I needed to do apples-to-apples comparison between rtsignals and epoll
for a client, so I fixed rtsig.c from 1.3e (see an earlier post) to
compile, then fixed it to work, and ported that to 1.4.3-stable.
NOTE WELL! Used only for benchmarking: the rtsig_dealloc routine may
not free everything it needs to!
Below are are diffs than can be applied by "patch" to
libevent-1.4.3-stable.tar.gz; then run:
./autogen.sh
./configure --with-rtsig
I also added a command line argument to bench.c to allow me to specify
how many trials are performed.
Many many thanks to Scott Lamb for posting "chartbench.py"
http://monkeymail.org/archives/libevent-users/2007-December/001085.html
and to the authors of libevent for giving me a platform I could
perform the testing on!
--- ./Makefile.in.orig 2008-04-05 17:06:34.000000000 -0400
+++ Makefile.in 2008-05-09 20:51:20.000000000 -0400
@@ -40,7 +40,7 @@
$(srcdir)/config.h.in $(top_srcdir)/configure ChangeLog \
config.guess config.sub devpoll.c epoll.c epoll_sub.c evport.c \
install-sh kqueue.c ltmain.sh missing mkinstalldirs poll.c \
- select.c signal.c
+ rtsig.c select.c signal.c
ACLOCAL_M4 = $(top_srcdir)/aclocal.m4
am__aclocal_m4_deps = $(top_srcdir)/configure.in
am__configure_deps = $(am__aclocal_m4_deps) $(CONFIGURE_DEPENDENCIES) \
--- ./event.c.orig 2008-02-25 02:34:37.000000000 -0500
+++ event.c 2008-05-09 20:38:32.000000000 -0400
@@ -78,6 +78,9 @@
#ifdef WIN32
extern const struct eventop win32ops;
#endif
+#ifdef HAVE_RTSIG
+extern const struct eventop rtsigops;
+#endif
/* In order of preference */
const struct eventop *eventops[] = {
@@ -102,6 +105,9 @@
#ifdef WIN32
&win32ops,
#endif
+#ifdef HAVE_RTSIG
+ &rtsigops,
+#endif
NULL
};
--- ./config.h.in.orig 2008-05-09 20:40:59.000000000 -0400
+++ config.h.in 2008-05-09 20:53:11.000000000 -0400
@@ -78,6 +78,9 @@
/* Define to 1 if you have the <port.h> header file. */
#undef HAVE_PORT_H
+/* Define if your system supports POSIX realtime signals */
+#undef HAVE_RTSIG
+
/* Define to 1 if you have the `select' function. */
#undef HAVE_SELECT
@@ -93,6 +96,9 @@
/* Define to 1 if you have the <signal.h> header file. */
#undef HAVE_SIGNAL_H
+/* Define to 1 if you have the `sigtimedwait' function. */
+#undef HAVE_SIGTIMEDWAIT
+
/* Define to 1 if you have the <stdarg.h> header file. */
#undef HAVE_STDARG_H
@@ -192,6 +198,9 @@
/* Define if kqueue works correctly with pipes */
#undef HAVE_WORKING_KQUEUE
+/* Define if realtime signals work on pipes */
+#undef HAVE_WORKING_RTSIG
+
/* Name of package */
#undef PACKAGE
--- ./event-config.h.orig 2008-04-05 17:06:51.000000000 -0400
+++ event-config.h 2008-05-09 20:53:54.000000000 -0400
@@ -9,13 +9,13 @@
/* config.h.in. Generated from configure.in by autoheader. */
/* Define if clock_gettime is available in libc */
-/* #undef _EVENT_DNS_USE_CPU_CLOCK_FOR_ID */
+#define _EVENT_DNS_USE_CPU_CLOCK_FOR_ID 1
/* Define is no secure id variant is available */
-#define _EVENT_DNS_USE_GETTIMEOFDAY_FOR_ID 1
+/* #undef _EVENT_DNS_USE_GETTIMEOFDAY_FOR_ID */
/* Define to 1 if you have the `clock_gettime' function. */
-/* #undef _EVENT_HAVE_CLOCK_GETTIME */
+#define _EVENT_HAVE_CLOCK_GETTIME 1
/* Define if /dev/poll is available */
/* #undef _EVENT_HAVE_DEVPOLL */
@@ -24,10 +24,10 @@
#define _EVENT_HAVE_DLFCN_H 1
/* Define if your system supports the epoll system calls */
-/* #undef _EVENT_HAVE_EPOLL */
+#define _EVENT_HAVE_EPOLL 1
/* Define to 1 if you have the `epoll_ctl' function. */
-/* #undef _EVENT_HAVE_EPOLL_CTL */
+#define _EVENT_HAVE_EPOLL_CTL 1
/* Define if your system supports event ports */
/* #undef _EVENT_HAVE_EVENT_PORTS */
@@ -54,16 +54,16 @@
#define _EVENT_HAVE_INTTYPES_H 1
/* Define to 1 if you have the `kqueue' function. */
-#define _EVENT_HAVE_KQUEUE 1
+/* #undef _EVENT_HAVE_KQUEUE */
/* Define to 1 if you have the `nsl' library (-lnsl). */
-/* #undef _EVENT_HAVE_LIBNSL */
