Adding upstream version 1.7.2.upstream/1.7.2

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

1 files changed, 782 insertions, 0 deletions

diff --git a/poll/unix/z_asio.c b/poll/unix/z_asio.c
new file mode 100644
index 0000000..48b531c
--- /dev/null
+++ b/poll/unix/z_asio.c
@@ -0,0 +1,782 @@
+/* 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.
+ *
+ *
+ ******************************************************************************
+ *
+ * This implementation is based on a design by John Brooks (IBM Pok) which uses
+ * the z/OS sockets async i/o facility.  When a
+ * socket is added to the pollset, an async poll is issued for that individual
+ * socket.  It specifies that the kernel should send an IPC message when the
+ * socket becomes ready.  The IPC messages are sent to a single message queue
+ * that is part of the pollset.  apr_pollset_poll waits on the arrival of IPC
+ * messages or the specified timeout.
+ *
+ * Since z/OS does not support async i/o for pipes or files at present, this
+ * implementation falls back to using ordinary poll() when
+ * APR_POLLSET_THREADSAFE is unset.
+ *
+ * Greg Ames
+ * April 2012
+ */
+
+#include "apr.h"
+#include "apr_hash.h"
+#include "apr_poll.h"
+#include "apr_time.h"
+#include "apr_portable.h"
+#include "apr_arch_inherit.h"
+#include "apr_arch_file_io.h"
+#include "apr_arch_networkio.h"
+#include "apr_arch_poll_private.h"
+
+#ifdef HAVE_AIO_MSGQ
+
+#include <sys/msg.h>  	/* msgget etc   */
+#include <time.h>     	/* timestruct   */
+#include <poll.h>     	/* pollfd       */
+#include <limits.h>     /* MAX_INT      */
+
+struct apr_pollset_private_t
+{
+    int             msg_q;              /* IPC message queue. The z/OS kernel sends messages
+                                         * to this queue when our async polls on individual
+                                         * file descriptors complete
+                                         */
+    apr_pollfd_t    *result_set;
+    apr_uint32_t    size;
+
+#if APR_HAS_THREADS
+    /* A thread mutex to protect operations on the rings and the hash */
+    apr_thread_mutex_t *ring_lock;
+#endif
+
+    /* A hash of all active elements used for O(1) _remove operations */
+    apr_hash_t      *elems;
+
+    APR_RING_HEAD(ready_ring_t,       asio_elem_t)      ready_ring;
+    APR_RING_HEAD(prior_ready_ring_t, asio_elem_t)      prior_ready_ring;
+    APR_RING_HEAD(free_ring_t,        asio_elem_t)      free_ring;
+
+    /* for pipes etc with no asio */
+    struct pollfd   *pollset;
+    apr_pollfd_t    *query_set;
+};
+
+typedef enum {
+    ASIO_INIT = 0,
+    ASIO_REMOVED,
+    ASIO_COMPLETE
+} asio_state_e;
+
+typedef struct asio_elem_t asio_elem_t;
+
+struct asio_msgbuf_t {
+    long         msg_type;       /* must be > 0 */
+    asio_elem_t *msg_elem;
+};
+
+struct asio_elem_t
+{
+    APR_RING_ENTRY(asio_elem_t) link;
+    apr_pollfd_t                pfd;
+    struct pollfd               os_pfd;
+    struct aiocb                a;
+    asio_state_e                state;
+    struct asio_msgbuf_t        msg;
+};
+
+#define DEBUG 0
+
+/* DEBUG settings: 0 - no debug messages at all,
+ *                 1 - should not occur messages,
+ *                 2 - apr_pollset_* entry and exit messages,
+ *                 3 - state changes, memory usage,
+ *                 4 - z/OS, APR, and internal calls,
+ *                 5 - everything else except the timer pop path,
+ *                 6 - everything, including the Event 1 sec timer pop path
+ *
