TCP server: when using the trace option ("-trace"), the trace output contained…

TCP server: when using the trace option ("-trace"), the trace output contained unnecessary stack traces when stopping the server.

h2/src/main/org/h2/server/TcpServerThread.java

@@ -199,8 +199,10 @@ public class TcpServerThread implements Runnable {
             }
             transfer.writeInt(SessionRemote.STATUS_ERROR).writeString(e.getSQLState()).writeString(message)
                     .writeString(sql).writeInt(e.getErrorCode()).writeString(trace).flush();
-        } catch (IOException e2) {
+        } catch (Exception e2) {
+            if (!transfer.isClosed()) {
                 server.traceError(e2);
+            }
             // if writing the error does not work, close the connection
             stop = true;
         }

h2/src/main/org/h2/value/Transfer.java

@@ -73,10 +73,12 @@ public class Transfer {
      * Initialize the transfer object. This method will try to open an input and
      * output stream.
      */
-    public void init() throws IOException {
+    public synchronized void init() throws IOException {
+        if (socket != null) {
             in = new DataInputStream(new BufferedInputStream(socket.getInputStream(), Transfer.BUFFER_SIZE));
             out = new DataOutputStream(new BufferedOutputStream(socket.getOutputStream(), Transfer.BUFFER_SIZE));
         }
+    }
 
     /**
      * Write pending changes.
@@ -277,10 +279,12 @@ public class Transfer {
     /**
      * Close the transfer object and the socket.
      */
-    public void close() {
+    public synchronized void close() {
         if (socket != null) {
             try {
+                if (out != null) {
                     out.flush();
+                }
                 if (socket != null) {
                     socket.close();
                 }
@@ -613,4 +617,8 @@ public class Transfer {
         this.version = version;
     }
 
+    public synchronized boolean isClosed() {
+        return socket == null || socket.isClosed();
+    }
+
 }