more minimal tuning, add truly minimal example

4 files changed, 116 insertions, 27 deletions

diff --git a/Changes b/Changes
index 57f6cb8..9997f15 100644
--- a/Changes
+++ b/Changes
@@ -1,8 +1,9 @@
 Revision history for libev, a high-performance and full-featured event loop.
 
+TODO: accept() documentation
 	- ev_embed_stop did not correctly stop the watcher (very good
           testcase by Vladimir Timofeev).
-	- applied win32 fixes by Michael Lenaghan.
+	- applied win32 fixes by Michael Lenaghan (also James Mansion).
         - remove dependency on sys/queue.h on freebsd (patch by Vanilla Hsu).
         - configure now prepends -O3, not appends it, so one can still
           override it.
@@ -14,6 +15,7 @@ Revision history for libev, a high-performance and full-featured event loop.
         - implement EV_AVOID_STDIO option.
         - do not use sscanf to parse linux version number (smaller, faster,
           no sscanf dependency).
+        - new EV_CHILD_ENABLE and EV_SIGNAL_ENABLE configurable settings.
 
 3.9  Thu Dec 31 07:59:59 CET 2009
 	- signalfd is no longer used by default and has to be requested
diff --git a/ev.c b/ev.c
index d0a160a..2a66b60 100644
--- a/ev.c
+++ b/ev.c
@@ -209,12 +209,13 @@ extern "C" {
 #elif defined (MAX_SIG)
 # define EV_NSIG (MAX_SIG+1)
 #elif defined (SIGARRAYSIZE)
-# define EV_NSIG SIGARRAYSIZE /* Assume ary[SIGARRAYSIZE] */
+# define EV_NSIG (SIGARRAYSIZE) /* Assume ary[SIGARRAYSIZE] */
 #elif defined (_sys_nsig)
 # define EV_NSIG (_sys_nsig) /* Solaris 2.5 */
 #else
 # error "unable to find value for NSIG, please report"
-/* to make it compile regardless, just remove the above line */
+/* to make it compile regardless, just remove the above line, */
+/* but consider reporting it, too! :) */
 # define EV_NSIG 65
 #endif
 
@@ -994,7 +995,7 @@ fd_kill (EV_P_ int fd)
     }
 }
 
-/* check whether the given fd is atcually valid, for error recovery */
+/* check whether the given fd is actually valid, for error recovery */
 inline_size int
 fd_valid (int fd)
 {
@@ -1046,6 +1047,20 @@ fd_rearm_all (EV_P)
       }
 }
 
+/* used to prepare libev internal fd's */
+/* this is not fork-safe */
+inline_speed void
+fd_intern (int fd)
+{
+#ifdef _WIN32
+  unsigned long arg = 1;
+  ioctlsocket (EV_FD_TO_WIN32_HANDLE (fd), FIONBIO, &arg);
+#else
+  fcntl (fd, F_SETFD, FD_CLOEXEC);
+  fcntl (fd, F_SETFL, O_NONBLOCK);
+#endif
+}
+
 /*****************************************************************************/
 
 /*
@@ -1207,26 +1222,14 @@ static ANSIG signals [EV_NSIG - 1];
 
 /*****************************************************************************/
 
-/* used to prepare libev internal fd's */
-/* this is not fork-safe */
-inline_speed void
-fd_intern (int fd)
-{
-#ifdef _WIN32
-  unsigned long arg = 1;
-  ioctlsocket (EV_FD_TO_WIN32_HANDLE (fd), FIONBIO, &arg);
-#else
-  fcntl (fd, F_SETFD, FD_CLOEXEC);
-  fcntl (fd, F_SETFL, O_NONBLOCK);
-#endif
-}
+#if EV_SIGNAL_ENABLE || EV_ASYNC_ENABLE
 
 static void noinline
 evpipe_init (EV_P)
 {
   if (!ev_is_active (&pipe_w))
     {
-#if EV_USE_EVENTFD
+# if EV_USE_EVENTFD
       evfd = eventfd (0, EFD_NONBLOCK | EFD_CLOEXEC);
       if (evfd < 0 && errno == EINVAL)
         evfd = eventfd (0, 0);
@@ -1238,7 +1241,7 @@ evpipe_init (EV_P)
           ev_io_set (&pipe_w, evfd, EV_READ);
         }
       else
-#endif
+# endif
         {
           while (pipe (evpipe))
             ev_syserr ("(libev) error creating signal/async pipe");
@@ -1259,6 +1262,7 @@ evpipe_write (EV_P_ EV_ATOMIC_T *flag)
   if (!*flag)
     {
       int old_errno = errno; /* save errno because write might clobber it */
+      char dummy;
 
