From 0398e01a5032434abef05a26e2f9eeb058fecb31 Mon Sep 17 00:00:00 2001
From: Richard Basch <probe@mit.edu>
Date: Mon, 1 Aug 1994 04:42:17 +0000
Subject: Don't do signal blocking; simply set a semaphore flag indicating it
 is in critical code, and let the main loop deal with the flag being set. This
 saves on context switches into the kernel for this rare condition.

---
 server/main.c | 72 +++++++++++++++++++++++++++++++++++++++++++----------------
 1 file changed, 53 insertions(+), 19 deletions(-)

(limited to 'server/main.c')

diff --git a/server/main.c b/server/main.c
index 19832b8..b3ec4e4 100644
--- a/server/main.c
+++ b/server/main.c
@@ -99,9 +99,10 @@ static int do_net_setup P((void)), initialize P((void));
 static void usage P((void)), do_reset P((void));
 static SIGNAL_RETURN_TYPE bye P((int)),
 		dbug_on P((int)), dbug_off P((int)),
-		dump_db P((int)), dump_strings P((int)),
+		sig_dump_db P((int)), sig_dump_strings P((int)),
 		reset P((int)), reap P((int));
 static void read_from_dump P((char *dumpfile));
+static void dump_db P((void)), dump_strings P((void));
 
 #ifndef DEBUG
 static void detach P((void));
@@ -142,6 +143,9 @@ int zalone;
 
 struct timeval t_local;			/* store current time for other uses */
 
+static int dump_db_flag = 0;
+static int dump_strings_flag = 0;
+
 u_long npackets;			/* number of packets processed */
 long uptime;				/* when we started operations */
 static int nofork;
@@ -286,10 +290,11 @@ main(argc, argv)
 	action.sa_handler = reap;
 	sigaction(SIGCHLD, &action, NULL);
 
-	action.sa_handler = dump_db;
+	action.sa_handler = sig_dump_db;
 	sigaction(SIGFPE, &action, NULL);
+	sigaction(SIGXCPU, &action, NULL);
 
-	action.sa_handler = dump_strings;
+	action.sa_handler = sig_dump_strings;
 	sigaction(SIGEMT, &action, NULL);
 
 	action.sa_handler = reset;
@@ -300,15 +305,19 @@ main(argc, argv)
 	(void) signal(SIGUSR1, dbug_on);
 	(void) signal(SIGUSR2, dbug_off);
 	(void) signal(SIGCHLD, reap);
-	(void) signal(SIGFPE, dump_db);
-	(void) signal(SIGEMT, dump_strings);
+	(void) signal(SIGFPE, sig_dump_db);
+	(void) signal(SIGXCPU, sig_dump_db);
+	(void) signal(SIGEMT, sig_dump_strings);
 	(void) signal(SIGHUP, reset);
 #endif /* POSIX */
 
 	syslog(LOG_NOTICE, "Ready for action");
 
+	/* Initialize t_local for other uses */
+	(void) gettimeofday(&t_local, (struct timezone *)0);
 	/* GO! */
 	uptime = NOW;
+
 #ifdef DEBUG_MALLOC
 	malloc_inuse(&m_size);
 #endif
@@ -316,11 +325,17 @@ main(argc, argv)
 		if (doreset)
 			do_reset();
 
+		if (dump_db_flag)
+		    dump_db();
+		if (dump_strings_flag)
+		    dump_strings();
+
+		nexthost_tv.tv_usec = 0;
 		tvp = &nexthost_tv;
+
 		if (nexttimo != 0L) {
 			nexthost_tv.tv_sec = nexttimo - NOW;
-			nexthost_tv.tv_usec = 0;
-			if (nexthost_tv.tv_sec < 0) {
+			if (nexthost_tv.tv_sec <= 0) {
 				/* timeout has passed! */
 				/* so we process one timeout, then pop to
 				   select, polling for input.  This way we get
@@ -331,7 +346,7 @@ main(argc, argv)
 				nexthost_tv.tv_sec = 0;
 			}
 		} else {			/* no timeouts to process */
-			tvp = (struct timeval *) NULL;
+			nexthost_tv.tv_sec = 15;
 		}
 		readable = interesting;
 		if (msgs_queued()) {
@@ -340,8 +355,8 @@ main(argc, argv)
 			nfound = 1;
 			FD_ZERO(&readable);
 		} else 
-			nfound = select(nfildes, &readable, (fd_set *) NULL,
-					(fd_set *) NULL, tvp);
+			nfound = select(nfildes, &readable, (fd_set *) 0,
+					(fd_set *) 0, tvp);
 
 		/* Initialize t_local for other uses */
 		(void) gettimeofday(&t_local, (struct timezone *)0);
@@ -578,11 +593,17 @@ int fork_for_dump = 0;
 
 static SIGNAL_RETURN_TYPE
 #ifdef __STDC__
-dump_strings (int sig)
+sig_dump_strings (int sig)
 #else
-dump_strings(sig)
+sig_dump_strings(sig)
      int sig;
 #endif
+{
+	dump_strings_flag = 1;
+	SIG_RETURN;
+}
+
+static void dump_strings()
 {
     FILE *fp;
     int oerrno = errno;
@@ -590,7 +611,8 @@ dump_strings(sig)
     if (!fp) {
 	syslog (LOG_ERR, "can't open strings dump file: %m");
 	errno = oerrno;
-	SIG_RETURN;
+	dump_strings_flag = 0;
+	return;
     }
     syslog (LOG_INFO, "dumping strings to disk");
     print_zstring_table(fp);
@@ -599,16 +621,23 @@ dump_strings(sig)
     else
 	syslog (LOG_INFO, "dump done");
     oerrno = errno;
-    SIG_RETURN;
+    dump_strings_flag = 0;
+    return;
 }
 
 static SIGNAL_RETURN_TYPE
 #ifdef __STDC__
-dump_db(int sig)
+sig_dump_db(int sig)
 #else
-dump_db(sig)
+sig_dump_db(sig)
      int sig;
 #endif
+{
+	dump_db_flag = 1;
+	SIG_RETURN;
+}
+
+static void dump_db()
 {
 	/* dump the in-core database to human-readable form on disk */
 	FILE *fp;
@@ -627,11 +656,15 @@ dump_db(sig)
 	    pid = -1;
 #endif
 	if (pid > 0)
-	    SIG_RETURN;
+	{
+		dump_db_flag = 0;
+		return;
+	}
 	if ((fp = fopen("/usr/tmp/zephyr.db", "w")) == (FILE *)0) {
 		syslog(LOG_ERR, "can't open dump database");
 		errno = oerrno;
-		SIG_RETURN;
+		dump_db_flag = 0;
+		return;
 	}
 	syslog(LOG_INFO, "dumping to disk");
 	server_dump_servers(fp);
@@ -644,7 +677,8 @@ dump_db(sig)
 	if (pid == 0)
 	    exit (0);
 	errno = oerrno;
-	SIG_RETURN;
+	dump_db_flag = 0;
+	return;
 }
 
 static SIGNAL_RETURN_TYPE
-- 
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