/Tutorial4

MagpieBridge Tutorial4 - Tracing and Logging

Primary LanguageNewLisp

In this tutorial we will extend the code from Tutorial 2 to write a trace file that can be used to visualize the client server communication using the LSP Inspector. Then we will also add our own logger, that can be used to log messages in our own custom format.

Add tracing

To add the tracing, all we need to do is to create a PrintWriterthat specifies, where the log is written to and add it to our ServerConfiguration in TutorialMain.java:

    try {
      File logFile = Files.createTempFile("magpie_server_trace", ".lsp").toFile();
      defaultConfig.setLSPMessageTracer(new PrintWriter(logFile));
    } catch (IOException e) {
      ...
    }

Once the server is started, there will now be a log file created in the temp directory. When the file is finished, it can be openened with the web based LSP Inspector to visualize the requests and responses exchanged between the client and the server:

lspInspector screenshot

An example trace file is available here: magpie_server_trace.lsp

Add custom logger

Next we want to create our own logger that only logs diagnostics published by the server.

For this we can extend the ServerConfiguration once more, by calling defaultConfig.setMagpieMessageLogger(new DiagnosticsLogger());

class DiagnosticsLogger implements MagpieMessageLogger {

    private PrintWriter logWriter;

    public DiagnosticsLogger() {
      File logFile;
      try {
        logFile = Files.createTempFile("magpie_server_diag", ".log").toFile();
        this.logWriter = new PrintWriter(logFile);
      } catch (IOException e) {
        e.printStackTrace();
      }

    }

    @Override
    public Function<MessageConsumer, MessageConsumer> getWrapper() {
      return (MessageConsumer c) -> {
        MessageConsumer wrapping = (Message message) -> {
          //only log messages with method 'textDocument/publishDiagnostics'
          if (message instanceof NotificationMessage && "textDocument/publishDiagnostics".equals(((NotificationMessage) message).getMethod())) {
            logWriter.println(message);
            logWriter.flush();
          }
          // hand the message to the wrapped consumer so it can be processed by the server
          c.consume(message);
        };
        return wrapping;
      };
    }

    @Override
    public void cleanUp() {
      // close the log file
      if (logWriter != null) {
        logWriter.flush();
        logWriter.close();
        logWriter = null;
      }
    }
  }

The finished code can be downloaded at Tutorial4