+ *  each DEBUG level includes all messages produced by lower numbered levels
+ */
+
+#if DEBUG
+
+#include <assert.h>
+#include <unistd.h>	/* getpid       */
+
+#define DBG_BUFF char dbg_msg_buff[256];
+
+#define DBG_TEST(lvl) if (lvl <= DEBUG) {
+
+#define DBG_CORE(msg)               sprintf(dbg_msg_buff, "% 8d " __FUNCTION__ \
+                                        " "  msg, getpid()),                   \
+                                    fprintf(stderr, "%s", dbg_msg_buff);
+#define DBG_CORE1(msg, var1)        sprintf(dbg_msg_buff, "% 8d " __FUNCTION__ \
+                                        " " msg, getpid(), var1),              \
+                                    fprintf(stderr, "%s", dbg_msg_buff);
+#define DBG_CORE2(msg, var1, var2)  sprintf(dbg_msg_buff, "% 8d " __FUNCTION__ \
+                                        " " msg, getpid(), var1, var2),        \
+                                    fprintf(stderr, "%s", dbg_msg_buff);
+#define DBG_CORE3(msg, var1, var2, var3)                                       \
+                                    sprintf(dbg_msg_buff, "% 8d " __FUNCTION__ \
+                                        " " msg, getpid(), var1, var2, var3),  \
+                                    fprintf(stderr, "%s", dbg_msg_buff);
+#define DBG_CORE4(msg, var1, var2, var3, var4)                                 \
+                                    sprintf(dbg_msg_buff, "% 8d " __FUNCTION__ \
+                                        " " msg, getpid(), var1, var2, var3, var4),\
+                                    fprintf(stderr, "%s", dbg_msg_buff);
+
+#define DBG_END }
+
+#define DBG(lvl, msg)   DBG_TEST(lvl)   \
+                        DBG_CORE(msg)   \
+                        DBG_END
+
+#define DBG1(lvl, msg, var1)    DBG_TEST(lvl)           \
+                                DBG_CORE1(msg, var1)    \
+                                DBG_END
+
+#define DBG2(lvl, msg, var1, var2)      DBG_TEST(lvl)               \
+                                        DBG_CORE2(msg, var1, var2)  \
+                                        DBG_END
+
+#define DBG3(lvl, msg, var1, var2, var3)                        \
+                        DBG_TEST(lvl)                           \
+                        DBG_CORE3(msg, var1, var2, var3)        \
+                        DBG_END
+
+#define DBG4(lvl, msg, var1, var2, var3, var4)                  \
+                        DBG_TEST(lvl)                           \
+                        DBG_CORE4(msg, var1, var2, var3, var4)  \
+                        DBG_END
+
+#else  /* DEBUG is 0 */
+#define DBG_BUFF
+#define DBG(lvl, msg)                            ((void)0)
+#define DBG1(lvl, msg, var1)                     ((void)0)
+#define DBG2(lvl, msg, var1, var2)               ((void)0)
+#define DBG3(lvl, msg, var1, var2, var3)         ((void)0)
+#define DBG4(lvl, msg, var1, var2, var3, var4)   ((void)0)
+
+#endif /* DEBUG */
+
+static int asyncio(struct aiocb *a)
+{
+    DBG_BUFF
+    int rv;
+
+#ifdef _LP64
+#define AIO BPX4AIO
+#else
+#define AIO BPX1AIO
+#endif
+
+    AIO(sizeof(struct aiocb), a, &rv, &errno, __err2ad());
+    DBG2(4, "BPX4AIO aiocb %p rv %d\n",
+             a, rv);
+#ifdef DEBUG
+    if (rv < 0) {
+        DBG2(4, "errno %d errnojr %08x\n",
+                 errno, *__err2ad());
+    }
+#endif
+    return rv;
+}
+
+static apr_int16_t get_event(apr_int16_t event)
+{
+    DBG_BUFF
+    apr_int16_t rv = 0;
+    DBG(4, "entered\n");
+
+    if (event & APR_POLLIN)
+        rv |= POLLIN;
