Gauge and CachedGauge support (#59)

mikejihbe · Oct 8, 2018 · d3a7a8b · d3a7a8b
1 parent 71f3b93
commit d3a7a8b
Show file tree

Hide file tree

Showing 15 changed files with 164 additions and 15 deletions.
diff --git a/index.d.ts b/index.d.ts
@@ -3,7 +3,7 @@
 import events = require("events");
 
 declare namespace metrics {
-  type Metric = Meter | Timer | Counter | Histogram;
+  type Metric = Meter | Timer | Counter | Histogram | Gauge;
 
   type MeterPrintObj = {
     type: "meter",
@@ -82,6 +82,22 @@ declare namespace metrics {
     });
   }
 
+  class Gauge {
+    type: "gauge";
+
+    constructor(valueFn: () => any);
+    value: () => any
+
+    printObj: () => ({
+      type: "gauge";
+      value: any;
+    })
+  }
+
+  class CachedGauge extends Gauge {
+    constructor(valueFn: () => any, expirationInMs: number);
+  }
+
   type HistogramPrintObj = {
     type: "histogram",
 

diff --git a/index.js b/index.js
@@ -6,6 +6,8 @@ exports.Histogram = Metrics.Histogram;
 exports.Meter = Metrics.Meter;
 exports.Counter = Metrics.Counter;
 exports.Timer = Metrics.Timer;
+exports.Gauge = Metrics.Gauge;
+exports.CachedGauge = Metrics.CachedGauge;
 
 exports.Server = Reporting.Server;
 exports.Report = Reporting.Report;

diff --git a/metrics/cached_gauge.js b/metrics/cached_gauge.js
@@ -0,0 +1,21 @@
+var Gauge = require('./gauge'),
+  util = require('util');
+
+function now() {
+  return new Date().getTime();
+}
+
+function CachedGauge(valueFn, expirationInMs) {
+  var value, lastRefresh;
+  Gauge.call(this, function() {
+    if (!lastRefresh || now() - lastRefresh > expirationInMs) {
+      value = valueFn();
+      lastRefresh = now();
+    }
+    return value;
+  });
+}
+
+util.inherits(CachedGauge, Gauge);
+
+module.exports = CachedGauge
diff --git a/metrics/gauge.js b/metrics/gauge.js
@@ -0,0 +1,8 @@
+var Gauge = module.exports = function Gauge(valueFn) {
+  this.value = valueFn;
+  this.type = 'gauge';
+}
+
+Gauge.prototype.printObj = function() {
+  return {type: 'gauge', value: this.value()};
+}
diff --git a/metrics/index.js b/metrics/index.js
@@ -3,4 +3,6 @@ exports.Counter = require('./counter');
 exports.Histogram = require('./histogram');
 exports.Meter = require('./meter');
 exports.Timer = require('./timer');
+exports.Gauge = require('./gauge');
+exports.CachedGauge = require('./cached_gauge');
 
diff --git a/reporting/console-reporter.js b/reporting/console-reporter.js
@@ -54,6 +54,14 @@ ConsoleReporter.prototype.report = function() {
     });
     console.log();
   }
+
+  if(metrics.gauges.length != 0) {
+    printWithBanner('Gauges');
+    metrics.gauges.forEach(function (gauge) {
+      printGauge(gauge);
+    });
+    console.log();
+  }
 };
 
 function printWithBanner(name) {
@@ -120,5 +128,10 @@ function printHistogram(histogram) {
   console.log('            99.9%% <= %s%s', ff(percentiles[.999]), durationUnit);
 }
 
+function printGauge(gauge) {
+  console.log(gauge.name);
+  console.log('             value = %s', JSON.stringify(gauge.value()));
+}
+
 module.exports = ConsoleReporter;
 
diff --git a/reporting/csv-reporter.js b/reporting/csv-reporter.js
@@ -44,7 +44,11 @@ CsvReporter.prototype.report = function() {
     if(histogram.min != null) {
       self.reportHistogram.bind(self)(histogram, timestamp);
     }
-  })
+  });
+
+  metrics.gauges.forEach(function(gauge) {
+    self.reportGauge.bind(self)(gauge, timestamp);
+  });
 };
 
 CsvReporter.prototype.write = function(timestamp, name, header, line, values) {
@@ -135,4 +139,9 @@ CsvReporter.prototype.reportHistogram = function(histogram, timestamp) {
     ]);
 };
 
