go dlv
Contents
dlv
dlv 是golang 的调试工具
简易例子
func main() {
slice := make([]int, 0)
for i := 1; i < 10; i++ {
slice = append(slice, i)
}
}cd 代码根目录
$ dlv deug
Type 'help' for list of commands.
(dlv) (dlv) help
The following commands are available:
Running the program:
call ------------------------ Resumes process, injecting a function call (EXPERIMENTAL!!!)
continue (alias: c) --------- Run until breakpoint or program termination.
next (alias: n) ------------- Step over to next source line.
rebuild --------------------- Rebuild the target executable and restarts it. It does not work if the executable was not built by delve.
restart (alias: r) ---------- Restart process.
step (alias: s) ------------- Single step through program.
step-instruction (alias: si) Single step a single cpu instruction.
stepout (alias: so) --------- Step out of the current function.
Manipulating breakpoints:
break (alias: b) ------- Sets a breakpoint.
breakpoints (alias: bp) Print out info for active breakpoints.
clear ------------------ Deletes breakpoint.
clearall --------------- Deletes multiple breakpoints.
condition (alias: cond) Set breakpoint condition.
on --------------------- Executes a command when a breakpoint is hit.
toggle ----------------- Toggles on or off a breakpoint.
trace (alias: t) ------- Set tracepoint.
watch ------------------ Set watchpoint.
Viewing program variables and memory:
args ----------------- Print function arguments.
display -------------- Print value of an expression every time the program stops.
examinemem (alias: x) Examine raw memory at the given address.
locals --------------- Print local variables.
print (alias: p) ----- Evaluate an expression.
regs ----------------- Print contents of CPU registers.
set ------------------ Changes the value of a variable.
vars ----------------- Print package variables.
whatis --------------- Prints type of an expression.
Listing and switching between threads and goroutines:
goroutine (alias: gr) -- Shows or changes current goroutine
goroutines (alias: grs) List program goroutines.
thread (alias: tr) ----- Switch to the specified thread.
threads ---------------- Print out info for every traced thread.
Viewing the call stack and selecting frames:
deferred --------- Executes command in the context of a deferred call.
down ------------- Move the current frame down.
frame ------------ Set the current frame, or execute command on a different frame.
stack (alias: bt) Print stack trace.
up --------------- Move the current frame up.
Other commands:
config --------------------- Changes configuration parameters.
disassemble (alias: disass) Disassembler.
dump ----------------------- Creates a core dump from the current process state
edit (alias: ed) ----------- Open where you are in $DELVE_EDITOR or $EDITOR
exit (alias: quit | q) ----- Exit the debugger.
funcs ---------------------- Print list of functions.
help (alias: h) ------------ Prints the help message.
libraries ------------------ List loaded dynamic libraries
list (alias: ls | l) ------- Show source code.
source --------------------- Executes a file containing a list of delve commands
sources -------------------- Print list of source files.
transcript ----------------- Appends command output to a file.
types ---------------------- Print list of types
Type help followed by a command for full documentation.break
设置一个断点
(dlv) break main.main
Breakpoint 1 set at 0x1058eea for main.main() ./main.go:3breakpoints
查看设置的断点
(dlv) breakpoints
Breakpoint runtime-fatal-throw (enabled) at 0x102dae0 for runtime.throw() /usr/local/go/src/runtime/panic.go:1188 (0)
Breakpoint unrecovered-panic (enabled) at 0x102de40 for runtime.fatalpanic() /usr/local/go/src/runtime/panic.go:1271 (0)
print runtime.curg._panic.arg
Breakpoint 1 (enabled) at 0x1058eea for main.main() ./main.go:3 (0)vars
查看全部包级的变量。
因为最终的目标程序可能含有大量的全局变量，我们可以通过一个正则参数选择想查看的全局变量：
(dlv) vars main
runtime.main_init_done = chan bool nil
runtime.mainStarted = falsecontinue 执行下一个断点
(dlv) continue
> main.main() ./main.go:3 (hits goroutine(1):1 total:1) (PC: 0x1058eea)
1: package main
2:
=> 3: func main() {
4: slice := make([]int, 0)
5: for i := 1; i < 10; i++ {
6: slice = append(slice, i)
7: }
8: }
(dlv) next
或者 n单步执行， =>表示所运行的位置
(dlv) n
> main.main() ./main.go:5 (PC: 0x1058f0d)
1: package main
2:
3: func main() {
4: slice := make([]int, 0)
=> 5: for i := 1; i < 10; i++ {
6: slice = append(slice, i)
7: }
8: }locals
打印局部变量
(dlv) locals
slice = []int len: 2, cap: 2, [...]