+    if (event & APR_POLLPRI)
+        rv |= POLLPRI;
+    if (event & APR_POLLOUT)
+        rv |= POLLOUT;
+    if (event & APR_POLLERR)
+        rv |= POLLERR;
+    if (event & APR_POLLHUP)
+        rv |= POLLHUP;
+    if (event & APR_POLLNVAL)
+        rv |= POLLNVAL;
+
+    DBG(4, "exiting\n");
+    return rv;
+}
+
+static apr_int16_t get_revent(apr_int16_t event)
+{
+    DBG_BUFF
+    apr_int16_t rv = 0;
+    DBG(4, "entered\n");
+
+    if (event & POLLIN)
+        rv |= APR_POLLIN;
+    if (event & POLLPRI)
+        rv |= APR_POLLPRI;
+    if (event & POLLOUT)
+        rv |= APR_POLLOUT;
+    if (event & POLLERR)
+        rv |= APR_POLLERR;
+    if (event & POLLHUP)
+        rv |= APR_POLLHUP;
+    if (event & POLLNVAL)
+        rv |= APR_POLLNVAL;
+
+    DBG(4, "exiting\n");
+    return rv;
+}
+
+static apr_status_t asio_pollset_cleanup(apr_pollset_t *pollset)
+{
+    DBG_BUFF
+    int rv;
+
+    DBG(4, "entered\n");
+    if (pollset->flags & APR_POLLSET_THREADSAFE) { 
+        rv = msgctl(pollset->p->msg_q, IPC_RMID, NULL);
+        DBG1(4, "asio_pollset_cleanup: msgctl(IPC_RMID) returned %d\n", rv);
+    }
+
+    return rv;
+}
+
+static apr_status_t asio_pollset_create(apr_pollset_t *pollset,
+                                        apr_uint32_t size,
+                                        apr_pool_t *p,
+                                        apr_uint32_t flags)
+{
+    DBG_BUFF
+    apr_status_t rv;
+    apr_pollset_private_t *priv;
+
+    DBG1(2, "entered, flags: %x\n", flags);
+
+    priv = pollset->p = apr_pcalloc(p, sizeof(*priv));
+
+    if (flags & APR_POLLSET_THREADSAFE) {
+#if APR_HAS_THREADS
+        if ((rv = apr_thread_mutex_create(&(priv->ring_lock),
+                                           APR_THREAD_MUTEX_DEFAULT,
+                                           p)) != APR_SUCCESS) {
+            DBG1(1, "apr_thread_mutex_create returned %d\n", rv);
+            pollset->p = NULL;
+            return rv;
+        }
+        rv = msgget(IPC_PRIVATE, S_IWUSR+S_IRUSR); /* user r/w perms */
+        if (rv < 0) {
+#if DEBUG
+            perror(__FUNCTION__ " msgget returned < 0 ");
+#endif
+            pollset->p = NULL;
+            return rv;
+        }
+
+        DBG2(4, "pollset %p msgget was OK, rv=%d\n", pollset, rv);
+        priv->msg_q = rv;
+        priv->elems   = apr_hash_make(p);
+
+        APR_RING_INIT(&priv->free_ring, asio_elem_t, link);
+        APR_RING_INIT(&priv->prior_ready_ring, asio_elem_t, link);
+
+#else  /* APR doesn't have threads but caller wants a threadsafe pollset */
+        pollset->p = NULL;
+        return APR_ENOTIMPL;
+#endif
+
+    } else {  /* APR_POLLSET_THREADSAFE not set, i.e. no async i/o,
+               * init fields only needed in old style pollset
+               */
+
+        priv->pollset = apr_palloc(p, size * sizeof(struct pollfd));
+        priv->query_set = apr_palloc(p, size * sizeof(apr_pollfd_t));
+
+        if ((!priv->pollset) || (!priv->query_set)) {
+            pollset->p = NULL;
+            return APR_ENOMEM;
+        }
+    }
+
+    pollset->nelts   = 0;
+    pollset->flags   = flags;
+    pollset->pool    = p;
+    priv->size    = size;
+    priv->result_set = apr_palloc(p, size * sizeof(apr_pollfd_t));
+    if (!priv->result_set) {
+        if (flags & APR_POLLSET_THREADSAFE) {
+            msgctl(priv->msg_q, IPC_RMID, NULL);
+        }
+        pollset->p = NULL;
+        return APR_ENOMEM;
+    }
+
+    DBG2(2, "exiting, pollset: %p, type: %s\n",
+             pollset,