+#define _EVENT_HAVE_LIBNSL 1
/* Define to 1 if you have the `resolv' library (-lresolv). */
#define _EVENT_HAVE_LIBRESOLV 1
/* Define to 1 if you have the `rt' library (-lrt). */
-/* #undef _EVENT_HAVE_LIBRT */
+#define _EVENT_HAVE_LIBRT 1
/* Define to 1 if you have the `socket' library (-lsocket). */
/* #undef _EVENT_HAVE_LIBSOCKET */
@@ -86,6 +86,9 @@
/* Define to 1 if you have the <port.h> header file. */
/* #undef _EVENT_HAVE_PORT_H */
+/* Define if your system supports POSIX realtime signals */
+#define _EVENT_HAVE_RTSIG 1
+
/* Define to 1 if you have the `select' function. */
#define _EVENT_HAVE_SELECT 1
@@ -101,6 +104,9 @@
/* Define to 1 if you have the <signal.h> header file. */
#define _EVENT_HAVE_SIGNAL_H 1
+/* Define to 1 if you have the `sigtimedwait' function. */
+#define _EVENT_HAVE_SIGTIMEDWAIT 1
+
/* Define to 1 if you have the <stdarg.h> header file. */
#define _EVENT_HAVE_STDARG_H 1
@@ -117,7 +123,7 @@
#define _EVENT_HAVE_STRING_H 1
/* Define to 1 if you have the `strlcpy' function. */
-#define _EVENT_HAVE_STRLCPY 1
+/* #undef _EVENT_HAVE_STRLCPY */
/* Define to 1 if you have the `strsep' function. */
#define _EVENT_HAVE_STRSEP 1
@@ -135,10 +141,10 @@
/* #undef _EVENT_HAVE_SYS_DEVPOLL_H */
/* Define to 1 if you have the <sys/epoll.h> header file. */
-/* #undef _EVENT_HAVE_SYS_EPOLL_H */
+#define _EVENT_HAVE_SYS_EPOLL_H 1
/* Define to 1 if you have the <sys/event.h> header file. */
-#define _EVENT_HAVE_SYS_EVENT_H 1
+/* #undef _EVENT_HAVE_SYS_EVENT_H */
/* Define to 1 if you have the <sys/ioctl.h> header file. */
#define _EVENT_HAVE_SYS_IOCTL_H 1
@@ -198,7 +204,10 @@
#define _EVENT_HAVE_VASPRINTF 1
/* Define if kqueue works correctly with pipes */
-#define _EVENT_HAVE_WORKING_KQUEUE 1
+/* #undef _EVENT_HAVE_WORKING_KQUEUE */
+
+/* Define if realtime signals work on pipes */
+#define _EVENT_HAVE_WORKING_RTSIG 1
/* Name of package */
#define _EVENT_PACKAGE "libevent"
--- ./configure.in.orig 2008-04-05 17:03:51.000000000 -0400
+++ configure.in 2008-05-09 20:50:44.000000000 -0400
@@ -32,6 +32,11 @@
dnl AC_DISABLE_SHARED
AC_SUBST(LIBTOOL_DEPS)
+dnl Check for optional stuff
+AC_ARG_WITH(rtsig,
+ [ --with-rtsig compile with support for real time signals
(experimental)],
+ [usertsig=yes], [usertsig=no])
+
dnl Checks for libraries.
AC_CHECK_LIB(socket, socket)
AC_CHECK_LIB(resolv, inet_aton)
@@ -164,10 +169,58 @@
fi
havepoll=no
+havertsig=no
AC_CHECK_FUNCS(poll, [havepoll=yes], )
if test "x$havepoll" = "xyes" ; then
AC_LIBOBJ(poll)
needsignal=yes
+
+ if test "x$usertsig" = "xyes" ; then
+ AC_CHECK_FUNCS(sigtimedwait, [havertsig=yes], )
+ fi
+fi
+if test "x$havertsig" = "xyes" ; then
+ AC_MSG_CHECKING(for F_SETSIG in fcntl.h)
+ AC_EGREP_CPP(yes,
+[
+#define _GNU_SOURCE
+#include <fcntl.h>
+#ifdef F_SETSIG
+yes
+#endif
+], [ AC_MSG_RESULT(yes) ], [ AC_MSG_RESULT(no); havertsig=no])
+fi
+if test "x$havertsig" = "xyes" ; then
+ AC_DEFINE(HAVE_RTSIG, 1, [Define if your system supports POSIX realtime
signals])
+ AC_LIBOBJ(rtsig)
+ AC_MSG_CHECKING(for working rtsig on pipes)
+ AC_TRY_RUN(
+[
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <signal.h>
+#include <unistd.h>
+
+int sigio()
+{
+ exit(0);
+}
+
+int main()
+{
+ int fd[2];
+
+ pipe(fd);
+ signal(SIGIO, sigio);
+ fcntl(fd[0], F_SETOWN, getpid());
+ fcntl(fd[0], F_SETSIG, SIGIO);
+ fcntl(fd[0], F_SETFL, fcntl(fd[0], F_GETFL) | O_ASYNC);
+ write(fd[1], "", 1);
+ return 1;
+}
+], [ AC_MSG_RESULT(yes)
+ AC_DEFINE(HAVE_WORKING_RTSIG, 1, [Define if realtime signals work on
pipes])],
+ AC_MSG_RESULT(no))
fi
haveepoll=no
--- ./rtsig.c.orig 2008-05-12 17:00:50.000000000 -0400
+++ rtsig.c 2008-05-12 17:00:27.000000000 -0400
@@ -0,0 +1,1018 @@
+/*
+ * rtsig.c from 1.3e with fixes to compile and run on Fedora 8
+ * (2.6.24.5-85.fc8) with libevent-1.4.3-stable to perform
+ * apples-to-apples benchmarking between rtsig and epoll.
