code review 129510043: runtime: convert Stack to Go.

src/pkg/runtime/mprof.go

 // Copyright 2009 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 runtime
 
 import (
         "unsafe"
 )
 
@@ skipping 123 matching lines @@
                                 p[idx].Stack0[i] = 0
                                 i++
                         }
                         idx++
                 }
         }
         gounlock(&proflock)
         return
 }
 
+// Stack formats a stack trace of the calling goroutine into buf
+// and returns the number of bytes written to buf.
+// If all is true, Stack formats stack traces of all other goroutines
+// into buf after the trace for the current goroutine.
+func Stack(buf []byte, all bool) int {
+        sp := gogetcallersp(unsafe.Pointer(&buf))
+        pc := gogetcallerpc(unsafe.Pointer(&buf))
+        mp := acquirem()
+        gp := mp.curg
+        if all {
+                semacquire(&worldsema, false)
+                mp.gcing = 1
+                releasem(mp)
+                stoptheworld()
+                if mp != acquirem() {
+                        gothrow("Stack: rescheduled")
+                }
+        }
+
+        n := 0
+        if len(buf) > 0 {
+                gp.writebuf = &buf[0]
+                gp.writenbuf = int32(len(buf))
+                traceback(pc, sp, 0, gp)
+                if all {
+                        tracebackothers(gp)
+                }
+                n = len(buf) - int(gp.writenbuf)
+                gp.writebuf = nil
+                gp.writenbuf = 0
+        }
+
+        if all {
+                mp.gcing = 0
+                semrelease(&worldsema)
+                starttheworld()
+        }
+        releasem(mp)
+        return n
+}
+
 // ThreadCreateProfile returns n, the number of records in the thread creation profile.
 // If len(p) >= n, ThreadCreateProfile copies the profile into p and returns n, true.
 // If len(p) < n, ThreadCreateProfile does not change p and returns n, false.
 //
 // Most clients should use the runtime/pprof package instead
 // of calling ThreadCreateProfile directly.
 func ThreadCreateProfile(p []StackRecord) (n int, ok bool) {
         first := (*m)(goatomicloadp(unsafe.Pointer(&allm)))
         for mp := first; mp != nil; mp = mp.alllink {
                 n++
         }
         if n <= len(p) {
                 ok = true
                 i := 0
                 for mp := first; mp != nil; mp = mp.alllink {
                         for s := range mp.createstack {
                                 p[i].Stack0[s] = uintptr(mp.createstack[s])
                         }
                         i++
                 }
         }
         return
 }