+             flags & APR_POLLSET_THREADSAFE ? "async" : "POSIX");
+
+
+    return APR_SUCCESS;
+
+} /* end of asio_pollset_create */
+
+static apr_status_t posix_add(apr_pollset_t      *pollset,
+                              const apr_pollfd_t *descriptor)
+{
+    DBG_BUFF
+    int fd;
+    apr_pool_t  *p = pollset->pool;
+    apr_pollset_private_t *priv = pollset->p;
+
+    DBG(4, "entered\n");
+
+    if (pollset->nelts == priv->size) {
+        return APR_ENOMEM;
+    }
+
+    priv->query_set[pollset->nelts] = *descriptor;
+    if (descriptor->desc_type == APR_POLL_SOCKET) {
+        fd = descriptor->desc.s->socketdes;
+    }
+    else {
+        fd = descriptor->desc.f->filedes;
+    }
+
+    priv->pollset[pollset->nelts].fd = fd;
+
+    priv->pollset[pollset->nelts].events =
+        get_event(descriptor->reqevents);
+
+    pollset->nelts++;
+
+    DBG2(4, "exiting, fd %d added to pollset %p\n", fd, pollset);
+
+    return APR_SUCCESS;
+}   /* end of posix_add */
+
+
+static apr_status_t asio_pollset_add(apr_pollset_t *pollset,
+                                     const apr_pollfd_t *descriptor)
+{
+    DBG_BUFF
+    asio_elem_t *elem;
+    apr_status_t rv = APR_SUCCESS;
+    apr_pollset_private_t *priv = pollset->p;
+
+    pollset_lock_rings();
+    DBG(2, "entered\n");
+
+    if (pollset->flags & APR_POLLSET_THREADSAFE) {
+
+        if (!APR_RING_EMPTY(&(priv->free_ring), asio_elem_t, link)) {
+            elem = APR_RING_FIRST(&(priv->free_ring));
+            APR_RING_REMOVE(elem, link);
+            DBG1(3, "used recycled memory at %08p\n", elem);
+            elem->state = ASIO_INIT;
+            elem->a.aio_cflags = 0;
+        }
+        else {
+            elem = (asio_elem_t *) apr_pcalloc(pollset->pool, sizeof(asio_elem_t));
+            DBG1(3, "alloced new memory at %08p\n", elem);
+
+            elem->a.aio_notifytype = AIO_MSGQ;
+            elem->a.aio_msgev_qid  = priv->msg_q;
+            DBG1(5, "aio_msgev_quid = %d \n", elem->a.aio_msgev_qid);
+            elem->a.aio_msgev_size = sizeof(asio_elem_t *);
+            elem->a.aio_msgev_flag = 0;     /* wait if queue is full */
+            elem->a.aio_msgev_addr = &(elem->msg);
+            elem->a.aio_buf        = &(elem->os_pfd);
+            elem->a.aio_nbytes     = 1;     /* number of pfds to poll */
+            elem->msg.msg_type     = 1;
+            elem->msg.msg_elem     = elem;
+        }
+
+        /* z/OS only supports async I/O for sockets for now */
+        elem->os_pfd.fd = descriptor->desc.s->socketdes;
+
+        APR_RING_ELEM_INIT(elem, link);
+        elem->a.aio_cmd       = AIO_SELPOLL;
+        elem->a.aio_cflags    &= ~AIO_OK2COMPIMD; /* not OK to complete inline*/
+        elem->pfd             = *descriptor;
+        elem->os_pfd.events   = get_event(descriptor->reqevents);
+
+        if (0 != asyncio(&elem->a)) {
+            rv = errno;
+            DBG3(4, "pollset %p asio failed fd %d, errno %p\n",
+                     pollset, elem->os_pfd.fd, rv);
+#if DEBUG
+            perror(__FUNCTION__ " asio failure");
+#endif
+        }
+        else {
+            DBG2(4, "good asio call, adding fd %d to pollset %p\n",
+                     elem->os_pfd.fd, pollset);
+
+            pollset->nelts++;
+            apr_hash_set(priv->elems, &(elem->os_pfd.fd), sizeof(int), elem);
+        }
+    }
+    else {
+        /* APR_POLLSET_THREADSAFE isn't set.  use POSIX poll in case
+         * pipes or files are used with this pollset
+         */
+
+        rv = posix_add(pollset, descriptor);