i = 3break && condition
可以使用 break 和 condition组合命令，在循环内部条件断点，例如下面这个操作
(dlv) break main.go:6
Breakpoint 2 set at 0x1058f24 for main.main() ./main.go:6
(dlv) condition 2 i==7
(dlv) continue
> main.main() ./main.go:6 (hits goroutine(1):1 total:1) (PC: 0x1058f24)
1: package main
2:
3: func main() {
4: slice := make([]int, 0)
5: for i := 1; i < 10; i++ {
=> 6: slice = append(slice, i)
7: }
8: }
(dlv) locals
slice = []int len: 6, cap: 8, [...]
i = 7
(dlv) break main.go:6根据行数设置一个断点，并且在i==7时生效
condition 2 i==7 2的意思是设置断点的索引(第几个断点 根据"Breakpoint 2 set at 0x1058f24 for main.main() ./main.go:6" 可知是2)
locals 一下显示 slice = []int len: 6, cap: 8, […] i = 7
print
打印局部变量
(dlv) print slice
[]int len: 6, cap: 8, [1,2,3,4,5,6]stack
查看当前执行函数的栈帧信息：
(dlv) stack
0 0x0000000001058f24 in main.main
at ./main.go:6
1 0x00000000010300b3 in runtime.main
at /usr/local/go/src/runtime/proc.go:255
2 0x0000000001056261 in runtime.goexit
at /usr/local/go/src/runtime/asm_amd64.s:1581goroutine or goroutines
goroutine 信息
(dlv) goroutine
Thread 4125012 at ./main.go:6
Goroutine 1:
Runtime: ./main.go:6 main.main (0x1058f24)
User: ./main.go:6 main.main (0x1058f24)
Go: <autogenerated>:1 runtime.newproc (0x1058369)
Start: /usr/local/go/src/runtime/proc.go:145 runtime.main (0x102fec0)
* Goroutine 1 - User: ./main.go:6 main.main (0x1058f24) (thread 4125012)
Goroutine 2 - User: /usr/local/go/src/runtime/proc.go:367 runtime.gopark (0x10304d2) [force gc (idle)]
Goroutine 3 - User: /usr/local/go/src/runtime/proc.go:367 runtime.gopark (0x10304d2) [GC sweep wait]
Goroutine 4 - User: /usr/local/go/src/runtime/proc.go:367 runtime.gopark (0x10304d2) [GC scavenge wait]
[4 goroutines]调试服务
已知一个服务已经在运行，可以用dlv attach pid来调试 ，例如
gameserver 是一个tcp服务，监听8840端口
▶ ./gameserver -c conf/conf.json
2022-10-13 09:22:41.593 INFO engine/server.go:29 game Server is listening on:8840查看gameserver的pid
$ ps -ef | grep gameserver
501 49913 34703 0 9:22AM ttys012 0:00.03 ./gameserver -c conf/conf.jsonpid 是49913
▶ dlv attach 49913
Type 'help' for list of commands.
