// Copyright 2016 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.

// +build linux,amd64

package main

// Test that we can collect a lot of colliding profiling signals from
// an external C thread. This used to fail when built with the race
// detector, because a call of the predeclared function copy was
// turned into a call to runtime.slicecopy, which is not marked nosplit.

/*
#include <signal.h>
#include <stdint.h>
#include <pthread.h>
#include <sched.h>

struct cgoTracebackArg {
	uintptr_t  context;
	uintptr_t  sigContext;
	uintptr_t* buf;
	uintptr_t  max;
};

static int raceprofCount;

// We want a bunch of different profile stacks that collide in the
// hash table maintained in runtime/cpuprof.go. This code knows the
// size of the hash table (1 << 10) and knows that the hash function
// is simply multiplicative.
void raceprofTraceback(void* parg) {
	struct cgoTracebackArg* arg = (struct cgoTracebackArg*)(parg);
	raceprofCount++;
	arg->buf[0] = raceprofCount * (1 << 10);
	arg->buf[1] = 0;
}

static void* raceprofThread(void* p) {
	int i;

	for (i = 0; i < 100; i++) {
		pthread_kill(pthread_self(), SIGPROF);
		sched_yield();
	}
	return 0;
}

void runRaceprofThread() {
	pthread_t tid;
	pthread_create(&tid, 0, raceprofThread, 0);
	pthread_join(tid, 0);
}
*/
import "C"

import (
	"bytes"
	"fmt"
	"runtime"
	"runtime/pprof"
	"unsafe"
)

func init() {
	register("CgoRaceprof", CgoRaceprof)
}

func CgoRaceprof() {
	runtime.SetCgoTraceback(0, unsafe.Pointer(C.raceprofTraceback), nil, nil)

	var buf bytes.Buffer
	pprof.StartCPUProfile(&buf)

	C.runRaceprofThread()
	fmt.Println("OK")
}
