Attachment 42905 Details for Bug 33337 – [6] Choose between poll and epoll at runtime

[patch] [6] Choose between poll and epoll at runtime

0001-Choose-between-poll-and-epoll-at-runtime.patch (text/plain), 18.83 KB, created by Simon McVittie on 2011-02-03 10:34:07 UTC

(hide)

Description:

Filename:

MIME Type:

Creator: Simon McVittie

Created: 2011-02-03 10:34:07 UTC

Size: 18.83 KB

patch

obsolete

>From d7eafb1b2adfeaa53975155f344e3ef9ca6fb34d Mon Sep 17 00:00:00 2001
>From: Simon McVittie <simon.mcvittie@collabora.co.uk>
>Date: Thu, 3 Feb 2011 17:04:02 +0000
>Subject: [PATCH 1/2] Choose between poll and epoll at runtime
>
>If we're compiled against glibc 2.9 or later, but then run on Linux
>2.6.26 or earlier (for instance, a Debian 6 chroot on a Debian 5 host),
>epoll_create1 won't work and we'll have to fall back to poll anyway.
>
>Bug: https://bugs.freedesktop.org/show_bug.cgi?id=33337
>Bug-NB: NB#225019
>---
> configure.in                 |    3 +
> dbus/Makefile.am             |    4 +-
> dbus/dbus-socket-set-epoll.c |  109 ++++++++++++++++++++++++++++--------------
> dbus/dbus-socket-set-poll.c  |  100 ++++++++++++++++++++++++--------------
> dbus/dbus-socket-set.c       |   47 ++++++++++++++++++
> dbus/dbus-socket-set.h       |   98 ++++++++++++++++++++++++++++++-------
> 6 files changed, 267 insertions(+), 94 deletions(-)
> create mode 100644 dbus/dbus-socket-set.c
>
>diff --git a/configure.in b/configure.in
>index 593845c..cdcc4e2 100644
>--- a/configure.in
>+++ b/configure.in
>@@ -933,6 +933,9 @@ fi
> if test x$enable_epoll,$have_linux_epoll = xyes,no; then
>     AC_MSG_ERROR([epoll support explicitly enabled but not available])
> fi
>+if test x$have_linux_epoll = xyes; then
>+  AC_DEFINE([DBUS_HAVE_LINUX_EPOLL], 1, [Define to use epoll(4) on Linux])
>+fi
> AM_CONDITIONAL([HAVE_LINUX_EPOLL], [test x$have_linux_epoll = xyes])
> 
> # kqueue checks
>diff --git a/dbus/Makefile.am b/dbus/Makefile.am
>index 7ef2b8e..9bd6e6d 100644
>--- a/dbus/Makefile.am
>+++ b/dbus/Makefile.am
>@@ -108,8 +108,6 @@ endif
> 
> if HAVE_LINUX_EPOLL
> DBUS_UTIL_arch_sources += dbus-socket-set-epoll.c
>-else
>-DBUS_UTIL_arch_sources += dbus-socket-set-poll.c
> endif
> 
> dbusinclude_HEADERS=				\
>@@ -244,6 +242,8 @@ DBUS_UTIL_SOURCES=				\
> 	dbus-shell.h				\
> 	$(DBUS_UTIL_arch_sources)		\
> 	dbus-socket-set.h			\
>+	dbus-socket-set.c			\
>+	dbus-socket-set-poll.c			\
> 	dbus-spawn.h				\
> 	dbus-string-util.c			\
> 	dbus-sysdeps-util.c			\
>diff --git a/dbus/dbus-socket-set-epoll.c b/dbus/dbus-socket-set-epoll.c
>index 0c6745f..b5c3209 100644
>--- a/dbus/dbus-socket-set-epoll.c
>+++ b/dbus/dbus-socket-set-epoll.c
>@@ -38,15 +38,54 @@
> 
> #ifndef DOXYGEN_SHOULD_SKIP_THIS
> 
>+typedef struct {
>+    DBusSocketSet parent;
>+    int epfd;
>+} DBusSocketSetEpoll;
>+
>+static inline DBusSocketSetEpoll *
>+socket_set_epoll_cast (DBusSocketSet *set)
>+{
>+  _dbus_assert (set->cls == &_dbus_socket_set_epoll_class);
>+  return (DBusSocketSetEpoll *) set;
>+}
>+
>+/* this is safe to call on a partially-allocated socket set */
>+static void
>+socket_set_epoll_free (DBusSocketSet *set)
>+{
>+  DBusSocketSetEpoll *self = socket_set_epoll_cast (set);
>+
>+  if (self == NULL)
>+    return;
>+
>+  if (self->epfd != -1)
>+    close (self->epfd);
>+
>+  dbus_free (self);
>+}
>+
> DBusSocketSet *
>-_dbus_socket_set_new (int size_hint)
>+_dbus_socket_set_epoll_new (void)
> {
>-  int epfd = epoll_create1 (EPOLL_CLOEXEC);
