[ViewVC] Diff of: cvs/libev/ev.c

Comparing libev/ev.c (file contents):
Revision 1.440 by root, Tue May 29 21:37:14 2012 UTC vs.
Revision 1.449 by root, Sun Sep 23 21:21:58 2012 UTC

 #define ECB_C     (__STDC__+0) /* this assumes that __STDC__ is either empty or a number */
 #define ECB_C99   (__STDC_VERSION__ >= 199901L)
 #define ECB_C11   (__STDC_VERSION__ >= 201112L)
 #define ECB_CPP   (__cplusplus+0)
-#define ECB_CPP98 (__cplusplus >= 199711L)
 #define ECB_CPP11 (__cplusplus >= 201103L)
 /*****************************************************************************/
 /* ECB_NO_THREADS - ecb is not used by multiple threads, ever */
   #endif
 #endif
 #ifndef ECB_MEMORY_FENCE
   #if ECB_GCC_VERSION(4,7)
-    /* see comment below about the C11 memory model. in short - avoid */
+    /* see comment below (stdatomic.h) about the C11 memory model. */
     #define ECB_MEMORY_FENCE         __atomic_thread_fence (__ATOMIC_SEQ_CST)
   #elif defined __clang && __has_feature (cxx_atomic)
-    /* see above */
+    /* see comment below (stdatomic.h) about the C11 memory model. */
     #define ECB_MEMORY_FENCE         __c11_atomic_thread_fence (__ATOMIC_SEQ_CST)
   #elif ECB_GCC_VERSION(4,4) || defined __INTEL_COMPILER || defined __clang__
     #define ECB_MEMORY_FENCE         __sync_synchronize ()
   #elif _MSC_VER >= 1400 /* VC++ 2005 */
     #pragma intrinsic(_ReadBarrier,_WriteBarrier,_ReadWriteBarrier)
 #ifndef ECB_MEMORY_FENCE
   #if ECB_C11 && !defined __STDC_NO_ATOMICS__
     /* we assume that these memory fences work on all variables/all memory accesses, */
     /* not just C11 atomics and atomic accesses */
     #include <stdatomic.h>
-    /* unfortunately, the C11 memory model seems to be very limited, and unable to express */
+    /* Unfortunately, neither gcc 4.7 nor clang 3.1 generate any instructions for */
-    /* simple barrier semantics. That means we need to take out thor's hammer. */
+    /* any fence other than seq_cst, which isn't very efficient for us. */
+    /* Why that is, we don't know - either the C11 memory model is quite useless */
+    /* for most usages, or gcc and clang have a bug */
+    /* I *currently* lean towards the latter, and inefficiently implement */
+    /* all three of ecb's fences as a seq_cst fence */
     #define ECB_MEMORY_FENCE         atomic_thread_fence (memory_order_seq_cst)
   #endif
 #endif
 #ifndef ECB_MEMORY_FENCE
 }
 static void *
 ev_realloc_emul (void *ptr, long size) EV_THROW
 {
-#if __GLIBC__
-  return realloc (ptr, size);
-#else
   /* some systems, notably openbsd and darwin, fail to properly
    * implement realloc (x, 0) (as required by both ansi c-89 and
    * the single unix specification, so work around them here.
+   * recently, also (at least) fedora and debian started breaking it,
+   * despite documenting it otherwise.
    */
   if (size)
     return realloc (ptr, size);
   free (ptr);
   return 0;
-#endif
 }
 static void *(*alloc)(void *ptr, long size) EV_THROW = ev_realloc_emul;
 void ecb_cold
 static void noinline ecb_cold
 evpipe_init (EV_P)
 {
   if (!ev_is_active (&pipe_w))
     {
+      int fds [2];
 # if EV_USE_EVENTFD
+      fds [0] = -1;
-      evfd = eventfd (0, EFD_NONBLOCK | EFD_CLOEXEC);
