Optionally disable ShutdownHook in NioClient (#359)

SvenssonWeb · web-flow · commit 6cdb8d0074c3 · 2024-12-06T22:09:31.000+01:00
diff --git a/README.adoc b/README.adoc
@@ -115,6 +115,13 @@ Do NOT use it.
 |1000
 |700
 
+.2+|dnsjava.nio.register_shutdown_hook
+3+|Register Shutdown Hook for automatic termination of NIO.
+If disabled, the nio selector thread will not automatically clean up on JVM termination.
+|Boolean
+|True
+|False
+
 .2+|dnsjava.harden_unknown_additional
 3+|Harden against unknown records in the authority section and additional section.
 If disabled, such records are copied from the upstream and presented to the client together with the answer.
diff --git a/src/main/java/org/xbill/DNS/NioClient.java b/src/main/java/org/xbill/DNS/NioClient.java
@@ -25,6 +25,8 @@
  * <dl>
  *   <dt>dnsjava.nio.selector_timeout
  *   <dd>Set selector timeout in milliseconds. Default/Max 1000, Min 1.
+ *   <dt>dnsjava.nio.register_shutdown_hook
+ *   <dd>Register Shutdown Hook termination of NIO. Default True.
  * </dl>
  *
  * @since 3.4
@@ -60,7 +62,9 @@ static Selector selector() throws IOException {
           selectorThread.start();
           closeThread = new Thread(() -> close(true));
           closeThread.setName("dnsjava NIO shutdown hook");
-          Runtime.getRuntime().addShutdownHook(closeThread);
+          if (Boolean.parseBoolean(System.getProperty("dnsjava.nio.register_shutdown_hook", "true"))) {
+            Runtime.getRuntime().addShutdownHook(closeThread);
+          }
         }
       }
     }

Original file line number	Diff line number	Diff line change
`@@ -25,6 +25,8 @@`
`25`	`25`	`* <dl>`
`26`	`26`	`* <dt>dnsjava.nio.selector_timeout`
`27`	`27`	`* <dd>Set selector timeout in milliseconds. Default/Max 1000, Min 1.`
	`28`	`+ * <dt>dnsjava.nio.register_shutdown_hook`
	`29`	`+ * <dd>Register Shutdown Hook termination of NIO. Default True.`
`28`	`30`	`* </dl>`
`29`	`31`	`*`
`30`	`32`	`* @since 3.4`
`@@ -60,7 +62,9 @@ static Selector selector() throws IOException {`
`60`	`62`	`selectorThread.start();`
`61`	`63`	`closeThread = new Thread(() -> close(true));`
`62`	`64`	`closeThread.setName("dnsjava NIO shutdown hook");`
`63`		`- Runtime.getRuntime().addShutdownHook(closeThread);`
	`65`	`+ if (Boolean.parseBoolean(System.getProperty("dnsjava.nio.register_shutdown_hook", "true"))) {`
	`66`	`+ Runtime.getRuntime().addShutdownHook(closeThread);`
	`67`	`+ }`
`64`	`68`	`}`
`65`	`69`	`}`
`66`	`70`	`}`