+    }
+
+    DBG1(2, "exiting, rv = %d\n", rv);
+
+    pollset_unlock_rings();
+    return rv;
+} /* end of asio_pollset_add */
+
+static posix_remove(apr_pollset_t *pollset, const apr_pollfd_t *descriptor)
+{
+    DBG_BUFF
+    apr_uint32_t i;
+    apr_pollset_private_t *priv = pollset->p;
+
+    DBG(4, "entered\n");
+    for (i = 0; i < pollset->nelts; i++) {
+        if (descriptor->desc.s == priv->query_set[i].desc.s) {
+            /* Found an instance of the fd: remove this and any other copies */
+            apr_uint32_t dst = i;
+            apr_uint32_t old_nelts = pollset->nelts;
+            pollset->nelts--;
+            for (i++; i < old_nelts; i++) {
+                if (descriptor->desc.s == priv->query_set[i].desc.s) {
+                    pollset->nelts--;
+                }
+                else {
+                    priv->pollset[dst] = priv->pollset[i];
+                    priv->query_set[dst] = priv->query_set[i];
+                    dst++;
+                }
+            }
+            DBG(4, "returning OK\n");
+            return APR_SUCCESS;
+        }
+    }
+
+    DBG(1, "returning APR_NOTFOUND\n");
+    return APR_NOTFOUND;
+
+}   /* end of posix_remove */
+
+static apr_status_t asio_pollset_remove(apr_pollset_t *pollset,
+                                        const apr_pollfd_t *descriptor)
+{
+    DBG_BUFF
+    asio_elem_t *elem;
+    apr_status_t rv = APR_SUCCESS;
+    apr_pollset_private_t *priv = pollset->p;
+    /* AIO_CANCEL is synchronous, so autodata works fine.  */
+    struct aiocb cancel_a = {0};   
+
+    int fd;
+
+    DBG(2, "entered\n");
+
+    if (!(pollset->flags & APR_POLLSET_THREADSAFE)) {
+        return posix_remove(pollset, descriptor);
+    }
+
+    pollset_lock_rings();
+
+#if DEBUG
+    assert(descriptor->desc_type == APR_POLL_SOCKET);
+#endif
+    /* zOS 1.12 doesn't support files for async i/o */
+    fd = descriptor->desc.s->socketdes;
+
+    elem = apr_hash_get(priv->elems, &(fd), sizeof(int));
+    if (elem == NULL) {
+        DBG1(1, "couldn't find fd %d\n", fd);
+        rv = APR_NOTFOUND;
+    } else {
+        DBG1(5, "hash found fd %d\n", fd);
+        /* delete this fd from the hash */
+        apr_hash_set(priv->elems, &(fd), sizeof(int), NULL);
+
+        if (elem->state == ASIO_INIT) {
+            /* asyncio call to cancel */
+            cancel_a.aio_cmd = AIO_CANCEL;
+            cancel_a.aio_buf = &elem->a;   /* point to original aiocb */
+
+            cancel_a.aio_cflags  = 0;
+            cancel_a.aio_cflags2 = 0;
+
+            /* we want the original aiocb to show up on the pollset message queue 
+             * before recycling its memory to eliminate race conditions
+             */
+
+            rv = asyncio(&cancel_a);
+            DBG1(4, "asyncio returned %d\n", rv);
+
+#if DEBUG
+            assert(rv == 1);
+#endif
+        }
+        elem->state = ASIO_REMOVED;
+        rv = APR_SUCCESS;
+    }
+
+    DBG1(2, "exiting, rv: %d\n", rv);
+
+    pollset_unlock_rings();
+
+    return rv;
+}   /* end of asio_pollset_remove */
+
+static posix_poll(apr_pollset_t *pollset,
+                  apr_interval_time_t timeout,
+                  apr_int32_t *num,
+                  const apr_pollfd_t **descriptors)
+{
+    DBG_BUFF
+    int rv;
+    apr_uint32_t i, j;
+    apr_pollset_private_t *priv = pollset->p;
+
+    DBG(4, "entered\n");
+
+    if (timeout > 0) {
+        timeout /= 1000;
+    }
+    rv = poll(priv->pollset, pollset->nelts, timeout);
+    (*num) = rv;
+    if (rv < 0) {