+      fds [1] = eventfd (0, EFD_NONBLOCK | EFD_CLOEXEC);
-      if (evfd < 0 && errno == EINVAL)
+      if (fds [1] < 0 && errno == EINVAL)
-        evfd = eventfd (0, 0);
+        fds [1] = eventfd (0, 0);
-      if (evfd >= 0)
+      if (fds [1] < 0)
-        {
-          evpipe [0] = -1;
-          fd_intern (evfd); /* doing it twice doesn't hurt */
-          ev_io_set (&pipe_w, evfd, EV_READ);
-        }
-      else
 # endif
         {
-          while (pipe (evpipe))
+          while (pipe (fds))
             ev_syserr ("(libev) error creating signal/async pipe");
-          fd_intern (evpipe [0]);
+          fd_intern (fds [0]);
-          fd_intern (evpipe [1]);
-          ev_io_set (&pipe_w, evpipe [0], EV_READ);
         }
+      fd_intern (fds [1]);
+      evpipe [0] = fds [0];
+      if (evpipe [1] < 0)
+        evpipe [1] = fds [1]; /* first call, set write fd */
+      else
+        {
+          /* on subsequent calls, do not change evpipe [1] */
+          /* so that evpipe_write can always rely on its value. */
+          /* this branch does not do anything sensible on windows, */
+          /* so must not be executed on windows */
+          dup2 (fds [1], evpipe [1]);
+          close (fds [1]);
+        }
+      ev_io_set (&pipe_w, evpipe [0] < 0 ? evpipe [1] : evpipe [0], EV_READ);
       ev_io_start (EV_A_ &pipe_w);
       ev_unref (EV_A); /* watcher should not keep loop alive */
     }
 }
       ECB_MEMORY_FENCE_RELEASE;
       old_errno = errno; /* save errno because write will clobber it */
 #if EV_USE_EVENTFD
-      if (evfd >= 0)
+      if (evpipe [0] < 0)
         {
           uint64_t counter = 1;
-          write (evfd, &counter, sizeof (uint64_t));
+          write (evpipe [1], &counter, sizeof (uint64_t));
         }
       else
 #endif
         {
 #ifdef _WIN32
   int i;
   if (revents & EV_READ)
     {
 #if EV_USE_EVENTFD
-      if (evfd >= 0)
+      if (evpipe [0] < 0)
         {
           uint64_t counter;
-          read (evfd, &counter, sizeof (uint64_t));
+          read (evpipe [1], &counter, sizeof (uint64_t));
         }
       else
 #endif
         {
           char dummy[4];
 void
 ev_feed_signal (int signum) EV_THROW
 {
 #if EV_MULTIPLICITY
+  ECB_MEMORY_FENCE_ACQUIRE;
   EV_P = signals [signum - 1].loop;
   if (!EV_A)
     return;
 #endif
-  if (!ev_active (&pipe_w))
-    return;
   signals [signum - 1].pending = 1;
   evpipe_write (EV_A_ &sig_pending);
 }
 static void
 void noinline
 ev_feed_signal_event (EV_P_ int signum) EV_THROW
 {
   WL w;
-  if (expect_false (signum <= 0 || signum > EV_NSIG))
+  if (expect_false (signum <= 0 || signum >= EV_NSIG))
     return;
   --signum;
 #if EV_MULTIPLICITY
 #if EV_ASYNC_ENABLE
       async_pending      = 0;
 #endif
       pipe_write_skipped = 0;
       pipe_write_wanted  = 0;
+      evpipe [0]         = -1;
+      evpipe [1]         = -1;
 #if EV_USE_INOTIFY
       fs_fd              = flags & EVFLAG_NOINOTIFY ? -1 : -2;
 #endif
 #if EV_USE_SIGNALFD
       sigfd              = flags & EVFLAG_SIGNALFD  ? -2 : -1;
   if (ev_is_active (&pipe_w))
     {
       /*ev_ref (EV_A);*/
       /*ev_io_stop (EV_A_ &pipe_w);*/
-#if EV_USE_EVENTFD
-      if (evfd >= 0)
-        close (evfd);