+ * by Phil Budne <[EMAIL PROTECTED]>
+ * May 2008
+ */
+/*
+ * Copyright (c) 2006 Mathew Mills <[EMAIL PROTECTED]>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+/*
+ * Meta-level comments: You know that a kernel interface is wrong if
+ * supporting it requires three times more code than any of the other
+ * kernel interfaces supported in libevent. Niels - 2006-02-22
+ */
+/**
+
+ "RTSIG" is a shorthand for using O_ASYNC to make descriptors send
+ signals when readable/writable and to use POSIX real-time signals
+ witch are queued unlike normal signals. At first blush this may
+ seem like a alternative to epoll, but a number of problems arise
+ when attempting to build an eventloop entirely out of rtsig.
+ Still, we can use rtsig in combination with poll() to
+ provide an eventloop that allows for many thousands of sockets
+ without huge overheads implicit with using select() or poll()
+ alone. epoll and kqueue are far superior to rtsig and should be
+ used where available, but rtsig has been in standard Linux kernels
+ for a long time and have a huge installation base. epoll requires
+ special patches for 2.4 kernels and 2.6 kernels are not yet nearly
+ so ubiquitous.
+
+ rtsig problems:
+ - O_ASYNC mechanisms work only on sockets - not pipes or tty's
+
+ - O_ASYNC signals are edge-triggered, POLLIN on packet arriving
+ or socket close; POLLOUT when a socket transitions from
+ non-writable to writable. Being edge-triggered means the
+ event-handler callbacks must transition the level ( reading
+ completely the socket buffer contents ) or it will be unable to
+ reliably receive notification again.
+
+ - rtsig implementations must be intimately involved in how a
+ process dispatches signals.
+
+ - delivering signals per-event can be expensive, CPU-wise, but
+ sigtimedwait() blocks on signals only and means non-sockets
+ cannot be serviced.
+
+ Theory of operation:
+ This libevent module uses rtsig to allow us to manage a set of
+ poll-event descriptors. We can drop uninteresting fd's from the
+ pollset if the fd will send a signal when it becomes interesting
+ again.
+
+ poll() offers us level-triggering and, when we have verified the
+ level of a socket, we can trust the edge-trigger nature of the
+ ASYNC signal.
+
+ As an eventloop we must poll for external events but leverage
+ kernel functionality to sleep between events ( until the loop's
+ next scheduled timed event ).
+
+ If we are polling on any non-sockets then we simply have no choice
+ about blocking on the poll() call. If we blocked on the
+ sigtimedwait() call as rtsig papers recommend we will not wake on
+ non-socket state transitions. As part of libevent, this module
+ must support non-socket polling.
+
+ Many applications, however, do not need to poll on non-sockets and
+ so this module should be able to optimize this case by using
+ sigtimedwait(). For this reason this module can actually trigger
+ events in each of three different ways:
+ - poll() returning ready events from descriptors in the pollset
+
+ - real-time signals dequeued via sigtimedwait()
+
+ - real-time signals that call an installed signal handler which in
+ turn writes the contents of siginfo to one end of a socketpair
+ DGRAM socket. The other end of the socket is always in the
+ pollset so poll will be guaranteed to return even if the signal is
+ received before entering poll().
+
+ non-socket descriptors force us to block on the poll() for the
+ duration of a dispatch. In this case we unblock (w/ sigprocmask)
+ the managed signals just before polling. Each managed signal is
+ handled by signal_handler() which send()'s the contents of siginfo
+ over the socketpair. Otherwise, we call poll() with a timeout of
+ 0ms so it checks the levels of the fd's in the pollset and returns
+ immediately. Any fd that is a socket and has no active state is
+ removed from the pollset for the next pass -- we will rely on
+ getting a signal for events on these fd's.
+
+ The receiving end of the siginfo socketpair is in the pollset
+ (permanently) so if we are polling on non-sockets, the delivery of
+ signals immediately following sigprocmask( SIG_UNBLOCK...) will
+ result in a readable op->signal_recv_fd which ensures the poll()
+ will return immediately. If the poll() call is blocking and a
+ signal arrives ( possibly a real-time signal from a socket not in
+ the pollset ) its handler will write the data to the socketpair
+ and interrupt the poll().
+
+ After every poll call we attempt a non-blocking recv from the
+ signal_recv_fd and continue to recv and dispatch the events until
+ recv indicates the socket buffer is empty.
+
+ One might raise concerns about receiving event activations from
+ both poll() and from the rtsig data in the signal_recv_fd.
+ Fortunately, libevent is already structured for event coalescing,
+ so this issue is mitigated ( though we do some work twice for the
+ same event making us less efficient ). I suspect that the cost of
+ turning off the O_ASYNC flag on fd's in the pollset is more
+ expensive than handling some events twice. Looking at the
+ kernel's source code for setting O_ASYNC, it looks like it takes a
+ global kernel lock...
+
+ After a poll and recv-loop for the signal_recv_fd, we finally do a
+ sigtimedwait(). sigtimedwait will only block if we haven't
+ blocked in poll() and we have not enqueued events from either the
+ poll or the recv-loop. Because sigtimedwait blocks all signals
+ that are not in the set of signals to be dequeued, we need to
+ dequeue almost all signals and make sure we dispatch them
+ correctly. We dequeue any signal that is not blocked as well as
+ all libevent-managed signals. If we get a signal that is not
+ managed by libevent we lookup the sigaction for the specific
+ signal and call that function ourselves.
