ibm-streams/src/languageClient/utils.ts

IBM Streams Support for Visual Studio Code

import { Registry } from '@ibmstreams/common';
import * as net from 'net';
import { ConfigurationTarget, window } from 'vscode';
import { Configuration, Logger, Settings } from '../utils';

/**
 * Check if a TCP port is available
 * @param port the port number
 */
export const isPortAvailable = (port: number): Promise<boolean> => {
  return new Promise((resolve, reject) => {
    const server = net.createServer();

    server.once('error', (err: NodeJS.ErrnoException) => {
      if (err.code === 'EADDRINUSE') {
        // Port is not available
        resolve(false);
      } else {
        reject(err);
      }
    });

    server.once('listening', () => {
      // Port is available
      server.once('close', () => {
        resolve(true);
      });

      // Close the server
      server.close();
    });

    // Start a TCP server listening for connections
    server.listen(port, '127.0.0.1');
  });
};

/**
 * Handle the user-provided port. If the port is not available, then prompt the user for a new port.
 * Returns an available port or `null`.
 * @param port the port number
 */
export const checkUserPort = async (port: number): Promise<number> => {
  try {
    const isAvailable = await isPortAvailable(port);
    if (!isAvailable) {
      const result = await window.showWarningMessage(
        `The SPL language server cannot be started on port ${port} because it is already in use. \
                Do you want to specify a different port number for this session or workspace?`,
        ...['Session', 'Workspace']
      );
      if (result) {
        const portInput = await window.showInputBox({
          prompt:
            'Specify a unique port number where the SPL language server will run',
          placeHolder: Settings.SERVER_PORT_DEFAULT.toString(),
          ignoreFocusOut: true
        });
        if (portInput) {
          const portInputNum = parseInt(portInput);
          if (result === 'Session') {
            // Re-check
            return checkUserPort(portInputNum);
          } else if (result === 'Workspace') {
            if (
              Configuration.getSetting(Settings.SERVER_PORT) === portInputNum
            ) {
              // Re-check
              return checkUserPort(portInputNum);
            }
            // Port in use re-check will happen automatically
            await Configuration.setSetting(
              Settings.SERVER_PORT,
              portInputNum,
              ConfigurationTarget.Workspace
            );
            return null;
          }
        }
      }
    }
    return port;
  } catch (err) {
    Registry.getDefaultMessageHandler().logError(
      `An error occurred while checking if port ${port} is available. ${err.message}`,
      { showNotification: true }
    );
    // Attempt to use the port
    return port;
  }
};