1 files changed, 190 insertions, 0 deletions
diff --git a/src/context/benchmark_test.go b/src/context/benchmark_test.go
new file mode 100644
index 0000000..144f473
--- /dev/null
+++ b/src/context/benchmark_test.go
@@ -0,0 +1,190 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package context_test
+
+import (
+	. "context"
+	"fmt"
+	"runtime"
+	"sync"
+	"testing"
+	"time"
+)
+
+func BenchmarkCommonParentCancel(b *testing.B) {
+	root := WithValue(Background(), "key", "value")
+	shared, sharedcancel := WithCancel(root)
+	defer sharedcancel()
+
+	b.ResetTimer()
+	b.RunParallel(func(pb *testing.PB) {
+		x := 0
+		for pb.Next() {
+			ctx, cancel := WithCancel(shared)
+			if ctx.Value("key").(string) != "value" {
+				b.Fatal("should not be reached")
+			}
+			for i := 0; i < 100; i++ {
+				x /= x + 1
+			}
+			cancel()
+			for i := 0; i < 100; i++ {
+				x /= x + 1
+			}
+		}
+	})
+}
+
+func BenchmarkWithTimeout(b *testing.B) {
+	for concurrency := 40; concurrency <= 4e5; concurrency *= 100 {
+		name := fmt.Sprintf("concurrency=%d", concurrency)
+		b.Run(name, func(b *testing.B) {
+			benchmarkWithTimeout(b, concurrency)
+		})
+	}
+}
+
+func benchmarkWithTimeout(b *testing.B, concurrentContexts int) {
+	gomaxprocs := runtime.GOMAXPROCS(0)
+	perPContexts := concurrentContexts / gomaxprocs
+	root := Background()
+
+	// Generate concurrent contexts.
+	var wg sync.WaitGroup
+	ccf := make([][]CancelFunc, gomaxprocs)
+	for i := range ccf {
+		wg.Add(1)
+		go func(i int) {
+			defer wg.Done()
+			cf := make([]CancelFunc, perPContexts)
+			for j := range cf {
+				_, cf[j] = WithTimeout(root, time.Hour)
+			}
+			ccf[i] = cf
+		}(i)
+	}
+	wg.Wait()
+
+	b.ResetTimer()
+	b.RunParallel(func(pb *testing.PB) {
+		wcf := make([]CancelFunc, 10)
+		for pb.Next() {
+			for i := range wcf {
+				_, wcf[i] = WithTimeout(root, time.Hour)
+			}
+			for _, f := range wcf {
+				f()
+			}
+		}
+	})
+	b.StopTimer()
+
+	for _, cf := range ccf {
+		for _, f := range cf {
+			f()
+		}
+	}
+}
+
+func BenchmarkCancelTree(b *testing.B) {
+	depths := []int{1, 10, 100, 1000}
+	for _, d := range depths {
+		b.Run(fmt.Sprintf("depth=%d", d), func(b *testing.B) {
+			b.Run("Root=Background", func(b *testing.B) {
+				for i := 0; i < b.N; i++ {
+					buildContextTree(Background(), d)
+				}
+			})
+			b.Run("Root=OpenCanceler", func(b *testing.B) {
+				for i := 0; i < b.N; i++ {
+					ctx, cancel := WithCancel(Background())
+					buildContextTree(ctx, d)
+					cancel()
+				}
+			})
+			b.Run("Root=ClosedCanceler", func(b *testing.B) {
+				for i := 0; i < b.N; i++ {
+					ctx, cancel := WithCancel(Background())
+					cancel()
+					buildContextTree(ctx, d)
+				}
+			})
+		})
+	}
+}
+
+func buildContextTree(root Context, depth int) {
+	for d := 0; d < depth; d++ {
+		root, _ = WithCancel(root)
+	}
+}
+
+func BenchmarkCheckCanceled(b *testing.B) {
+	ctx, cancel := WithCancel(Background())
+	cancel()
+	b.Run("Err", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			ctx.Err()
+		}
+	})
+	b.Run("Done", func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			select {
+			case <-ctx.Done():
+			default:
+			}
+		}
+	})
+}
+
+func BenchmarkContextCancelDone(b *testing.B) {
+	ctx, cancel := WithCancel(Background())
+	defer cancel()
+
+	b.RunParallel(func(pb *testing.PB) {
+		for pb.Next() {
+			select {
+			case <-ctx.Done():
+			default:
+			}
+		}
+	})
+}
+
+func BenchmarkDeepValueNewGoRoutine(b *testing.B) {
+	for _, depth := range []int{10, 20, 30, 50, 100} {
+		ctx := Background()
+		for i := 0; i < depth; i++ {
+			ctx = WithValue(ctx, i, i)
+		}
+
+		b.Run(fmt.Sprintf("depth=%d", depth), func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				var wg sync.WaitGroup
+				wg.Add(1)
+				go func() {
+					defer wg.Done()
+					ctx.Value(-1)
+				}()
+				wg.Wait()
+			}
+		})
+	}
+}
+
+func BenchmarkDeepValueSameGoRoutine(b *testing.B) {
+	for _, depth := range []int{10, 20, 30, 50, 100} {
+		ctx := Background()
+		for i := 0; i < depth; i++ {
+			ctx = WithValue(ctx, i, i)
+		}
+
+		b.Run(fmt.Sprintf("depth=%d", depth), func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				ctx.Value(-1)
+			}
+		})
+	}
+}