Class ActivePerfRecorder

packages/compiler-cli/src/ngtsc/perf/src/recorder.ts:25–117

 * A `PerfRecorder` that actively tracks performance statistics.
 */
export class ActivePerfRecorder implements PerfRecorder {
  private counters: number[];
  private phaseTime: number[];
  private bytes: number[];

  private currentPhase = PerfPhase.Unaccounted;
  private currentPhaseEntered: HrTime;

  /**
   * Creates an `ActivePerfRecorder` with its zero point set to the current time.
   */
  static zeroedToNow(): ActivePerfRecorder {
    return new ActivePerfRecorder(mark());
  }

  private constructor(private zeroTime: HrTime) {
    this.currentPhaseEntered = this.zeroTime;
    this.counters = Array(PerfEvent.LAST).fill(0);
    this.phaseTime = Array(PerfPhase.LAST).fill(0);
    this.bytes = Array(PerfCheckpoint.LAST).fill(0);

    // Take an initial memory snapshot before any other compilation work begins.
    this.memory(PerfCheckpoint.Initial);
  }

  reset(): void {
    this.counters = Array(PerfEvent.LAST).fill(0);
    this.phaseTime = Array(PerfPhase.LAST).fill(0);
    this.bytes = Array(PerfCheckpoint.LAST).fill(0);
    this.zeroTime = mark();
    this.currentPhase = PerfPhase.Unaccounted;
    this.currentPhaseEntered = this.zeroTime;
  }

  memory(after: PerfCheckpoint): void {
    this.bytes[after] = process.memoryUsage().heapUsed;
  }

  phase(phase: PerfPhase): PerfPhase {
    const previous = this.currentPhase;
    this.phaseTime[this.currentPhase] += timeSinceInMicros(this.currentPhaseEntered);
    this.currentPhase = phase;
    this.currentPhaseEntered = mark();
    return previous;
  }

  inPhase<T>(phase: PerfPhase, fn: () => T): T {
    const previousPhase = this.phase(phase);
    try {
      return fn();
    } finally {
      this.phase(previousPhase);
    }
  }

  eventCount(counter: PerfEvent, incrementBy: number = 1): void {
    this.counters[counter] += incrementBy;
  }