Retry launching in AbstractDebugTest on BindException

Debug tests infrequently run into:

java.net.BindException: Address already in use

This can occur when the chosen debug port is in use.
The port is chosen in StandardVMDebugger.getCommandLine(),
delegating to SocketUtil.findFreePort():

try (ServerSocket socket = new ServerSocket(0)) {
    return socket.getLocalPort();
}

Which can result in the socket being in use, at the time of the launch.

This change adds 3 retries to the launch, in case of BindException.

Fixes: #940

Author: trancexpress

org.eclipse.jdt.debug.tests/tests/org/eclipse/jdt/debug/tests/AbstractDebugTest.java

@@ -19,6 +19,7 @@
 import java.io.File;
 import java.io.PrintWriter;
 import java.io.StringWriter;
+import java.net.BindException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -177,6 +178,7 @@
 @SuppressWarnings("deprecation")
 public abstract class AbstractDebugTest extends TestCase implements  IEvaluationListener {
 
+	private static final int SOCKET_BIND_ERROR_MAX_RETRIES = 3;
 	private static boolean setupFirstTest = false;
 
 	public static final String MULTI_OUTPUT_PROJECT_NAME = "MultiOutput";
@@ -1490,13 +1492,7 @@ protected Object launchAndWait(ILaunchConfiguration configuration, DebugEventWai
 	 *             if the event is never received.
 	 */
 	protected Object launchAndWait(ILaunchConfiguration configuration, String mode, DebugEventWaiter waiter, boolean register) throws CoreException {
-		ILaunch launch;
-		try {
-			launch = configuration.launch(mode, new TimeoutMonitor(DEFAULT_TIMEOUT), false, register);
-		} catch (Throwable t) {
-			logProcessConsoleContents();
-			throw t;
-		}
+		ILaunch launch = launchConfig(configuration, mode, register);
 		Object suspendee= waiter.waitForEvent();
 		if (suspendee == null) {
 			StringBuilder buf = new StringBuilder();
@@ -1539,8 +1535,6 @@ protected Object launchAndWait(ILaunchConfiguration configuration, String mode,
 		return suspendee;
 	}
 
-
-
 	/**
 	 * Launches the type with the given name, and waits for a
 	 * suspend event in that program. Returns the thread in which the suspend
@@ -3224,6 +3218,28 @@ private static void logVMChange(String message, IVMInstall vm) {
 		JDIDebugPlugin.log(status);
 	}
 
+	private static ILaunch launchConfig(ILaunchConfiguration configuration, String mode, boolean register) throws CoreException {
+		ILaunch launch = null;
+		for (int retry = 1; retry <= SOCKET_BIND_ERROR_MAX_RETRIES; ++retry) {
+			try {
+				launch = configuration.launch(mode, new TimeoutMonitor(DEFAULT_TIMEOUT), false, register);
+				break;
+			} catch (CoreException e) {
+				Throwable cause = e.getStatus().getException();
+				if (retry < SOCKET_BIND_ERROR_MAX_RETRIES && cause instanceof BindException) {
+					// port might be in use between checking for a free port and launching, try a few times
+					DebugPlugin.log(Status.error("Could not bind socket for debugging, retry: " + retry, e));
+				} else {
+					throw e;
+				}
+			} catch (Throwable t) {
+				logProcessConsoleContents();
+				throw t;
+			}
+		}
+		return launch;
+	}
+
 	private static void logProcessConsoleContents() {
 		try {
 			StringBuilder buf = new StringBuilder();