X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/mLib/blobdiff_plain/a3ddb7786215525dc1c17b4bbce251f1d06be083..6c3a7cf785d56891d9f6d4aa74742ab1fdf203ee:/sel.c

diff --git a/sel.c b/sel.c
index b32aa8c..1cb6b5d 100644
--- a/sel.c
+++ b/sel.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: sel.c,v 1.2 1999/05/15 10:33:32 mdw Exp $
+ * $Id: sel.c,v 1.6 1999/09/26 14:28:11 mdw Exp $
  *
  * I/O multiplexing support
  *
@@ -30,6 +30,19 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: sel.c,v $
+ * Revision 1.6  1999/09/26 14:28:11  mdw
+ * (sel_select): Almost pointless efficiency tweak.
+ *
+ * Revision 1.5  1999/08/31 17:42:22  mdw
+ * New function `sel_force' to force a descriptor to be `selected'.
+ *
+ * Revision 1.4  1999/08/19 18:30:26  mdw
+ * Implement hooks for foreign select-using systems (currently not well
+ * tested).
+ *
+ * Revision 1.3  1999/05/21 22:13:59  mdw
+ * Use new `tv' macros.  Fix ordering bug for timeout selectors.
+ *
  * Revision 1.2  1999/05/15 10:33:32  mdw
  * Fix copyright notices.
  *
@@ -64,11 +77,15 @@
 
 void sel_init(sel_state *s)
 {
-  s->files = 0;
+  int i;
+
+  for (i = 0; i < SEL_MODES; i++) {
+    s->files[i] = 0;
+    FD_ZERO(&s->fd[i]);
+  }
   s->timers = 0;
-  FD_ZERO(&s->fd[SEL_READ]);
-  FD_ZERO(&s->fd[SEL_WRITE]);
-  FD_ZERO(&s->fd[SEL_EXC]);
+  s->hooks = 0;
+  s->args = 0;
 }
 
 /* --- @sel_initfile@ --- *
@@ -110,7 +127,7 @@ void sel_initfile(sel_state *s, sel_file *f,
 
 void sel_addfile(sel_file *f)
 {
-  sel_file **ff = &f->s->files;
+  sel_file **ff = &f->s->files[f->mode];
 
   /* --- This little dance looks like line-noise, but it does the job --- */
 
@@ -124,6 +141,24 @@ void sel_addfile(sel_file *f)
   FD_SET(f->fd, f->s->fd + f->mode);
 }
 
+/* --- @sel_force@ --- *
+ *
+ * Arguments:	@sel_file *f@ = pointer to file selector
+ *
+ * Returns:	---
+ *
+ * Use:		Forces a file selector to be considered ready.  This is only
+ *		useful during a call to @sel_select@.  Of particular use is
+ *		forcing a write selector when there's something interesting
+ *		ready for it.
+ */
+
+void sel_force(sel_file *f)
+{
+  if (f->s->args)
+    FD_SET(f->fd, &f->s->args->fd[f->mode]);
+}
+
 /* --- @sel_rmfile@ --- *
  *
  * Arguments:	@sel_file *f@ = pointer to a file block
@@ -169,7 +204,7 @@ void sel_addtimer(sel_state *s, sel_timer *t,
 
   /* --- More line noise --- */
   
-  while (*tt && tv_cmp(&(*tt)->tv, tv) > 0)
+  while (*tt && TV_CMP(&(*tt)->tv, <, tv))
     tt = &(*tt)->next;
   t->next = *tt;
   t->prev = (sel_timer *)tt;
@@ -194,6 +229,74 @@ void sel_rmtimer(sel_timer *t)
     t->next->prev = t->prev;
 }
 
+/* --- @sel_addhook@ --- *
+ *
+ * Arguments:	@sel_state *s@ = pointer to state block
+ *		@sel_hook *h@ = pointer to hook block
+ *		@sel_hookfn before, after@ = hook functions
+ *		@void *p@ = pointer argument to pass to hook functions
+ *
+ * Returns:	---
+ *
+ * Use:		Registers hook functions to be called on each select call.
+ */
+
+void sel_addhook(sel_state *s, sel_hook *h,
+		 sel_hookfn before, sel_hookfn after,
+		 void *p)
+{
+  h->before = before;
+  h->after = after;
+  h->p = p;
+  h->next = s->hooks;
+  h->prev = (sel_hook *)&s->hooks;
+  if (s->hooks)
+    s->hooks->prev = h;
+  s->hooks = h;
+}
+
+/* --- @sel_rmhook@ --- *
+ *
+ * Arguments:	@sel_hook *h@ = pointer to hook block
+ *
+ * Returns:	---
+ *
+ * Use:		Removes hook functions.
+ */
+
+void sel_rmhook(sel_hook *h)
+{
+  if (h->next)
+    h->next->prev = h->prev;
+  h->prev->next = h->next;
+}
+
+/* --- @sel_fdmerge@ --- *
+    *
+ * Arguments:   @fd_set *dest@ = destination FD set
+ *              @fd_set *fd@ = pointer to set to merge
+ *              @int maxfd@ = highest numbered descriptor in @fd@ + 1
+ *
+ * Returns:     Actual highest numbered descriptor.
+ *
+ * Use:         Merges file descriptor sets, and returns an accurate @maxfd@
+ *              value.
+ */
+
+int sel_fdmerge(fd_set *dest, fd_set *fd, int maxfd)
+{
+  int i, m = -1;
+
+  for (i = 0; i < maxfd; i++) {
+    if (FD_ISSET(i, fd)) {
+      FD_SET(i, dest);
+      m = i;
+    }
+  }
+
+  return (m + 1);
+}
+
 /* --- @sel_select@ --- *
  *
  * Arguments:	@sel_state *s@ = pointer to state block
@@ -205,48 +308,102 @@ void sel_rmtimer(sel_timer *t)
 
