[swss]: Add support for swss docker warm restart (#1982)

Signed-off-by: Jipan Yang <[email protected]>

Author: jipanyang

files/scripts/swss.sh

@@ -2,10 +2,29 @@
 
 start() {
     # Wait for redis server start before database clean
-    until [[ $(/usr/bin/docker exec database redis-cli ping | grep -c PONG) -gt 0 ]]; 
+    until [[ $(/usr/bin/docker exec database redis-cli ping | grep -c PONG) -gt 0 ]];
         do sleep 1;
     done
 
+    # Wait for configDB initialization
+    until [[ $(/usr/bin/docker exec database redis-cli -n 4 GET "CONFIG_DB_INITIALIZED") ]];
+        do sleep 1;
+    done
+
+    SYSTEM_WARM_START=`/usr/bin/docker exec database redis-cli -n 4 HGET "WARM_RESTART|system" enable`
+    SWSS_WARM_START=`/usr/bin/docker exec database redis-cli -n 4 HGET "WARM_RESTART|swss" enable`
+    # if warm start enabled, just do swss docker start.
+    # Don't flush DB or try to start other modules.
+    if [[ "$SYSTEM_WARM_START" == "true" ]] || [[ "$SWSS_WARM_START" == "true" ]]; then
+      RESTART_COUNT=`redis-cli -n 6 hget "WARM_RESTART_TABLE|orchagent" restart_count`
+      # We have to make sure db data has not been flushed.
+      if [[ -n "$RESTART_COUNT" ]]; then
+        /usr/bin/swss.sh start
+        /usr/bin/swss.sh attach
+        return 0
+      fi
+    fi
+
     # Flush DB
     /usr/bin/docker exec database redis-cli -n 0 FLUSHDB
     /usr/bin/docker exec database redis-cli -n 1 FLUSHDB
@@ -25,14 +44,22 @@ start() {
         /etc/init.d/xpnet.sh start
     fi
 
-    # start swss and syncd docker 
-    /usr/bin/swss.sh start 
+    # start swss and syncd docker
+    /usr/bin/swss.sh start
     /usr/bin/syncd.sh start
     /usr/bin/swss.sh attach
 }
 
 stop() {
     /usr/bin/swss.sh stop
+
+    SYSTEM_WARM_START=`redis-cli -n 4 hget "WARM_RESTART|system" enable`
+    SWSS_WARM_START=`redis-cli -n 4 hget "WARM_RESTART|swss" enable`
+    # if warm start enabled, just stop swss docker, then return
+    if [[ "$SYSTEM_WARM_START" == "true" ]] || [[ "$SWSS_WARM_START" == "true" ]]; then
+        return 0
+    fi
+
     /usr/bin/syncd.sh stop
 
     # platform specific tasks