+
+ Finally, I should mention that getting a SIGIO signal indicates
+ that the rtsig buffer has overflowed and we have lost events.
+ This forces us to add _every_ descriptor to the pollset to recover.
+
+*/
+
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+/* Enable F_SETSIG and F_SETOWN */
+#define _GNU_SOURCE
+
+#include <sys/types.h>
+#ifdef HAVE_SYS_TIME_H
+#include <sys/time.h>
+#else
+#include <sys/_time.h>
+#endif
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/poll.h>
+#include <sys/queue.h>
+#include <unistd.h>
+#include <sys/socket.h>
+
+#include "event.h"
+#include "event-internal.h"
+#include "log.h"
+
+#ifndef __NR_gettid
+#define gettid() getpid()
+#else
+#if ((__GLIBC__ > 2) || ((__GLIBC__ == 2) && (__GLIBC_MINOR__ >= 3)))
+#ifdef _syscall0
+_syscall0(pid_t,gettid)
+#else
+pid_t gettid(void) {
+ return syscall(__NR_gettid);
+}
+#endif
+#endif
+
+#endif
+
+#define EVLIST_NONSOCK 0x1000 /* event is for a non-socket file-descriptor */
+#define EVLIST_DONTDEL 0x2000 /* event should always be in the pollset */
+#define MAXBUFFERSIZE (1024 * 1024 * 2) /* max socketbuffer for signal-spair */
+#define INIT_MAX 16 /* init/min # of fd positions in our pollset */
+
+static int signal_send_fd[_NSIG]; /* the globalend of the signal socketpair */
+static int trouble[_NSIG]; /* 1 when signal-handler cant send to
signal_send_fd */
+
+struct rtdata;
+TAILQ_HEAD(rtdata_list, rtdata);
+
+struct rtsigop {
+ sigset_t sigs; /* signal mask for all _managed_ signals */
+ struct pollfd *poll; /* poll structures */
+ struct rtdata **ptodat; /* map poll_position to rtdata */
+ int cur; /* cur # fd's in a poll set */
+ int max; /* max # fd's in a poll set, start at 16 and grow
as needed */
+ int total; /* count of fd's we are watching now */
+ int signo; /* the signo we use for ASYNC fd notifications */
+ int nonsock; /* number of non-socket fd's we are watching */
+ int highestfd; /* highest fd accomodated by fdtodat */
+ struct rtdata_list **fdtodat; /* map fd to rtdata ( and thus to event )
*/
+ int signal_recv_fd; /* recv side of the signal_send_fd */
+ int signal_send_fd; /* recv side of the signal_send_fd */
+ struct event sigfdev; /* our own event structure for the signal fd */
+};
+
+struct rtdata {
+ /* rtdata holds rtsig-private state on each event */
+ TAILQ_ENTRY (rtdata) next;
+ struct event *ev;
+ int poll_position;
+};
+
+static void *rtsig_init(struct event_base *);
+static int rtsig_add(void *, struct event *);
+static int rtsig_del(void *, struct event *);
+static int rtsig_dispatch(struct event_base *, void *, struct timeval *);
+static void rtsig_dealloc (struct event_base *, void *);
+
+struct eventop rtsigops = {
+ "rtsig",
+ rtsig_init,
+ rtsig_add,
+ rtsig_del,
+ rtsig_dispatch,
+ rtsig_dealloc,
+ 1 /* need reinit ??? */
+};
+
+static void
+signal_handler(int sig, siginfo_t *info, void *ctx)
+{
+ /*
+ * the signal handler for all libevent-managed signals only
+ * used if we need to do a blocking poll() call due to
+ * non-socket fd's in the pollset.