 int sel_select(sel_state *s)
 {
-  fd_set fd[SEL_MODES];
-  struct timeval tv;
+  sel_args a;
   int err;
 
-  memcpy(fd, s->fd, sizeof(s->fd));
-  if (s->timers) {
-    struct timeval now;
-    gettimeofday(&now, 0);
-    tv_sub(&tv, &now, &s->timers->tv);
-    err = select(s->files ? s->files->fd + 1 : 0,
-		 fd + SEL_READ, fd + SEL_WRITE, fd + SEL_EXC,
-		 &tv);
-    gettimeofday(&tv, 0);
-  } else
-    err = select(s->files ? s->files->fd + 1 : 0,
-		 fd + SEL_READ, fd + SEL_WRITE, fd + SEL_EXC,
-		 0);
-
-  if (err < 0)
+  /* --- Initialize the argument block --- */
+
+  {
+    int i;
+    a.maxfd = 0;
+    for (i = 0; i < SEL_MODES; i++) {
+      if (s->files[i] && s->files[i]->fd >= a.maxfd)
+	a.maxfd = s->files[i]->fd + 1;
+    }
+  }
+
+  memcpy(a.fd, s->fd, sizeof(a.fd));
+  if (s->timers || s->hooks)
+    gettimeofday(&a.now, 0);
+  if (!s->timers)
+    a.tvp = 0;
+  else {
+    TV_SUB(&a.tv, &s->timers->tv, &a.now);
+    a.tvp = &a.tv;
+  }
+  s->args = &a;
+
+  /* --- Grind through the pre hooks --- */
+
+  {
+    sel_hook *h = s->hooks;
+    while (h) {
+      sel_hook *hh = h;
+      h = h->next;
+      if (hh->before)
+	hh->before(s, &a, hh->p);
+    }
+  }
+
+  /* --- Run the @select@ call --- */
+  
+  if ((err = select(a.maxfd,
+		    &a.fd[SEL_READ], &a.fd[SEL_WRITE], &a.fd[SEL_EXC],
+		    a.tvp)) < 0) {
+    s->args = 0;
     return (err);
+  }
+
+  if (a.tvp)
+    gettimeofday(&a.now, 0);
+
+  /* --- Run through the hooks again --- */
+
+  {
+    sel_hook *h = s->hooks;
+    while (h) {
+      sel_hook *hh = h;
+      h = h->next;
+      if (hh->after)
+	hh->after(s, &a, hh->p);
+    }
+  }
+
+  /* --- Run through the timers --- */
 
   {
     sel_timer *t, *tt;
-    for (t = s->timers; t && tv_cmp(&t->tv, &tv) <= 0; t = tt) {
+    for (t = s->timers; t && TV_CMP(&t->tv, <=, &a.now); t = tt) {
       tt = t->next;
       t->next = t->prev = t;
-      t->func(&tv, t->p);
+      t->func(&a.now, t->p);
     }
     s->timers = t;
     if (t)
       t->prev = (sel_timer *)&s->timers;
   }
 
+  /* --- And finally run through the files --- *
+   *
+   * Do reads first.  It's quite possible that a read might prompt a write,
+   * but the other way around is less likely.  Fortunately, the modes are
+   * in the right order for this.
+   */
+
   {
-    sel_file *f, *ff;
-    for (f = s->files; f; f = ff) {
-      ff = f->next;
-      if (FD_ISSET(f->fd, fd + f->mode))
-	f->func(f->fd, f->mode, f->p);
+    int i;
+
+    for (i = 0; i < SEL_MODES; i++) {
+      sel_file *f, *ff;
+      for (f = s->files[i]; f; f = ff) {
+	ff = f->next;
+	if (FD_ISSET(f->fd, a.fd + i))
+	  f->func(f->fd, i, f->p);
+      }
     }
   }
 
+  s->args = 0;
   return (0);
 }