;
-    int terminated;
-    int max_idlers;
-    int max_recycled_pools;
-    apr_uint32_t recycled_pools_count;
-    struct recycled_pool *volatile recycled_pools;
-};
-
-struct fd_queue_elem_t
-{
-    apr_socket_t *sd;
-    apr_pool_t *p;
-    void *baton;
-};
-
-static apr_status_t queue_info_cleanup(void *data_)
-{
-    fd_queue_info_t *qi = data_;
-    apr_thread_cond_destroy(qi->wait_for_idler);
-    apr_thread_mutex_destroy(qi->idlers_mutex);
-
-    /* Clean up any pools in the recycled list */
-    for (;;) {
-        struct recycled_pool *first_pool = qi->recycled_pools;
-        if (first_pool == NULL) {
-            break;
-        }
-        if (apr_atomic_casptr((void *)&qi->recycled_pools, first_pool->next,
-                              first_pool) == first_pool) {
-            apr_pool_destroy(first_pool->pool);
-        }
-    }
-
-    return APR_SUCCESS;
-}
-
-apr_status_t ap_queue_info_create(fd_queue_info_t **queue_info,
-                                  apr_pool_t *pool, int max_idlers,
-                                  int max_recycled_pools)
-{
-    apr_status_t rv;
-    fd_queue_info_t *qi;
-
-    qi = apr_pcalloc(pool, sizeof(*qi));
-
-    rv = apr_thread_mutex_create(&qi->idlers_mutex, APR_THREAD_MUTEX_DEFAULT,
-                                 pool);
-    if (rv != APR_SUCCESS) {
-        return rv;
-    }
-    rv = apr_thread_cond_create(&qi->wait_for_idler, pool);
-    if (rv != APR_SUCCESS) {
-        return rv;
-    }
-    qi->recycled_pools = NULL;
-    qi->max_recycled_pools = max_recycled_pools;
-    qi->max_idlers = max_idlers;
-    qi->idlers = zero_pt;
-    apr_pool_cleanup_register(pool, qi, queue_info_cleanup,
-                              apr_pool_cleanup_null);
-
-    *queue_info = qi;
-
-    return APR_SUCCESS;
-}
-
-apr_status_t ap_queue_info_set_idle(fd_queue_info_t *queue_info,
-                                    apr_pool_t *pool_to_recycle)
-{
-    apr_status_t rv;
-
-    ap_push_pool(queue_info, pool_to_recycle);
-
-    /* If other threads are waiting on a worker, wake one up */
-    if (apr_atomic_inc32(&queue_info->idlers) < zero_pt) {
-        rv = apr_thread_mutex_lock(queue_info->idlers_mutex);
-        if (rv != APR_SUCCESS) {
-            AP_DEBUG_ASSERT(0);
-            return rv;
-        }
-        rv = apr_thread_cond_signal(queue_info->wait_for_idler);
-        if (rv != APR_SUCCESS) {
-            apr_thread_mutex_unlock(queue_info->idlers_mutex);
-            return rv;
-        }
-        rv = apr_thread_mutex_unlock(queue_info->idlers_mutex);
-        if (rv != APR_SUCCESS) {
-            return rv;
-        }
-    }
-
-    return APR_SUCCESS;
-}
-
-apr_status_t ap_queue_info_try_get_idler(fd_queue_info_t *queue_info)
-{
-    /* Don't block if there isn't any idle worker. */
-    for (;;) {
-        apr_uint32_t idlers = queue_info->idlers;
-        if (idlers <= zero_pt) {
-            return APR_EAGAIN;
-        }
-        if (apr_atomic_cas32(&queue_info->idlers, idlers - 1,
-                             idlers) == idlers) {
-            return APR_SUCCESS;
-        }
-    }
-}
-
-apr_status_t ap_queue_info_wait_for_idler(fd_queue_info_t *queue_info,
-                                          int *had_to_block)
-{
-    apr_status_t rv;
-
-    /* Block if there isn't any idle worker.
-     * apr_atomic_add32(x, -1) does the same as dec32(x), except
-     * that it returns the previous value (unlike dec32's bool).
