supervisor PLC session closing, re-requesting status cache if missing

supervisor/session/plc.lua

@@ -7,6 +7,11 @@ local PROTOCOLS = comms.PROTOCOLS
 local RPLC_TYPES = comms.RPLC_TYPES
 local SCADA_MGMT_TYPES = comms.SCADA_MGMT_TYPES
 
+local print = util.print
+local println = util.println
+local print_ts = util.print_ts
+local println_ts = util.println_ts
+
 -- retry time constants in ms
 local INITIAL_WAIT = 1500
 local RETRY_PERIOD = 1000
@@ -38,6 +43,7 @@ function new_session(id, for_reactor, in_queue, out_queue)
         r_seq_num = nil,
         connected = true,
         received_struct = false,
+        received_status_cache = false,
         plc_conn_watchdog = util.new_watchdog(3),
         last_rtt = 0,
         -- periodic messages
@@ -48,6 +54,7 @@ function new_session(id, for_reactor, in_queue, out_queue)
         -- when to next retry one of these requests
         retry_times = {
             struct_req = (util.time() + 500),
+            status_req = (util.time() + 500),
             scram_req = 0,
             enable_req = 0,
             burn_rate_req = 0,
@@ -257,6 +264,7 @@ function new_session(id, for_reactor, in_queue, out_queue)
                         local status = pcall(_copy_status, pkt.data[6])
                         if status then
                             -- copied in status data OK
+                            self.received_status_cache = true
                         else
                             -- error copying status data
                             log._error(log_header .. "failed to parse status packet data")
@@ -365,18 +373,6 @@ function new_session(id, for_reactor, in_queue, out_queue)
     -- get the session database
     local get_db = function () return self.sDB end
 
-    -- close the connection
-    local close = function ()
-        self.plc_conn_watchdog.cancel()
-        self.connected = false
-        _send_mgmt(SCADA_MGMT_TYPES.CLOSE, {})
-    end
-
-    -- check if a timer matches this session's watchdog
-    local check_wd = function (timer)
-        return timer == self.plc_conn_watchdog.get_timer()
-    end
-
     -- get the reactor structure
     local get_struct = function ()
         if self.received_struct then
@@ -386,6 +382,29 @@ function new_session(id, for_reactor, in_queue, out_queue)
         end
     end
 
+    -- get the reactor structure
+    local get_status = function ()
+        if self.received_status_cache then
+            return self.sDB.mek_status
+        else
+            return nil
+        end
+    end
+
+    -- check if a timer matches this session's watchdog
+    local check_wd = function (timer)
+        return timer == self.plc_conn_watchdog.get_timer()
+    end
+
+    -- close the connection
+    local close = function ()
+        self.plc_conn_watchdog.cancel()
+        self.connected = false
+        _send_mgmt(SCADA_MGMT_TYPES.CLOSE, {})
+        println("connection to reactor " .. self.for_reactor .. " PLC closed by server")
+        log._info(log_header .. "session closed by server")
+    end
+
     -- iterate the session
     local iterate = function ()
         if self.connected then
@@ -442,6 +461,8 @@ function new_session(id, for_reactor, in_queue, out_queue)
 
             -- exit if connection was closed
             if not self.connected then
+                self.plc_conn_watchdog.cancel()
+                println("connection to reactor " .. self.for_reactor .. " PLC closed by remote host")
                 log._info(log_header .. "session closed by remote host")
                 return self.connected
             end
@@ -479,6 +500,15 @@ function new_session(id, for_reactor, in_queue, out_queue)
                 end
             end
 
+            -- status cache request retry
+
+            if not self.received_status_cache then
+                if rtimes.status_req - util.time() <= 0 then
+                    _send(RPLC_TYPES.MEK_STATUS, {})
+                    rtimes.status_req = util.time() + RETRY_PERIOD
+                end
+            end
+
             -- SCRAM request retry
 
             if not self.acks.scram then
@@ -522,9 +552,10 @@ function new_session(id, for_reactor, in_queue, out_queue)
     return {
         get_id = get_id,
         get_db = get_db,
-        close = close,
-        check_wd = check_wd,
         get_struct = get_struct,
+        get_status = get_status,
+        check_wd = check_wd,
+        close = close,
         iterate = iterate
     }
 end

supervisor/session/svsessions.lua

@@ -91,6 +91,22 @@ function establish_plc_session(local_port, remote_port, for_reactor)
     end
 end
 
+-- cleanly close a session
+local function _shutdown(session)
+    session.open = false
+    session.instance.close()
+
+    -- send packets in out queue (namely the close packet)
+    while session.out_queue.ready() do
+        local msg = session.out_queue.pop()
+        if msg.qtype == mqueue.TYPE.PACKET then
+            self.modem.transmit(session.r_port, session.l_port, msg.message.raw_sendable())
+        end
+    end
+
+    log._debug("closed session " .. session.instance.get_id() .. " on remote port " .. session.r_port)
+end
+
 -- check if a watchdog timer event matches that of one of the provided sessions
 local function _check_watchdogs(sessions, timer_event)
     for i = 1, #sessions do
@@ -98,9 +114,8 @@ local function _check_watchdogs(sessions, timer_event)
         if session.open then
             local triggered = session.instance.check_wd(timer_event)
             if triggered then
-                log._debug("watchdog closing session " .. session.instance.get_id() .. " on remote port " .. session.r_port)
+                log._debug("watchdog closing session " .. session.instance.get_id() .. " on remote port " .. session.r_port .. "...")
-                session.open = false
+                _shutdown(session)
-                session.instance.close()
             end
         end
     end
@@ -134,7 +149,6 @@ local function _iterate(sessions)
                 end
             else
                 session.open = false
-                session.instance.close()
             end
         end
     end
@@ -189,18 +203,7 @@ local function _close(sessions)
     for i = 1, #sessions do
         local session = sessions[i]
         if session.open then
-            session.open = false
+            _shutdown(session)
-            session.instance.close()
-
-            -- send packets in out queue (namely the close packet)
-            while session.out_queue.ready() do
-                local msg = session.out_queue.pop()
-                if msg.qtype == mqueue.TYPE.PACKET then
-                    self.modem.transmit(session.r_port, session.l_port, msg.message.raw_sendable())
-                end
-            end
-
-            log._debug("closed session " .. session.instance.get_id() .. " on remote port " .. session.r_port)
         end
     end
 end

supervisor/startup.lua

@@ -18,7 +18,7 @@ os.loadAPI("session/svsessions.lua")
 
 os.loadAPI("supervisor.lua")
 
-local SUPERVISOR_VERSION = "alpha-v0.1.12"
+local SUPERVISOR_VERSION = "alpha-v0.2.0"
 
 local print = util.print
 local println = util.println