X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/mLib/blobdiff_plain/97f65b001294338abed02a7b132d6be6517b3f1d..a4589237d33eb5ed0858371a668f652651f4bcda:/sel.c

diff --git a/sel.c b/sel.c
index 3f5493b..5dede9b 100644
--- a/sel.c
+++ b/sel.c
@@ -1,10 +1,10 @@
 /* -*-c-*-
  *
- * $Id: sel.c,v 1.1 1999/05/14 21:01:14 mdw Exp $
+ * $Id: sel.c,v 1.13 2004/04/08 01:36:13 mdw Exp $
  *
  * I/O multiplexing support
  *
- * (c) 1999 Mark Wooding
+ * (c) 1999 Straylight/Edgeware
  */
 
 /*----- Licensing notice --------------------------------------------------* 
@@ -27,16 +27,9 @@
  * MA 02111-1307, USA.
  */
 
-/*----- Revision history --------------------------------------------------* 
- *
- * $Log: sel.c,v $
- * Revision 1.1  1999/05/14 21:01:14  mdw
- * Integrated `select' handling bits from the background resolver project.
- *
- */
-
 /*----- Header files ------------------------------------------------------*/
 
+#include <assert.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -46,8 +39,21 @@
 #include <unistd.h>
 
 #include "sel.h"
+#include "sub.h"
 #include "tv.h"
 
+/*----- Data structures ---------------------------------------------------*/
+
+typedef struct sel_pendfile {
+  struct sel_pendfile *next;
+  sel_file *f;
+} pfile;
+
+typedef struct sel_pendtimer {
+  struct sel_pendtimer *next;
+  sel_timer *t;
+} ptimer;
+
 /*----- Main code ---------------------------------------------------------*/
 
 /* --- @sel_init@ --- *
@@ -61,11 +67,15 @@
 
 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@ --- *
@@ -94,6 +104,7 @@ void sel_initfile(sel_state *s, sel_file *f,
   f->mode = mode;
   f->func = func;
   f->p = p;
+  f->pend = 0;
 }
 
 /* --- @sel_addfile@ --- *
@@ -107,20 +118,38 @@ 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 --- */
 
   while (*ff && (*ff)->fd > f->fd)
     ff = &(*ff)->next;
   f->next = *ff;
-  f->prev = (sel_file *)ff;
+  f->prev = ff;
   if (*ff)
-    (*ff)->prev = f;
+    (*ff)->prev = &f->next;
   *ff = 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
@@ -132,10 +161,14 @@ void sel_addfile(sel_file *f)
 
 void sel_rmfile(sel_file *f)
 {
-  f->prev->next = f->next;
+  *f->prev = f->next;
   if (f->next)
     f->next->prev = f->prev;
   FD_CLR(f->fd, f->s->fd + f->mode);
+  if (f->pend) {
+    f->pend->f = 0;
+    f->pend = 0;
+  }
 }
 
 /* --- @sel_addtimer@ --- *
@@ -157,21 +190,23 @@ void sel_addtimer(sel_state *s, sel_timer *t,
 		  void *p)
 {
   sel_timer **tt = &s->timers;
+  { sel_timer *q; for (q = s->timers; q; q = q->next) assert(q != t); }
 
   /* --- Set up the timer block --- */
 
   t->tv = *tv;
   t->func = func;
   t->p = p;
+  t->pend = 0;
 
   /* --- 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;
+  t->prev = tt;
   if (*tt)
-    (*tt)->prev = t;
+    (*tt)->prev = &t->next;
   *tt = t;
 }
 
@@ -186,9 +221,82 @@ void sel_addtimer(sel_state *s, sel_timer *t,
 
 void sel_rmtimer(sel_timer *t)
 {
-  t->prev->next = t->next;
-  if (t->next)
-    t->next->prev = t->prev;
+  if (t->pend) {
+    t->pend->t = 0;
+    t->pend = 0;
+  } else {
+    *t->prev = t->next;
+    if (t->next)
+      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 = &s->hooks;
+  if (s->hooks)
+    s->hooks->prev = &h->next;
+  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 = 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@ --- *
@@ -202,48 +310,143 @@ 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 {
+    if (TV_CMP(&s->timers->tv, >, &a.now))
+      TV_SUB(&a.tv, &s->timers->tv, &a.now);
+    else {
+      a.tv.tv_sec = 0;
+      a.tv.tv_usec = 0;
+    }
+    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_timer *t, *tt;
-    for (t = s->timers; t && tv_cmp(&t->tv, &tv) <= 0; t = tt) {
-      tt = t->next;
-      t->next = t->prev = t;
-      t->func(&tv, t->p);
+    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 --- */
+
+  if (s->timers) {
+    ptimer *pthead, *pt, **ptt = &pthead;
+    sel_timer *t;
+
+    for (t = s->timers; t && TV_CMP(&t->tv, <=, &a.now); t = t->next) {
+      pt = CREATE(ptimer);
+      pt->t = t;
+      t->pend = pt;
+      *ptt = pt;
+      ptt = &pt->next;
+    }
+    *ptt = 0;
+    if (t) {
+      *t->prev = 0;
+      t->prev = &s->timers;
     }
     s->timers = t;
-    if (t)
-      t->prev = (sel_timer *)&s->timers;
+    while (pthead) {
+      pt = pthead;
+      pthead = pt->next;
+      t = pt->t;
+      if (t) {
+	t->pend = 0;
+	t->next = 0;
+	t->prev = &t->next;
+	t->func(&a.now, t->p);
+      }
+      DESTROY(pt);
+    }
   }
 
+  /* --- 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++) {
+      pfile *pfhead, *pf, **pff = &pfhead;
+      sel_file *f;
+
+      for (f = s->files[i]; f; f = f->next) {
+	if (!FD_ISSET(f->fd, &a.fd[i]))
+	  continue;
+	pf = CREATE(pfile);
+	pf->f = f;
+	f->pend = pf;
+	*pff = pf;
+	pff = &pf->next;
+      }
+      *pff = 0;
+      while (pfhead) {
+	pf = pfhead;
+	pfhead = pf->next;
+	f = pf->f;
+	if (f) {
+	  f->pend = 0;
+	  f->func(f->fd, i, f->p);
+	}
+	DESTROY(pf);
+      }
     }
   }
 
+  s->args = 0;
   return (0);
 }