+        return apr_get_netos_error();
+    }
+    if (rv == 0) {
+        return APR_TIMEUP;
+    }
+    j = 0;
+    for (i = 0; i < pollset->nelts; i++) {
+        if (priv->pollset[i].revents != 0) {
+            priv->result_set[j] = priv->query_set[i];
+            priv->result_set[j].rtnevents =
+                get_revent(priv->pollset[i].revents);
+            j++;
+        }
+    }
+    if (descriptors)
+        *descriptors = priv->result_set;
+
+    DBG(4, "exiting ok\n");
+    return APR_SUCCESS;
+
+}   /* end of posix_poll */
+
+static process_msg(apr_pollset_t *pollset, struct asio_msgbuf_t *msg)
+{
+    DBG_BUFF
+    asio_elem_t *elem = msg->msg_elem;
+
+    switch(elem->state) {
+    case ASIO_REMOVED:
+        DBG2(5, "for cancelled elem, recycling memory - elem %08p, fd %d\n",
+                elem, elem->os_pfd.fd);
+        APR_RING_INSERT_TAIL(&(pollset->p->free_ring), elem,
+                             asio_elem_t, link);
+        break;
+    case ASIO_INIT:
+        DBG2(4, "adding to ready ring: elem %08p, fd %d\n",
+                elem, elem->os_pfd.fd);
+        elem->state = ASIO_COMPLETE;
+        APR_RING_INSERT_TAIL(&(pollset->p->ready_ring), elem,
+                             asio_elem_t, link);
+        break;
+    default:
+        DBG3(1, "unexpected state: elem %08p, fd %d, state %d\n",
+            elem, elem->os_pfd.fd, elem->state);
+#if DEBUG
+        assert(0);
+#endif
+    }
+}
+
+static apr_status_t asio_pollset_poll(apr_pollset_t *pollset,
+                                      apr_interval_time_t timeout,
+                                      apr_int32_t *num,
+                                      const apr_pollfd_t **descriptors)
+{
+    DBG_BUFF
+    int i, ret;
+    asio_elem_t *elem, *next_elem;
+    struct asio_msgbuf_t msg_buff;
+    struct timespec tv;
+    apr_status_t rv = APR_SUCCESS;
+    apr_pollset_private_t *priv = pollset->p;
+
+    DBG(6, "entered\n"); /* chatty - traces every second w/Event */
+
+    if ((pollset->flags & APR_POLLSET_THREADSAFE) == 0 ) {
+        return posix_poll(pollset, timeout, num, descriptors);
+    }
+
+    pollset_lock_rings();
+    APR_RING_INIT(&(priv->ready_ring), asio_elem_t, link);
+
+    while (!APR_RING_EMPTY(&(priv->prior_ready_ring), asio_elem_t, link)) {
+        elem = APR_RING_FIRST(&(priv->prior_ready_ring));
+        DBG3(5, "pollset %p elem %p fd %d on prior ready ring\n",
+                pollset,
+                elem,
+                elem->os_pfd.fd);
+
+        APR_RING_REMOVE(elem, link);
+
+        /*
+         * since USS does not remember what's in our pollset, we have
+         * to re-add fds which have not been apr_pollset_remove'd
+         *
+         * there may have been too many ready fd's to return in the
+         * result set last time. re-poll inline for both cases
+         */
+
+        if (elem->state == ASIO_REMOVED) {
+
+            /* 
+             * async i/o is done since it was found on prior_ready
+             * the state says the caller is done with it too 
+             * so recycle the elem 
+             */
+             
+            APR_RING_INSERT_TAIL(&(priv->free_ring), elem,
+                                 asio_elem_t, link);
+            continue;  /* do not re-add if it has been _removed */
+        }
+
+        elem->state = ASIO_INIT;
+        elem->a.aio_cflags     = AIO_OK2COMPIMD;
+
+        if (0 != (ret = asyncio(&elem->a))) {
+            if (ret == 1) {
+                DBG(4, "asyncio() completed inline\n");
