a2800276 · February 23, 2012 10:23 · Feb 23, 2012
diff --git a/benchmark.js b/benchmark.js
@@ -0,0 +1,138 @@
+
+// Fairly straightforward port of go's benchmark impl.
+// see: http://golang.org/pkg/testing/
+// todo: result formatting facilities ...
+
+
+
+var Benchmark = function () {
+}
+
+function ns () {
+  // this is for ease of porting, JS doesn't
+  // support sub ms accurracy ...
+  return new Date().getTime() * 1e6
+}
+
+function startTimer () {
+  if (!this.start) {
+    this.start = ns() 
+  }
+}
+
+function stopTimer () {
+  if (this.start > 0) {
+    this.ns = ns() - this.start 
+  }
+  this.start = 0
+}
+
+function resetTimer() {
+  if (this.start > 0) {
+    this.start = ns()
+  }
+  this.ns = 0
+}
+
+// can be used from inside of the benchmark function
+// to indicate the number of bytes processed in order
+// for the information to be used in reports.
+function setBytes(n) {
+  this.bytes = n
+}
+
+function nsPerOp() {
+  if (this.N <= 0) {
+    return 0  
+  }
+  return this.ns / this.N
+}
+
+function runN(n) {
+  this.N = n
+  this.resetTimer()
+  this.startTimer()
+  this.F()
+  this.stopTimer()
+}
+
+
+function roundDown10(n) {
+  var tens = 0
+  for ( ; n>10 ; ) {
+    n /= 10
+    ++tens
+  }
+  var result = 1
+  for (var i =0; i<tens ; ++i) {
+    result *= 10
+  }
+  return result
+}
+
+function roundUp(n) {
+  var base = roundDown10(n)
+  if (n < (2 * base)) {
+    return 2*base
+  } 
+  if (n < (5 * base)) {
+    return 5 * base
+  }
+
+  return 10 * base
+}
+
+function run () {
+  var n = 1,
+      min = Math.min,
+      max = Math.max
+
+  this.runN(n)
+  var time = 1e9 // we want the benchmark to run at least this long (1s)
+  for ( ; this.ns < time && n < 1e9; ) {
+    var last = n
+    if (this.nsPerOp() === 0) { 
+      n = 1e9
+    } else {
+      n = time/this.nsPerOp()
+    }
+    n = max(min(n+n/2, 100*last), last+1)
+    n = roundUp(n)
+    this.runN(n)
+  }
+  return {
+      N : this.N
+    , ns: this.ns
+    , bytes: this.bytes
+  }
+}
+
+
+Benchmark.prototype.startTimer = startTimer
+Benchmark.prototype.stopTimer  = stopTimer
+Benchmark.prototype.resetTimer  = resetTimer
+Benchmark.prototype.setBytes  = setBytes
+Benchmark.prototype.nsPerOp  = nsPerOp
+Benchmark.prototype.runN  = runN
+Benchmark.prototype.run = run
+
+
+function bench (f) {
+  var b = new Benchmark()
+  b.F = function () {
+    for (b.i=0; b.i<b.N; ++b.i) {
+      f(b)
+    }
+  }
+  return b.run()
+}
+
+function f(b) {
+  var d = new Date().toString()
+  var dd = new Date(d)
+}
+
+exports.Benchmark = Benchmark
+exports.bench = bench
+
+//console.log(bench(f))