The first step is certainly to consistently check the error returns of
all your system calls. Right now you are ignoring the error returns
of your SHMAT calls.
Ian
On Thu, Mar 21, 2019 at 8:24 AM <615912...@qq.com> wrote:
>
> Here is my code.
> package main
>
> /*
> #include <string.h>
> #include <stdio.h>
> #include <stdlib.h>
> static void memcpy_c(char *dest, int offs1, char *src, int offs2, int cnt) {
> if (src == 0 || dest == 0) {
> printf("a null ptr.\n");
> return;
> }
> int a = 0;
> long i = 0;
> memcpy(dest + offs1, src+offs2, cnt);
> while (1){
> if (i >= cnt) {
> break;
> }
> i++;
> }
> char tmp[] = "yesss";
> printf("a null ptr.%d, %d,%ld,%ld\n", offs1, offs2, dest, src);
> }
> static void set_int32(char *addr, int offset, int num) {
> int* d = (int *)(addr + 4 * offset);
> *d = num;
> }
> static int get_int32(char *addr, int offset) {
> int *d = (int *)(addr + 4 * offset);
> return *d;
> }
> static void get_data(char *addr, int offset, int cnt) {
> char tmp[cnt];
> memcpy(tmp, addr+offset, cnt);
> printf("get data%s", tmp);
> }
> */
> import "C"
> import (
> "fmt"
> "github.com/go-ini/ini"
> "math/rand"
> "strconv"
> "syscall"
> "unsafe"
> )
>
> //memcpy(dest + offs1, tmp, 5);
> //printf("%d, %d\n", *(dest + offs1+i), *(src+offs2+i));
> const (
> // IpcCreate create if key nonexistent
> IpcCreate = 00001000
> )
>
> type MemPoolMng struct {
> data_start_ptr uintptr
> offs_start_ptr uintptr
> offs_key uintptr
> data_key uintptr
> data_cnt int
> mem_helper unsafe.Pointer
> }
>
> func NewMemPoolMng() *MemPoolMng {
> return &MemPoolMng{}
> }
>
> func (mp_mgr *MemPoolMng) Init() bool {
> cfg, err := ini.Load("./cfg.ini")
> if err != nil {
> return false
> }
>
> tmp_offs_key, err1 :=
> strconv.Atoi(cfg.Section("mempool").Key("offs_key").String())
> tmp_data_key, err2 :=
> strconv.Atoi(cfg.Section("mempool").Key("data_key").String())
> if err1 != nil {
> return false
> }
> if err2 != nil {
> return false
> }
>
> //get share memory from shmid.
> offs_id, _, err3 := syscall.Syscall(syscall.SYS_SHMGET,
> uintptr(tmp_offs_key), 1<<32, IpcCreate|0600)
> data_id, _, err4 := syscall.Syscall(syscall.SYS_SHMGET,
> uintptr(tmp_data_key), 1<<15, IpcCreate|0600)
> if err3 != 0 {
> return false
> }
> if err4 != 0 {
> return false
> }
> mp_mgr.offs_key = offs_id
> mp_mgr.data_key = data_id
> mp_mgr.mem_helper = C.malloc(1 << 32)
>
> // Share memory struct: |data_size(4)| offset1 | offset2 | offset3 |...
> offs_shmaddr, _, err5 := syscall.Syscall(syscall.SYS_SHMAT, offs_id, 0, 0)
> if err5 != 0 {
> return false
> }
> defer syscall.Syscall(syscall.SYS_SHMDT, offs_shmaddr, 0, 0)
> mp_mgr.data_cnt = *(*int)(unsafe.Pointer(uintptr(offs_shmaddr)))
>
> fmt.Printf("MemPoolMng init success(%d).\n", mp_mgr.data_cnt)
> return true
> }
>
> // Save the offset of each data with a contiguous address.