-     */
-    if (apr_atomic_add32(&queue_info->idlers, -1) <= zero_pt) {
-        rv = apr_thread_mutex_lock(queue_info->idlers_mutex);
-        if (rv != APR_SUCCESS) {
-            AP_DEBUG_ASSERT(0);
-            apr_atomic_inc32(&(queue_info->idlers));    /* back out dec */
-            return rv;
-        }
-        /* Re-check the idle worker count to guard against a
-         * race condition.  Now that we're in the mutex-protected
-         * region, one of two things may have happened:
-         *   - If the idle worker count is still negative, the
-         *     workers are all still busy, so it's safe to
-         *     block on a condition variable.
-         *   - If the idle worker count is non-negative, then a
-         *     worker has become idle since the first check
-         *     of queue_info->idlers above.  It's possible
-         *     that the worker has also signaled the condition
-         *     variable--and if so, the listener missed it
-         *     because it wasn't yet blocked on the condition
-         *     variable.  But if the idle worker count is
-         *     now non-negative, it's safe for this function to
-         *     return immediately.
-         *
-         *     A "negative value" (relative to zero_pt) in
-         *     queue_info->idlers tells how many
-         *     threads are waiting on an idle worker.
-         */
-        if (queue_info->idlers < zero_pt) {
-            if (had_to_block) {
-                *had_to_block = 1;
-            }
-            rv = apr_thread_cond_wait(queue_info->wait_for_idler,
-                                      queue_info->idlers_mutex);
-            if (rv != APR_SUCCESS) {
-                apr_status_t rv2;
-                AP_DEBUG_ASSERT(0);
-                rv2 = apr_thread_mutex_unlock(queue_info->idlers_mutex);
-                if (rv2 != APR_SUCCESS) {
-                    return rv2;
-                }
-                return rv;
-            }
-        }
-        rv = apr_thread_mutex_unlock(queue_info->idlers_mutex);
-        if (rv != APR_SUCCESS) {
-            return rv;
-        }
-    }
-
-    if (queue_info->terminated) {
-        return APR_EOF;
-    }
-    else {
-        return APR_SUCCESS;
-    }
-}
-
-apr_uint32_t ap_queue_info_num_idlers(fd_queue_info_t *queue_info)
-{
-    apr_uint32_t val;
-    val = apr_atomic_read32(&queue_info->idlers);
-    if (val <= zero_pt)
-        return 0;
-    return val - zero_pt;
-}
-
-void ap_push_pool(fd_queue_info_t *queue_info, apr_pool_t *pool_to_recycle)
-{
-    struct recycled_pool *new_recycle;
-    /* If we have been given a pool to recycle, atomically link
-     * it into the queue_info's list of recycled pools
-     */
-    if (!pool_to_recycle)
-        return;
-
-    if (queue_info->max_recycled_pools >= 0) {
-        apr_uint32_t cnt = apr_atomic_read32(&queue_info->recycled_pools_count);
-        if (cnt >= queue_info->max_recycled_pools) {
-            apr_pool_destroy(pool_to_recycle);
-            return;
-        }
-        apr_atomic_inc32(&queue_info->recycled_pools_count);
-    }
-
-    apr_pool_clear(pool_to_recycle);
-    new_recycle = apr_palloc(pool_to_recycle, sizeof *new_recycle);
-    new_recycle->pool = pool_to_recycle;
-    for (;;) {
-        /*
-         * Save queue_info->recycled_pool in local variable next because
-         * new_recycle->next can be changed after apr_atomic_casptr
-         * function call. For gory details see PR 44402.
-         */
-        struct recycled_pool *next = queue_info->recycled_pools;
-        new_recycle->next = next;
-        if (apr_atomic_casptr((void*) &(queue_info->recycled_pools),
-                              new_recycle, next) == next)
-            break;
-    }
-}
-
-void ap_pop_pool(apr_pool_t **recycled_pool, fd_queue_info_t *queue_info)
-{
-    /* Atomically pop a pool from the recycled list */
-
-    /* This function is safe only as long as it is single threaded because
-     * it reaches into the queue and accesses "next" which can change.
-     * We are OK today because it is only called from the listener thread.
-     * cas-based pushes do not have the same limitation - any number can
-     * happen concurrently with a single cas-based pop.
