src/metrics/metrics.js

   1 import os from 'os';
   2
   3 /** @module cytube-common/metrics/metrics */
   4
   5 const MEM_RSS = 'memory:rss';
   6 const LOAD_1MIN = 'load:1min';
   7 const TIMESTAMP = 'time';
   8 const logger = require('@calzoneman/jsli')('metrics');
   9
  10 var delegate = null;
  11 var reportInterval = null;
  12 var reportHooks = [];
  13 let warnedNoReporter = false;
  14
  15 function warnNoReporter() {
  16     if (!warnedNoReporter) {
  17         warnedNoReporter = true;
  18         logger.warn('No metrics reporter configured.  Metrics will not be recorded.');
  19     }
  20 }
  21
  22 /**
  23  * Increment a metrics counter by the specified amount.
  24  *
  25  * @param {string} counter name of the counter to increment
  26  * @param {number} value optional value to increment by (default 1)
  27  */
  28 export function incCounter(counter, amount = 1) {
  29     if (delegate === null) {
  30         warnNoReporter();
  31     } else {
  32         delegate.incCounter(counter, amount);
  33     }
  34 }
  35
  36 /**
  37  * Start a timer.  Returns a handle to use to end the timer.
  38  *
  39  * @param {string} timer name
  40  * @return {object} timer handle
  41  */
  42 export function startTimer(timer) {
  43     return {
  44         timer: timer,
  45         hrtime: process.hrtime()
  46     };
  47 }
  48
  49 /**
  50  * Stop a timer and record the time (as an average)
  51  *
  52  * @param {object} handle timer handle to Stop
  53  */
  54 export function stopTimer(handle) {
  55     if (delegate === null) {
  56         warnNoReporter();
  57         return;
  58     }
  59     const [seconds, ns] = process.hrtime(handle.hrtime);
  60     delegate.addTime(handle.timer, seconds*1e3 + ns/1e6);
  61 }
  62
  63 /**
  64  * Add a property to the current metrics period.
  65  *
  66  * @param {string} property property name to add
  67  * @param {any} property value
  68  */
  69 export function addProperty(property, value) {
  70     if (delegate === null) {
  71         warnNoReporter();
  72     } else {
  73         delegate.addProperty(property, value);
  74     }
  75 }
  76
  77 /**
  78  * Set the metrics reporter to record to.
  79  *
  80  * @param {MetricsReporter} reporter reporter to record metrics to
  81  */
  82 export function setReporter(reporter) {
  83     delegate = reporter;
  84 }
  85
  86 /**
  87  * Set the interval at which to report metrics.
  88  *
  89  * @param {number} interval time in milliseconds between successive reports
  90  */
  91 export function setReportInterval(interval) {
  92     clearInterval(reportInterval);
  93     if (!isNaN(interval) && interval >= 0) {
  94         reportInterval = setInterval(reportLoop, interval);
  95     }
  96 }
  97
  98 /**
  99  * Add a callback to add additional metrics before reporting.
 100  *
 101  * @param {function(metricsReporter)} hook callback to be invoked before reporting
 102  */
 103 export function addReportHook(hook) {
 104     reportHooks.push(hook);
 105 }
 106
 107 export function clearReportHooks() {
 108     reportHooks = [];
 109 }
 110
 111 /**
 112  * Force metrics to be reported right now.
 113  */
 114 export function flush() {
 115     reportLoop();
 116 }
 117
 118 function addDefaults() {
 119     addProperty(MEM_RSS, process.memoryUsage().rss / 1048576);
 120     addProperty(LOAD_1MIN, os.loadavg()[0]);
 121     addProperty(TIMESTAMP, new Date());
 122 }
 123
 124 function reportLoop() {
 125     if (delegate !== null) {
 126         try {
 127             addDefaults();
 128             reportHooks.forEach(hook => {
 129                 hook(delegate);
 130             });
 131             delegate.report();
 132         } catch (error) {
 133             logger.error(error.stack);
 134         }
 135     }
 136 }