#201 coordinator apisessions for pocket access
This commit is contained in:
Mikayla Fischler
247
coordinator/session/api.lua
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247
coordinator/session/api.lua
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local comms = require("scada-common.comms")
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local log = require("scada-common.log")
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local mqueue = require("scada-common.mqueue")
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local util = require("scada-common.util")
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local api = {}
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local PROTOCOL = comms.PROTOCOL
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-- local CAPI_TYPE = comms.CAPI_TYPE
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local SCADA_MGMT_TYPE = comms.SCADA_MGMT_TYPE
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local println = util.println
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-- retry time constants in ms
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-- local INITIAL_WAIT = 1500
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-- local RETRY_PERIOD = 1000
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local API_S_CMDS = {
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}
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local API_S_DATA = {
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}
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api.API_S_CMDS = API_S_CMDS
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api.API_S_DATA = API_S_DATA
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local PERIODICS = {
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KEEP_ALIVE = 2000
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}
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-- pocket API session
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---@nodiscard
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---@param id integer session ID
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---@param in_queue mqueue in message queue
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---@param out_queue mqueue out message queue
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---@param timeout number communications timeout
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function api.new_session(id, in_queue, out_queue, timeout)
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local log_header = "api_session(" .. id .. "): "
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local self = {
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-- connection properties
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seq_num = 0,
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r_seq_num = nil,
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connected = true,
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conn_watchdog = util.new_watchdog(timeout),
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last_rtt = 0,
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-- periodic messages
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periodics = {
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keep_alive = 0
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},
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-- when to next retry one of these requests
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retry_times = {
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},
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-- command acknowledgements
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acks = {
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},
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-- session database
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---@class api_db
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sDB = {
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}
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}
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---@class api_session
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local public = {}
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-- mark this API session as closed, stop watchdog
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local function _close()
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self.conn_watchdog.cancel()
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self.connected = false
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end
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-- send a CAPI packet
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---@param msg_type CAPI_TYPE
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---@param msg table
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local function _send(msg_type, msg)
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local s_pkt = comms.scada_packet()
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local c_pkt = comms.capi_packet()
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c_pkt.make(msg_type, msg)
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s_pkt.make(self.seq_num, PROTOCOL.COORD_API, c_pkt.raw_sendable())
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out_queue.push_packet(s_pkt)
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self.seq_num = self.seq_num + 1
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end
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-- send a SCADA management packet
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---@param msg_type SCADA_MGMT_TYPE
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---@param msg table
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local function _send_mgmt(msg_type, msg)
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local s_pkt = comms.scada_packet()
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local m_pkt = comms.mgmt_packet()
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m_pkt.make(msg_type, msg)
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s_pkt.make(self.seq_num, PROTOCOL.SCADA_MGMT, m_pkt.raw_sendable())
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out_queue.push_packet(s_pkt)
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self.seq_num = self.seq_num + 1
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end
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-- handle a packet
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---@param pkt mgmt_frame|capi_frame
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local function _handle_packet(pkt)
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-- check sequence number
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if self.r_seq_num == nil then
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self.r_seq_num = pkt.scada_frame.seq_num()
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elseif self.r_seq_num >= pkt.scada_frame.seq_num() then
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log.warning(log_header .. "sequence out-of-order: last = " .. self.r_seq_num .. ", new = " .. pkt.scada_frame.seq_num())
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return
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else
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self.r_seq_num = pkt.scada_frame.seq_num()
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end
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-- process packet
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if pkt.scada_frame.protocol() == PROTOCOL.COORD_API then
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---@cast pkt capi_frame
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-- feed watchdog
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self.conn_watchdog.feed()
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-- handle packet by type
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if pkt.type == nil then
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else
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log.debug(log_header .. "handler received unsupported CAPI packet type " .. pkt.type)
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end
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elseif pkt.scada_frame.protocol() == PROTOCOL.SCADA_MGMT then
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---@cast pkt mgmt_frame
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if pkt.type == SCADA_MGMT_TYPE.KEEP_ALIVE then
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-- keep alive reply
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if pkt.length == 2 then
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local srv_start = pkt.data[1]
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-- local api_send = pkt.data[2]
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local srv_now = util.time()
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self.last_rtt = srv_now - srv_start
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if self.last_rtt > 750 then
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log.warning(log_header .. "API KEEP_ALIVE round trip time > 750ms (" .. self.last_rtt .. "ms)")
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end
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-- log.debug(log_header .. "API RTT = " .. self.last_rtt .. "ms")
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-- log.debug(log_header .. "API TT = " .. (srv_now - api_send) .. "ms")
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else
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log.debug(log_header .. "SCADA keep alive packet length mismatch")
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end
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elseif pkt.type == SCADA_MGMT_TYPE.CLOSE then
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-- close the session
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_close()
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else
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log.debug(log_header .. "handler received unsupported SCADA_MGMT packet type " .. pkt.type)
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end
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end
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end
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-- PUBLIC FUNCTIONS --
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-- get the session ID
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---@nodiscard
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function public.get_id() return id end
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-- get the session database
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---@nodiscard
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function public.get_db() return self.sDB end
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-- check if a timer matches this session's watchdog
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---@nodiscard
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function public.check_wd(timer)
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return self.conn_watchdog.is_timer(timer) and self.connected
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end
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-- close the connection
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function public.close()
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_close()
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_send_mgmt(SCADA_MGMT_TYPE.CLOSE, {})
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println("connection to API session " .. id .. " closed by server")
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log.info(log_header .. "session closed by server")
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end
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-- iterate the session
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---@nodiscard
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---@return boolean connected
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function public.iterate()
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if self.connected then
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------------------
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-- handle queue --
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------------------
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local handle_start = util.time()
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while in_queue.ready() and self.connected do
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-- get a new message to process
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local message = in_queue.pop()
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if message ~= nil then
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if message.qtype == mqueue.TYPE.PACKET then
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-- handle a packet
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_handle_packet(message.message)
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elseif message.qtype == mqueue.TYPE.COMMAND then
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-- handle instruction
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elseif message.qtype == mqueue.TYPE.DATA then
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-- instruction with body
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end
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end
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-- max 100ms spent processing queue
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if util.time() - handle_start > 100 then
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log.warning(log_header .. "exceeded 100ms queue process limit")
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break
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end
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end
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-- exit if connection was closed
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if not self.connected then
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println("connection to API session " .. id .. " closed by remote host")
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log.info(log_header .. "session closed by remote host")
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return self.connected
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end
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----------------------
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-- update periodics --
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----------------------
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local elapsed = util.time() - self.periodics.last_update
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local periodics = self.periodics
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-- keep alive
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periodics.keep_alive = periodics.keep_alive + elapsed
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if periodics.keep_alive >= PERIODICS.KEEP_ALIVE then
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_send_mgmt(SCADA_MGMT_TYPE.KEEP_ALIVE, { util.time() })
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periodics.keep_alive = 0
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end
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self.periodics.last_update = util.time()
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---------------------
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-- attempt retries --
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---------------------
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-- local rtimes = self.retry_times
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end
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return self.connected
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end
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return public
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end
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return api
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