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// Copyright 2011 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 pprof_test

import (

        "bytes"

        "hash/crc32"

        "runtime"

        . "runtime/pprof"

        "strings"

        "testing"

        "unsafe"

)

func TestCPUProfile(t *testing.T) {

        switch runtime.GOOS {

        case "darwin":

                // see Apple Bug Report #9177434 (copied into change description)

                return

        case "plan9":

                // unimplemented

                return

        }

        buf := make([]byte, 100000)

        var prof bytes.Buffer

        if err := StartCPUProfile(&prof); err != nil {

                t.Fatal(err)

        }

        // This loop takes about a quarter second on a 2 GHz laptop.

        // We only need to get one 100 Hz clock tick, so we've got

        // a 25x safety buffer.

        for i := 0; i < 1000; i++ {

                crc32.ChecksumIEEE(buf)

        }

        StopCPUProfile()

        // Convert []byte to []uintptr.

        bytes := prof.Bytes()

        val := *(*[]uintptr)(unsafe.Pointer(&bytes))

        val = val[:len(bytes)/int(unsafe.Sizeof(uintptr(0)))]

        if len(val) < 10 {

                t.Fatalf("profile too short: %#x", val)

        }

        if val[0] != 0 || val[1] != 3 || val[2] != 0 || val[3] != 1e6/100 || val[4] != 0 {

                t.Fatalf("unexpected header %#x", val[:5])

        }

        // Check that profile is well formed and contains ChecksumIEEE.

        found := false

        val = val[5:]

        for len(val) > 0 {

                if len(val) < 2 || val[0] < 1 || val[1] < 1 || uintptr(len(val)) < 2+val[1] {

                        t.Fatalf("malformed profile.  leftover: %#x", val)

                }

                for _, pc := range val[2 : 2+val[1]] {

                        f := runtime.FuncForPC(pc)

                        if f == nil {

                                continue

                        }

                        if strings.Contains(f.Name(), "ChecksumIEEE") {

                                found = true

                        }

                }

                val = val[2+val[1]:]

        }

        if !found {

                t.Fatal("did not find ChecksumIEEE in the profile")

        }

}