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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")
        }
}