       *flag = 1;
 
@@ -1270,7 +1274,7 @@ evpipe_write (EV_P_ EV_ATOMIC_T *flag)
         }
       else
 #endif
-        write (evpipe [1], &old_errno, 1);
+        write (evpipe [1], &dummy, 1);
 
       errno = old_errno;
     }
@@ -1381,12 +1385,13 @@ sigfdcb (EV_P_ ev_io *iow, int revents)
 }
 #endif
 
+#endif
+
 /*****************************************************************************/
 
+#if EV_CHILD_ENABLE
 static WL childs [EV_PID_HASHSIZE];
 
-#ifndef _WIN32
-
 static ev_signal childev;
 
 #ifndef WIFCONTINUED
@@ -1664,8 +1669,10 @@ loop_init (EV_P_ unsigned int flags)
 
       ev_prepare_init (&pending_w, pendingcb);
 
+#if EV_SIGNAL_ENABLE || EV_ASYNC_ENABLE
       ev_init (&pipe_w, pipecb);
       ev_set_priority (&pipe_w, EV_MAXPRI);
+#endif
     }
 }
 
@@ -1925,8 +1932,10 @@ ev_loop_verify (EV_P)
   array_verify (EV_A_ (W *)checks, checkcnt);
 
 # if 0
+#if EV_CHILD_ENABLE
   for (w = (ev_child *)childs [chain & (EV_PID_HASHSIZE - 1)]; w; w = (ev_child *)((WL)w)->next)
   for (signum = EV_NSIG; signum--; ) if (signals [signum].pending)
+#endif
 # endif
 #endif
 }
@@ -1952,7 +1961,7 @@ ev_default_loop (unsigned int flags)
 
       if (ev_backend (EV_A))
         {
-#ifndef _WIN32
+#if EV_CHILD_ENABLE
           ev_signal_init (&childev, childcb, SIGCHLD);
           ev_set_priority (&childev, EV_MAXPRI);
           ev_signal_start (EV_A_ &childev);
@@ -1975,7 +1984,7 @@ ev_default_destroy (void)
 
   ev_default_loop_ptr = 0;
 
-#ifndef _WIN32
+#if EV_CHILD_ENABLE
   ev_ref (EV_A); /* child watcher */
   ev_signal_stop (EV_A_ &childev);
 #endif
@@ -2727,6 +2736,8 @@ ev_periodic_again (EV_P_ ev_periodic *w)
 # define SA_RESTART 0
 #endif
 
+#if EV_SIGNAL_ENABLE
+
 void noinline
 ev_signal_start (EV_P_ ev_signal *w)
 {
@@ -2842,6 +2853,10 @@ ev_signal_stop (EV_P_ ev_signal *w)
   EV_FREQUENT_CHECK;
 }
 
+#endif
+
+#if EV_CHILD_ENABLE
+
 void
 ev_child_start (EV_P_ ev_child *w)
 {
@@ -2874,6 +2889,8 @@ ev_child_stop (EV_P_ ev_child *w)
   EV_FREQUENT_CHECK;
 }
 
+#endif
+
 #if EV_STAT_ENABLE
 
 # ifdef _WIN32
diff --git a/ev.h b/ev.h
index 06ff8cc..661ff98 100644
--- a/ev.h
+++ b/ev.h
@@ -74,14 +74,26 @@ typedef double ev_tstamp;
 # define EV_FORK_ENABLE 1
 #endif
 
-#ifndef EV_EMBED_ENABLE
-# define EV_EMBED_ENABLE 1
+#ifndef EV_SIGNAL_ENABLE
+# define EV_SIGNAL_ENABLE 1
+#endif
+
+#ifndef EV_CHILD_ENABLE
+# ifdef _WIN32
+#  define EV_CHILD_ENABLE 0
+# else
+#  define EV_CHILD_ENABLE 1
+#endif
 #endif
 
 #ifndef EV_ASYNC_ENABLE
 # define EV_ASYNC_ENABLE 1
 #endif
 
+#ifndef EV_EMBED_ENABLE
+# define EV_EMBED_ENABLE 1
+#endif
+
 #ifndef EV_WALK_ENABLE
 # define EV_WALK_ENABLE 0 /* not yet */
 #endif
@@ -93,6 +105,11 @@ typedef double ev_tstamp;
 
