Imported Upstream version 1upstream/1

1 files changed, 92 insertions, 35 deletions

diff --git a/src/pkg/testing/benchmark.go b/src/pkg/testing/benchmark.go
index fd0bd8665..41290594e 100644
--- a/src/pkg/testing/benchmark.go
+++ b/src/pkg/testing/benchmark.go
@@ -16,7 +16,7 @@ var matchBenchmarks = flag.String("test.bench", "", "regular expression to selec
 var benchTime = flag.Float64("test.benchtime", 1, "approximate run time for each benchmark, in seconds")
 
 // An internal type but exported because it is cross-package; part of the implementation
-// of gotest.
+// of the "go test" command.
 type InternalBenchmark struct {
 	Name string
 	F    func(b *B)
@@ -25,19 +25,21 @@ type InternalBenchmark struct {
 // B is a type passed to Benchmark functions to manage benchmark
 // timing and to specify the number of iterations to run.
 type B struct {
+	common
 	N         int
 	benchmark InternalBenchmark
-	ns        int64
 	bytes     int64
-	start     int64
+	timerOn   bool
+	result    BenchmarkResult
 }
 
 // StartTimer starts timing a test.  This function is called automatically
 // before a benchmark starts, but it can also used to resume timing after
 // a call to StopTimer.
 func (b *B) StartTimer() {
-	if b.start == 0 {
-		b.start = time.Nanoseconds()
+	if !b.timerOn {
+		b.start = time.Now()
+		b.timerOn = true
 	}
 }
 
@@ -45,19 +47,19 @@ func (b *B) StartTimer() {
 // while performing complex initialization that you don't
 // want to measure.
 func (b *B) StopTimer() {
-	if b.start > 0 {
-		b.ns += time.Nanoseconds() - b.start
+	if b.timerOn {
+		b.duration += time.Now().Sub(b.start)
+		b.timerOn = false
 	}
-	b.start = 0
 }
 
 // ResetTimer sets the elapsed benchmark time to zero.
 // It does not affect whether the timer is running.
 func (b *B) ResetTimer() {
-	if b.start > 0 {
-		b.start = time.Nanoseconds()
+	if b.timerOn {
+		b.start = time.Now()
 	}
-	b.ns = 0
+	b.duration = 0
 }
 
 // SetBytes records the number of bytes processed in a single operation.
@@ -68,7 +70,7 @@ func (b *B) nsPerOp() int64 {
 	if b.N <= 0 {
 		return 0
 	}
-	return b.ns / int64(b.N)
+	return b.duration.Nanoseconds() / int64(b.N)
 }
 
 // runN runs a single benchmark for the specified number of iterations.
@@ -125,23 +127,38 @@ func roundUp(n int) int {
 	return 10 * base
 }
 
-// run times the benchmark function.  It gradually increases the number
+// run times the benchmark function in a separate goroutine.
+func (b *B) run() BenchmarkResult {
+	go b.launch()
+	<-b.signal
+	return b.result
+}
+
+// launch launches the benchmark function.  It gradually increases the number
 // of benchmark iterations until the benchmark runs for a second in order
 // to get a reasonable measurement.  It prints timing information in this form
 //		testing.BenchmarkHello	100000		19 ns/op
-func (b *B) run() BenchmarkResult {
+// launch is run by the fun function as a separate goroutine.
+func (b *B) launch() {
 	// Run the benchmark for a single iteration in case it's expensive.
 	n := 1
+
+	// Signal that we're done whether we return normally
+	// or by FailNow's runtime.Goexit.
+	defer func() {
+		b.signal <- b
+	}()
+
 	b.runN(n)
 	// Run the benchmark for at least the specified amount of time.
-	time := int64(*benchTime * 1e9)
-	for b.ns < time && n < 1e9 {
+	d := time.Duration(*benchTime * float64(time.Second))
+	for !b.failed && b.duration < d && n < 1e9 {
 		last := n
 		// Predict iterations/sec.
 		if b.nsPerOp() == 0 {
 			n = 1e9
 		} else {
-			n = int(time / b.nsPerOp())
+			n = int(d.Nanoseconds() / b.nsPerOp())
 		}
 		// Run more iterations than we think we'll need for a second (1.5x).
 		// Don't grow too fast in case we had timing errors previously.
@@ -151,28 +168,28 @@ func (b *B) run() BenchmarkResult {
 		n = roundUp(n)
 		b.runN(n)
 	}
-	return BenchmarkResult{b.N, b.ns, b.bytes}
+	b.result = BenchmarkResult{b.N, b.duration, b.bytes}
 }
 
