From 9ac8a202d1b97d21075a08b521f6a9b0f5190439 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ian@liberator.relativity.greenend.org.uk>
Date: Sun, 9 Jan 2011 16:54:39 +0000
Subject: [PATCH] hostside: multiplex: spot when restart is looping and abandon
 it

---
 hostside/TODO      |  1 -
 hostside/multiplex | 26 +++++++++++++++++++++++++-
 2 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/hostside/TODO b/hostside/TODO
index dec646e..89640cc 100644
--- a/hostside/TODO
+++ b/hostside/TODO
@@ -1,5 +1,4 @@
 
-multiplex should have restart loop limiting
 why did removing +persist.* not fix it
 should expire dumps, eventually
 want realtime kernel for bessar
diff --git a/hostside/multiplex b/hostside/multiplex
index 7a014dd..4988c44 100755
--- a/hostside/multiplex
+++ b/hostside/multiplex
@@ -13,6 +13,7 @@
 #    $permissions         [list allow|super|deny $ipaddrhex $maskhex ...]
 #    $realtime            pipes
 #    $realtime_retry      [list $timeoutid $awaitedpongmsg|{} $buf]
+#    $realtime_last_retries        [list $now $now $now ... $now]
 #    $replay("$pri $key") $rhs     $pri is \d\d; causes replay of  "$key $rhs"
 #    $detect0($seg)       unset -> 1 or irrelevant; [after ...]
 #    $conns($conn)        1
@@ -37,6 +38,10 @@
 #    $realtime         any          unset      set       unset
 #    $realtime_retry   unset        {}         {}        [list ...]
 #
+# realtime_last_retries is unset at startup, and becomes unset when we
+# enter auto mode.  unset means in auto mode we have to set it.
+# It contains the last few startup times.
+#
 # replay priorities and messages:
 #    10 stastate
 #    40 warning realtime-failed
@@ -234,7 +239,7 @@ proc local/select-replay {conn args} {
 #---------- automatic realtime restart ----------
 
 proc global/!realtime {conn args} {
-    global realtime realtime_retry
+    global realtime realtime_retry realtime_last_retries
     nargs $args 1
     set how [lindex $args 0]
 
@@ -258,6 +263,7 @@ proc global/!realtime {conn args} {
 	auto {
 	    realtime-retry-reset
 	    set realtime_retry {}
+	    catch { unset realtime_last_retries }
 	}
 	stop - start - start-manual {
 	    realtime-retry-reset
@@ -291,9 +297,26 @@ proc realtime-retry-reset {} {
 
 proc realtime-retry-check {} {
     global realtime_retry realtime
+    global realtime_last_retries restart_min_mean_interval
     if {![info exists realtime_retry]} return
     if {[llength $realtime_retry]} return
     if {[info exists realtime]} return
+
+    if {![info exists realtime_last_retries]} {
+	set realtime_last_retries {0 0 0 0 0}
+    }
+    set oldest [lindex $realtime_last_retries 0]
+    set now [clock seconds]
+    if {$now - $oldest <
+	$restart_min_mean_interval * [llength $realtime_last_retries]} {
+	xmit-relevantly-savereplay 40 \
+	    "warning realtime-failed" looping-disabled
+	unset realtime_retry
+	return
+    }
+    set realtime_last_retries [lrange $realtime_last_retries 1 end]
+    lappend realtime_last_retries $now
+
     realtime-start {}
 }
 
@@ -831,6 +854,7 @@ proc startup {} {
     setting testmode 0 {[01]}
     setting lputs 0 {[01]}
     setting dev_railway {} {/.*}
+    setting restart_min_mean_interval 5 {^\d+}
     parse-argv {}
     
     uplevel #0 source $libdir/multiplex-config
-- 
2.30.2