-     */
-
-    *recycled_pool = NULL;
-
-
-    /* Atomically pop a pool from the recycled list */
-    for (;;) {
-        struct recycled_pool *first_pool = queue_info->recycled_pools;
-        if (first_pool == NULL) {
-            break;
-        }
-        if (apr_atomic_casptr((void *)&queue_info->recycled_pools,
-                              first_pool->next, first_pool) == first_pool) {
-            *recycled_pool = first_pool->pool;
-            if (queue_info->max_recycled_pools >= 0)
-                apr_atomic_dec32(&queue_info->recycled_pools_count);
-            break;
-        }
-    }
-}
-
-void ap_free_idle_pools(fd_queue_info_t *queue_info)
-{
-    apr_pool_t *p;
-
-    queue_info->max_recycled_pools = 0;
-    for (;;) {
-        ap_pop_pool(&p, queue_info);
-        if (p == NULL)
-            break;
-        apr_pool_destroy(p);
-    }
-    apr_atomic_set32(&queue_info->recycled_pools_count, 0);
-}
-
-
-apr_status_t ap_queue_info_term(fd_queue_info_t *queue_info)
-{
-    apr_status_t rv;
-    rv = apr_thread_mutex_lock(queue_info->idlers_mutex);
-    if (rv != APR_SUCCESS) {
-        return rv;
-    }
-    queue_info->terminated = 1;
-    apr_thread_cond_broadcast(queue_info->wait_for_idler);
-    return apr_thread_mutex_unlock(queue_info->idlers_mutex);
-}
-
-/**
- * Detects when the fd_queue_t is full. This utility function is expected
- * to be called from within critical sections, and is not threadsafe.
- */
-#define ap_queue_full(queue) ((queue)->nelts == (queue)->bounds)
-
-/**
- * Detects when the fd_queue_t is empty. This utility function is expected
- * to be called from within critical sections, and is not threadsafe.
- */
-#define ap_queue_empty(queue) ((queue)->nelts == 0 && APR_RING_EMPTY(&queue->timers ,timer_event_t, link))
-
-/**
- * Callback routine that is called to destroy this
- * fd_queue_t when its pool is destroyed.
- */
-static apr_status_t ap_queue_destroy(void *data)
-{
-    fd_queue_t *queue = data;
-
-    /* Ignore errors here, we can't do anything about them anyway.
-     * XXX: We should at least try to signal an error here, it is
-     * indicative of a programmer error. -aaron */
-    apr_thread_cond_destroy(queue->not_empty);
-    apr_thread_mutex_destroy(queue->one_big_mutex);
-
-    return APR_SUCCESS;
-}
-
-/**
- * Initialize the fd_queue_t.
- */
-apr_status_t ap_queue_init(fd_queue_t *queue, int queue_capacity,
-                           apr_pool_t *a)
-{
-    int i;
-    apr_status_t rv;
-
-    if ((rv = apr_thread_mutex_create(&queue->one_big_mutex,
-                                      APR_THREAD_MUTEX_DEFAULT,
-                                      a)) != APR_SUCCESS) {
-        return rv;
-    }
-    if ((rv = apr_thread_cond_create(&queue->not_empty, a)) != APR_SUCCESS) {
-        return rv;
-    }
-
-    APR_RING_INIT(&queue->timers, timer_event_t, link);
-
-    queue->data = apr_palloc(a, queue_capacity * sizeof(fd_queue_elem_t));
-    queue->bounds = queue_capacity;
-    queue->nelts = 0;
-    queue->in = 0;
-    queue->out = 0;
-
-    /* Set all the sockets in the queue to NULL */
-    for (i = 0; i < queue_capacity; ++i)
-        queue->data[i].sd = NULL;
-
-    apr_pool_cleanup_register(a, queue, ap_queue_destroy,
-                              apr_pool_cleanup_null);
-
-    return APR_SUCCESS;
-}
-
-/**
- * Push a new socket onto the queue.
