poll: Implement APR_POLLSET_NOCOPY for kqueue.

Like with epoll, it allows to be lockless if the lifetime of the pollfd(s) is
garanteed by the user.



git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@1897518 13f79535-47bb-0310-9956-ffa450edef68

3 files changed, 234 insertions, 168 deletions

diff --git a/poll/unix/epoll.c b/poll/unix/epoll.c
index c00a1094d..89c41a404 100644
--- a/poll/unix/epoll.c
+++ b/poll/unix/epoll.c
@@ -123,7 +123,7 @@ static apr_status_t impl_pollset_create(apr_pollset_t *pollset,
     }
 #endif
 
-    pollset->p = apr_palloc(p, sizeof(apr_pollset_private_t));
+    pollset->p = apr_pcalloc(p, sizeof(apr_pollset_private_t));
 #if APR_HAS_THREADS
     if ((flags & APR_POLLSET_THREADSAFE) &&
         !(flags & APR_POLLSET_NOCOPY) &&
diff --git a/poll/unix/kqueue.c b/poll/unix/kqueue.c
index e8a1ef95b..aa4251f1b 100644
--- a/poll/unix/kqueue.c
+++ b/poll/unix/kqueue.c
@@ -75,9 +75,12 @@ static apr_status_t impl_pollset_create(apr_pollset_t *pollset,
                                         apr_uint32_t flags)
 {
     apr_status_t rv;
-    pollset->p = apr_palloc(p, sizeof(apr_pollset_private_t));
+
+    pollset->p = apr_pcalloc(p, sizeof(apr_pollset_private_t));
+
 #if APR_HAS_THREADS
     if (flags & APR_POLLSET_THREADSAFE &&
+        !(flags & APR_POLLSET_NOCOPY) &&
         ((rv = apr_thread_mutex_create(&pollset->p->ring_lock,
                                        APR_THREAD_MUTEX_DEFAULT,
                                        p)) != APR_SUCCESS)) {
@@ -99,14 +102,9 @@ static apr_status_t impl_pollset_create(apr_pollset_t *pollset,
      * for the same descriptor)
      */
     pollset->p->setsize = 2 * size;
-
-    pollset->p->ke_set =
-        (struct kevent *) apr_palloc(p, pollset->p->setsize * sizeof(struct kevent));
-
-    memset(pollset->p->ke_set, 0, pollset->p->setsize * sizeof(struct kevent));
+    pollset->p->ke_set = apr_pcalloc(p, pollset->p->setsize * sizeof(struct kevent));
 
     pollset->p->kqueue_fd = kqueue();
-
     if (pollset->p->kqueue_fd == -1) {
         pollset->p = NULL;
         return apr_get_netos_error();
@@ -133,9 +131,11 @@ static apr_status_t impl_pollset_create(apr_pollset_t *pollset,
 
     pollset->p->result_set = apr_palloc(p, pollset->p->setsize * sizeof(apr_pollfd_t));
 
-    APR_RING_INIT(&pollset->p->query_ring, pfd_elem_t, link);
-    APR_RING_INIT(&pollset->p->free_ring, pfd_elem_t, link);
-    APR_RING_INIT(&pollset->p->dead_ring, pfd_elem_t, link);
+    if (!(flags & APR_POLLSET_NOCOPY)) {
+        APR_RING_INIT(&pollset->p->query_ring, pfd_elem_t, link);
+        APR_RING_INIT(&pollset->p->free_ring, pfd_elem_t, link);
+        APR_RING_INIT(&pollset->p->dead_ring, pfd_elem_t, link);
+    }
 
     return APR_SUCCESS;
 }
@@ -144,20 +144,22 @@ static apr_status_t impl_pollset_add(apr_pollset_t *pollset,
                                      const apr_pollfd_t *descriptor)
 {
     apr_os_sock_t fd;
-    pfd_elem_t *elem;
+    pfd_elem_t *elem = NULL;
     apr_status_t rv = APR_SUCCESS;
 
-    pollset_lock_rings();
+    if (!(pollset->flags & APR_POLLSET_NOCOPY)) {
+        pollset_lock_rings();
 
