perf(mqtt): reduce memory usage

Signed-off-by: Jianhui Zhao <zhaojh329@gmail.com>

mqtt.lua

@@ -8,15 +8,15 @@ local dns = require 'eco.dns'
 
 local M = {}
 
-local function mqtt_io_loop(mt)
-    local done = mt.done
-    local con = mt.con
-    local w = mt.iow
+local function mqtt_io_loop(con)
+    local done = con.done
+    local __con = con.con
+    local w = con.iow
 
     while not done.v do
         local ev = eco.READ
 
-        if con:want_write() then
+        if __con:want_write() then
             ev = ev | eco.WRITE
         end
 
@@ -32,13 +32,13 @@ local function mqtt_io_loop(mt)
         end
 
         if ev & eco.READ > 0 then
-            if not con:loop_read(1) then
+            if not __con:loop_read(1) then
                 break
             end
         end
 
         if ev & eco.WRITE > 0 then
-            if not con:loop_write(1) then
+            if not __con:loop_write(1) then
                 break
             end
         end
@@ -47,12 +47,12 @@ local function mqtt_io_loop(mt)
     done.v = true
 end
 
-local function check_keepalive_loop(mt)
-    local done = mt.done
-    local con = mt.con
+local function check_keepalive_loop(con)
+    local done = con.done
+    local __con = con.con
 
     while not done.v do
-        if not con:loop_misc() then
+        if not __con:loop_misc() then
             break
         end
         time.sleep(1)
@@ -64,95 +64,79 @@ end
 local methods = {}
 
 function methods:destroy()
-    local mt = getmetatable(self)
-    mt.done.v = true
+    self.done.v = true
 
-    if mt.ior then
-        mt.ior:cancel()
+    if self.ior then
+        self.ior:cancel()
     end
 
-    if mt.iow then
-        mt.iow:cancel()
+    if self.iow then
+        self.iow:cancel()
     end
 
-    return mt.con:destroy()
+    return self.con:destroy()
 end
 
 function methods:disconnect()
-    local mt = getmetatable(self)
-    return mt.con:disconnect()
+    return self.con:disconnect()
 end
 
 function methods:reinitialise(id, clean_session)
-    local mt = getmetatable(self)
-    return mt.con:reinitialise(id, clean_session)
+    return self.con:reinitialise(id, clean_session)
 end
 
 function methods:will_set(topic, payload, qos, retain)
-    local mt = getmetatable(self)
-    return mt.con:will_set(topic, payload, qos, retain)
+    return self.con:will_set(topic, payload, qos, retain)
 end
 
 function methods:will_clear()
-    local mt = getmetatable(self)
-    return mt.con:will_clear()
+    return self.con:will_clear()
 end
 
 function methods:login_set(username, password)
-    local mt = getmetatable(self)
-    return mt.con:login_set(username, password)
+    return self.con:login_set(username, password)
 end
 
 function methods:tls_insecure_set(insecure)
-    local mt = getmetatable(self)
-    return mt.con:tls_insecure_set(insecure)
+    return self.con:tls_insecure_set(insecure)
 end
 
 function methods:tls_set(cafile, capath, certfile, keyfile)
-    local mt = getmetatable(self)
-    return mt.con:tls_set(cafile, capath, certfile, keyfile)
+    return self.con:tls_set(cafile, capath, certfile, keyfile)
 end
 
 function methods:tls_psk_set(psk, identity, ciphers)
-    local mt = getmetatable(self)
-    return mt.con:tls_psk_set(psk, identity, ciphers)
+    return self.con:tls_psk_set(psk, identity, ciphers)
 end
 
 function methods:tls_opts_set(cert_required, tls_version, ciphers)
-    local mt = getmetatable(self)
-    return mt.con:tls_psk_set(cert_required, tls_version, ciphers)
+    return self.con:tls_psk_set(cert_required, tls_version, ciphers)
 end
 
 function methods:option(option, value)
-    local mt = getmetatable(self)
-    return mt.con:option(option, value)
+    return self.con:option(option, value)
 end
 
 function methods:publish(topic, payload, qos, retain)
-    local mt = getmetatable(self)
-    return mt.con:publish(topic, payload, qos, retain)
+    return self.con:publish(topic, payload, qos, retain)
 end
 
 function methods:subscribe(topic, qos)
-    local mt = getmetatable(self)
-    return mt.con:subscribe(topic, qos)
+    return self.con:subscribe(topic, qos)
 end
 
 function methods:unsubscribe(topic)
-    local mt = getmetatable(self)
-    return mt.con:unsubscribe(topic)
+    return self.con:unsubscribe(topic)
 end
 
 function methods:set_callback(typ, func)
-    local mt = getmetatable(self)
-    return mt.con:callback_set(typ, function(...)
+    return self.con:callback_set(typ, function(...)
         eco.run(func, ...)
     end)
 end
 
 local function try_connect(con, address, port, keepalive)
-    local mt = getmetatable(con)
-    local __con = mt.con
+    local __con = con.con
 
     local s, err = socket.connect_tcp(address, port)
     if not s then
@@ -167,11 +151,11 @@ local function try_connect(con, address, port, keepalive)
         return false, err
     end
 
-    mt.iow = eco.watcher(eco.IO, __con:socket(), eco.WRITE)
-    mt.done.v = false
+    con.iow = eco.watcher(eco.IO, __con:socket(), eco.WRITE)
+    con.done.v = false
 
-    eco.run(mqtt_io_loop, mt)
-    eco.run(check_keepalive_loop, mt)
+    eco.run(mqtt_io_loop, con)
+    eco.run(check_keepalive_loop, con)
 
     return true
 end
@@ -196,15 +180,18 @@ function methods:connect(host, port, keepalive)
     return false, err
 end
 
+local metatable = {
+    __index = methods,
+    __gc = methods.destroy
+}
+
 function M.new(id, clean_session)
     local con = mqtt.new(eco.context(), id, clean_session)
 
-    return setmetatable({}, {
-        __index = methods,
-        __gc = methods.destroy,
+    return setmetatable({
         con = con,
         done = { v = true }
-    })
+    }, metatable)
 end
 
 return setmetatable(M, { __index = mqtt })