Query weather with async timeouts

Fixes #81

weather-widget/weather.lua

@@ -6,7 +6,9 @@
 -- @copyright 2018 Pavel Makhov
 -------------------------------------------------
 
+local socket = require("socket")
 local http = require("socket.http")
+local ltn12 = require("ltn12")
 local json = require("json")
 local naughty = require("naughty")
 local wibox = require("wibox")
@@ -14,6 +16,13 @@ local gears = require("gears")
 
 local secrets = require("awesome-wm-widgets.secrets")
 
+local weather_api_url = (
+    'https://api.openweathermap.org/data/2.5/weather'
+    .. '?q='     .. secrets.weather_widget_city
+    .. '&appid=' .. secrets.weather_widget_api_key
+    .. '&units=' .. secrets.weather_widget_units
+)
+
 local path_to_icons = "/usr/share/icons/Arc/status/symbolic/"
 
 local icon_widget = wibox.widget {
@@ -93,18 +102,34 @@ local weather_timer = gears.timer({ timeout = 60 })
 local resp
 
 weather_timer:connect_signal("timeout", function ()
-    local resp_json, status = http.request('https://api.openweathermap.org/data/2.5/weather?q='
+    local resp_json = {}
-            .. secrets.weather_widget_city
+    local res, status = http.request{
-            .. '&appid=' .. secrets.weather_widget_api_key
+        url=weather_api_url,
-            .. '&units=' .. secrets.weather_widget_units)
+        sink=ltn12.sink.table(resp_json),
-    if (status ~= 200 and resp_json ~= nil) then
+        -- ref:
+        -- http://w3.impa.br/~diego/software/luasocket/old/luasocket-2.0/http.html
+        create=function()
+            -- ref: https://stackoverflow.com/a/6021774/595220
+            local req_sock = socket.tcp()
+            -- 't' — overall timeout
+            req_sock:settimeout(0.2, 't')
+            -- 'b' — block timeout
+            req_sock:settimeout(0.001, 'b')
+            return req_sock
+        end
+    }
+    if (resp_json ~= nil) then
+        resp_json = table.concat(resp_json)
+    end
+
+    if (status ~= 200 and resp_json ~= nil and resp_json ~= '') then
         local err_resp = json.decode(resp_json)
         naughty.notify{
             title = 'Weather Widget Error',
             text = err_resp.message,
             preset = naughty.config.presets.critical,
         }
-    elseif (resp_json ~= nil) then
+    elseif (resp_json ~= nil and resp_json ~= '') then
         resp = json.decode(resp_json)
         icon_widget.image = path_to_icons .. icon_map[resp.weather[1].icon]
         temp_widget:set_text(string.gsub(resp.main.temp, "%.%d+", "")