>+  DBusSocketSetEpoll *self;
>+
>+  self = dbus_new0 (DBusSocketSetEpoll, 1);
> 
>-  if (epfd == -1)
>+  if (self == NULL)
>     return NULL;
> 
>-  return _DBUS_INT_TO_POINTER (epfd);
>+  self->parent.cls = &_dbus_socket_set_epoll_class;
>+
>+  self->epfd = epoll_create1 (EPOLL_CLOEXEC);
>+
>+  if (self->epfd == -1)
>+    {
>+      socket_set_epoll_free ((DBusSocketSet *) self);
>+      return NULL;
>+    }
>+
>+  return (DBusSocketSet *) self;
> }
> 
> static uint32_t
>@@ -79,13 +118,13 @@ epoll_events_to_watch_flags (uint32_t events)
>   return flags;
> }
> 
>-dbus_bool_t
>-_dbus_socket_set_add (DBusSocketSet  *self,
>+static dbus_bool_t
>+socket_set_epoll_add (DBusSocketSet  *set,
>                       int             fd,
>                       unsigned int    flags,
>                       dbus_bool_t     enabled)
> {
>-  int epfd = _DBUS_POINTER_TO_INT (self);
>+  DBusSocketSetEpoll *self = socket_set_epoll_cast (set);
>   struct epoll_event event;
>   int err;
> 
>@@ -98,11 +137,11 @@ _dbus_socket_set_add (DBusSocketSet  *self,
>   else
>     {
>       /* We need to add *something* to reserve space in the kernel's data
>-       * structures: see _dbus_socket_set_disable for more details */
>+       * structures: see socket_set_epoll_disable for more details */
>       event.events = EPOLLET;
>     }
> 
>-  if (epoll_ctl (epfd, EPOLL_CTL_ADD, fd, &event) == 0)
>+  if (epoll_ctl (self->epfd, EPOLL_CTL_ADD, fd, &event) == 0)
>     return TRUE;
> 
>   /* Anything except ENOMEM, ENOSPC means we have an internal error. */
>@@ -132,19 +171,19 @@ _dbus_socket_set_add (DBusSocketSet  *self,
>   return FALSE;
> }
> 
>-void
>-_dbus_socket_set_enable (DBusSocketSet  *self,
>+static void
>+socket_set_epoll_enable (DBusSocketSet  *set,
>                          int             fd,
>                          unsigned int    flags)
> {
>-  int epfd = _DBUS_POINTER_TO_INT (self);
>+  DBusSocketSetEpoll *self = socket_set_epoll_cast (set);
>   struct epoll_event event;
>   int err;
> 
>   event.data.fd = fd;
>   event.events = watch_flags_to_epoll_events (flags);
> 
>-  if (epoll_ctl (epfd, EPOLL_CTL_MOD, fd, &event) == 0)
>+  if (epoll_ctl (self->epfd, EPOLL_CTL_MOD, fd, &event) == 0)
>     return;
> 
>   err = errno;
>@@ -172,16 +211,16 @@ _dbus_socket_set_enable (DBusSocketSet  *self,
>     }
> }
> 
>-void
>-_dbus_socket_set_disable (DBusSocketSet  *self,
>+static void
>+socket_set_epoll_disable (DBusSocketSet  *set,
>                           int             fd)
> {
>-  int epfd = _DBUS_POINTER_TO_INT (self);
>+  DBusSocketSetEpoll *self = socket_set_epoll_cast (set);
>   struct epoll_event event;
>   int err;
> 
>   /* The naive thing to do would be EPOLL_CTL_DEL, but that'll probably
>-   * free resources in the kernel. When we come to do _dbus_socket_set_enable,
>+   * free resources in the kernel. When we come to do socket_set_epoll_enable,
>    * there might not be enough resources to bring it back!
>    *
>    * The next idea you might have is to set the flags to 0. However, events
>@@ -199,7 +238,7 @@ _dbus_socket_set_disable (DBusSocketSet  *self,
>   event.data.fd = fd;
>   event.events = EPOLLET;
> 
>-  if (epoll_ctl (epfd, EPOLL_CTL_MOD, fd, &event) == 0)
>+  if (epoll_ctl (self->epfd, EPOLL_CTL_MOD, fd, &event) == 0)
>     return;
> 
>   err = errno;
>@@ -207,14 +246,14 @@ _dbus_socket_set_disable (DBusSocketSet  *self,
>               strerror (err));
