Merge pull request #32 from wongak/stack_build_tag

add build tag for Go 1.3+. See #31

.travis.yml

@@ -0,0 +1,9 @@
+language: go
+
+go:
+	- 1.0
+	- 1.1
+	- 1.2
+	- 1.3
+	- release
+	- tip

stack/stack.go

@@ -7,7 +7,6 @@ import (
 	"path/filepath"
 	"runtime"
 	"strings"
-	"sync"
 )
 
 // Call records a single function invocation from a goroutine stack. It is a
@@ -113,6 +112,20 @@ func (pc Call) Format(s fmt.State, c rune) {
 	}
 }
 
+// Callers returns a Trace for the current goroutine with element 0
+// identifying the calling function.
+func Callers() Trace {
+	pcs := poolBuf()
+	pcs = pcs[:cap(pcs)]
+	n := runtime.Callers(2, pcs)
+	cs := make([]Call, n)
+	for i, pc := range pcs[:n] {
+		cs[i] = Call(pc)
+	}
+	putPoolBuf(pcs)
+	return cs
+}
+
 // name returns the import path qualified name of the function containing the
 // call.
 func (pc Call) name() string {
@@ -151,24 +164,6 @@ func (pcs Trace) Format(s fmt.State, c rune) {
 	s.Write([]byte("]"))
 }
 
-var pcStackPool = sync.Pool{
-	New: func() interface{} { return make([]uintptr, 1000) },
-}
-
-// Callers returns a Trace for the current goroutine with element 0
-// identifying the calling function.
-func Callers() Trace {
-	pcs := pcStackPool.Get().([]uintptr)
-	pcs = pcs[:cap(pcs)]
-	n := runtime.Callers(2, pcs)
-	cs := make([]Call, n)
-	for i, pc := range pcs[:n] {
-		cs[i] = Call(pc)
-	}
-	pcStackPool.Put(pcs)
-	return cs
-}
-
 // TrimBelow returns a slice of the Trace with all entries below pc removed.
 func (pcs Trace) TrimBelow(pc Call) Trace {
 	for len(pcs) > 0 && pcs[0] != pc {

stack/stack_pool.go

@@ -0,0 +1,19 @@
+// +build go1.3
+
+package stack
+
+import (
+	"sync"
+)
+
+var pcStackPool = sync.Pool{
+	New: func() interface{} { return make([]uintptr, 1000) },
+}
+
+func poolBuf() []uintptr {
+	return pcStackPool.Get().([]uintptr)
+}
+
+func putPoolBuf(p []uintptr) {
+	pcStackPool.Put(p)
+}

stack/stack_pool_chan.go

@@ -0,0 +1,27 @@
+// +build !go1.3
+
+package stack
+
+const (
+	stackPoolSize = 64
+)
+
+var (
+	pcStackPool = make(chan []uintptr, stackPoolSize)
+)
+
+func poolBuf() []uintptr {
+	select {
+	case p := <-pcStackPool:
+		return p
+	default:
+		return make([]uintptr, 1000)
+	}
+}
+
+func putPoolBuf(p []uintptr) {
+	select {
+	case pcStackPool <- p:
+	default:
+	}
+}