servertime/dist/Timer.js

Add server-timing header to your node.js app, with nanosecond precision.

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = void 0;

function _defineProperty(obj, key, value) { if (key in obj) { Object.defineProperty(obj, key, { value: value, enumerable: true, configurable: true, writable: true }); } else { obj[key] = value; } return obj; }

/**
 * Keeps track of timing data for events and turns that data into a `server-timing` header.
 */
class Timer {
  /* We use a "dummy" timer which does nothing in production mode. */
  constructor(options) {
    _defineProperty(this, "_isDummy", void 0);

    _defineProperty(this, "_clock", void 0);

    _defineProperty(this, "_records", void 0);

    this._isDummy = options.isDummy || false;
    this._clock = options.clock;
    this._records = {};
  }
  /**
   * Start timing an event.
   * @param slug - The slug to use for timing.  The same slug must be supplied to `end(slug)` in order
   *   for this timing to show up in the final header.
   * @param [label] - Label to use in the server-timing header.
   */


  start(slug, label) {
    if (this._isDummy) {
      return;
    }

    if (this._records[slug]) {
      console.error(`serverTime: Attempting to add slug we've already seen ${slug}`);
    } else {
      this._records[slug] = {
        label: label || slug,
        start: this._clock.start()
      };
    }
  }
  /**
   * Stop timing an event.
   * @param slug - The slug to supplied to `start()`.
   */


  end(slug) {
    if (this._isDummy) {
      return;
    }

    const record = this._records[slug];

    if (record) {
      record.time = this._clock.diff(record.start);
    }
  }
  /**
   * Set the timing for an event.
   * @param slug - The slug to use for timing.
   * @param ms - Time, in milliseconds.  Can be a float.
   */


  setTime(slug, l, m) {
    const ms = m ? m : l;
    const label = m ? l : slug;
    this._records[slug] = {
      label,
      time: ms
    };
  }
  /**
   * Time the duration of a promise.
   * @param slug - The slug to use for timing.
   * @param promise - The promise to time.
   * @return - Returns the passed in `promise`.
   */


  timePromise(slug, l, p) {
    const promise = p ? p : l;
    const label = p ? l : slug;

    if (!this._isDummy) {
      this.start(slug, label);
      promise.then(() => this.end(slug), () => this.end(slug));
    }

    return promise;
  }
  /**
   * Return the server-timing header.
   * @return {string} - The header.
   */


  getHeader() {
    if (this._isDummy) {
      return null;
    }

    return Object.keys(this._records) // Filter out any results where we never called 'end'
    .filter(slug => 'time' in this._records[slug]).map(slug => {
      const record = this._records[slug];

      if (!record.label || record.label === slug) {
        return `${slug};dur=${this._records[slug].time}`;
      } else {
        return `${slug};desc="${this._records[slug].label}";dur=${this._records[slug].time}`;
      }
    }).join(', ');
  }

}

exports.default = Timer;
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