-    if (!APR_RING_EMPTY(&(pollset->p->free_ring), pfd_elem_t, link)) {
-        elem = APR_RING_FIRST(&(pollset->p->free_ring));
-        APR_RING_REMOVE(elem, link);
-    }
-    else {
-        elem = (pfd_elem_t *) apr_palloc(pollset->pool, sizeof(pfd_elem_t));
-        APR_RING_ELEM_INIT(elem, link);
+        if (!APR_RING_EMPTY(&(pollset->p->free_ring), pfd_elem_t, link)) {
+            elem = APR_RING_FIRST(&(pollset->p->free_ring));
+            APR_RING_REMOVE(elem, link);
+        }
+        else {
+            elem = (pfd_elem_t *) apr_palloc(pollset->pool, sizeof(pfd_elem_t));
+            APR_RING_ELEM_INIT(elem, link);
+        }
+        elem->pfd = *descriptor;
     }
-    elem->pfd = *descriptor;
 
     if (descriptor->desc_type == APR_POLL_SOCKET) {
         fd = descriptor->desc.s->socketdes;
@@ -167,7 +169,14 @@ static apr_status_t impl_pollset_add(apr_pollset_t *pollset,
     }
 
     if (descriptor->reqevents & APR_POLLIN) {
-        EV_SET(&pollset->p->kevent, fd, EVFILT_READ, EV_ADD, 0, 0, elem);
+        if (pollset->flags & APR_POLLSET_NOCOPY) {
+            EV_SET(&pollset->p->kevent, fd, EVFILT_READ, EV_ADD, 0, 0,
+                   descriptor);
+        }
+        else {
+            EV_SET(&pollset->p->kevent, fd, EVFILT_READ, EV_ADD, 0, 0,
+                   elem);
+        }
 
         if (kevent(pollset->p->kqueue_fd, &pollset->p->kevent, 1, NULL, 0,
                    NULL) == -1) {
@@ -176,7 +185,14 @@ static apr_status_t impl_pollset_add(apr_pollset_t *pollset,
     }
 
     if (descriptor->reqevents & APR_POLLOUT && rv == APR_SUCCESS) {
-        EV_SET(&pollset->p->kevent, fd, EVFILT_WRITE, EV_ADD, 0, 0, elem);
+        if (pollset->flags & APR_POLLSET_NOCOPY) {
+            EV_SET(&pollset->p->kevent, fd, EVFILT_WRITE, EV_ADD, 0, 0,
+                   descriptor);
+        }
+        else {
+            EV_SET(&pollset->p->kevent, fd, EVFILT_WRITE, EV_ADD, 0, 0,
+                   elem);
+        }
 
         if (kevent(pollset->p->kqueue_fd, &pollset->p->kevent, 1, NULL, 0,
                    NULL) == -1) {
@@ -184,14 +200,16 @@ static apr_status_t impl_pollset_add(apr_pollset_t *pollset,
         }
     }
 
-    if (rv == APR_SUCCESS) {
-        APR_RING_INSERT_TAIL(&(pollset->p->query_ring), elem, pfd_elem_t, link);
-    }
-    else {
-        APR_RING_INSERT_TAIL(&(pollset->p->free_ring), elem, pfd_elem_t, link);
-    }
+    if (!(pollset->flags & APR_POLLSET_NOCOPY)) {
+        if (rv == APR_SUCCESS) {
+            APR_RING_INSERT_TAIL(&(pollset->p->query_ring), elem, pfd_elem_t, link);
+        }
+        else {
+            APR_RING_INSERT_TAIL(&(pollset->p->free_ring), elem, pfd_elem_t, link);
+        }
 
-    pollset_unlock_rings();
+        pollset_unlock_rings();
+    }
 
     return rv;
 }
@@ -199,12 +217,9 @@ static apr_status_t impl_pollset_add(apr_pollset_t *pollset,
 static apr_status_t impl_pollset_remove(apr_pollset_t *pollset,
                                         const apr_pollfd_t *descriptor)
 {
-    pfd_elem_t *ep;
     apr_status_t rv;
     apr_os_sock_t fd;
 