+ */
+
+ siginfo_t *i = info;
+ siginfo_t i_local;
+
+ if (trouble[sig - 1]) {
+ i_local.si_signo = SIGIO;
+ i_local.si_errno = 0;
+ i_local.si_code = 0;
+ i = &i_local;
+ trouble[sig - 1] = 0;
+ }
+
+ if (send(signal_send_fd[sig - 1], i, sizeof(*i),
+ MSG_DONTWAIT|MSG_NOSIGNAL) == -1)
+ trouble[sig - 1] = 1;
+}
+
+static void
+donothing(int fd, short event, void *arg)
+{
+ /*
+ * callback for our signal_recv_fd event structure
+ * we don't want to act on these events, we just want to wake the poll()
+ */
+};
+
+static void
+signotset(sigset_t *set)
+{
+ int i, l;
+ l = sizeof(*set) / 4;
+ for (i = 0; i < l; i++) {
+ ((unsigned *)set)[i] = ~((unsigned *)set)[i];
+ }
+}
+
+/* The next three functions manage our private data about each event struct */
+
+static int
+grow_fdset(struct rtsigop *op, int newhigh)
+{
+ /*
+ * grow the fd -> rtdata array because we have encountered a
+ * new fd too high to fit in the existing array
+ */
+
+ struct rtdata_list **p;
+ struct rtdata_list *datset;
+ int i,x;
+ int newcnt = (newhigh + 1) << 1;
+
+ if (newhigh <= op->highestfd)
+ return (0);
+
+ p = op->fdtodat;
+ p = realloc(op->fdtodat, sizeof(struct rtdata_list *) * newcnt);
+ if (p == NULL)
+ return (-1);
+ op->fdtodat = p;
+
+ datset = calloc(newcnt - (op->highestfd + 1),
+ sizeof(struct rtdata_list));
+ if (datset == NULL)
+ return (-1);
+
+ for (i = op->highestfd + 1, x = 0; i < newcnt; i++, x++) {
+ op->fdtodat[i] = &(datset[x]);
+ TAILQ_INIT(op->fdtodat[i]);
+ }
+
+ op->highestfd = newcnt - 1;
+ return (0);
+}
+
+static struct rtdata *
+ev2dat(struct rtsigop *op, struct event *ev, int create)
+{
+ /*
+ * given an event struct, find the dat structure that
+ * corresponds to it if create is non-zero and the rtdata
+ * structure does not exist, create it return NULL if not
+ * found
+ */
+
+ int found = 0;
+ int fd = ev->ev_fd;
+ struct rtdata *ret = NULL;
+
+ if (op->highestfd < fd && create)
+ if (grow_fdset(op, fd) == -1)
+ return (NULL);
+
+ TAILQ_FOREACH(ret, op->fdtodat[fd], next) {
+ if (ret->ev == ev) {
+ found = 1;
+ break;
+ }
+ }
+
+ if (!found) {
+ if (!create)
+ return (NULL);
+
+ ret = calloc(1, sizeof(struct rtdata));
+ if (ret == NULL)
+ return (NULL);
+ ret->ev = ev;
+ ret->poll_position = -1;
+ TAILQ_INSERT_TAIL(op->fdtodat[fd], ret, next);
+ }
+
+ return (ret);
+}
+
+static void
+dat_del(struct rtsigop *op, struct rtdata *dat)
+{
+ /*
+ * delete our private notes about a given event struct
+ * called from rtsig_del() only
+ */
+ int fd;
+ if (dat == NULL)
+ return;
+ fd = dat->ev->ev_fd;
+
+ TAILQ_REMOVE(op->fdtodat[fd], dat, next);
+ memset(dat, 0, sizeof(*dat));
+ free(dat);
+}
+
+
+static void
+set_sigaction(int sig)
+{
+ /*
+ * set the standard handler for any libevent-managed signal,
+ * including the rtsig used for O_ASYNC notifications
+ */
+ struct sigaction act;
+
+ act.sa_flags = SA_RESTART | SA_SIGINFO;
+ sigfillset(&(act.sa_mask));
+ act.sa_sigaction = &signal_handler;
+ sigaction(sig, &act, NULL);
+}
+
+static int
+find_rt_signal()
+{
+ /* find an unused rtsignal */
+ struct sigaction act;
+ int sig = SIGRTMIN;
+
+ while (sig <= SIGRTMAX) {
+ if (sigaction(sig, NULL, &act) != 0) {
+ if (errno == EINTR)
+ continue;
+ } else {
+ if (act.sa_flags & SA_SIGINFO) {
+ if (act.sa_sigaction == NULL)
+ return (sig);
+ } else {
+ if (act.sa_handler == SIG_DFL)
+ return (sig);
+ }
+ }
+ sig++;
+ }
+ return (0);
+}
+
+/*
+ * the next three functions manage our pollset and the memory management for
+ * fd -> rtdata -> event -> poll_position maps
+ */
+
+static int
+poll_add(struct rtsigop *op, struct event *ev, struct rtdata *dat)
+{
+ struct pollfd *pfd;
+ int newmax = op->max << 1;
+ int pp;
+
+ if (op->poll == NULL)
+ return (0);
+
+ if (dat == NULL)
+ dat = ev2dat(op, ev, 0);
+
+ if (dat == NULL)
+ return (0);
+
+ pp = dat->poll_position;
+
+ if (pp != -1) {
+ pfd = &op->poll[pp];
+ if (ev->ev_events & EV_READ)
+ pfd->events |= POLLIN;
+
+ if (ev->ev_events & EV_WRITE)
+ pfd->events |= POLLOUT;
+
+ return (0);
+ }
+
+ if (op->cur == op->max) {
+ void *p = realloc(op->poll, sizeof(*op->poll) * newmax);
+ if (p == NULL) {
+ errno = ENOMEM;
+ return (-1);
+ }
+ op->poll = p;
+
+ p = realloc(op->ptodat, sizeof(*op->ptodat) * newmax);
+ if (p == NULL) {
+ /* shrink the pollset back down */
+ op->poll = realloc(op->poll,
+ sizeof(*op->poll) * op->max);
+ errno = ENOMEM;
+ return (-1);
