UploadPack: don't prematurely terminate timer in case of error

In uploadWithExceptionPropagation don't prematurely terminate timer in
case of error to enable reporting it to the client. Expose a close
method so that callers can terminate it at the appropriate time.

If the timer is already terminated when trying to report it to the
client this failed with the error java.lang.IllegalStateException:
"Timer already terminated".

Bug: 579670
Change-Id: I95827442ccb0f9b1ede83630cf7c51cf619c399a

org.eclipse.jgit.http.server/src/org/eclipse/jgit/http/server/UploadPackServlet.java

@@ -195,6 +195,8 @@ public void flush() throws IOException {
 				log(up.getRepository(), e.getCause());
 				consumeRequestBody(req);
 				out.close();
+			} finally {
+				up.close();
 			}
 		};
 

org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java

@@ -39,6 +39,7 @@
 import static org.eclipse.jgit.util.RefMap.toRefMap;
 
 import java.io.ByteArrayOutputStream;
+import java.io.Closeable;
 import java.io.EOFException;
 import java.io.IOException;
 import java.io.InputStream;
@@ -104,7 +105,7 @@
 /**
  * Implements the server side of a fetch connection, transmitting objects.
  */
-public class UploadPack {
+public class UploadPack implements Closeable {
 	/** Policy the server uses to validate client requests */
 	public enum RequestPolicy {
 		/** Client may only ask for objects the server advertised a reference for. */
@@ -730,6 +731,17 @@ private boolean useProtocolV2() {
 				&& clientRequestedV2;
 	}
 
+	@Override
+	public void close() {
+		if (timer != null) {
+			try {
+				timer.terminate();
+			} finally {
+				timer = null;
+			}
+		}
+	}
+
 	/**
 	 * Execute the upload task on the socket.
 	 *
@@ -777,6 +789,8 @@ public void upload(InputStream input, OutputStream output,
 				throw new UploadPackInternalServerErrorException(err);
 			}
 			throw err;
+		} finally {
+			close();
 		}
 	}
 
@@ -786,6 +800,10 @@ public void upload(InputStream input, OutputStream output,
 	 * <p>
 	 * If the client passed extra parameters (e.g., "version=2") through a side
 	 * channel, the caller must call setExtraParameters first to supply them.
+	 * Callers of this method should call {@link #close()} to terminate the
+	 * internal interrupt timer thread. If the caller fails to terminate the
+	 * thread, it will (eventually) terminate itself when the InterruptTimer
+	 * instance is garbage collected.
 	 *
 	 * @param input
 	 *            raw input to read client commands from. Caller must ensure the
@@ -842,13 +860,6 @@ public void uploadWithExceptionPropagation(InputStream input,
 		} finally {
 			msgOut = NullOutputStream.INSTANCE;
 			walk.close();
-			if (timer != null) {
-				try {
-					timer.terminate();
-				} finally {
-					timer = null;
-				}
-			}
 		}
 	}