 // The results of a benchmark run.
 type BenchmarkResult struct {
-	N     int   // The number of iterations.
-	Ns    int64 // The total time taken.
-	Bytes int64 // Bytes processed in one iteration.
+	N     int           // The number of iterations.
+	T     time.Duration // The total time taken.
+	Bytes int64         // Bytes processed in one iteration.
 }
 
 func (r BenchmarkResult) NsPerOp() int64 {
 	if r.N <= 0 {
 		return 0
 	}
-	return r.Ns / int64(r.N)
+	return r.T.Nanoseconds() / int64(r.N)
 }
 
 func (r BenchmarkResult) mbPerSec() float64 {
-	if r.Bytes <= 0 || r.Ns <= 0 || r.N <= 0 {
+	if r.Bytes <= 0 || r.T <= 0 || r.N <= 0 {
 		return 0
 	}
-	return float64(r.Bytes) * float64(r.N) / float64(r.Ns) * 1e3
+	return (float64(r.Bytes) * float64(r.N) / 1e6) / r.T.Seconds()
 }
 
 func (r BenchmarkResult) String() string {
@@ -187,17 +204,17 @@ func (r BenchmarkResult) String() string {
 		// The format specifiers here make sure that
 		// the ones digits line up for all three possible formats.
 		if nsop < 10 {
-			ns = fmt.Sprintf("%13.2f ns/op", float64(r.Ns)/float64(r.N))
+			ns = fmt.Sprintf("%13.2f ns/op", float64(r.T.Nanoseconds())/float64(r.N))
 		} else {
-			ns = fmt.Sprintf("%12.1f ns/op", float64(r.Ns)/float64(r.N))
+			ns = fmt.Sprintf("%12.1f ns/op", float64(r.T.Nanoseconds())/float64(r.N))
 		}
 	}
 	return fmt.Sprintf("%8d\t%s%s", r.N, ns, mb)
 }
 
 // An internal function but exported because it is cross-package; part of the implementation
-// of gotest.
-func RunBenchmarks(matchString func(pat, str string) (bool, os.Error), benchmarks []InternalBenchmark) {
+// of the "go test" command.
+func RunBenchmarks(matchString func(pat, str string) (bool, error), benchmarks []InternalBenchmark) {
 	// If no flag was specified, don't run benchmarks.
 	if len(*matchBenchmarks) == 0 {
 		return
@@ -205,7 +222,7 @@ func RunBenchmarks(matchString func(pat, str string) (bool, os.Error), benchmark
 	for _, Benchmark := range benchmarks {
 		matched, err := matchString(*matchBenchmarks, Benchmark.Name)
 		if err != nil {
-			println("invalid regexp for -test.bench:", err.String())
+			fmt.Fprintf(os.Stderr, "testing: invalid regexp for -test.bench: %s\n", err)
 			os.Exit(1)
 		}
 		if !matched {
@@ -213,24 +230,64 @@ func RunBenchmarks(matchString func(pat, str string) (bool, os.Error), benchmark
 		}
 		for _, procs := range cpuList {
 			runtime.GOMAXPROCS(procs)
-			b := &B{benchmark: Benchmark}
+			b := &B{
+				common: common{
+					signal: make(chan interface{}),
+				},
+				benchmark: Benchmark,
+			}
 			benchName := Benchmark.Name
 			if procs != 1 {
 				benchName = fmt.Sprintf("%s-%d", Benchmark.Name, procs)
 			}
-			print(fmt.Sprintf("%s\t", benchName))
+			fmt.Printf("%s\t", benchName)
 			r := b.run()
-			print(fmt.Sprintf("%v\n", r))
+			if b.failed {
+				// The output could be very long here, but probably isn't.
+				// We print it all, regardless, because we don't want to trim the reason
+				// the benchmark failed.
+				fmt.Printf("--- FAIL: %s\n%s", benchName, b.output)
+				continue
+			}
+			fmt.Printf("%v\n", r)
+			// Unlike with tests, we ignore the -chatty flag and always print output for
+			// benchmarks since the output generation time will skew the results.
+			if len(b.output) > 0 {
+				b.trimOutput()
+				fmt.Printf("--- BENCH: %s\n%s", benchName, b.output)
+			}
 			if p := runtime.GOMAXPROCS(-1); p != procs {
-				print(fmt.Sprintf("%s left GOMAXPROCS set to %d\n", benchName, p))
+				fmt.Fprintf(os.Stderr, "testing: %s left GOMAXPROCS set to %d\n", benchName, p)
+			}
+		}
+	}
+}
+
+// trimOutput shortens the output from a benchmark, which can be very long.
+func (b *B) trimOutput() {
+	// The output is likely to appear multiple times because the benchmark
+	// is run multiple times, but at least it will be seen. This is not a big deal
+	// because benchmarks rarely print, but just in case, we trim it if it's too long.
+	const maxNewlines = 10
+	for nlCount, j := 0, 0; j < len(b.output); j++ {
+		if b.output[j] == '\n' {
+			nlCount++
+			if nlCount >= maxNewlines {
+				b.output = append(b.output[:j], "\n\t... [output truncated]\n"...)
+				break
 			}
 		}
 	}
 }
 
 // Benchmark benchmarks a single function. Useful for creating
-// custom benchmarks that do not use gotest.
+// custom benchmarks that do not use the "go test" command.
 func Benchmark(f func(b *B)) BenchmarkResult {
-	b := &B{benchmark: InternalBenchmark{"", f}}
+	b := &B{
+		common: common{
+			signal: make(chan interface{}),
+		},
+		benchmark: InternalBenchmark{"", f},
+	}
 	return b.run()
 }