+ }
+ op->ptodat = p;
+ op->max = newmax;
+ }
+
+ pfd = &op->poll[op->cur];
+ pfd->fd = ev->ev_fd;
+ pfd->revents = 0;
+ pfd->events = 0;
+
+ if (ev->ev_events & EV_READ)
+ pfd->events |= POLLIN;
+
+ if (ev->ev_events & EV_WRITE)
+ pfd->events |= POLLOUT;
+
+ op->ptodat[op->cur] = dat;
+ dat->poll_position = op->cur;
+ op->cur++;
+
+ return (0);
+}
+
+static void
+poll_free(struct rtsigop *op, int n)
+{
+ if (op->poll == NULL)
+ return;
+
+ op->cur--;
+
+ if (n < op->cur) {
+ memcpy(&op->poll[n], &op->poll[op->cur], sizeof(*op->poll));
+ op->ptodat[n] = op->ptodat[op->cur];
+ op->ptodat[n]->poll_position = n;
+ }
+
+
+ /* less then half the max in use causes us to shrink */
+ if (op->max > INIT_MAX && op->cur < op->max >> 1) {
+ op->max >>= 1;
+ op->poll = realloc(op->poll, sizeof(*op->poll) * op->max);
+ op->ptodat = realloc(op->ptodat, sizeof(*op->ptodat) * op->max);
+ }
+}
+
+static void
+poll_remove(struct rtsigop *op, struct event *ev, struct rtdata *dat)
+{
+ int pp;
+ if (dat == NULL)
+ dat = ev2dat(op, ev, 0);
+
+ if (dat == NULL) return;
+
+ pp = dat->poll_position;
+ if (pp != -1) {
+ poll_free(op, pp);
+ dat->poll_position = -1;
+ }
+}
+
+static void
+activate(struct event *ev, int flags)
+{
+ /* activate an event, possibly removing one-shot events */
+ if (!(ev->ev_events & EV_PERSIST))
+ event_del(ev);
+ event_active(ev, flags, 1);
+}
+
+#define FD_CLOSEONEXEC(x) do { \
+ if (fcntl(x, F_SETFD, 1) == -1) \
+ event_warn("fcntl(%d, F_SETFD)", x); \
+} while (0)
+
+static void *
+rtsig_init(struct event_base *base)
+{
+ struct rtsigop *op;
+ int sockets[2];
+ int optarg;
+ struct rtdata *dat;
+ int flags;
+
+ if (getenv("EVENT_NORTSIG"))
+ goto err;
+
+ op = calloc(1, sizeof(*op));
+ if (op == NULL)
+ goto err;
+
+ op->max = INIT_MAX;
+ op->poll = malloc(sizeof(*op->poll) * op->max);
+ if (op->poll == NULL)
+ goto err_free_op;
+
+ op->signo = find_rt_signal();
+ if (op->signo == 0)
+ goto err_free_poll;
+
+ op->nonsock = 0;
+
+ if (socketpair(PF_UNIX, SOCK_DGRAM, 0, sockets) != 0)
+ goto err_free_poll;
+
+ FD_CLOSEONEXEC(sockets[0]);
+ FD_CLOSEONEXEC(sockets[1]);
+
+ signal_send_fd[op->signo - 1] = sockets[0];
+ trouble[op->signo - 1] = 0;
+ op->signal_send_fd = sockets[0];
+ op->signal_recv_fd = sockets[1];
+ flags = fcntl(op->signal_recv_fd, F_GETFL);
+ fcntl(op->signal_recv_fd, F_SETFL, flags | O_NONBLOCK);
+
+ optarg = MAXBUFFERSIZE;
+ setsockopt(signal_send_fd[op->signo - 1],
+ SOL_SOCKET, SO_SNDBUF,
+ &optarg, sizeof(optarg));
+
+ optarg = MAXBUFFERSIZE;
+ setsockopt(op->signal_recv_fd,
+ SOL_SOCKET, SO_RCVBUF,
+ &optarg, sizeof(optarg));
+
+ op->highestfd = -1;
+ op->fdtodat = NULL;
+ if (grow_fdset(op, 1) == -1)
+ goto err_close_pair;
+
+ op->ptodat = malloc(sizeof(*op->ptodat) * op->max);
+ if (op->ptodat == NULL)
+ goto err_close_pair;
+
+ sigemptyset(&op->sigs);
+ sigaddset(&op->sigs, SIGIO);
+ sigaddset(&op->sigs, op->signo);
+ sigprocmask(SIG_BLOCK, &op->sigs, NULL);
+ set_sigaction(SIGIO);
+ set_sigaction(op->signo);
+
+ event_set(&(op->sigfdev), op->signal_recv_fd, EV_READ|EV_PERSIST,
+ donothing, NULL);
+ op->sigfdev.ev_flags |= EVLIST_DONTDEL;
+ dat = ev2dat(op, &(op->sigfdev), 1);
+ poll_add(op, &(op->sigfdev), dat);
+
+ return (op);
+
+ err_close_pair:
+ close(op->signal_recv_fd);
+ close(signal_send_fd[op->signo - 1]);
+
+ err_free_poll:
+ free(op->poll);
+
+ err_free_op:
+ free(op);
+ err:
+ return (NULL);
+}
+
+static int
+rtsig_add(void *arg, struct event *ev)
+{
+ struct rtsigop *op = (struct rtsigop *) arg;
+ int flags, i;
+ struct stat statbuf;
+ struct rtdata *dat;
+
+ if (ev->ev_events & EV_SIGNAL) {
+ int signo = EVENT_SIGNAL(ev);
+
+ sigaddset(&op->sigs, EVENT_SIGNAL(ev));
+ if (sigprocmask(SIG_BLOCK, &op->sigs, NULL) == -1)
+ return (-1);
+
+ set_sigaction(signo);
+
+ signal_send_fd[signo - 1] = op->signal_send_fd;
+ trouble[signo - 1] = 0;
+
+ return (0);
+ }
+
+ if (!(ev->ev_events & (EV_READ|EV_WRITE)))
+ return (0);
+
+ if (-1 == fstat(ev->ev_fd, &statbuf))
+ return (-1);
+
+ if (!S_ISSOCK(statbuf.st_mode))
+ ev->ev_flags |= EVLIST_NONSOCK;
+
+ flags = fcntl(ev->ev_fd, F_GETFL);
+ if (flags == -1)
+ return (-1);
+
+ if (!(flags & O_ASYNC)) {
+ if (fcntl(ev->ev_fd, F_SETSIG, op->signo) == -1 ||
+ fcntl(ev->ev_fd, F_SETOWN, (int) gettid()) == -1)
+ return (-1);
+
+ /*
+ * the overhead of always handling writeable edges
+ * isn't going to be that bad...
