From 078b9f3137ad17feef21f0ac9fa593a07bb2ab83 Mon Sep 17 00:00:00 2001
From: Sheng Yang <sheng.yang@cloud.com>
Date: Thu, 25 Aug 2011 17:54:22 -0700
Subject: [PATCH] bug 11266: Add lockfile for scripts in system vm

Otherwise it's easy to trigger the racy issue.

This one just contained fix for reconfigLB.sh
---
 patches/systemvm/debian/config/root/func.sh   | 44 +++++++++++++++++++
 .../systemvm/debian/config/root/reconfigLB.sh | 19 ++++++--
 2 files changed, 60 insertions(+), 3 deletions(-)
 create mode 100644 patches/systemvm/debian/config/root/func.sh

diff --git a/patches/systemvm/debian/config/root/func.sh b/patches/systemvm/debian/config/root/func.sh
new file mode 100644
index 00000000000..c1a921a86c9
--- /dev/null
+++ b/patches/systemvm/debian/config/root/func.sh
@@ -0,0 +1,44 @@
+#!/bin/bash
+
+# getLockFile() parameters
+# $1 lock filename
+# $2 timeout seconds
+getLockFile() {
+    __locked=0
+    __LOCKFILE="/tmp/$1.lock"
+    if [ $2 ]
+    then
+        __TIMEOUT=$2
+    else
+        __TIMEOUT=10
+    fi
+
+    for i in `seq 1 $__TIMEOUT`
+    do
+        if [ ! -e $__LOCKFILE ]
+        then
+            touch $__LOCKFILE
+            __locked=1
+            break
+        fi
+        sleep 1
+        logger -t cloud "sleep 1 second wait for the lock file " $__LOCKFILE
+    done
+    if [ $__locked -ne 1 ]
+    then
+	logger -t cloud "fail to acquire the lock file $__LOCKFILE after $__TIMEOUT seconds time out!"
+    fi
+    echo $__locked
+}
+
+# releaseLockFile() parameters
+# $1 lock filename
+# $2 locked(1) or not(0)
+releaseLockFile() {
+    __LOCKFILE="/tmp/$1.lock"
+    __locked=$2
+    if [ "$__locked" == "1" ]
+    then
+        rm $__LOCKFILE
+    fi
+}
diff --git a/patches/systemvm/debian/config/root/reconfigLB.sh b/patches/systemvm/debian/config/root/reconfigLB.sh
index 38b07142f99..ef4ac7be011 100755
--- a/patches/systemvm/debian/config/root/reconfigLB.sh
+++ b/patches/systemvm/debian/config/root/reconfigLB.sh
@@ -18,9 +18,18 @@
   # You should have received a copy of the GNU General Public License
   # along with this program.  If not, see <http://www.gnu.org/licenses/>.
   #
- 
 
+name="reconfigLB"
 
+source func.sh
+locked=$(getLockFile $name)
+if [ "$locked" != "1" ]
+then
+    logger -t cloud "Fail to get the lock for " $name
+    exit 1
+fi
+
+ret=0
 # save previous state
   mv /etc/haproxy/haproxy.cfg /etc/haproxy/haproxy.cfg.old
   mv /var/run/haproxy.pid /var/run/haproxy.pid.old
@@ -32,7 +41,7 @@
     echo "New haproxy instance successfully loaded, stopping previous one."
     kill -KILL $(cat /var/run/haproxy.pid.old)
     rm -f /var/run/haproxy.pid.old
-    exit 0
+    ret=0
   else
     echo "New instance failed to start, resuming previous one."
     kill -TTIN $(cat /var/run/haproxy.pid.old)
@@ -40,5 +49,9 @@
     mv /var/run/haproxy.pid.old /var/run/haproxy.pid
     mv /etc/haproxy/haproxy.cfg /etc/haproxy/haproxy.cfg.new
     mv /etc/haproxy/haproxy.cfg.old /etc/haproxy/haproxy.cfg
-    exit 1
+    ret=1
   fi
+
+releaseLockFile $name $locked
+
+exit $ret