testing: add Benchmark to allow benchmarks to be run without gotest.

R=rsc
CC=golang-dev
https://golang.org/cl/2506042

diff --git a/src/cmd/gotest/gotest b/src/cmd/gotest/gotest
index 7a7e225df236cb5cc7b1d4ced62138598d28c698..112192ecdc78dff5f0e1178a741b0dc0a5be0d78 100755 (executable)
--- a/src/cmd/gotest/gotest
+++ b/src/cmd/gotest/gotest
@@ -157,10 +157,10 @@ importpath=$(gomake -s importpath)
        done
        echo '}'
        # benchmark array
-       echo 'var benchmarks = []testing.Benchmark{'
+       echo 'var benchmarks = []testing.InternalBenchmark{'
        for i in $benchmarks
        do
-               echo '  testing.Benchmark{"'$i'", '$i'},'
+               echo '  testing.InternalBenchmark{"'$i'", '$i'},'
        done
        echo '}'
 

diff --git a/src/pkg/testing/benchmark.go b/src/pkg/testing/benchmark.go
index bdec30250ecbd82aad484b2d16b73fcca2d44937..7c30e4e4ea4a97531f97ecfe054c3d910df63001 100644 (file)
--- a/src/pkg/testing/benchmark.go
+++ b/src/pkg/testing/benchmark.go
@@ -15,7 +15,7 @@ var matchBenchmarks = flag.String("benchmarks", "", "regular expression to selec
 
 // An internal type but exported because it is cross-package; part of the implementation
 // of gotest.
-type Benchmark struct {
+type InternalBenchmark struct {
        Name string
        F    func(b *B)
 }
@@ -24,7 +24,7 @@ type Benchmark struct {
 // timing and to specify the number of iterations to run.
 type B struct {
        N         int
-       benchmark Benchmark
+       benchmark InternalBenchmark
        ns        int64
        bytes     int64
        start     int64
@@ -117,7 +117,7 @@ func roundUp(n int) int {
 // 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() {
+func (b *B) run() BenchmarkResult {
        // Run the benchmark for a single iteration in case it's expensive.
        n := 1
        b.runN(n)
@@ -138,17 +138,36 @@ func (b *B) run() {
                n = roundUp(n)
                b.runN(n)
        }
-       ns := b.nsPerOp()
+       return BenchmarkResult{b.N, b.ns, 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 // The total number of bytes processed.
+}
+
+func (r BenchmarkResult) NsPerOp() int64 {
+       if r.N <= 0 {
+               return 0
+       }
+       return r.Ns / int64(r.N)
+}
+
+func (r BenchmarkResult) String() string {
+       ns := r.NsPerOp()
        mb := ""
-       if ns > 0 && b.bytes > 0 {
-               mb = fmt.Sprintf("\t%7.2f MB/s", (float64(b.bytes)/1e6)/(float64(ns)/1e9))
+       if ns > 0 && r.Bytes > 0 {
+               mb = fmt.Sprintf("\t%7.2f MB/s", (float64(r.Bytes)/1e6)/(float64(ns)/1e9))
        }
-       fmt.Printf("%s\t%8d\t%10d ns/op%s\n", b.benchmark.Name, b.N, b.nsPerOp(), mb)
+       return fmt.Sprintf("%8d\t%10d ns/op%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 []Benchmark) {
+func RunBenchmarks(matchString func(pat, str string) (bool, os.Error), benchmarks []InternalBenchmark) {
        // If no flag was specified, don't run benchmarks.
        if len(*matchBenchmarks) == 0 {
                return
@@ -163,6 +182,14 @@ func RunBenchmarks(matchString func(pat, str string) (bool, os.Error), benchmark
                        continue
                }
                b := &B{benchmark: Benchmark}
-               b.run()
+               r := b.run()
+               fmt.Printf("%s\t%v\n", Benchmark.Name, r)
        }
 }
+
+// Benchmark benchmarks a single function. Useful for creating
+// custom benchmarks that do not use gotest.
+func Benchmark(name string, f func(b *B)) BenchmarkResult {
+       b := &B{benchmark: InternalBenchmark{name, f}}
+       return b.run()
+}