From 4eb666da31191588d89629ebc38ee98f02ee89b4 Mon Sep 17 00:00:00 2001
From: chatty
Date: Tue, 28 Nov 2000 17:06:08 +0000
Subject: Amelioration de la gestion des timers dans Scan Amelioration de la
 gestion des timers dans LoopScan

---
 comm/Multiplexer.cc | 64 ++++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 46 insertions(+), 18 deletions(-)

(limited to 'comm')

diff --git a/comm/Multiplexer.cc b/comm/Multiplexer.cc
index 1823705..c1bf8b6 100644
--- a/comm/Multiplexer.cc
+++ b/comm/Multiplexer.cc
@@ -3,7 +3,7 @@
  *
  *	by Michel Beaudouin-Lafon
  *
- *	Copyright 1990-1993
+ *	Copyright 1990-1995
  *	Laboratoire de Recherche en Informatique (LRI)
  *
  *	Channel sets, or multiplexers
@@ -415,10 +415,8 @@ UchMultiplexer :: Scan (bool nointr, bool poll)
 		timeout = &tout;
 		tout.tv_sec = tout.tv_usec = 0;
 	}
-	
+
 	while (ret <= 0) {
-		CcuCoreTimer::Fire (&Timers);
-	
 		if (ReadCount == 0 && WriteCount == 0 && SelectCount == 0)
 			return 0;
 		
@@ -431,30 +429,46 @@ UchMultiplexer :: Scan (bool nointr, bool poll)
 			nfd--;
 		}
 	
-//printf ("Scan: read %x, write %x, TimeOut %d", ReadMask, WriteMask, TimeOut);
 		rmsk = ReadMask;
 		wmsk = WriteMask;
+
+		/* let's fiddle with ret to skip select if we are late with timers */
+		ret = -1;
 		if (!poll && TimeOut != -1) {
 			CcuTimeStamp now;
 			Millisecond delay = TimeOut - now;
-//printf (", timeout in %d ms", delay);
+			/* if delay < 0, select is unhappy */
+			if (delay < 0)
+				ret = 0;
 			tout.tv_sec = delay / 1000;
 			tout.tv_usec = 1000 * (delay % 1000);
 			timeout = &tout;
 		}
-//printf ("\n");
-		
-		ret = select (NFILE, FD_SET_TYPE(&rmsk) /*read*/,  FD_SET_TYPE(&wmsk) /*write*/, 0 /*except*/, timeout);
-		if (ret < 0 || ret == 0 && poll) {
-//printf ("select failed: %d, errno %d\n", ret, errno);
-			if (nointr && ret == -1 && errno == EINTR)
+
+		/* skipping select is a trick to avoid problems with timers. However,
+		    something more general should be done to:
+			- manage priorities (I'm not sure the current situation is sound)
+			- handle situations when we are late.
+		*/
+		if (ret != 0)
+			ret = select (NFILE, FD_SET_TYPE(&rmsk),  FD_SET_TYPE(&wmsk), 0, timeout);
+
+		if (ret == 0) {
+			if (TimeOut != -1)
+				/* Fire might be called without reason if polling is on. Too bad... */
+				CcuCoreTimer::Fire (&Timers);
+			else if (!poll)
+				fprintf (stderr, "select returned 0 without reason!\n");
+			return 0;
+		} else if (ret < 0) {
+			if (nointr && errno == EINTR)
 				continue;
-			return ret;
+			else
+				return ret;
 		}
 	}
 	
 	for (fd = 0, nfd = ret; nfd; fd++) {
-//printf ("Scan: handle %d: r %d, w %d\n", fd, FD_ISSET (fd, &rmsk), FD_ISSET (fd, &wmsk));
 		if (FD_ISSET (fd, &wmsk)) {
 			nfd --;
 			UchChannel* ch = Channels [fd];
@@ -511,8 +525,10 @@ UchMultiplexer :: LoopScan (bool nointr)
 		if (SigFired)
 			HandleDeferredSignals ();
 
+#if 0
 		/* Then, timers */
 		CcuCoreTimer::Fire (&Timers);
+#endif
 
 		/* Then, I/Os */
 		if (ReadCount == 0 && WriteCount == 0 && SelectCount == 0)
@@ -530,7 +546,9 @@ UchMultiplexer :: LoopScan (bool nointr)
 		}
 		if (nfd)	// a handler returned true.
 			continue;
-		
+
+		/* let's fiddle with ret to skip select if we are late with timers */
+		nfd = -1;
 		rmsk = ReadMask;
 		wmsk = WriteMask;
 		struct timeval tv;
@@ -538,15 +556,25 @@ UchMultiplexer :: LoopScan (bool nointr)
 		if (TimeOut != -1) {
 			CcuTimeStamp now;
 			Millisecond delay = TimeOut - now;
+			if (delay < 0)
+				nfd = 0;
 			tv.tv_sec = delay / 1000;
 			tv.tv_usec = 1000 * (delay % 1000);
 			timeout = &tv;
 		}
-		nfd = select (NFILE, FD_SET_TYPE(&rmsk) /*read*/, FD_SET_TYPE(&wmsk) /*write*/, 0 /*except*/, timeout);
-		if (nfd < 0) {
+		if (nfd != 0)
+			nfd = select (NFILE, FD_SET_TYPE(&rmsk), FD_SET_TYPE(&wmsk), 0, timeout);
+		if (nfd == 0) {
+			if (TimeOut != -1)
+				CcuCoreTimer::Fire (&Timers);
+			else
+				fprintf (stderr, "select returned 0 without reason!\n");
+			continue;
+		} else if (nfd < 0) {
 			if (nointr && nfd == -1 && errno == EINTR)
 				continue;
-			return isMpxError;
+			else
+				return isMpxError;
 		}
 
 		for (fd = fd0; nfd; (fd < NFILE) ? fd++ : (fd = 0)) {
-- 
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