-    pollset_lock_rings();
-
     if (descriptor->desc_type == APR_POLL_SOCKET) {
         fd = descriptor->desc.s->socketdes;
     }
@@ -231,20 +246,26 @@ static apr_status_t impl_pollset_remove(apr_pollset_t *pollset,
         }
     }
 
-    for (ep = APR_RING_FIRST(&(pollset->p->query_ring));
-         ep != APR_RING_SENTINEL(&(pollset->p->query_ring),
-                                 pfd_elem_t, link);
-         ep = APR_RING_NEXT(ep, link)) {
+    if (!(pollset->flags & APR_POLLSET_NOCOPY)) {
+        pfd_elem_t *ep;
+
+        pollset_lock_rings();
 
-        if (descriptor->desc.s == ep->pfd.desc.s) {
-            APR_RING_REMOVE(ep, link);
-            APR_RING_INSERT_TAIL(&(pollset->p->dead_ring),
-                                 ep, pfd_elem_t, link);
-            break;
+        for (ep = APR_RING_FIRST(&(pollset->p->query_ring));
+             ep != APR_RING_SENTINEL(&(pollset->p->query_ring),
+                                     pfd_elem_t, link);
+             ep = APR_RING_NEXT(ep, link)) {
+
+            if (descriptor->desc.s == ep->pfd.desc.s) {
+                APR_RING_REMOVE(ep, link);
+                APR_RING_INSERT_TAIL(&(pollset->p->dead_ring),
+                                     ep, pfd_elem_t, link);
+                break;
+            }
         }
-    }
 
-    pollset_unlock_rings();
+        pollset_unlock_rings();
+    }
 
     return rv;
 }
@@ -282,7 +303,13 @@ static apr_status_t impl_pollset_poll(apr_pollset_t *pollset,
         const apr_pollfd_t *fd;
 
         for (i = 0, j = 0; i < ret; i++) {
-            fd = &((pfd_elem_t *)pollset->p->ke_set[i].udata)->pfd;
+            if (pollset->flags & APR_POLLSET_NOCOPY) {
+                fd = (apr_pollfd_t *)pollset->p->ke_set[i].udata;
+            }
+            else {
+                fd = &((pfd_elem_t *)pollset->p->ke_set[i].udata)->pfd;
+            }
+
             if ((pollset->flags & APR_POLLSET_WAKEABLE) &&
                 fd->desc_type == APR_POLL_FILE &&
                 fd->desc.f == pollset->wakeup_pipe[0]) {
@@ -305,13 +332,15 @@ static apr_status_t impl_pollset_poll(apr_pollset_t *pollset,
         }
     }
 
-    pollset_lock_rings();
+    if (!(pollset->flags & APR_POLLSET_NOCOPY)) {
+        pollset_lock_rings();
 
-    /* Shift all PFDs in the Dead Ring to the Free Ring */
-    APR_RING_CONCAT(&(pollset->p->free_ring), &(pollset->p->dead_ring),
-                    pfd_elem_t, link);
+        /* Shift all PFDs in the Dead Ring to the Free Ring */
+        APR_RING_CONCAT(&(pollset->p->free_ring), &(pollset->p->dead_ring),
+                        pfd_elem_t, link);
 
-    pollset_unlock_rings();
+        pollset_unlock_rings();
+    }
 
     return rv;
 }
diff --git a/poll/unix/port.c b/poll/unix/port.c
index 638a8cba7..f5c7a01c4 100644
--- a/poll/unix/port.c
+++ b/poll/unix/port.c
@@ -159,7 +159,7 @@ static apr_status_t impl_pollset_create(apr_pollset_t *pollset,
                                              apr_uint32_t flags)
 {
     apr_status_t rv = APR_SUCCESS;
-    pollset->p = apr_palloc(p, sizeof(apr_pollset_private_t));
+    pollset->p = apr_pcalloc(p, sizeof(apr_pollset_private_t));
 #if APR_HAS_THREADS
     if (flags & APR_POLLSET_THREADSAFE &&
         ((rv = apr_thread_mutex_create(&pollset->p->ring_lock,
@@ -206,10 +206,12 @@ static apr_status_t impl_pollset_create(apr_pollset_t *pollset,
 
     pollset->p->result_set = apr_palloc(p, size * sizeof(apr_pollfd_t));
 
