X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/mLib/blobdiff_plain/1226c514d496f4552b43682c8ca3dde7d87f952a..0ae5e7b3fd62e0251d21f3abbc187f4c7585f85f:/sel.c

diff --git a/sel.c b/sel.c
index de8cdef..04d9ed5 100644
--- a/sel.c
+++ b/sel.c
@@ -1,6 +1,6 @@
 /* -*-c-*-
  *
- * $Id: sel.c,v 1.4 1999/08/19 18:30:26 mdw Exp $
+ * $Id: sel.c,v 1.8 2000/03/23 20:42:08 mdw Exp $
  *
  * I/O multiplexing support
  *
@@ -30,6 +30,18 @@
 /*----- Revision history --------------------------------------------------* 
  *
  * $Log: sel.c,v $
+ * Revision 1.8  2000/03/23 20:42:08  mdw
+ * Rearrange timeout handling to avoid list corruptions.
+ *
+ * Revision 1.7  1999/12/11 11:12:17  mdw
+ * Fix comment formatting error.
+ *
+ * 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).
@@ -71,12 +83,15 @@
 
 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;
   s->hooks = 0;
-  FD_ZERO(&s->fd[SEL_READ]);
-  FD_ZERO(&s->fd[SEL_WRITE]);
-  FD_ZERO(&s->fd[SEL_EXC]);
+  s->args = 0;
 }
 
 /* --- @sel_initfile@ --- *
@@ -118,7 +133,7 @@ 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 --- */
 
@@ -132,6 +147,24 @@ 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
@@ -245,7 +278,7 @@ void sel_rmhook(sel_hook *h)
 }
 
 /* --- @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
@@ -286,7 +319,15 @@ int sel_select(sel_state *s)
 
   /* --- Initialize the argument block --- */
 
-  a.maxfd = s->files ? s->files->fd + 1 : 0;
+  {
+    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);
@@ -296,6 +337,7 @@ int sel_select(sel_state *s)
     TV_SUB(&a.tv, &s->timers->tv, &a.now);
     a.tvp = &a.tv;
   }
+  s->args = &a;
 
   /* --- Grind through the pre hooks --- */
 
@@ -313,8 +355,10 @@ int sel_select(sel_state *s)
   
   if ((err = select(a.maxfd,
 		    &a.fd[SEL_READ], &a.fd[SEL_WRITE], &a.fd[SEL_EXC],
-		    a.tvp)) < 0)
+		    a.tvp)) < 0) {
+    s->args = 0;
     return (err);
+  }
 
   if (a.tvp)
     gettimeofday(&a.now, 0);
@@ -333,29 +377,43 @@ int sel_select(sel_state *s)
 
   /* --- Run through the timers --- */
 
-  {
+  if (s->timers && TV_CMP(&s->timers->tv, <=, &a.now)) {
     sel_timer *t, *tt;
-    for (t = s->timers; t && TV_CMP(&t->tv, <=, &a.now); t = tt) {
+    tt = s->timers;
+    for (t = tt; t && TV_CMP(&t->tv, <=, &a.now); t = t->next)
+      ;
+    if (t) {
+      t->prev->next = 0;
+      t->prev = (sel_timer *)&s->timers;
+    }
+    s->timers = t;
+    for (t = tt; t; t = tt) {
       tt = t->next;
-      t->next = t->prev = t;
       t->func(&a.now, t->p);
     }
-    s->timers = t;
-    if (t)
-      t->prev = (sel_timer *)&s->timers;
   }
 
-  /* --- And finally run through the files --- */
+  /* --- 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, a.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);
 }