From d202a490113a968b50669912bd5a871dda94c268 Mon Sep 17 00:00:00 2001
From: Mikayla Fischler <mikayla@ky8.io>
Date: Fri, 21 Oct 2022 15:15:56 -0400
Subject: [PATCH] #108 resolved TCD race condition

---
 coordinator/startup.lua                  |  3 +--
 graphics/elements/animations/waiting.lua |  2 +-
 graphics/flasher.lua                     |  3 ++-
 scada-common/tcallbackdsp.lua            | 24 ++++++++++++++++++++++++
 4 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/coordinator/startup.lua b/coordinator/startup.lua
index fac7ab8..0c4e579 100644
--- a/coordinator/startup.lua
+++ b/coordinator/startup.lua
@@ -16,7 +16,7 @@ local config       = require("coordinator.config")
 local coordinator  = require("coordinator.coordinator")
 local renderer     = require("coordinator.renderer")
 
-local COORDINATOR_VERSION = "alpha-v0.5.6"
+local COORDINATOR_VERSION = "alpha-v0.5.7"
 
 local print = util.print
 local println = util.println
@@ -146,7 +146,6 @@ end
 ---@return boolean ui_ok started ok
 local function init_start_ui()
     log_graphics("starting UI...")
-    -- util.psleep(3)
 
     local draw_start = util.time_ms()
 
diff --git a/graphics/elements/animations/waiting.lua b/graphics/elements/animations/waiting.lua
index 5c03d09..2b08092 100644
--- a/graphics/elements/animations/waiting.lua
+++ b/graphics/elements/animations/waiting.lua
@@ -85,7 +85,7 @@ local function waiting(args)
         if state >= 12 then state = 0 end
 
         if run_animation then
-            tcd.dispatch(0.5, animate)
+            tcd.dispatch_unique(0.5, animate)
         end
     end
 
diff --git a/graphics/flasher.lua b/graphics/flasher.lua
index 97afd83..02f0dcd 100644
--- a/graphics/flasher.lua
+++ b/graphics/flasher.lua
@@ -38,13 +38,14 @@ local function callback_250ms()
 
         callback_counter = callback_counter + 1
 
-        tcd.dispatch(0.25, callback_250ms)
+        tcd.dispatch_unique(0.25, callback_250ms)
     end
 end
 
 -- start the flasher periodic
 function flasher.init()
     active = true
+    callback_counter = 0
     registry = { {}, {}, {} }
     callback_250ms()
 end
diff --git a/scada-common/tcallbackdsp.lua b/scada-common/tcallbackdsp.lua
index 65b8ec9..3371c98 100644
--- a/scada-common/tcallbackdsp.lua
+++ b/scada-common/tcallbackdsp.lua
@@ -2,6 +2,9 @@
 -- Timer Callback Dispatcher
 --
 
+local log  = require("scada-common.log")
+local util = require("scada-common.util")
+
 local tcallbackdsp = {}
 
 local registry = {}
@@ -14,6 +17,27 @@ function tcallbackdsp.dispatch(time, f)
     registry[os.startTimer(time)] = { callback = f }
 end
 
+-- request a function to be called after the specified time, aborting any registered instances of that function reference
+---@param time number seconds
+---@param f function callback function
+function tcallbackdsp.dispatch_unique(time, f)
+    -- ignore if already registered
+    for timer, entry in pairs(registry) do
+        if entry.callback == f then
+            -- found an instance of this function reference, abort it
+            log.debug(util.c("TCD: aborting duplicate timer callback (timer: ", timer, ", function: ", f, ")"))
+
+            -- cancel event and remove from registry (even if it fires it won't call)
+---@diagnostic disable-next-line: undefined-field
+            os.cancelTimer(timer)
+            registry[timer] = nil
+        end
+    end
+
+---@diagnostic disable-next-line: undefined-field
+    registry[os.startTimer(time)] = { callback = f }
+end
+
 -- lookup a timer event and execute the callback if found
 ---@param event integer timer event timer ID
 function tcallbackdsp.handle(event)