+CsvReporter.prototype.reportGauge = function(gauge, timestamp) {
+  var write = this.write.bind(this);
+  write(timestamp, gauge.name, 'value', '%s', [JSON.stringify(gauge.value())]);
+}
+
 module.exports = CsvReporter;
diff --git a/reporting/graphite-reporter.js b/reporting/graphite-reporter.js
@@ -89,6 +89,12 @@ GraphiteReporter.prototype.report = function() {
       }
     })
   }
+
+  if(metrics.gauges.length != 0) {
+    metrics.counters.forEach(function (gauge) {
+      self.reportGauge.bind(self)(gauge, timestamp);
+    })
+  }
 };
 
 GraphiteReporter.prototype.send = function(name, value, timestamp) {
@@ -155,4 +161,10 @@ GraphiteReporter.prototype.reportHistogram = function(histogram, timestamp) {
   send(util.format('%s.%s', histogram.name, 'p999'), percentiles[.999], timestamp);
 };
 
-module.exports = GraphiteReporter;
+GraphiteReporter.prototype.reportGauge = function(gauge, timestamp) {
+  var send = this.send.bind(this);
+
+  send(gauge.name, JSON.stringify(gauge.count), timestamp);
+};
+
+module.exports = GraphiteReporter;
diff --git a/reporting/scheduled-reporter.js b/reporting/scheduled-reporter.js
@@ -3,6 +3,7 @@ var Counter = require('../metrics').Counter,
   Histogram = require('../metrics').Histogram,
   Meter = require('../metrics').Meter,
   Timer = require('../metrics').Timer,
+  Gauge = require('../metrics').Gauge,
   util = require('util'),
   EventEmitter = require('events').EventEmitter;
 
@@ -54,6 +55,7 @@ ScheduledReporter.prototype.getMetrics = function() {
   var timers = [];
   var counters = [];
   var histograms = [];
+  var gauges = [];
 
   var trackedMetrics = this.registry.trackedMetrics;
   // Flatten metric name to be namespace.name is has a namespace and separate out metrics
@@ -66,20 +68,21 @@ ScheduledReporter.prototype.getMetrics = function() {
       } else {
         metric.name = name;
       }
-      var metricType = Object.getPrototypeOf(metric);
-      if(metricType === Meter.prototype) {
+      if(metric instanceof Meter) {
         meters.push(metric);
-      } else if(metricType == Timer.prototype) {
+      } else if(metric instanceof Timer) {
         timers.push(metric);
-      } else if(metricType == Counter.prototype) {
+      } else if(metric instanceof Counter) {
         counters.push(metric);
-      } else if(metricType == Histogram.prototype) {
+      } else if(metric instanceof Histogram) {
         histograms.push(metric);
+      } else if(metric instanceof Gauge) {
+        gauges.push(metric);
       }
     }
   }
 
-  return { meters: meters, timers: timers, counters: counters, histograms: histograms };
+  return { meters: meters, timers: timers, counters: counters, histograms: histograms, gauges: gauges };
 };
 
 module.exports = ScheduledReporter;
diff --git a/test/unit/cached_gauge.js b/test/unit/cached_gauge.js
@@ -0,0 +1,33 @@
+var expect = require('chai').expect
+  , describe = require('mocha').describe
+  , it = require('mocha').it
+  , CachedGauge = require('../../metrics/cached_gauge');
+
+describe('CachedGauge', function() {
+  function seqFn() {
+    var i = 0;
+    return function() {
+      return i++;
+    }
+  }
+
+  it('should call function when asked for a value for the first time.', function() {
+    var gauge = new CachedGauge(seqFn(), 100);
+    expect(gauge.printObj()).to.have.property('value', 0);
+  });
+
+  it('should not call function before expiration timeout.', function() {
+    var gauge = new CachedGauge(seqFn(), 1000);
+    expect(gauge.printObj()).to.have.property('value', 0);
+    expect(gauge.printObj()).to.have.property('value', 0);
+  });
+
+  it('should call function after expiration timeout.', function(done) {
+    var gauge = new CachedGauge(seqFn(), 50);
+    expect(gauge.printObj()).to.have.property('value', 0);
+    setTimeout(function() {
+      expect(gauge.printObj()).to.have.property('value', 1);
+      done();
+    }, 100);
+  });
+});
diff --git a/test/unit/console_reporter.js b/test/unit/console_reporter.js
@@ -29,7 +29,7 @@ describe('ConsoleReporter', function () {
 