> |data_cnt|0|offsset1|offset2|......|
> func (mp_mgr *MemPoolMng) PutData(data *[]byte) bool {
> if mp_mgr.data_cnt >= 1024 || len(*data) == 0 {
> return false
> }
> offs_shmaddr, _, _ := syscall.Syscall(syscall.SYS_SHMAT, mp_mgr.offs_key, 0,
> 0)
> //data_shmaddr, _, _ := syscall.Syscall(syscall.SYS_SHMAT, mp_mgr.data_key,
> uintptr(mp_mgr.mem_helper), 0)
> data_shmaddr, _, _ := syscall.Syscall(syscall.SYS_SHMAT, mp_mgr.data_key, 0,
> 0)
> defer syscall.Syscall(syscall.SYS_SHMDT, offs_shmaddr, 0, 0)
> defer syscall.Syscall(syscall.SYS_SHMDT, data_shmaddr, 0, 0)
> data_cnt := *(*int)(unsafe.Pointer(uintptr(offs_shmaddr)))
> per_offs := C.get_int32((*C.char)(unsafe.Pointer(offs_shmaddr)),
> C.int(data_cnt+1))
>
> // step 1: Put data.
> //C.memcpy_c((*C.char)(mp_mgr.mem_helper), per_offs,
> (C.CString)(string(*data)), 0, C.int(len(*data)))
> C.memcpy_c((*C.char)(unsafe.Pointer(data_shmaddr)), per_offs,
> (C.CString)(string(*data)), 0, C.int(len(*data)))
> //C.memcpy(unsafe.Pointer(data_shmaddr+uintptr(per_offs)),
> unsafe.Pointer((C.CString)(string(*data))), C.ulong(len(*data)))
> //C.memcpy(unsafe.Pointer(data_shmaddr),
> unsafe.Pointer((C.CString)(string(*data))), 48000)
>
> // step 2: Modify offset.
> cur_offs := int(per_offs) + len(*data)
> C.set_int32((*C.char)(unsafe.Pointer(offs_shmaddr)), C.int(data_cnt+2),
> C.int(cur_offs))
>
> // step 3: Modify data_cnt
> data_cnt += 1
> *(*int)(unsafe.Pointer(uintptr(offs_shmaddr))) = data_cnt
>
> //C.memcpy_c((*C.char)(unsafe.Pointer(data_shmaddr)),
> (*C.char)(unsafe.Pointer(offs_shmaddr)), 4)
>
> //for i := 0; i <= data_cnt+2; i++ {
> for i := 0; i <= -1; i++ {
> fmt.Printf("%d ", C.get_int32((*C.char)(unsafe.Pointer(offs_shmaddr)),
> C.int(i)))
> }
> for i := 0; i < 10; i++ {
> //
> fmt.Println(C.get_int32((*C.char)(unsafe.Pointer(offs_shmaddr+uintptr(data_cnt-i))),
> 0))
> }
> return true
> }
>
> func (mp_mgr *MemPoolMng) GetData() []byte {
> offs_shmaddr, _, _ := syscall.Syscall(syscall.SYS_SHMAT, mp_mgr.offs_key, 0,
> 0)
> syscall.Syscall(syscall.SYS_SHMAT, mp_mgr.data_key, 0, 0)
> data_shmaddr, _, _ := syscall.Syscall(syscall.SYS_SHMAT, mp_mgr.data_key, 0,
> 0)
> //data_shmaddr, _, _ := syscall.Syscall(syscall.SYS_SHMAT, mp_mgr.data_key,
> uintptr(mp_mgr.mem_helper), 0)
> data_cnt := *(*int)(unsafe.Pointer(uintptr(offs_shmaddr)))
> if data_cnt == 0 {
> return []byte{}
> }
>
> // Generate a probability based on the insertion time of the data. The last
> one has probability n/(1+2+...+n).
