Function acquireRunnerLock

cli/src/persistence.ts:228–264

(
  maxAttempts: number = 5,
  delayIncrementMs: number = 200
)

 * Returns the file handle to hold for the runner's lifetime, or null if locked.
 */
export async function acquireRunnerLock(
  maxAttempts: number = 5,
  delayIncrementMs: number = 200
): Promise<FileHandle | null> {
  for (let attempt = 1; attempt <= maxAttempts; attempt++) {
    try {
      // 'wx' ensures we only create if it doesn't exist (atomic lock acquisition)
      const fileHandle = await open(configuration.runnerLockFile, 'wx');
      // Write PID to lock file for debugging
      await fileHandle.writeFile(String(process.pid));
      return fileHandle;
    } catch (error: any) {
      if (error.code === 'EEXIST') {
        // Lock file exists, check if process is still running
        try {
          const lockPid = readFileSync(configuration.runnerLockFile, 'utf-8').trim();
          if (lockPid && !isNaN(Number(lockPid))) {
            if (!isProcessAlive(Number(lockPid))) {
              // Process doesn't exist, remove stale lock
              unlinkSync(configuration.runnerLockFile);
              continue; // Retry acquisition
            }
          }
        } catch {
          // Can't read lock file, might be corrupted
        }
      }

      if (attempt === maxAttempts) {
        return null;
      }
      const delayMs = attempt * delayIncrementMs;
      await new Promise(resolve => setTimeout(resolve, delayMs));
    }
  }
  return null;
}

/**
 * Release runner lock by closing handle and deleting lock file