 /*****************************************************************************/
 
+#if EV_CHILD_ENABLE && !EV_SIGNAL_ENABLE
+# undef EV_SIGNAL_ENABLE
+# define EV_SIGNAL_ENABLE 1
+#endif
+
 #if EV_STAT_ENABLE
 # ifdef _WIN32
 #  include <time.h>
@@ -632,7 +649,9 @@ void ev_resume  (EV_P);
 /* accepts any ev_watcher type */
 void ev_feed_event     (EV_P_ void *w, int revents);
 void ev_feed_fd_event  (EV_P_ int fd, int revents);
+#if EV_SIGNAL_ENABLE
 void ev_feed_signal_event (EV_P_ int signum);
+#endif
 void ev_invoke         (EV_P_ void *w, int revents);
 int  ev_clear_pending  (EV_P_ void *w);
 
@@ -653,12 +672,16 @@ void ev_periodic_again (EV_P_ ev_periodic *w);
 #endif
 
 /* only supported in the default loop */
+#if EV_SIGNAL_ENABLE
 void ev_signal_start   (EV_P_ ev_signal *w);
 void ev_signal_stop    (EV_P_ ev_signal *w);
+#endif
 
 /* only supported in the default loop */
+# if EV_CHILD_ENABLE
 void ev_child_start    (EV_P_ ev_child *w);
 void ev_child_stop     (EV_P_ ev_child *w);
+# endif
 
 # if EV_STAT_ENABLE
 void ev_stat_start     (EV_P_ ev_stat *w);
diff --git a/ev.pod b/ev.pod
index f13391d..8c586e7 100644
--- a/ev.pod
+++ b/ev.pod
@@ -3868,11 +3868,21 @@ defined to be C<0>, then they are not.
 If undefined or defined to be C<1>, then fork watchers are supported. If
 defined to be C<0>, then they are not.
 
+=item EV_SIGNAL_ENABLE
+
+If undefined or defined to be C<1>, then signal watchers are supported. If
+defined to be C<0>, then they are not.
+
 =item EV_ASYNC_ENABLE
 
 If undefined or defined to be C<1>, then async watchers are supported. If
 defined to be C<0>, then they are not.
 
+=item EV_CHILD_ENABLE
+
+If undefined or defined to be C<1> (and C<_WIN32> is not defined), then
+child watchers are supported. If defined to be C<0>, then they are not.
+
 =item EV_MINIMAL
 
 If you need to shave off some kilobytes of code at the expense of some
@@ -3883,13 +3893,50 @@ the default 4-heap.
 
 You can save even more by disabling watcher types you do not need
 and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert>
-(C<-DNDEBUG>) will usually reduce code size a lot.
+(C<-DNDEBUG>) will usually reduce code size a lot. Disabling inotify,
+eventfd and signalfd will further help, and disabling backends one doesn't
+need (e.g. poll, epoll, kqueue, ports) will help further.
 
 Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to
 provide a bare-bones event library. See C<ev.h> for details on what parts
 of the API are still available, and do not complain if this subset changes
 over time.
 
+This example set of settings reduces the compiled size of libev from 24Kb
+to 8Kb on my GNU/Linux amd64 system (and leaves little in - there is also
+an effect on the amount of memory used). With an intelligent-enough linker
+further unused functions might be left out as well automatically.
+
+   // tuning and API changes
+   #define EV_MINIMAL 2
+   #define EV_MULTIPLICITY 0
+   #define EV_MINPRI 0
+   #define EV_MAXPRI 0
+
+   // OS-specific backends
+   #define EV_USE_INOTIFY 0
+   #define EV_USE_EVENTFD 0
+   #define EV_USE_SIGNALFD 0
+   #define EV_USE_REALTIME 0
+   #define EV_USE_MONOTONIC 0
+   #define EV_USE_CLOCK_SYSCALL 0
+
+   // disable all backends except select
+   #define EV_USE_POLL 0
+   #define EV_USE_PORT 0
+   #define EV_USE_KQUEUE 0
+   #define EV_USE_EPOLL 0
+
+   // disable all watcher types that cna be disabled
+   #define EV_STAT_ENABLE 0
+   #define EV_PERIODIC_ENABLE 0
+   #define EV_IDLE_ENABLE 0
+   #define EV_FORK_ENABLE 0
+   #define EV_SIGNAL_ENABLE 0
+   #define EV_CHILD_ENABLE 0
+   #define EV_ASYNC_ENABLE 0
+   #define EV_EMBED_ENABLE 0
+
 =item EV_AVOID_STDIO
 
 If this is set to C<1> at compiletime, then libev will avoid using stdio