*** empty log message ***

4 files changed, 71 insertions, 11 deletions

diff --git a/Changes b/Changes
index 647c1d6..0d386a6 100644
--- a/Changes
+++ b/Changes
@@ -1,5 +1,8 @@
 Revision history for libev, a high-performance and full-featured event loop.
 
+	- new config symbol, EV_USE_CLOCK_SYSCALL, to make libev use
+          a direct syscall - slower, but no dependency on librt et al.
+
 3.49 Wed Nov 19 11:26:53 CET 2008
 	- ev_stat watchers will now use inotify as a mere hint on
           kernels <2.6.25, or if the filesystem is not in the
diff --git a/ev.c b/ev.c
index c872176..538f6a5 100644
--- a/ev.c
+++ b/ev.c
@@ -49,6 +49,18 @@ extern "C" {
 #  include "config.h"
 # endif
 
+# if HAVE_CLOCK_SYSCALL
+#  ifndef EV_USE_CLOCK_SYSCALL
+#   define EV_USE_CLOCK_SYSCALL 1
+#   ifndef EV_USE_REALTIME
+#    define EV_USE_REALTIME  0
+#   endif
+#   ifndef EV_USE_MONOTONIC
+#    define EV_USE_MONOTONIC 1
+#   endif
+#  endif
+# endif
+
 # if HAVE_CLOCK_GETTIME
 #  ifndef EV_USE_MONOTONIC
 #   define EV_USE_MONOTONIC 1
@@ -166,6 +178,14 @@ extern "C" {
 
 /* this block tries to deduce configuration from header-defined symbols and defaults */
 
+#ifndef EV_USE_CLOCK_SYSCALL
+# if __linux && __GLIBC__ >= 2
+#  define EV_USE_CLOCK_SYSCALL 1
+# else
+#  define EV_USE_CLOCK_SYSCALL 0
+# endif
+#endif
+
 #ifndef EV_USE_MONOTONIC
 # if defined (_POSIX_MONOTONIC_CLOCK) && _POSIX_MONOTONIC_CLOCK >= 0
 #  define EV_USE_MONOTONIC 1
@@ -302,6 +322,15 @@ extern "C" {
 # include <winsock.h>
 #endif
 
+/* on linux, we can use a (slow) syscall to avoid a dependency on pthread, */
+/* which makes programs even slower. might work on other unices, too. */
+#if EV_USE_CLOCK_SYSCALL
+# include <syscall.h>
+# define clock_gettime(id, ts) syscall (SYS_clock_gettime, (id), (ts))
+# undef EV_USE_MONOTONIC
+# define EV_USE_MONOTONIC 1
+#endif
+
 #if EV_USE_EVENTFD
 /* our minimum requirement is glibc 2.7 which has the stub, but not the header */
 # include <stdint.h>
diff --git a/ev.pod b/ev.pod
index 48e39da..3803d11 100644
--- a/ev.pod
+++ b/ev.pod
@@ -3001,6 +3001,9 @@ of the libev API and adds file handle abstractions, asynchronous DNS and
 more on top of it. It can be found via gem servers. Its homepage is at
 L<http://rev.rubyforge.org/>.
 
+Roger Pack reports that using the link order C<-lws2_32 -lmsvcrt-ruby-190>
+makes rev work even on mingw.
+
 =item D
 
 Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to
@@ -3186,15 +3189,18 @@ implementations for some libevent functions (such as logging, which is not
 supported). It will also not define any of the structs usually found in
 F<event.h> that are not directly supported by the libev core alone.
 
+In stanbdalone mode, libev will still try to automatically deduce the
+configuration, but has to be more conservative.
+
 =item EV_USE_MONOTONIC
 
 If defined to be C<1>, libev will try to detect the availability of the
-monotonic clock option at both compile time and runtime. Otherwise no use
-of the monotonic clock option will be attempted. If you enable this, you
-usually have to link against librt or something similar. Enabling it when
-the functionality isn't available is safe, though, although you have
+monotonic clock option at both compile time and runtime. Otherwise no
+use of the monotonic clock option will be attempted. If you enable this,
+you usually have to link against librt or something similar. Enabling it
+when the functionality isn't available is safe, though, although you have
 to make sure you link against any libraries where the C<clock_gettime>
-function is hiding in (often F<-lrt>).
+function is hiding in (often F<-lrt>). See also C<EV_USE_CLOCK_SYSCALL>.
 
 =item EV_USE_REALTIME
 
@@ -3205,6 +3211,16 @@ be attempted. This effectively replaces C<gettimeofday> by C<clock_get
 (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the
 note about libraries in the description of C<EV_USE_MONOTONIC>, though.
 
+=item EV_USE_CLOCK_SYSCALL
+
+If defined to be C<1>, libev will try to use a direct syscall instead
+of calling the system-provided C<clock_gettime> function. This option
+exists because on GNU/Linux, C<clock_gettime> is in C<librt>, but C<librt>
+unconditionally pulls in C<libpthread>, slowing down single-threaded
+programs needlessly. Using a direct syscall is slightly slower, because
+no optimised vdso implementation can be used, but avoids the pthread
+dependency. Defaults to C<1> on GNU/Linux with glibc 2.x or higher.
+
 =item EV_USE_NANOSLEEP
 
 If defined to be C<1>, libev will assume that C<nanosleep ()> is available
@@ -3229,11 +3245,11 @@ will not be compiled in.
 
 If defined to C<1>, then the select backend will use the system C<fd_set>
 structure. This is useful if libev doesn't compile due to a missing
-C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on
-exotic systems. This usually limits the range of file descriptors to some
-low limit such as 1024 or might have other limitations (winsocket only
-allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might
-influence the size of the C<fd_set> used.
+C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout
+on exotic systems. This usually limits the range of file descriptors to
+some low limit such as 1024 or might have other limitations (winsocket
+only allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation,
+configures the maximum size of the C<fd_set>.
 
 =item EV_SELECT_IS_WINSOCKET
 
diff --git a/libev.m4 b/libev.m4
index 393835e..2ba20eb 100644
--- a/libev.m4
+++ b/libev.m4
@@ -7,7 +7,19 @@ AC_CHECK_HEADERS(sys/inotify.h sys/epoll.h sys/event.h sys/queue.h port.h poll.h
 AC_CHECK_FUNCS(inotify_init epoll_ctl kqueue port_create poll select eventfd)
  
 AC_CHECK_FUNC(clock_gettime, [], [ 
-   if test -z "$LIBEV_M4_AVOID_LIBRT"; then
+   dnl on linux, try syscall wrapper first
+   if test $(uname) = Linux; then
+      AC_MSG_CHECKING(for clock_gettime syscall)
+      AC_LINK_IFELSE([AC_LANG_PROGRAM(
+                      [#include <syscall.h>
+                       #include <time.h>],
+                      [struct timespec ts; int status = syscall (SYS_clock_gettime, CLOCK_REALTIME, &ts)])],
+                     [ac_have_clock_syscall=1
+                      AC_DEFINE(HAVE_CLOCK_SYSCALL, 1, "use syscall interface for clock_gettime")
+                      AC_MSG_RESULT(yes)],
+                     [AC_MSG_RESULT(no)])
+   fi
+   if test -z "$LIBEV_M4_AVOID_LIBRT" && test -z "$ac_have_clock_syscall"; then
       AC_CHECK_LIB(rt, clock_gettime) 
       unset ac_cv_func_clock_gettime
       AC_CHECK_FUNCS(clock_gettime)