-    APR_RING_INIT(&pollset->p->query_ring, pfd_elem_t, link);
-    APR_RING_INIT(&pollset->p->add_ring, pfd_elem_t, link);
-    APR_RING_INIT(&pollset->p->free_ring, pfd_elem_t, link);
-    APR_RING_INIT(&pollset->p->dead_ring, pfd_elem_t, link);
+    if (!(pollset->flags & APR_POLLSET_NOCOPY)) {
+        APR_RING_INIT(&pollset->p->query_ring, pfd_elem_t, link);
+        APR_RING_INIT(&pollset->p->add_ring, pfd_elem_t, link);
+        APR_RING_INIT(&pollset->p->free_ring, pfd_elem_t, link);
+        APR_RING_INIT(&pollset->p->dead_ring, pfd_elem_t, link);
+    }
 
     return rv;
 }
@@ -222,19 +224,6 @@ static apr_status_t impl_pollset_add(apr_pollset_t *pollset,
     int res;
     apr_status_t rv = APR_SUCCESS;
 
-    pollset_lock_rings();
-
-    if (!APR_RING_EMPTY(&(pollset->p->free_ring), pfd_elem_t, link)) {
-        elem = APR_RING_FIRST(&(pollset->p->free_ring));
-        APR_RING_REMOVE(elem, link);
-    }
-    else {
-        elem = (pfd_elem_t *) apr_palloc(pollset->pool, sizeof(pfd_elem_t));
-        APR_RING_ELEM_INIT(elem, link);
-        elem->on_query_ring = 0;
-    }
-    elem->pfd = *descriptor;
-
     if (descriptor->desc_type == APR_POLL_SOCKET) {
         fd = descriptor->desc.s->socketdes;
     }
@@ -242,27 +231,52 @@ static apr_status_t impl_pollset_add(apr_pollset_t *pollset,
         fd = descriptor->desc.f->filedes;
     }
 
-    /* If another thread is polling, notify the kernel immediately; otherwise,
-     * wait until the next call to apr_pollset_poll().
-     */
-    if (apr_atomic_read32(&pollset->p->waiting)) {
+    if (pollset->flags & APR_POLLSET_NOCOPY) {
         res = port_associate(pollset->p->port_fd, PORT_SOURCE_FD, fd, 
-                             get_event(descriptor->reqevents), (void *)elem);
+                             get_event(descriptor->reqevents), (void *)descriptor);
 
         if (res < 0) {
             rv = apr_get_netos_error();
-            APR_RING_INSERT_TAIL(&(pollset->p->free_ring), elem, pfd_elem_t, link);
+        }
+    }
+    else {
+        pollset_lock_rings();
+
+        if (!APR_RING_EMPTY(&(pollset->p->free_ring), pfd_elem_t, link)) {
+            elem = APR_RING_FIRST(&(pollset->p->free_ring));
+            APR_RING_REMOVE(elem, link);
         }
         else {
-            elem->on_query_ring = 1;
-            APR_RING_INSERT_TAIL(&(pollset->p->query_ring), elem, pfd_elem_t, link);
+            elem = (pfd_elem_t *) apr_palloc(pollset->pool, sizeof(pfd_elem_t));
+            APR_RING_ELEM_INIT(elem, link);
+            elem->on_query_ring = 0;
+        }
+        elem->pfd = *descriptor;
+
+        /* If another thread is polling, notify the kernel immediately; otherwise,
+         * wait until the next call to apr_pollset_poll().
+         */
+        if (apr_atomic_read32(&pollset->p->waiting)) {
+            res = port_associate(pollset->p->port_fd, PORT_SOURCE_FD, fd, 
+                                 get_event(descriptor->reqevents), (void *)elem);
+
+            if (res < 0) {
+                rv = apr_get_netos_error();
+                APR_RING_INSERT_TAIL(&(pollset->p->free_ring), elem,
+                                     pfd_elem_t, link);
+            }
+            else {
+                elem->on_query_ring = 1;
+                APR_RING_INSERT_TAIL(&(pollset->p->query_ring), elem,
+                                     pfd_elem_t, link);
+            }
+        }
+        else {
+            APR_RING_INSERT_TAIL(&(pollset->p->add_ring), elem, pfd_elem_t, link);
         }
-    } 
-    else {
-        APR_RING_INSERT_TAIL(&(pollset->p->add_ring), elem, pfd_elem_t, link);
-    }
 
