From aff166e27d22ab0d80e773fe4f4b46db1b11e813 Mon Sep 17 00:00:00 2001
From: Mikayla Fischler <mikayla@ky8.io>
Date: Wed, 27 Apr 2022 19:06:01 -0400
Subject: [PATCH] added util adaptive_delay to replace repeated code

---
 reactor-plc/threads.lua | 16 ++++------------
 rtu/threads.lua         |  8 ++------
 scada-common/util.lua   | 10 ++++++++++
 3 files changed, 16 insertions(+), 18 deletions(-)

diff --git a/reactor-plc/threads.lua b/reactor-plc/threads.lua
index 5cc80bc..a9b95d7 100644
--- a/reactor-plc/threads.lua
+++ b/reactor-plc/threads.lua
@@ -287,12 +287,8 @@ function thread__iss(smem)
                 break
             end
 
-            -- delay before next check, only if >50ms since we did already yield
-            local sleep_for = ISS_SLEEP - (util.time() - last_update)
-            last_update = util.time()
-            if sleep_for >= 50 then
-                psleep(sleep_for / 1000.0)
-            end
+            -- delay before next check
+            last_update = util.adaptive_delay(ISS_SLEEP, last_update)
         end
     end
 
@@ -344,12 +340,8 @@ function thread__comms(smem)
                 break
             end
 
-            -- delay before next check, only if >50ms since we did already yield
-            local sleep_for = COMMS_SLEEP - (util.time() - last_update)
-            last_update = util.time()
-            if sleep_for >= 50 then
-                psleep(sleep_for / 1000.0)
-            end
+            -- delay before next check
+            last_update = util.adaptive_delay(COMMS_SLEEP, last_update)
         end
     end
 
diff --git a/rtu/threads.lua b/rtu/threads.lua
index d736ee1..fece382 100644
--- a/rtu/threads.lua
+++ b/rtu/threads.lua
@@ -144,12 +144,8 @@ function thread__comms(smem)
                 break
             end
 
-            -- delay before next check, only if >50ms since we did already yield
-            local sleep_for = COMMS_SLEEP - (util.time() - last_update)
-            last_update = util.time()
-            if sleep_for >= 50 then
-                psleep(sleep_for / 1000.0)
-            end
+            -- delay before next check
+            last_update = util.adaptive_delay(COMMS_SLEEP, last_update)
         end
     end
 
diff --git a/scada-common/util.lua b/scada-common/util.lua
index 69bc7f1..36761fd 100644
--- a/scada-common/util.lua
+++ b/scada-common/util.lua
@@ -50,6 +50,16 @@ function nop()
     psleep(0.05)
 end
 
+-- attempt to maintain a minimum loop timing (duration of execution)
+function adaptive_delay(target_timing, last_update)
+    local sleep_for = target_timing - (time() - last_update)
+    -- only if >50ms since worker loops already yield 0.05s
+    if sleep_for >= 50 then
+        psleep(sleep_for / 1000.0)
+    end
+    return time()
+end
+
 -- WATCHDOG --
 
 -- ComputerCraft OS Timer based Watchdog