Permalink
Fetching contributors…
Cannot retrieve contributors at this time
79 lines (70 sloc) 1.7 KB
package basictracer
import (
"bytes"
"fmt"
"runtime"
"strconv"
"sync"
)
const debugGoroutineIDTag = "_initial_goroutine"
type errAssertionFailed struct {
span *spanImpl
msg string
}
// Error implements the error interface.
func (err *errAssertionFailed) Error() string {
return fmt.Sprintf("%s:\n%+v", err.msg, err.span)
}
func (s *spanImpl) Lock() {
s.Mutex.Lock()
s.maybeAssertSanityLocked()
}
func (s *spanImpl) maybeAssertSanityLocked() {
if s.tracer == nil {
s.Mutex.Unlock()
panic(&errAssertionFailed{span: s, msg: "span used after call to Finish()"})
}
if s.tracer.options.DebugAssertSingleGoroutine {
startID := curGoroutineID()
curID, ok := s.raw.Tags[debugGoroutineIDTag].(uint64)
if !ok {
// This is likely invoked in the context of the SetTag which sets
// debugGoroutineTag.
return
}
if startID != curID {
s.Mutex.Unlock()
panic(&errAssertionFailed{
span: s,
msg: fmt.Sprintf("span started on goroutine %d, but now running on %d", startID, curID),
})
}
}
}
var goroutineSpace = []byte("goroutine ")
var littleBuf = sync.Pool{
New: func() interface{} {
buf := make([]byte, 64)
return &buf
},
}
// Credit to @bradfitz:
// https://github.com/golang/net/blob/master/http2/gotrack.go#L51
func curGoroutineID() uint64 {
bp := littleBuf.Get().(*[]byte)
defer littleBuf.Put(bp)
b := *bp
b = b[:runtime.Stack(b, false)]
// Parse the 4707 out of "goroutine 4707 ["
b = bytes.TrimPrefix(b, goroutineSpace)
i := bytes.IndexByte(b, ' ')
if i < 0 {
panic(fmt.Sprintf("No space found in %q", b))
}
b = b[:i]
n, err := strconv.ParseUint(string(b), 10, 64)
if err != nil {
panic(fmt.Sprintf("Failed to parse goroutine ID out of %q: %v", b, err))
}
return n
}