-    pollset_unlock_rings();
+        pollset_unlock_rings();
+    }
 
     return rv;
 }
@@ -275,9 +289,7 @@ static apr_status_t impl_pollset_remove(apr_pollset_t *pollset,
     apr_status_t rv = APR_SUCCESS;
     int res;
     int err = 0;
-    int found;
-
-    pollset_lock_rings();
+    int found = 0;
 
     if (descriptor->desc_type == APR_POLL_SOCKET) {
         fd = descriptor->desc.s->socketdes;
@@ -286,34 +298,36 @@ static apr_status_t impl_pollset_remove(apr_pollset_t *pollset,
         fd = descriptor->desc.f->filedes;
     }
 
-    /* Search the add ring first.  This ring is often shorter,
-     * and it often contains the descriptor being removed.  
-     * (For the common scenario where apr_pollset_poll() 
-     * returns activity for the descriptor and the descriptor
-     * is then removed from the pollset, it will have just 
-     * been moved to the add ring by apr_pollset_poll().)
-     *
-     * If it is on the add ring, it isn't associated with the
-     * event port yet/anymore.
-     */
-    found = 0;
-    for (ep = APR_RING_FIRST(&(pollset->p->add_ring));
-         ep != APR_RING_SENTINEL(&(pollset->p->add_ring),
-                                 pfd_elem_t, link);
-         ep = APR_RING_NEXT(ep, link)) {
-
-        if (descriptor->desc.s == ep->pfd.desc.s) {
-            found = 1;
-            APR_RING_REMOVE(ep, link);
-            APR_RING_INSERT_TAIL(&(pollset->p->free_ring),
-                                 ep, pfd_elem_t, link);
-            break;
+    if (!(pollset->flags & APR_POLLSET_NOCOPY)) {
+        pollset_lock_rings();
+
+        /* Search the add ring first.  This ring is often shorter,
+         * and it often contains the descriptor being removed.  
+         * (For the common scenario where apr_pollset_poll() 
+         * returns activity for the descriptor and the descriptor
+         * is then removed from the pollset, it will have just 
+         * been moved to the add ring by apr_pollset_poll().)
+         *
+         * If it is on the add ring, it isn't associated with the
+         * event port yet/anymore.
+         */
+        for (ep = APR_RING_FIRST(&(pollset->p->add_ring));
+             ep != APR_RING_SENTINEL(&(pollset->p->add_ring),
+                                     pfd_elem_t, link);
+             ep = APR_RING_NEXT(ep, link)) {
+
+            if (descriptor->desc.s == ep->pfd.desc.s) {
+                found = 1;
+                APR_RING_REMOVE(ep, link);
+                APR_RING_INSERT_TAIL(&(pollset->p->free_ring),
+                                     ep, pfd_elem_t, link);
+                break;
+            }
         }
     }
 
     if (!found) {
         res = port_dissociate(pollset->p->port_fd, PORT_SOURCE_FD, fd);
-
         if (res < 0) {
             /* The expected case for this failure is that another
              * thread's call to port_getn() returned this fd and
@@ -325,25 +339,29 @@ static apr_status_t impl_pollset_remove(apr_pollset_t *pollset,
             rv = APR_NOTFOUND;
         }
 
