Method acquire

src/utils.ts:237–279

* Acquire the lock. Throws if the lock is held by another live process.

()

   * Acquire the lock. Throws if the lock is held by another live process.
   */
  acquire(): void {
    // Check for existing lock
    if (fs.existsSync(this.lockPath)) {
      try {
        const content = fs.readFileSync(this.lockPath, 'utf-8').trim();
        const pid = parseInt(content, 10);
        const stat = fs.statSync(this.lockPath);
        const lockAge = Date.now() - stat.mtimeMs;

        // Treat locks older than the timeout as stale, regardless of PID
        if (lockAge < FileLock.STALE_TIMEOUT_MS && !isNaN(pid) && this.isProcessAlive(pid)) {
          throw new Error(
            `CodeGraph database is locked by another process (PID ${pid}). ` +
            `If this is stale, run 'codegraph unlock' or delete ${this.lockPath}`
          );
        }

        // Stale lock (dead process or timed out) - remove it
        fs.unlinkSync(this.lockPath);
      } catch (err) {
        if (err instanceof Error && err.message.includes('locked by another')) {
          throw err;
        }
        // Other errors reading lock file - try to remove it
        try { fs.unlinkSync(this.lockPath); } catch { /* ignore */ }
      }
    }

    // Write our PID to the lock file using exclusive create flag
    try {
      fs.writeFileSync(this.lockPath, String(process.pid), { flag: 'wx' });
      this.held = true;
    } catch (err: any) {
      if (err.code === 'EEXIST') {
        // Race condition: another process grabbed the lock between our check and write
        throw new Error(
          'CodeGraph database is locked by another process. ' +
          `If this is stale, run 'codegraph unlock' or delete ${this.lockPath}`
        );
      }
      throw err;
    }
  }

  /**
   * Release the lock