Make remote_watch update exactly once during the specified interval

config/awesome/helpers.lua

@@ -386,26 +386,25 @@ end
 
 -- Useful for periodically checking the output of a command that
 -- requires internet access.
--- Ensures that `command` will be run only once during the desired
+-- Ensures that `command` will be run EXACTLY once during the desired
 -- `interval`, even if awesome restarts multiple times during this time.
 -- Saves output in `output_file` and checks its last modification
 -- time to determine whether to run the command again or not.
 -- Passes the output of `command` to `callback` function.
 function helpers.remote_watch(command, interval, output_file, callback)
-
     local run_the_thing = function()
         -- Pass output to callback AND write it to file
         awful.spawn.easy_async_with_shell(command.." | tee "..output_file, function(out) callback(out) end)
     end
 
-    gears.timer {
+    local timer
+    timer = gears.timer {
         timeout = interval,
         call_now = true,
         autostart = true,
         single_shot = false,
         callback = function()
             awful.spawn.easy_async_with_shell("date -r "..output_file.." +%s", function(last_update, _, __, exitcode)
-
                 -- Probably the file does not exist yet (first time
                 -- running after reboot)
                 if exitcode == 1 then
@@ -414,14 +413,21 @@ function helpers.remote_watch(command, interval, output_file, callback)
                 end
 
                 local diff = os.time() - tonumber(last_update)
-                if diff > interval then
+                if diff >= interval then
                     run_the_thing()
                 else
                     -- Pass the date saved in the file since it is fresh enough
                     awful.spawn.easy_async_with_shell("cat "..output_file, function(out) callback(out) end)
+
+                    -- Schedule an update for when the remaining time to complete the interval passes
+                    timer:stop()
+                    gears.timer.start_new(interval - diff, function()
+                        run_the_thing()
+                        timer:again()
+                    end)
                 end
             end)
-    end
+        end
     }
 end