- *
- * precondition: ap_queue_info_wait_for_idler has already been called
- *               to reserve an idle worker thread
- */
-apr_status_t ap_queue_push(fd_queue_t *queue, apr_socket_t *sd,
-                           void *baton, apr_pool_t *p)
-{
-    fd_queue_elem_t *elem;
-    apr_status_t rv;
-
-    if ((rv = apr_thread_mutex_lock(queue->one_big_mutex)) != APR_SUCCESS) {
-        return rv;
-    }
-
-    AP_DEBUG_ASSERT(!queue->terminated);
-    AP_DEBUG_ASSERT(!ap_queue_full(queue));
-
-    elem = &queue->data[queue->in];
-    queue->in++;
-    if (queue->in >= queue->bounds)
-        queue->in -= queue->bounds;
-    elem->sd = sd;
-    elem->baton = baton;
-    elem->p = p;
-    queue->nelts++;
-
-    apr_thread_cond_signal(queue->not_empty);
-
-    if ((rv = apr_thread_mutex_unlock(queue->one_big_mutex)) != APR_SUCCESS) {
-        return rv;
-    }
-
-    return APR_SUCCESS;
-}
-
-apr_status_t ap_queue_push_timer(fd_queue_t *queue, timer_event_t *te)
-{
-    apr_status_t rv;
-
-    if ((rv = apr_thread_mutex_lock(queue->one_big_mutex)) != APR_SUCCESS) {
-        return rv;
-    }
-
-    AP_DEBUG_ASSERT(!queue->terminated);
-
-    APR_RING_INSERT_TAIL(&queue->timers, te, timer_event_t, link);
-
-    apr_thread_cond_signal(queue->not_empty);
-
-    if ((rv = apr_thread_mutex_unlock(queue->one_big_mutex)) != APR_SUCCESS) {
-        return rv;
-    }
-
-    return APR_SUCCESS;
-}
-
-/**
- * Retrieves the next available socket from the queue. If there are no
- * sockets available, it will block until one becomes available.
- * Once retrieved, the socket is placed into the address specified by
- * 'sd'.
- */
-apr_status_t ap_queue_pop_something(fd_queue_t *queue, apr_socket_t **sd,
-                                    void **baton, apr_pool_t **p,
-                                    timer_event_t **te_out)
-{
-    fd_queue_elem_t *elem;
-    timer_event_t *te;
-    apr_status_t rv;
-
-    if ((rv = apr_thread_mutex_lock(queue->one_big_mutex)) != APR_SUCCESS) {
-        return rv;
-    }
-
-    /* Keep waiting until we wake up and find that the queue is not empty. */
-    if (ap_queue_empty(queue)) {
-        if (!queue->terminated) {
-            apr_thread_cond_wait(queue->not_empty, queue->one_big_mutex);
-        }
-        /* If we wake up and it's still empty, then we were interrupted */
-        if (ap_queue_empty(queue)) {
-            rv = apr_thread_mutex_unlock(queue->one_big_mutex);
-            if (rv != APR_SUCCESS) {
-                return rv;
-            }
-            if (queue->terminated) {
-                return APR_EOF; /* no more elements ever again */
-            }
-            else {
-                return APR_EINTR;
-            }
-        }
-    }
-
-    te = NULL;
-    if (te_out) {
-        if (!APR_RING_EMPTY(&queue->timers, timer_event_t, link)) {
-            te = APR_RING_FIRST(&queue->timers);
-            APR_RING_REMOVE(te, link);
-        }
-        *te_out = te;
-    }
-    if (!te) {
-        elem = &queue->data[queue->out];
-        queue->out++;
-        if (queue->out >= queue->bounds)
-            queue->out -= queue->bounds;
-        queue->nelts--;
-        *sd = elem->sd;
-        if (baton) {
-            *baton = elem->baton;
-        }
-        *p = elem->p;
-#ifdef AP_DEBUG
-        elem->sd = NULL;
-        elem->p = NULL;
-#endif /* AP_DEBUG */
-    }
-
-    rv = apr_thread_mutex_unlock(queue->one_big_mutex);
-    return rv;
-}
-
-static apr_status_t queue_interrupt(fd_queue_t *queue, int all, int term)
-{
-    apr_status_t rv;
-
-    if ((rv = apr_thread_mutex_lock(queue->one_big_mutex)) != APR_SUCCESS) {
-        return rv;
-    }
-    /* we must hold one_big_mutex when setting this... otherwise,
-     * we could end up setting it and waking everybody up just after a
-     * would-be popper checks it but right before they block
-     */
-    if (term) {
-        queue->terminated = 1;
-    }
-    if (all)
-        apr_thread_cond_broadcast(queue->not_empty);
-    else
-        apr_thread_cond_signal(queue->not_empty);
-    return apr_thread_mutex_unlock(queue->one_big_mutex);
-}
-
-apr_status_t ap_queue_interrupt_all(fd_queue_t *queue)
-{
-    return queue_interrupt(queue, 1, 0);
-}
-
-apr_status_t ap_queue_interrupt_one(fd_queue_t *queue)
-{
-    return queue_interrupt(queue, 0, 0);
-}
-
-apr_status_t ap_queue_term(fd_queue_t *queue)
-{
-    return queue_interrupt(queue, 1, 1);
-}
-
 #endif /* WIN32 */