handlebars.js/tests/bench/util/benchwarmer.js

var _ = require('underscore'),
  Benchmark = require('benchmark');

function BenchWarmer() {
  this.benchmarks = [];
  this.currentBenches = [];
  this.names = [];
  this.times = {};
  this.minimum = Infinity;
  this.maximum = -Infinity;
  this.errors = {};
}

BenchWarmer.prototype = {
  winners: function(benches) {
    return Benchmark.filter(benches, 'fastest');
  },
  suite: function(suite, fn) {
    this.suiteName = suite;
    this.times[suite] = {};
    this.first = true;

    var self = this;

    fn(function(name, benchFn) {
      self.push(name, benchFn);
    });
  },
  push: function(name, fn) {
    if (this.names.indexOf(name) === -1) {
      this.names.push(name);
    }

    var first = this.first,
      suiteName = this.suiteName,
      self = this;
    this.first = false;

    var bench = new Benchmark(fn, {
      name: this.suiteName + ': ' + name,
      onComplete: function() {
        if (first) {
          self.startLine(suiteName);
        }
        self.writeBench(bench);
        self.currentBenches.push(bench);
      },
      onError: function() {
        self.errors[this.name] = this;
      }
    });
    bench.suiteName = this.suiteName;
    bench.benchName = name;

    this.benchmarks.push(bench);
  },

  bench: function(callback) {
    var self = this;

    this.printHeader('ops/msec', true);

    Benchmark.invoke(this.benchmarks, {
      name: 'run',
      onComplete: function() {
        self.scaleTimes();

        self.startLine('');

        console.log('\n');
        self.printHeader('scaled');
        _.each(self.scaled, function(value, name) {
          self.startLine(name);

          _.each(self.names, function(lang) {
            self.writeValue(value[lang] || '');
          });
        });
        console.log('\n');

        var errors = false,
          prop,
          bench;
        for (prop in self.errors) {
          if (
            Object.prototype.hasOwnProperty.call(self, prop) &&
            self.errors[prop].error.message !== 'EWOT'
          ) {
            errors = true;
            break;
          }
        }

        if (errors) {
          console.log('\n\nErrors:\n');
          Object.keys(self.errors).forEach(function(prop) {
            if (self.errors[prop].error.message !== 'EWOT') {
              bench = self.errors[prop];
              console.log('\n' + bench.name + ':\n');
              console.log(bench.error.message);
              if (bench.error.stack) {
                console.log(bench.error.stack.join('\n'));
              }
              console.log('\n');
            }
          });
        }

        callback();
      }
    });

    console.log('\n');
  },

  scaleTimes: function() {
    var scaled = (this.scaled = {});
    _.each(
      this.times,
      function(times, name) {
        var output = (scaled[name] = {});

        _.each(
          times,
          function(time, lang) {
            output[lang] = (
              ((time - this.minimum) / (this.maximum - this.minimum)) *
              100
            ).toFixed(2);
          },
          this
        );
      },
      this
    );
  },

  printHeader: function(title, winners) {
    var benchSize = 0,
      names = this.names,
      i,
      l;

    for (i = 0, l = names.length; i < l; i++) {
      var name = names[i];

      if (benchSize < name.length) {
        benchSize = name.length;
      }
    }

    this.nameSize = benchSize + 2;
    this.benchSize = 20;
    var horSize = 0;

    this.startLine(title);
    horSize = horSize + this.benchSize;
    for (i = 0, l = names.length; i < l; i++) {
      this.writeValue(names[i]);
      horSize = horSize + this.benchSize;
    }

    if (winners) {
      console.log('WINNER(S)');
      horSize = horSize + 'WINNER(S)'.length;
    }

    console.log('\n' + new Array(horSize + 1).join('-'));
  },

  startLine: function(name) {
    var winners = Benchmark.map(this.winners(this.currentBenches), function(
      bench
    ) {
      return bench.name.split(': ')[1];
    });

    this.currentBenches = [];

    console.log(winners.join(', '));
    console.log('\n');

    if (name) {
      this.writeValue(name);
    }
  },
  writeBench: function(bench) {
    var out;

    if (!bench.error) {
      var count = bench.hz,
        moe = (count * bench.stats.rme) / 100,
        minimum,
        maximum;

      count = Math.round(count / 1000);
      moe = Math.round(moe / 1000);
      minimum = count - moe;
      maximum = count + moe;

      out = count + ' ±' + moe + ' (' + bench.cycles + ')';

      this.times[bench.suiteName][bench.benchName] = count;
      this.minimum = Math.min(this.minimum, minimum);
      this.maximum = Math.max(this.maximum, maximum);
    } else if (bench.error.message === 'EWOT') {
      out = 'NA';
    } else {
      out = 'E';
    }
    this.writeValue(out);
  },

  writeValue: function(out) {
    var padding = this.benchSize - out.length + 1;
    out = out + new Array(padding).join(' ');
    console.log(out);
  }
};

module.exports = BenchWarmer;