fix: race condition in screen state monitoring

Author: luisbocanegra

package/contents/ui/RunCommand.qml

@@ -9,7 +9,12 @@ P5Support.DataSource {
     property var callbacks: ({})
 
     function exec(cmd, callback) {
-        if (callback) {
+        // ensure each command is unique to avoid race condition where the
+        // same command runs twice but the first run fails deleting the callback
+        // that was going to be used by the second one
+        cmd = cmd + ";t=$(date +%N)";
+        // console.log("running", cmd, "callback", callback);
+        if (callback && typeof callback === "function") {
             callbacks[cmd] = callback;
         }
         dataSource.connectSource(cmd);
@@ -22,14 +27,17 @@ P5Support.DataSource {
     signal exited(string cmd, int exitCode, int exitStatus, string stdout, string stderr)
 
     onExited: (cmd, exitCode, exitStatus, stdout, stderr) => {
-        if (exitCode === 0 && cmd in callbacks) {
-            callbacks[cmd]({
-                cmd,
-                exitCode,
-                exitStatus,
-                stdout,
-                stderr
-            });
+        if (cmd in callbacks) {
+            if (typeof callbacks[cmd] === "function") {
+                callbacks[cmd]({
+                    cmd,
+                    exitCode,
+                    exitStatus,
+                    stdout,
+                    stderr
+                });
+            }
+            delete callbacks[cmd];
         }
     }
 

package/contents/ui/ScreenModel.qml

@@ -17,7 +17,6 @@
  */
 
 import QtQuick
-import org.kde.plasma.plasma5support as P5Support
 
 Item {
     id: root
@@ -30,25 +29,6 @@ Item {
 
     RunCommand {
         id: runCommand
-        onExited: (cmd, exitCode, exitStatus, stdout, stderr) => {
-            if (cmd === root.screenStateCmd)
-                root.screenStateCmdRunning = false;
-            if (exitCode !== 0)
-                return;
-            if (cmd === root.screenStateCmd) {
-                if (stdout.length > 0) {
-                    stdout = stdout.trim().toLowerCase();
-                    root.screenIsOff = stdout === "0" || stdout.includes("off");
-                }
-            }
-        }
-    }
-
-    function dumpProps(obj) {
-        console.error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
-        for (var k of Object.keys(obj)) {
-            print(k + "=" + obj[k] + "\n");
-        }
     }
 
     DBusSignalMonitor {
@@ -67,11 +47,17 @@ Item {
         id: screenTimer
         running: root.checkScreenState
         repeat: true
-        interval: 200
+        interval: 1000
         onTriggered: {
             if (root.checkScreenState && !root.screenStateCmdRunning) {
                 root.screenStateCmdRunning = true;
-                runCommand.exec(root.screenStateCmd);
+                runCommand.exec(root.screenStateCmd, output => {
+                    root.screenStateCmdRunning = false;
+                    if (output.exitCode === 0 && output.stdout.length > 0) {
+                        const out = output.stdout.trim().toLowerCase();
+                        root.screenIsOff = out === "0" || out === "off";
+                    }
+                });
             }
         }
     }