> total := data_cnt * (data_cnt + 1) / 2
> random := rand.Intn(total) + 1
> data_i := 0
> for i := 1; i <= data_cnt; i++ {
> a := i * (i - 1) / 2
> b := i * (i + 1) / 2
> if random > a && random <= b {
> data_i = i
> break
> }
> }
>
> per_offs := C.get_int32((*C.char)(unsafe.Pointer(uintptr(offs_shmaddr))),
> C.int(data_i))
> cur_offs := C.get_int32((*C.char)(unsafe.Pointer(uintptr(offs_shmaddr))),
> C.int(data_i+1))
> if cur_offs <= per_offs {
> return []byte{}
> }
>
> record := C.GoBytes(unsafe.Pointer(data_shmaddr+uintptr(per_offs)),
> cur_offs-per_offs)
> //record :=
> C.GoBytes(unsafe.Pointer(uintptr(mp_mgr.mem_helper)+uintptr(per_offs)),
> cur_offs-per_offs)
> fmt.Println(cur_offs-per_offs, len(record))
> if len(record) > 10 {
> return record[:10]
> }
> return record
> }
>
>
>
>
> 在 2019年3月19日星期二 UTC+8上午11:51:48，Ian Lance Taylor写道：
>>
>> On Mon, Mar 18, 2019 at 8:17 PM <6159...@qq.com> wrote:
>> >
>> > shmid, _, err := syscall.Syscall(syscall.SYS_SHMGET, uintptr(10001),
>> > 1<<32, IpcCreate|0600)
>> > data_shmaddr, _, _ := syscall.Syscall(syscall.SYS_SHMAT, shmid, 0, 0)
>> > C.memcpy(unsafe.Pointer(data_shmaddr+uintptr(per_offs)),
>> > unsafe.Pointer((C.CString)(string(*data))), C.ulong(len(*data)))
>> >
>> > I'm trying to use syscall shmat/shmget, but it seems like i can't map all
>> > the address that i wanted.
>> > 'per_offs' is a int value far less than 1<<32, below is what i got.
>> >
>> > fatal error: unexpected signal during runtime execution
>> > [signal SIGSEGV: segmentation violation code=0x1 addr=0x7fe3502cca80
>> > pc=0x7fe34d9320b4]
>> >
>> > runtime stack:
>> > runtime.throw(0x552be5, 0x2a)
>> > /data1/user1/go_env/go/src/runtime/panic.go:619 +0x81
>> > runtime.sigpanic()
>> > /data1/user1/go_env/go/src/runtime/signal_unix.go:372 +0x28e
>> >
>> > goroutine 1 [syscall]:
>> > runtime.cgocall(0x4fe960, 0xc4200edd40, 0x29)
>> > /data1/user1/go_env/go/src/runtime/cgocall.go:128 +0x64 fp=0xc4200edd00
>> > sp=0xc4200edcc8 pc=0x403034
>> > main._Cfunc_memcpy(0x7fe3502cca80, 0x7fe3440008c0, 0x1, 0x0)
>> > _cgo_gotypes.go:78 +0x4e fp=0xc4200edd40 sp=0xc4200edd00 pc=0x4fdb7e
>> > main.(*MemPoolMng).PutData.func1(0x7fe3502cca80, 0x7fe3440008c0, 0x1, 0x1)
>> > /data1/user2/GoServer/mempool_go/mempool_mgr.go:107 +0x99 fp=0xc4200edd78
>> > sp=0xc4200edd40 pc=0x4fe7a9
>> > main.(*MemPoolMng).PutData(0xc4200182d0, 0xc420158000, 0xf4240)
>> > /data1/user2/GoServer/mempool_go/mempool_mgr.go:107 +0x1da fp=0xc4200ede58
>> > sp=0xc4200edd78 pc=0x4fe37a
>> > main.handleProtoClient(0x565720, 0xc42000e060)
>> > /data1/user2/GoServer/mempool_go/server.go:58 +0x16f fp=0xc4200eded0
>> > sp=0xc4200ede58 pc=0x4fcf8f
>> > main.main()
>> > /data1/user2/GoServer/mempool_go/server.go:39 +0x261 fp=0xc4200edf88
>> > sp=0xc4200eded0 pc=0x4fcca1
>> > runtime.main()
>> > /data1/user1/go_env/go/src/runtime/proc.go:198 +0x212 fp=0xc4200edfe0
>> > sp=0xc4200edf88 pc=0x42b772
>> > runtime.goexit()
>> > /data1/user1/go_env/go/src/runtime/asm_amd64.s:2361 +0x1 fp=0xc4200edfe8
>> > sp=0xc4200edfe0 pc=0x455601
>> > exit status 2
>>
>>
>> 1) Always check the returned error value.
>>
>> 2) Show us a complete, standalone, program.
>>
>> Ian
>
> --
> You received this message because you are subscribed to the Google Groups
> "golang-nuts" group.
> To unsubscribe from this group and stop receiving emails from it, send an
> email to golang-nuts+unsubscr...@googlegroups.com.
> For more options, visit https://groups.google.com/d/optout.
--
You received this message because you are subscribed to the Google Groups
"golang-nuts" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to golang-nuts+unsubscr...@googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