(dlv)至此就可以愉快的调试网络服务了，以客户端发送一个鉴权包作为了例子
例子
(dlv) break OnTraffic
Command failed: Location "OnTraffic" ambiguous: github.com/cat3306/gameserver/engine.(*Server).OnTraffic, github.com/panjf2000/gnet/v2.(*BuiltinEventEngine).OnTraffic…
(dlv) break github.com/cat3306/gameserver/engine.(*Server).OnTraffic
Breakpoint 1 set at 0x1282d2f for github.com/cat3306/gameserver/engine.(*Server).OnTraffic() /Users/joker/code/go/src/github.com/cat3306/gameserver/engine/server.go:32OnTraffic 有网络数据时回调的函数，这时候运行客户端，并且发送一个鉴权的数据包，客户端阻塞住了
dlv这边执行continue，可以看到=>指向OnTraffic,表示服务运行到这里了
(dlv) continue
> github.com/cat3306/gameserver/engine.(*Server).OnTraffic() /Users/joker/code/go/src/github.com/cat3306/gameserver/engine/server.go:32 (hits goroutine(25):1 total:1) (PC: 0x1282d2f)
Warning: debugging optimized function
27: func (s *Server) OnBoot(e gnet.Engine) (action gnet.Action) {
28: s.eng = e
29: glog.Logger.Sugar().Infof("game Server is listening on:%d", conf.GameConfig.Port)
30: return
31: }
=> 32: func (s *Server) OnTraffic(c gnet.Conn) gnet.Action {
33: defer func() {
34: err := recover()
35: if err != nil {
36: glog.Logger.Sugar().Errorf("OnTraffic panic %v", err)
37: }
(dlv) netx or n单步运行
> github.com/cat3306/gameserver/engine.(*Server).OnTraffic() /Users/joker/code/go/src/github.com/cat3306/gameserver/engine/server.go:40 (PC: 0x1282d9b)
Warning: debugging optimized function
35: if err != nil {
36: glog.Logger.Sugar().Errorf("OnTraffic panic %v", err)
37: }
38: }()
39: s.eng.CountConnections()
40: context, err := protocol.Decode(c)
=> 41: if err != nil {
42: glog.Logger.Sugar().Warnf("OnTraffic err:%s", err.Error())
43: return gnet.None
44: }
45: if context == nil {打印context
print context
(dlv) print context
*github.com/cat3306/gameserver/protocol.Context {
Payload: []uint8 len: 552, cap: 65526, [123,34,67,105,112,104,101,114,84,101,120,116,34,58,34,79,84,70,105,68,102,56,69,102,75,109,52,75,83,81,80,117,56,76,101,98,43,98,103,82,43,78,119,97,120,75,81,56,70,47,79,65,55,54,111,66,100,55,89,49,79,121,85,122,...+488 more],
CodeType: Json (2),
Proto: 2105448169,
Conn: github.com/panjf2000/gnet/v2.Conn(*github.com/panjf2000/gnet/v2.conn) *{
ctx: interface {} nil,
peer: golang.org/x/sys/unix.Sockaddr(*golang.org/x/sys/unix.SockaddrInet6) ...,
localAddr: net.Addr(*net.TCPAddr) ...,
remoteAddr: net.Addr(*net.TCPAddr) ...,
loop: *(*"github.com/panjf2000/gnet/v2.eventloop")(0xc00015acf0),
outboundBuffer: *(*"github.com/panjf2000/gnet/v2/pkg/buffer/elastic.Buffer")(0xc000242cd0),
pollAttachment: *(*"github.com/panjf2000/gnet/v2/internal/netpoll.PollAttachment")(0xc000241d10),
inboundBuffer: (*"github.com/panjf2000/gnet/v2/pkg/buffer/elastic.RingBuffer")(0xc0001b0418),
buffer: []uint8 len: 0, cap: 64974, [],
fd: 19,
isDatagram: false,
opened: true,
id: "TljczpztN",
property: map[string]string [],
propertyLock: (*sync.RWMutex)(0xc0001b0460),},
connMgr: *github.com/cat3306/gameserver/protocol.ConnManager nil,}print这个命令非常强大,可以打印具体的字段，比如
(dlv) print context.Proto
2105448169
(dlv) print context.CodeType
Json (2)
(dlv) print context.Conn.id
"TljczpztN"
(dlv) print context.Conn.remoteAddr
net.Addr(*net.TCPAddr) *{
IP: net.IP len: 16, cap: 16, [0,0,0,0,0,0,0,0,0,0,255,255,127,0,0,1],
