handlebars.js/bench/benchwarmer.js

var Benchmark = require("benchmark");

var BenchWarmer = function(names) {
  this.benchmarks = [];
  this.currentBenches = [];
  this.names = [];
  this.errors = {};
};

var print = require("sys").print;

BenchWarmer.prototype = {
  winners: function(benches) {
    var result = Benchmark.filter(benches, function(bench) { return bench.cycles; });

    if (result.length > 1) {
      result.sort(function(a, b) { return b.compare(a); });
      first = result[0];
      last  = result[result.length - 1];

      var winners = [];

      Benchmark.each(result, function(bench) {
        if (bench.compare(first) === 0) {
          winners.push(bench);
        }
      });

      return winners;
    } else {
      return result;
    }
  },
  suite: function(suite, fn) {
    this.suiteName = 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(function() {
      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;
      }
    });

    this.benchmarks.push(bench);
  },
  bench: function() {
    var benchSize = 0, names = this.names, self = this, 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("ops/msec");
    horSize = horSize + "ops/msec    ".length;
    for(i=0, l=names.length; i<l; i++) {
      print(names[i] + new Array(this.benchSize - names[i].length + 1).join(" "));
      horSize = horSize + this.benchSize;
    }

    print("WINNER(S)");
    horSize = horSize + "WINNER(S)".length;

    print("\n" + new Array(horSize + 1).join("-"));

    Benchmark.invoke(this.benchmarks, {
      name: "run",
      onComplete: function() {
        var errors = false, prop, bench;
        for(prop in self.errors) { if(self.errors.hasOwnProperty(prop)) { errors = true; break; } }

        if(errors) {
          print("\n\nErrors:\n");
          for(prop in self.errors) {
            if(self.errors.hasOwnProperty(prop)) {
              bench = self.errors[prop];
              print("\n" + bench.name + ":\n");
              print(bench.error.message);
              if(bench.error.stack) {
                print(bench.error.stack.join("\n"));
              }
              print("\n");
            }
          }
        }
      }
    });
  },
  startLine: function(name) {
    var winners = Benchmark.map(this.winners(this.currentBenches), function(bench) {
      return bench.name.split(": ")[1];
    });

    this.currentBenches = [];

    print(winners.join(", "));
    print("\n");
    var padding = this.nameSize - name.length + 1;
    name = name + new Array(padding).join(" ");
    print(name);
  },
  writeBench: function(bench) {
    var out;

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

      out = Math.round(count / 1000) + " ±" + Math.round(moe / 1000) + " (" + bench.cycles + ")";
    } else {
      out = "E";
    }

    var padding = this.benchSize - out.length + 1;
    out = out + new Array(padding).join(" ");
    print(out);
  }
};

module.exports = BenchWarmer;