     // validate line by line.  This may be overkill but will detect when
     // unanticipated changes affect reported output.
-    expect(data.length).to.equal(44);
+    expect(data.length).to.equal(48);
     expect(data[0]).to.equal('Counters -----------------------------------------------------------------------');
     expect(data[1]).to.equal('basicCount');
     expect(data[2]).to.equal('             count = 5');
@@ -75,5 +75,9 @@ describe('ConsoleReporter', function () {
     expect(data[41]).to.equal('              99% <= 199.98');
     expect(data[42]).to.equal('            99.9% <= 200.00');
     expect(data[43]).to.equal('');
+    expect(data[44]).to.equal('Gauges -------------------------------------------------------------------------');
+    expect(data[45]).to.equal('myapp.Gauge');
+    expect(data[46]).to.equal('             value = 0.8');
+    expect(data[47]).to.equal('');
   });
-});
+});
diff --git a/test/unit/csv_reporter.js b/test/unit/csv_reporter.js
@@ -36,7 +36,8 @@ describe('CsvReporter', function () {
     var meterFile = path.join(tmpdir, 'myapp.Meter.csv');
     var timerFile = path.join(tmpdir, 'myapp.Timer.csv');
     var histFile = path.join(tmpdir, 'myapp.Histogram.csv');
-    var files = [counterFile, meterFile, timerFile, histFile];
+    var gaugeFile = path.join(tmpdir, 'myapp.Gauge.csv');
+    var files = [counterFile, meterFile, timerFile, histFile, gaugeFile];
 
     setTimeout(function() {
       debug("Reading files %s.  Each file should have 1 header and 3 recordings.", files);
@@ -65,6 +66,11 @@ describe('CsvReporter', function () {
             data.slice(1, 4).forEach(function (line) {
               expect(line).to.match(/.*,100,200,101,2,58.02298395176403,101,151.5,191.89999999999998,197.96,199.98,200/);
             });
+          } else if (f === gaugeFile) {
+            expect(data[0]).to.equal('t,value');
+            data.slice(1, 4).forEach(function (line) {
+              expect(line).to.match(/.*,0.8/);
+            });
           } else {
             expect(data[0]).to.equal('t,count,max,mean,min,stddev,p50,p75,p95,p98,p99,p999,mean_rate,m1_rate,m5_rate,m15_rate,rate_unit,duration_unit');
             data.slice(1, 4).forEach(function (line) {
@@ -83,4 +89,4 @@ describe('CsvReporter', function () {
       done();
     }, 3500);
   });
-});
+});
diff --git a/test/unit/gauge.js b/test/unit/gauge.js
@@ -0,0 +1,14 @@
+var expect = require('chai').expect
+  , describe = require('mocha').describe
+  , it = require('mocha').it
+  , Gauge = require('../../metrics/gauge');
+
+describe('Gauge', function() {
+  it('should call function every time value is requested.', function() {
+    var i = 0;
+    var gauge = new Gauge(function() { return i++; });
+
+    expect(gauge.printObj()).to.have.property('value', 0);
+    expect(gauge.printObj()).to.have.property('value', 1);
+  });
+});
diff --git a/test/unit/graphite_reporter.js b/test/unit/graphite_reporter.js
@@ -67,7 +67,8 @@ describe('GraphiteReporter', function () {
             // Meter should have 5 values.
             // Timer should have 15 values.
             // Histogram should have 11 values.
-            expect(tsData.length).to.equal(32);
+            // Gauge should have 1 value.
+            expect(tsData.length).to.equal(33);
             // Metric names should start with host name.
             tsData.forEach(function (metric) {
               expect(metric[0]).to.startsWith('host1.');
@@ -98,4 +99,4 @@ describe('GraphiteReporter', function () {
       reporter.start(1000);
     });
   });
-});
+});
diff --git a/test/unit/helper.js b/test/unit/helper.js
@@ -4,6 +4,7 @@ var metrics = require('../../'),
   Timer = metrics.Timer,
   Meter = metrics.Meter,
   Histogram = metrics.Histogram,
+  CachedGauge = metrics.CachedGauge,
   util = require('util');
 
 function getSampleReport() {
@@ -19,11 +20,15 @@ function getSampleReport() {
   for (var i = 1; i <= 100; i++) {
     hist.update(i*2);
   }
+  var gauge = new CachedGauge(function () {
+    return 0.8
+  }, 10000);
   var report = new Report();
   report.addMetric("basicCount", counter);
   report.addMetric("myapp.Meter", meter);
   report.addMetric("myapp.Timer", timer);
   report.addMetric("myapp.Histogram", hist);
+  report.addMetric("myapp.Gauge", gauge);
   return report;
 }