> }
> 
>-void
>-_dbus_socket_set_remove (DBusSocketSet  *self,
>+static void
>+socket_set_epoll_remove (DBusSocketSet  *set,
>                          int             fd)
> {
>-  int epfd = _DBUS_POINTER_TO_INT (self);
>+  DBusSocketSetEpoll *self = socket_set_epoll_cast (set);
>   int err;
> 
>-  if (epoll_ctl (epfd, EPOLL_CTL_DEL, fd, NULL) == 0)
>+  if (epoll_ctl (self->epfd, EPOLL_CTL_DEL, fd, NULL) == 0)
>     return;
> 
>   err = errno;
>@@ -225,22 +264,20 @@ _dbus_socket_set_remove (DBusSocketSet  *self,
>  * but it makes things simpler... */
> #define N_STACK_DESCRIPTORS 64
> 
>-/** This is basically Linux's epoll_wait(2) implemented in terms of poll(2);
>- * it returns results into a caller-supplied buffer so we can be reentrant. */
>-int
>-_dbus_socket_set_poll (DBusSocketSet   *self,
>+static int
>+socket_set_epoll_poll (DBusSocketSet   *set,
>                        DBusSocketEvent *revents,
>                        int              max_events,
>                        int              timeout_ms)
> {
>-  int epfd = _DBUS_POINTER_TO_INT (self);
>+  DBusSocketSetEpoll *self = socket_set_epoll_cast (set);
>   struct epoll_event events[N_STACK_DESCRIPTORS];
>   int n_ready;
>   int i;
> 
>   _dbus_assert (max_events > 0);
> 
>-  n_ready = epoll_wait (epfd, events,
>+  n_ready = epoll_wait (self->epfd, events,
>                         MIN (_DBUS_N_ELEMENTS (events), max_events),
>                         timeout_ms);
> 
>@@ -256,14 +293,14 @@ _dbus_socket_set_poll (DBusSocketSet   *self,
>   return n_ready;
> }
> 
>-/* this is safe to call on a partially-allocated socket set */
>-void
>-_dbus_socket_set_free (DBusSocketSet *self)
>-{
>-  int epfd = _DBUS_POINTER_TO_INT (self);
>-
>-  close (epfd);
>-}
>+DBusSocketSetClass _dbus_socket_set_epoll_class = {
>+    socket_set_epoll_free,
>+    socket_set_epoll_add,
>+    socket_set_epoll_remove,
>+    socket_set_epoll_enable,
>+    socket_set_epoll_disable,
>+    socket_set_epoll_poll
>+};
> 
> #ifdef TEST_BEHAVIOUR_OF_EPOLLET
> /* usage: cat /dev/null | ./epoll
>diff --git a/dbus/dbus-socket-set-poll.c b/dbus/dbus-socket-set-poll.c
>index 918c965..65a1fd2 100644
>--- a/dbus/dbus-socket-set-poll.c
>+++ b/dbus/dbus-socket-set-poll.c
>@@ -32,12 +32,13 @@
> 
> #ifndef DOXYGEN_SHOULD_SKIP_THIS
> 
>-struct DBusSocketSet {
>+typedef struct {
>+    DBusSocketSet      parent;
>     DBusPollFD        *fds;
>     int                n_fds;
>     int                n_reserved;
>     int                n_allocated;
>-};
>+} DBusSocketSetPoll;
> 
> #define REALLOC_INCREMENT 8
> #define MINIMUM_SIZE 8
>@@ -49,19 +50,38 @@ struct DBusSocketSet {
> #define DEFAULT_SIZE_HINT MINIMUM_SIZE
> #endif
> 
>+static inline DBusSocketSetPoll *
>+socket_set_poll_cast (DBusSocketSet *set)
>+{
>+  _dbus_assert (set->cls == &_dbus_socket_set_poll_class);
>+  return (DBusSocketSetPoll *) set;
>+}
>+
>+/* this is safe to call on a partially-allocated socket set */
>+static void
>+socket_set_poll_free (DBusSocketSet *set)
>+{
>+  DBusSocketSetPoll *self = socket_set_poll_cast (set);
>+
>+  dbus_free (self->fds);
>+  dbus_free (self);
>+  _dbus_verbose ("freed socket set %p\n", self);
>+}
>+
> DBusSocketSet *
>-_dbus_socket_set_new (int size_hint)
>+_dbus_socket_set_poll_new (int size_hint)
> {
>-  DBusSocketSet *ret;
>+  DBusSocketSetPoll *ret;
> 
>   if (size_hint <= 0)
>     size_hint = DEFAULT_SIZE_HINT;
> 
>-  ret = dbus_new0 (DBusSocketSet, 1);