-        for (ep = APR_RING_FIRST(&(pollset->p->query_ring));
-             ep != APR_RING_SENTINEL(&(pollset->p->query_ring),
-                                     pfd_elem_t, link);
-             ep = APR_RING_NEXT(ep, link)) {
-
-            if (descriptor->desc.s == ep->pfd.desc.s) {
-                APR_RING_REMOVE(ep, link);
-                ep->on_query_ring = 0;
-                APR_RING_INSERT_TAIL(&(pollset->p->dead_ring),
-                                     ep, pfd_elem_t, link);
-                if (ENOENT == err) {
-                    rv = APR_SUCCESS;
+        if (!(pollset->flags & APR_POLLSET_NOCOPY)) {
+            for (ep = APR_RING_FIRST(&(pollset->p->query_ring));
+                 ep != APR_RING_SENTINEL(&(pollset->p->query_ring),
+                                         pfd_elem_t, link);
+                 ep = APR_RING_NEXT(ep, link)) {
+
+                if (descriptor->desc.s == ep->pfd.desc.s) {
+                    APR_RING_REMOVE(ep, link);
+                    ep->on_query_ring = 0;
+                    APR_RING_INSERT_TAIL(&(pollset->p->dead_ring),
+                                         ep, pfd_elem_t, link);
+                    if (ENOENT == err) {
+                        rv = APR_SUCCESS;
+                    }
+                    break;
                 }
-                break;
             }
+            pollset_unlock_rings();
         }
     }
-
-    pollset_unlock_rings();
+    else if (!(pollset->flags & APR_POLLSET_NOCOPY)) {
+        pollset_unlock_rings();
+    }
 
     return rv;
 }
@@ -363,73 +381,89 @@ static apr_status_t impl_pollset_poll(apr_pollset_t *pollset,
     *num = 0;
     nget = 1;
 
-    pollset_lock_rings();
+    if (!(pollset->flags & APR_POLLSET_NOCOPY)) {
+        pollset_lock_rings();
 
-    apr_atomic_inc32(&pollset->p->waiting);
+        apr_atomic_inc32(&pollset->p->waiting);
 
-    while (!APR_RING_EMPTY(&(pollset->p->add_ring), pfd_elem_t, link)) {
-        ep = APR_RING_FIRST(&(pollset->p->add_ring));
-        APR_RING_REMOVE(ep, link);
+        while (!APR_RING_EMPTY(&(pollset->p->add_ring), pfd_elem_t, link)) {
+            ep = APR_RING_FIRST(&(pollset->p->add_ring));
+            APR_RING_REMOVE(ep, link);
 
-        if (ep->pfd.desc_type == APR_POLL_SOCKET) {
-            fd = ep->pfd.desc.s->socketdes;
-        }
-        else {
-            fd = ep->pfd.desc.f->filedes;
-        }
+            if (ep->pfd.desc_type == APR_POLL_SOCKET) {
+                fd = ep->pfd.desc.s->socketdes;
+            }
+            else {
+                fd = ep->pfd.desc.f->filedes;
+            }
 
-        ret = port_associate(pollset->p->port_fd, PORT_SOURCE_FD, 
-                             fd, get_event(ep->pfd.reqevents), ep);
-        if (ret < 0) {
-            rv = apr_get_netos_error();
-            APR_RING_INSERT_TAIL(&(pollset->p->free_ring), ep, pfd_elem_t, link);
-            break;
-        }
+            ret = port_associate(pollset->p->port_fd, PORT_SOURCE_FD, 
+                                 fd, get_event(ep->pfd.reqevents), ep);
+            if (ret < 0) {
+                rv = apr_get_netos_error();
+                APR_RING_INSERT_TAIL(&(pollset->p->free_ring), ep, pfd_elem_t, link);
+                break;
+            }
 
-        ep->on_query_ring = 1;
-        APR_RING_INSERT_TAIL(&(pollset->p->query_ring), ep, pfd_elem_t, link);
-    }
+            ep->on_query_ring = 1;
+            APR_RING_INSERT_TAIL(&(pollset->p->query_ring), ep, pfd_elem_t, link);
+        }
 
-    pollset_unlock_rings();
+        pollset_unlock_rings();
 
