Function canReuseExistingServer

src/cm/lsp/serverLauncher.ts:258–294

(
  server: LspServerDefinition,
  session: string,
)

 * Returns the port number if the server is alive, null otherwise.
 */
export async function canReuseExistingServer(
  server: LspServerDefinition,
  session: string,
): Promise<number | null> {
  const bridge = server.launcher?.bridge;
  const serverName =
    resolveServerExecutable(server) ||
    bridge?.command ||
    server.launcher?.command ||
    server.id;

  const portInfo = await getLspPort(serverName, session);
  if (!portInfo) {
    return null;
  }

  const url = `ws://127.0.0.1:${portInfo.port}/`;
  const status = await checkAxsBridgeStatus(url, 1000);
  const alive =
    status === "alive" ||
    (status === "unsupported" &&
      (await checkServerAliveViaWebSocket(url, 1000)));

  if (alive) {
    addLspLog(server.id, "info", `Reusing existing server on port ${portInfo.port}`);
    console.info(
      `[LSP:${server.id}] Reusing existing server on port ${portInfo.port}`,
    );
    return portInfo.port;
  }

  console.info(
    `[LSP:${server.id}] Found stale port file, will start new server`,
  );
  addLspLog(server.id, "warn", "Found stale port file, starting a new server");
  return null;
}

function resolveStartCommand(
  server: LspServerDefinition,