+                /* it's ready now */
+                elem->state = ASIO_COMPLETE;
+                APR_RING_INSERT_TAIL(&(priv->ready_ring), elem, asio_elem_t,
+                                     link);
+            }
+            else {
+                DBG2(1, "asyncio() failed, ret: %d, errno: %d\n",
+                        ret, errno);
+                pollset_unlock_rings();
+                return errno;
+            }
+        }
+        DBG1(4, "asyncio() completed rc %d\n", ret);
+    }
+
+    DBG(6, "after prior ready loop\n"); /* chatty w/timeouts, hence 6 */
+
+    /* Gather async poll completions that have occurred since the last call */
+    while (0 < msgrcv(priv->msg_q, &msg_buff, sizeof(asio_elem_t *), 0,
+                      IPC_NOWAIT)) {
+        process_msg(pollset, &msg_buff);
+    }
+
+    /* Suspend if nothing is ready yet. */
+    if (APR_RING_EMPTY(&(priv->ready_ring), asio_elem_t, link)) {
+
+        if (timeout >= 0) {
+            tv.tv_sec  = apr_time_sec(timeout);
+            tv.tv_nsec = apr_time_usec(timeout) * 1000;
+        } else {
+            tv.tv_sec = INT_MAX;  /* block until something is ready */
+        }
+
+        DBG2(6, "nothing on the ready ring "
+                "- blocking for %d seconds %d ns\n",
+                tv.tv_sec, tv.tv_nsec);
+
+        pollset_unlock_rings();   /* allow other apr_pollset_* calls while blocked */
+
+        if (0 >= (ret = __msgrcv_timed(priv->msg_q, &msg_buff,
+                                       sizeof(asio_elem_t *), 0, NULL, &tv))) {
+#if DEBUG
+            if (errno == EAGAIN) {
+                DBG(6, "__msgrcv_timed timed out\n"); /* timeout path, so 6 */
+            }
+            else {
+                DBG(1, "__msgrcv_timed failed!\n");
+            }
+#endif
+            return (errno == EAGAIN) ? APR_TIMEUP : errno;
+        }
+
+        pollset_lock_rings();
+
+        process_msg(pollset, &msg_buff);
+    }
+
+    APR_RING_INIT(&priv->prior_ready_ring, asio_elem_t, link);
+
+    (*num) = 0;
+    elem = APR_RING_FIRST(&(priv->ready_ring));
+
+    for (i = 0;
+
+        i < priv->size
+                && elem != APR_RING_SENTINEL(&(priv->ready_ring), asio_elem_t, link);
+        i++) {
+             DBG2(5, "ready ring: elem %08p, fd %d\n", elem, elem->os_pfd.fd);
+
+             priv->result_set[i] = elem->pfd;
+             priv->result_set[i].rtnevents
+                                    = get_revent(elem->os_pfd.revents);
+             (*num)++;
+
+             elem = APR_RING_NEXT(elem, link);
+
+#if DEBUG
+             if (elem == APR_RING_SENTINEL(&(priv->ready_ring), asio_elem_t, link)) {
+                 DBG(5, "end of ready ring reached\n");
+             }
+#endif
+    }
+
+    if (descriptors) {
+        *descriptors = priv->result_set;
+    }
+
+    /* if the result size is too small, remember which descriptors
+     * haven't had results reported yet.  we will look
+     * at these descriptors on the next apr_pollset_poll call
+     */
+
+    APR_RING_CONCAT(&priv->prior_ready_ring, &(priv->ready_ring), asio_elem_t, link);
+
+    DBG1(2, "exiting, rv = %d\n", rv);
+
+    pollset_unlock_rings();
+
+    return rv;
+}  /* end of asio_pollset_poll */
+
+static const apr_pollset_provider_t impl = {
+    asio_pollset_create,
+    asio_pollset_add,
+    asio_pollset_remove,
+    asio_pollset_poll,
+    asio_pollset_cleanup,
+    "asio"
+};
+
+const apr_pollset_provider_t *apr_pollset_provider_aio_msgq = &impl;
+
+#endif /* HAVE_AIO_MSGQ */