>+  ret = dbus_new0 (DBusSocketSetPoll, 1);
> 
>   if (ret == NULL)
>     return NULL;
> 
>+  ret->parent.cls = &_dbus_socket_set_poll_class;
>   ret->n_fds = 0;
>   ret->n_allocated = size_hint;
> 
>@@ -69,14 +89,14 @@ _dbus_socket_set_new (int size_hint)
> 
>   if (ret->fds == NULL)
>     {
>-      /* _dbus_socket_set_free specifically supports half-constructed
>+      /* socket_set_poll_free specifically supports half-constructed
>        * socket sets */
>-      _dbus_socket_set_free (ret);
>+      socket_set_poll_free ((DBusSocketSet *) ret);
>       return NULL;
>     }
> 
>   _dbus_verbose ("new socket set at %p\n", ret);
>-  return ret;
>+  return (DBusSocketSet *) ret;
> }
> 
> static short
>@@ -92,12 +112,13 @@ watch_flags_to_poll_events (unsigned int flags)
>   return events;
> }
> 
>-dbus_bool_t
>-_dbus_socket_set_add (DBusSocketSet  *self,
>-                      int             fd,
>-                      unsigned int    flags,
>-                      dbus_bool_t     enabled)
>+static dbus_bool_t
>+socket_set_poll_add (DBusSocketSet  *set,
>+                     int             fd,
>+                     unsigned int    flags,
>+                     dbus_bool_t     enabled)
> {
>+  DBusSocketSetPoll *self = socket_set_poll_cast (set);
> #ifndef DBUS_DISABLE_ASSERT
>   int i;
> 
>@@ -138,11 +159,12 @@ _dbus_socket_set_add (DBusSocketSet  *self,
>   return TRUE;
> }
> 
>-void
>-_dbus_socket_set_enable (DBusSocketSet *self,
>-                         int            fd,
>-                         unsigned int   flags)
>+static void
>+socket_set_poll_enable (DBusSocketSet *set,
>+                        int            fd,
>+                        unsigned int   flags)
> {
>+  DBusSocketSetPoll *self = socket_set_poll_cast (set);
>   int i;
> 
>   for (i = 0; i < self->n_fds; i++)
>@@ -163,10 +185,11 @@ _dbus_socket_set_enable (DBusSocketSet *self,
>   self->n_fds++;
> }
> 
>-void
>-_dbus_socket_set_disable (DBusSocketSet *self,
>-                          int            fd)
>+static void
>+socket_set_poll_disable (DBusSocketSet *set,
>+                         int            fd)
> {
>+  DBusSocketSetPoll *self = socket_set_poll_cast (set);
>   int i;
> 
>   for (i = 0; i < self->n_fds; i++)
>@@ -185,11 +208,13 @@ _dbus_socket_set_disable (DBusSocketSet *self,
>     }
> }
> 
>-void
>-_dbus_socket_set_remove (DBusSocketSet *self,
>-                         int            fd)
>+static void
>+socket_set_poll_remove (DBusSocketSet *set,
>+                        int            fd)
> {
>-  _dbus_socket_set_disable (self, fd);
>+  DBusSocketSetPoll *self = socket_set_poll_cast (set);
>+
>+  socket_set_poll_disable (set, fd);
>   self->n_reserved--;
> 
>   _dbus_verbose ("after removing fd %d from %p, %d en/%d res/%d alloc\n",
>@@ -240,12 +265,13 @@ watch_flags_from_poll_revents (short revents)
> 
> /** This is basically Linux's epoll_wait(2) implemented in terms of poll(2);
>  * it returns results into a caller-supplied buffer so we can be reentrant. */
>-int
>-_dbus_socket_set_poll (DBusSocketSet   *self,
>-                       DBusSocketEvent *revents,
>-                       int              max_events,
>-                       int              timeout_ms)
>+static int
>+socket_set_poll_poll (DBusSocketSet   *set,
>+                      DBusSocketEvent *revents,
>+                      int              max_events,
>+                      int              timeout_ms)