+ */
+ if (fcntl(ev->ev_fd, F_SETFL, flags | O_ASYNC|O_RDWR))
+ return (-1);
+ }
+
+#ifdef O_ONESIGFD
+ /*
+ * F_SETAUXFL and O_ONESIGFD are defined in a non-standard
+ * linux kernel patch to coalesce events for fds
+ */
+ fcntl(ev->ev_fd, F_SETAUXFL, O_ONESIGFD);
+#endif
+
+ dat = ev2dat(op, ev, 1);
+ if (dat == NULL)
+ return (-1);
+
+ op->total++;
+ if (ev->ev_flags & EVLIST_NONSOCK)
+ op->nonsock++;
+
+ if (poll_add(op, ev, dat) == -1) {
+ /* must check the level of new fd's */
+ i = errno;
+ fcntl(ev->ev_fd, F_SETFL, flags);
+ errno = i;
+ return (-1);
+ }
+
+ return (0);
+}
+
+static int
+rtsig_del(void *arg, struct event *ev)
+{
+ struct rtdata *dat;
+ struct rtsigop *op = (struct rtsigop *) arg;
+
+ if (ev->ev_events & EV_SIGNAL) {
+ sigset_t sigs;
+
+ sigdelset(&op->sigs, EVENT_SIGNAL(ev));
+
+ sigemptyset(&sigs);
+ sigaddset(&sigs, EVENT_SIGNAL(ev));
+ return (sigprocmask(SIG_UNBLOCK, &sigs, NULL));
+ }
+
+ if (!(ev->ev_events & (EV_READ|EV_WRITE)))
+ return (0);
+
+ dat = ev2dat(op, ev, 0);
+ poll_remove(op, ev, dat);
+ dat_del(op, dat);
+ op->total--;
+ if (ev->ev_flags & EVLIST_NONSOCK)
+ op->nonsock--;
+
+ return (0);
+}
+
+/*
+ * the following do_X functions implement the different stages of a single
+ * eventloop pass: poll(), recv(sigsock), sigtimedwait()
+ *
+ * do_siginfo_dispatch() is a common factor to both do_sigwait() and
+ * do_signals_from_socket().
+ */
+
+static inline int
+do_poll(struct rtsigop *op, struct timespec *ts, struct timespec **ts_p)
+{
+ int res = 0;
+ int i = 0;
+
+ if (op->cur > 1) {
+ /* non-empty poll set (modulo the signalfd) */
+ if (op->nonsock) {
+ int timeout = -1;
+
+ if (*ts_p != NULL)
+ timeout = (*ts_p)->tv_nsec / 1000000
+ + (*ts_p)->tv_sec * 1000;
+
+ sigprocmask(SIG_UNBLOCK, &(op->sigs), NULL);
+
+ res = poll(op->poll, op->cur, timeout);
+
+ sigprocmask(SIG_BLOCK, &(op->sigs), NULL);
+
+ ts->tv_sec = 0;
+ ts->tv_nsec = 0;
+ if (*ts_p)
+ *ts_p = ts;
+ } else {
+ res = poll(op->poll, op->cur, 0);
+ }
+
+ if (res < 0) {
+ return (errno == EINTR ? 0 : -1);
+ } else if (res) {
+ ts->tv_sec = 0;
+ ts->tv_nsec = 0;
+ if (*ts_p)
+ *ts_p = ts;
+ }
+
+ i = 0;
+ while (i < op->cur) {
+ struct rtdata *dat = op->ptodat[i];
+ struct event *ev = dat->ev;
+
+ if (op->poll[i].revents) {
+ int flags = 0;
+
+ if (op->poll[i].revents & (POLLIN | POLLERR))
+ flags |= EV_READ;
+
+ if (op->poll[i].revents & POLLOUT)
+ flags |= EV_WRITE;
+
+ if (!(ev->ev_events & EV_PERSIST)) {
+ poll_remove(op, ev, op->ptodat[i]);
+ event_del(ev);
+ } else {
+ i++;
+ }
+
+ event_active(ev, flags, 1);
+ } else {
+ if (ev->ev_flags &
(EVLIST_NONSOCK|EVLIST_DONTDEL)) {
+ i++;
+ } else {
+ poll_remove(op, ev, op->ptodat[i]);
+ }
+ }
+ }
+ }
+ return (res);
+}
+
+static inline int
+do_siginfo_dispatch(struct event_base *base, struct rtsigop *op,
+ siginfo_t *info)
+{
+ int signum;
+ struct rtdata *dat, *next_dat;
+ struct event *ev, *next_ev;
+
+ if (info == NULL)
+ return (-1);
+
+ signum = info->si_signo;
+ if (signum == op->signo) {
+ int flags, sigok = 0;
+ flags = 0;
+
+ if (info->si_band & (POLLIN|POLLERR))
+ flags |= EV_READ;
+ if (info->si_band & POLLOUT)
+ flags |= EV_WRITE;
+
+ if (!flags)
+ return (0);
+
+ if (info->si_fd > op->highestfd)
+ return (-1);
+
+ dat = TAILQ_FIRST(op->fdtodat[info->si_fd]);
+ while (dat != TAILQ_END(op->fdtodat[info->si_fd])) {
+ next_dat = TAILQ_NEXT(dat, next);
+ if (flags & dat->ev->ev_events) {
+ ev = dat->ev;
