From 64667af499e878f67b09e60bdf6ed0c2a549d545 Mon Sep 17 00:00:00 2001
From: Vincent Latombe <vincent@latombe.net>
Date: Wed, 28 Aug 2024 09:54:25 +0200
Subject: [PATCH] Implement ComputerListener#onIdle

Introduces a new computer listener fired whenever a Computer becomes idle.
---
 core/src/main/java/hudson/model/Computer.java          | 2 ++
 core/src/main/java/hudson/slaves/ComputerListener.java | 7 +++++++
 2 files changed, 9 insertions(+)

diff --git a/core/src/main/java/hudson/model/Computer.java b/core/src/main/java/hudson/model/Computer.java
index 14a311381a37..903751b90c13 100644
--- a/core/src/main/java/hudson/model/Computer.java
+++ b/core/src/main/java/hudson/model/Computer.java
@@ -1102,6 +1102,8 @@ protected void removeExecutor(final Executor e) {
                     if (ciBase != null) { // TODO confirm safe to assume non-null and use getInstance()
                         ciBase.removeComputer(Computer.this);
                     }
+                } else if (isIdle()) {
+                    Listeners.notify(ComputerListener.class, false, l -> l.onIdle(this));
                 }
             }
         };
diff --git a/core/src/main/java/hudson/slaves/ComputerListener.java b/core/src/main/java/hudson/slaves/ComputerListener.java
index bd794c456c50..f5d220c1104e 100644
--- a/core/src/main/java/hudson/slaves/ComputerListener.java
+++ b/core/src/main/java/hudson/slaves/ComputerListener.java
@@ -211,6 +211,13 @@ public void onTemporarilyOffline(Computer c, OfflineCause cause) {}
      */
     public void onConfigurationChange() {}
 
+    /**
+     * Indicates that the computer has become idle.
+     *
+     * @since TODO
+     */
+    public void onIdle(Computer c) {}
+
     /**
      * Registers this {@link ComputerListener} so that it will start receiving events.
      *