Retry upload for any SocketException not just a ConnectException

Previously, DevTools would retry the upload of the changes to an
application in the event of a ConnectException. If a different
network-level failure occurred, it would not be retried and would
cause the file watching thread to die.

This commit attempts to make things more robust by retrying all
SocketExceptions and not just ConnectExceptions. A warning is
logged when a failure occurs. A separate debug message that
includes the exception is also logged.

Closes gh-10317

Author: wilkinsona

spring-boot-project/spring-boot-devtools/src/main/java/org/springframework/boot/devtools/remote/client/ClassPathChangeUploader.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2018 the original author or authors.
+ * Copyright 2012-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,8 +19,8 @@
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.ObjectOutputStream;
-import java.net.ConnectException;
 import java.net.MalformedURLException;
+import java.net.SocketException;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.net.URL;
@@ -117,9 +117,10 @@ private void performUpload(ClassLoaderFiles classLoaderFiles, byte[] bytes)
 					logUpload(classLoaderFiles);
 					return;
 				}
-				catch (ConnectException ex) {
-					logger.warn("Failed to connect when uploading to " + this.uri
+				catch (SocketException ex) {
+					logger.warn("A failure occurred when uploading to " + this.uri
 							+ ". Upload will be retried in 2 seconds");
+					logger.debug("Upload failure", ex);
 					Thread.sleep(2000);
 				}
 			}

spring-boot-project/spring-boot-devtools/src/test/java/org/springframework/boot/devtools/remote/client/ClassPathChangeUploaderTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2018 the original author or authors.
+ * Copyright 2012-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,7 +20,7 @@
 import java.io.File;
 import java.io.IOException;
 import java.io.ObjectInputStream;
-import java.net.ConnectException;
+import java.net.SocketException;
 import java.util.Collection;
 import java.util.Iterator;
 import java.util.LinkedHashSet;
@@ -111,10 +111,10 @@ public void sendsClassLoaderFiles() throws Exception {
 	}
 
 	@Test
-	public void retriesOnConnectException() throws Exception {
+	public void retriesOnSocketException() throws Exception {
 		File sourceFolder = this.temp.newFolder();
 		ClassPathChangedEvent event = createClassPathChangedEvent(sourceFolder);
-		this.requestFactory.willRespond(new ConnectException());
+		this.requestFactory.willRespond(new SocketException());
 		this.requestFactory.willRespond(HttpStatus.OK);
 		this.uploader.onApplicationEvent(event);
 		assertThat(this.requestFactory.getExecutedRequests()).hasSize(2);