+ poll_add(op, ev, dat);
+ activate(ev, flags & ev->ev_events);
+ sigok = 1;
+ }
+ dat = next_dat;
+ }
+ } else if (signum == SIGIO) {
+ TAILQ_FOREACH(ev, &base->eventqueue, ev_next) {
+ if (ev->ev_events & (EV_READ|EV_WRITE))
+ poll_add(op, ev, NULL);
+ }
+ return (1); /* 1 means the caller should poll() again */
+
+ } else if (sigismember(&op->sigs, signum)) {
+ /* managed signals are queued */
+ ev = TAILQ_FIRST(&base->sig.signalqueue);
+ while (ev != TAILQ_END(&base->sig.signalqueue)) {
+ next_ev = TAILQ_NEXT(ev, ev_signal_next);
+ if (EVENT_SIGNAL(ev) == signum)
+ activate(ev, EV_SIGNAL);
+ ev = next_ev;
+ }
+ } else {
+ /* dispatch unmanaged signals immediately */
+ struct sigaction sa;
+ if (sigaction(signum, NULL, &sa) == 0) {
+ if ((sa.sa_flags & SA_SIGINFO) && sa.sa_sigaction) {
+ (*sa.sa_sigaction)(signum, info, NULL);
+ } else if (sa.sa_handler) {
+ if ((int)sa.sa_handler != 1)
+ (*sa.sa_handler)(signum);
+ } else {
+ if (signum != SIGCHLD) {
+ /* non-blocked SIG_DFL */
+ kill(gettid(), signum);
+ }
+ }
+ }
+ }
+
+ return (0);
+}
+
+/*
+ * return 1 if we should poll again
+ * return 0 if we are all set
+ * return -1 on error
+ */
+static inline int
+do_sigwait(struct event_base *base, struct rtsigop *op,
+ struct timespec *ts, struct timespec **ts_p, sigset_t *sigs)
+{
+ for (;;) {
+ siginfo_t info;
+ int signum;
+
+ signum = sigtimedwait(sigs, &info, *ts_p);
+
+ ts->tv_sec = 0;
+ ts->tv_nsec = 0;
+ *ts_p = ts;
+
+ if (signum == -1) {
+ if (errno == EAGAIN || errno == EINTR)
+ return (0);
+ return (-1);
+ } else if (1 == do_siginfo_dispatch(base, op, &info)) {
+ return (1);
+ }
+ }
+
+ /* NOTREACHED */
+}
+
+static inline int
+do_signals_from_socket(struct event_base *base, struct rtsigop *op,
+ struct timespec *ts, struct timespec **ts_p)
+{
+ int fd = op->signal_recv_fd;
+ siginfo_t info;
+ int res;
+
+ for (;;) {
+ res = recv(fd, &info, sizeof(info), MSG_NOSIGNAL);
+ if (res == -1) {
+ if (errno == EAGAIN)
+ return (0);
+ if (errno == EINTR)
+ continue;
+ return (-1);
+ } else {
+ ts->tv_sec = 0;
+ ts->tv_nsec = 0;
+ *ts_p = ts;
+ if (1 == do_siginfo_dispatch(base, op, &info))
+ return (1);
+ }
+ }
+ /* NOTREACHED */
+}
+
+static int
+rtsig_dispatch(struct event_base *base, void *arg, struct timeval *tv)
+{
+ struct rtsigop *op = (struct rtsigop *) arg;
+ struct timespec ts, *ts_p = NULL;
+ int res;
+ sigset_t sigs;
+
+ if (tv != NULL) {
+ ts.tv_sec = tv->tv_sec;
+ ts.tv_nsec = tv->tv_usec * 1000;
+ ts_p = &ts;
+ }
+
+ poll_for_level:
+ /* ts and ts_p can be modified in do_XXX() */
+ res = do_poll(op, &ts, &ts_p);
+
+ res = do_signals_from_socket(base, op, &ts, &ts_p);
+ if (res == 1)
+ goto poll_for_level;
+ else if (res == -1)
+ return (-1);
+
+ /*
+ * the mask = managed_signals | unblocked-signals
+ * MM - if this is not blocking do we need to cast the net this wide?
+ */
+ sigemptyset(&sigs);
+ sigprocmask(SIG_BLOCK, &sigs, &sigs);
+ signotset(&sigs);
+ sigorset(&sigs, &sigs, &op->sigs);
+
+ res = do_sigwait(base, op, &ts, &ts_p, &sigs);
+
+ if (res == 1)
+ goto poll_for_level;
+ else if (res == -1)
+ return (-1);
+
+ return (0);
+}
+
+
+static void
+rtsig_dealloc(struct event_base *base, void *arg)
+{
+ struct rtsigop *op = arg;
+
+ evsignal_dealloc(base);
+ if (op->poll)
+ free(op->poll);
+ if (op->ptodat)
+ free(op->ptodat);
+
+ memset(op, 0, sizeof(struct rtsigop));
+ free(op);
+}
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