> {
>+  DBusSocketSetPoll *self = socket_set_poll_cast (set);
>   int i;
>   int n_events;
>   int n_ready;
>@@ -282,13 +308,13 @@ _dbus_socket_set_poll (DBusSocketSet   *self,
>   return n_events;
> }
> 
>-/* this is safe to call on a partially-allocated socket set */
>-void
>-_dbus_socket_set_free (DBusSocketSet *self)
>-{
>-  dbus_free (self->fds);
>-  dbus_free (self);
>-  _dbus_verbose ("freed socket set %p\n", self);
>-}
>+DBusSocketSetClass _dbus_socket_set_poll_class = {
>+    socket_set_poll_free,
>+    socket_set_poll_add,
>+    socket_set_poll_remove,
>+    socket_set_poll_enable,
>+    socket_set_poll_disable,
>+    socket_set_poll_poll
>+};
> 
> #endif /* !DOXYGEN_SHOULD_SKIP_THIS */
>diff --git a/dbus/dbus-socket-set.c b/dbus/dbus-socket-set.c
>new file mode 100644
>index 0000000..210d600
>--- /dev/null
>+++ b/dbus/dbus-socket-set.c
>@@ -0,0 +1,47 @@
>+/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
>+/*
>+ * dbus-socket-set.c - used to bolt file descriptors onto a bus
>+ *
>+ * Copyright Â© 2011 Nokia Corporation
>+ *
>+ * Licensed under the Academic Free License version 2.1
>+ *
>+ * This program is free software; you can redistribute it and/or modify
>+ * it under the terms of the GNU General Public License as published by
>+ * the Free Software Foundation; either version 2 of the License, or
>+ * (at your option) any later version.
>+ *
>+ * This program is distributed in the hope that it will be useful,
>+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
>+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>+ * GNU General Public License for more details.
>+ *
>+ * You should have received a copy of the GNU General Public License
>+ * along with this program; if not, write to the Free Software
>+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
>+ * MA  02110-1301  USA
>+ *
>+ */
>+
>+#include <config.h>
>+#include <dbus/dbus-socket-set.h>
>+
>+DBusSocketSet *
>+_dbus_socket_set_new (int size_hint)
>+{
>+  DBusSocketSet *ret;
>+
>+#ifdef DBUS_HAVE_LINUX_EPOLL
>+  ret = _dbus_socket_set_epoll_new ();
>+
>+  if (ret != NULL)
>+    return ret;
>+#endif
>+
>+  ret = _dbus_socket_set_poll_new (size_hint);
>+
>+  if (ret != NULL)
>+    return ret;
>+
>+  return NULL;
>+}
>diff --git a/dbus/dbus-socket-set.h b/dbus/dbus-socket-set.h
>index 4a1112b..3b71a92 100644
>--- a/dbus/dbus-socket-set.h
>+++ b/dbus/dbus-socket-set.h
>@@ -37,26 +37,86 @@ typedef struct {
> 
> typedef struct DBusSocketSet DBusSocketSet;
> 
>+typedef struct DBusSocketSetClass DBusSocketSetClass;
>+struct DBusSocketSetClass {
>+    void            (*free)     (DBusSocketSet   *self);
>+    dbus_bool_t     (*add)      (DBusSocketSet   *self,
>+                                 int              fd,
>+                                 unsigned int     flags,
>+                                 dbus_bool_t      enabled);
>+    void            (*remove)   (DBusSocketSet   *self,
>+                                 int              fd);
>+    void            (*enable)   (DBusSocketSet   *self,
>+                                 int              fd,
>+                                 unsigned int     flags);
>+    void            (*disable)  (DBusSocketSet   *self,
>+                                 int              fd);
>+    int             (*poll)     (DBusSocketSet   *self,
>+                                 DBusSocketEvent *revents,
>+                                 int              max_events,