-    if (rv != APR_SUCCESS) {
-        apr_atomic_dec32(&pollset->p->waiting);
-        return rv;
+        if (rv != APR_SUCCESS) {
+            apr_atomic_dec32(&pollset->p->waiting);
+            return rv;
+        }
     }
 
     rv = call_port_getn(pollset->p->port_fd, pollset->p->port_set, 
                         pollset->nalloc, &nget, timeout);
 
-    /* decrease the waiting ASAP to reduce the window for calling 
-       port_associate within apr_pollset_add() */
-    apr_atomic_dec32(&pollset->p->waiting);
+    if (!(pollset->flags & APR_POLLSET_NOCOPY)) {
+        /* decrease the waiting ASAP to reduce the window for calling 
+           port_associate within apr_pollset_add() */
+        apr_atomic_dec32(&pollset->p->waiting);
 
-    pollset_lock_rings();
+        pollset_lock_rings();
+    }
 
     for (i = 0, j = 0; i < nget; i++) {
-        ep = (pfd_elem_t *)pollset->p->port_set[i].portev_user;
+        const apr_poll_fd_t *pfd;
+
+        if (pollset->flags & APR_POLLSET_NOCOPY) {
+            pfd = (apr_pollfd_t *)pollset->p->port_set[i].portev_user;
+        }
+        else {
+            ep = (pfd_elem_t *)pollset->p->port_set[i].portev_user;
+            pfd = &ep->pfd;
+        }
+
         if ((pollset->flags & APR_POLLSET_WAKEABLE) &&
-            ep->pfd.desc_type == APR_POLL_FILE &&
-            ep->pfd.desc.f == pollset->wakeup_pipe[0]) {
+            pfd->desc_type == APR_POLL_FILE &&
+            pfd->desc.f == pollset->wakeup_pipe[0]) {
             apr_poll_drain_wakeup_pipe(&pollset->wakeup_set, pollset->wakeup_pipe);
             rv = APR_EINTR;
         }
         else {
-            pollset->p->result_set[j] = ep->pfd;
+            pollset->p->result_set[j] = *pfd;
             pollset->p->result_set[j].rtnevents =
                 get_revent(pollset->p->port_set[i].portev_events);
             j++;
         }
-        /* If the ring element is still on the query ring, move it
-         * to the add ring for re-association with the event port
-         * later.  (It may have already been moved to the dead ring
-         * by a call to pollset_remove on another thread.)
-         */
-        if (ep->on_query_ring) {
-            APR_RING_REMOVE(ep, link);
-            ep->on_query_ring = 0;
-            APR_RING_INSERT_TAIL(&(pollset->p->add_ring), ep,
-                                 pfd_elem_t, link);
+
+        if (!(pollset->flags & APR_POLLSET_NOCOPY)) {
+            /* If the ring element is still on the query ring, move it
+             * to the add ring for re-association with the event port
+             * later.  (It may have already been moved to the dead ring
+             * by a call to pollset_remove on another thread.)
+             */
+            if (ep->on_query_ring) {
+                APR_RING_REMOVE(ep, link);
+                ep->on_query_ring = 0;
+                APR_RING_INSERT_TAIL(&(pollset->p->add_ring), ep,
+                                     pfd_elem_t, link);
+            }
         }
     }
     if ((*num = j)) { /* any event besides wakeup pipe? */
@@ -439,10 +473,13 @@ static apr_status_t impl_pollset_poll(apr_pollset_t *pollset,
         }
     }
 
-    /* Shift all PFDs in the Dead Ring to the Free Ring */
-    APR_RING_CONCAT(&(pollset->p->free_ring), &(pollset->p->dead_ring), pfd_elem_t, link);
+    if (!(pollset->flags & APR_POLLSET_NOCOPY)) {
+        /* Shift all PFDs in the Dead Ring to the Free Ring */
+        APR_RING_CONCAT(&(pollset->p->free_ring), &(pollset->p->dead_ring),
+                        pfd_elem_t, link);
 
-    pollset_unlock_rings();
+        pollset_unlock_rings();
+    }
 
     return rv;
 }