-#endif
-      if (evpipe [0] >= 0)
-        {
-          EV_WIN32_CLOSE_FD (evpipe [0]);
+      if (evpipe [0] >= 0) EV_WIN32_CLOSE_FD (evpipe [0]);
-          EV_WIN32_CLOSE_FD (evpipe [1]);
+      if (evpipe [1] >= 0) EV_WIN32_CLOSE_FD (evpipe [1]);
-        }
     }
 #if EV_USE_SIGNALFD
   if (ev_is_active (&sigfd_w))
     close (sigfd);
 #endif
 #if EV_USE_INOTIFY
   infy_fork (EV_A);
 #endif
+#if EV_SIGNAL_ENABLE || EV_ASYNC_ENABLE
   if (ev_is_active (&pipe_w))
     {
       /* pipe_write_wanted must be false now, so modifying fd vars should be safe */
       ev_ref (EV_A);
       ev_io_stop (EV_A_ &pipe_w);
-#if EV_USE_EVENTFD
-      if (evfd >= 0)
-        close (evfd);
-#endif
       if (evpipe [0] >= 0)
-        {
-          EV_WIN32_CLOSE_FD (evpipe [0]);
+        EV_WIN32_CLOSE_FD (evpipe [0]);
-          EV_WIN32_CLOSE_FD (evpipe [1]);
-        }
-#if EV_SIGNAL_ENABLE || EV_ASYNC_ENABLE
       evpipe_init (EV_A);
-      /* now iterate over everything, in case we missed something */
+      /* iterate over everything, in case we missed something before */
-      pipecb (EV_A_ &pipe_w, EV_READ);
+      ev_feed_event (EV_A_ &pipe_w, EV_CUSTOM);
-#endif
     }
+#endif
   postfork = 0;
 }
 #if EV_MULTIPLICITY
 }
 void noinline
 ev_invoke_pending (EV_P)
 {
-  for (pendingpri = NUMPRI; pendingpri--; ) /* pendingpri is modified during the loop */
+  pendingpri = NUMPRI;
+  while (pendingpri) /* pendingpri possibly gets modified in the inner loop */
+    {
+      --pendingpri;
-    while (pendingcnt [pendingpri])
+      while (pendingcnt [pendingpri])
-      {
+        {
-        ANPENDING *p = pendings [pendingpri] + --pendingcnt [pendingpri];
+          ANPENDING *p = pendings [pendingpri] + --pendingcnt [pendingpri];
-        p->w->pending = 0;
+          p->w->pending = 0;
-        EV_CB_INVOKE (p->w, p->events);
+          EV_CB_INVOKE (p->w, p->events);
-        EV_FREQUENT_CHECK;
+          EV_FREQUENT_CHECK;
-      }
+        }
+    }
 }
 #if EV_IDLE_ENABLE
 /* make idle watchers pending. this handles the "call-idle */
 /* only when higher priorities are idle" logic */
         backend_poll (EV_A_ waittime);
         assert ((loop_done = EVBREAK_CANCEL, 1)); /* assert for side effect */
         pipe_write_wanted = 0; /* just an optimisation, no fence needed */
+        ECB_MEMORY_FENCE_ACQUIRE;
         if (pipe_write_skipped)
           {
             assert (("libev: pipe_w not active, but pipe not written", ev_is_active (&pipe_w)));
             ev_feed_event (EV_A_ &pipe_w, EV_CUSTOM);
           }
 #if EV_MULTIPLICITY
   assert (("libev: a signal must not be attached to two different loops",
            !signals [w->signum - 1].loop || signals [w->signum - 1].loop == loop));
   signals [w->signum - 1].loop = EV_A;
+  ECB_MEMORY_FENCE_RELEASE;
 #endif
   EV_FREQUENT_CHECK;
 #if EV_USE_SIGNALFD

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Comparing libev/ev.c (file contents): Revision 1.440 by root, Tue May 29 21:37:14 2012 UTC vs. Revision 1.449 by root, Sun Sep 23 21:21:58 2012 UTC

Diff Legend

Comparing libev/ev.c (file contents):
Revision 1.440 by root, Tue May 29 21:37:14 2012 UTC vs.
Revision 1.449 by root, Sun Sep 23 21:21:58 2012 UTC