>+                                 int              timeout_ms);
>+};
>+
>+struct DBusSocketSet {
>+    DBusSocketSetClass *cls;
>+};
>+
> DBusSocketSet *_dbus_socket_set_new           (int               size_hint);
>-void           _dbus_socket_set_free          (DBusSocketSet    *self);
>-
>-dbus_bool_t    _dbus_socket_set_add           (DBusSocketSet    *self,
>-                                               int               fd,
>-                                               unsigned int      flags,
>-                                               dbus_bool_t       enabled);
>-void           _dbus_socket_set_remove        (DBusSocketSet    *self,
>-                                               int               fd);
>-
>-void           _dbus_socket_set_enable        (DBusSocketSet    *self,
>-                                               int               fd,
>-                                               unsigned int      flags);
>-void           _dbus_socket_set_disable       (DBusSocketSet    *self,
>-                                               int               fd);
>-
>-int            _dbus_socket_set_poll          (DBusSocketSet    *self,
>-                                               DBusSocketEvent  *revents,
>-                                               int               max_events,
>-                                               int               timeout_ms);
>+
>+static inline void
>+_dbus_socket_set_free (DBusSocketSet *self)
>+{
>+  (self->cls->free) (self);
>+}
>+
>+static inline dbus_bool_t
>+_dbus_socket_set_add (DBusSocketSet *self,
>+                      int            fd,
>+                      unsigned int   flags,
>+                      dbus_bool_t    enabled)
>+{
>+  return (self->cls->add) (self, fd, flags, enabled);
>+}
>+
>+static inline void
>+_dbus_socket_set_remove (DBusSocketSet *self,
>+                         int            fd)
>+{
>+  (self->cls->remove) (self, fd);
>+}
>+
>+static inline void
>+_dbus_socket_set_enable (DBusSocketSet *self,
>+                         int            fd,
>+                         unsigned int   flags)
>+{
>+  (self->cls->enable) (self, fd, flags);
>+}
>+
>+static inline void
>+_dbus_socket_set_disable (DBusSocketSet *self,
>+                          int            fd)
>+{
>+  (self->cls->disable) (self, fd);
>+}
>+
>+
>+static inline int
>+_dbus_socket_set_poll (DBusSocketSet    *self,
>+                       DBusSocketEvent  *revents,
>+                       int               max_events,
>+                       int               timeout_ms)
>+{
>+  return (self->cls->poll) (self, revents, max_events, timeout_ms);
>+}
>+
>+/* concrete implementations, not necessarily built on all platforms */
>+
>+extern DBusSocketSetClass _dbus_socket_set_poll_class;
>+extern DBusSocketSetClass _dbus_socket_set_epoll_class;
>+
>+DBusSocketSet *_dbus_socket_set_poll_new  (int  size_hint);
>+DBusSocketSet *_dbus_socket_set_epoll_new (void);
> 
> #endif /* !DOXYGEN_SHOULD_SKIP_THIS */
> #endif /* multiple-inclusion guard */
>-- 
>1.7.2.3
>

Actions: View | Splinter Review

Attachments on bug 33337: 42531 | 42532 | 42533 | 42534 | 42535 | 42905 | 42906 | 45390 | 47907 | 47908 | 47909 | 47910 | 47911 | 47912 | 53061

Use of freedesktop.org services, including Bugzilla, is subject to our Code of Conduct. How we collect and use information is described in our Privacy Policy.