Port: 54783,
Zone: "",}
(dlv) 设置另一个断点，然后continue进入执行handler的函数
(dlv) break ExeHandler
Breakpoint 3 set at 0x12829f2 for github.com/cat3306/gameserver/engine.(*HandlerManager).ExeHandler() /Users/joker/code/go/src/github.com/cat3306/gameserver/engine/handlermgr.go:190
(dlv) continue
> github.com/cat3306/gameserver/engine.(*HandlerManager).ExeHandler() /Users/joker/code/go/src/github.com/cat3306/gameserver/engine/handlermgr.go:190 (hits goroutine(25):1 total:1) (PC: 0x12829f2)
Warning: debugging optimized function
185: f(ctx, nil)
186: return nil
187: }
188: return HandlerNotFound
189: }
=> 190: func (h *HandlerManager) ExeHandler(auth bool, ctx *protocol.Context) {
191: err := h.exeSyncHandler(auth, ctx)
192: if !errors.Is(err, HandlerNotFound) {
193: return
194: }
195: err = h.exeAsyncHandler(auth, ctx)中间过程和前面一样，直接跳到ClientAuth 函数，这是真正执行鉴权的逻辑
(dlv) break ClientAuth
Breakpoint 4 set at 0x127c652 for github.com/cat3306/gameserver/router.(*ClientAuth).ClientAuth() /Users/joker/code/go/src/github.com/cat3306/gameserver/router/auth.go:37
(dlv) continue
> github.com/cat3306/gameserver/router.(*ClientAuth).ClientAuth() /Users/joker/code/go/src/github.com/cat3306/gameserver/router/auth.go:37 (hits goroutine(25):1 total:1) (PC: 0x127c652)
Warning: debugging optimized function
32: var req struct {
33: CipherText []byte `json:"CipherText"`
34: Text string `json:"Text"`
35: }
36:
=> 37: func (c *ClientAuth) ClientAuth(ctx *protocol.Context, v interface{}) {
38: err := ctx.Bind(&req)
39: if err != nil {
40: glog.Logger.Sugar().Errorf("param err:%s", err.Error())
41: }
42: //glog.Logger.Sugar().Errorf("req.CipherText:%s,c.rawPrivateKey:%s", req.CipherText, c.rawPrivateKey)
(dlv) 一步步运行
(dlv) n
> github.com/cat3306/gameserver/router.(*ClientAuth).ClientAuth() /Users/joker/code/go/src/github.com/cat3306/gameserver/router/auth.go:39 (PC: 0x127c68f)
Warning: debugging optimized function
34: Text string `json:"Text"`
35: }
36:
37: func (c *ClientAuth) ClientAuth(ctx *protocol.Context, v interface{}) {
38: err := ctx.Bind(&req)
=> 39: if err != nil {
40: glog.Logger.Sugar().Errorf("param err:%s", err.Error())
41: }
42: //glog.Logger.Sugar().Errorf("req.CipherText:%s,c.rawPrivateKey:%s", req.CipherText, c.rawPrivateKey)
43: text := cryptoutil.RsaDecrypt(req.CipherText, c.rawPrivateKey)
44: if string(text) != req.Text {
(dlv) ctx.Bind(&req) 是将字节流映射到结构上，类似于gin context.Bind()，打印req，会发现客户端发来两个字段
一个是被公钥加了密的密文二进制流CipherText，一个是明文Text其值为life is short
(dlv) print req
struct { CipherText []uint8 "json:\"CipherText\""; Text string "json:\"Text\"" } {
CipherText: []uint8 len: 384, cap: 384, [57,49,98,13,255,4,124,169,184,41,36,15,187,194,222,111,230,224,71,227,112,107,18,144,240,95,206,3,190,168,5,222,216,212,236,148,204,52,225,73,181,250,211,246,199,214,42,29,173,72,121,43,235,162,22,72,61,18,45,24,130,202,208,84,...+320 more],
Text: "life is short",}
(dlv) 鉴权的逻辑也很简单，服务器用自己的私钥去解客户端发过来的密文，解出来的明文和客户端发的明文一样，说明鉴权成功，如果不一样则鉴权失败
鉴权成功后，会给Conn 写一个auth 的property
> github.com/cat3306/gameserver/router.(*ClientAuth).ClientAuth() /Users/joker/code/go/src/github.com/cat3306/gameserver/router/auth.go:50 (PC: 0x127c8d0)
Warning: debugging optimized function
45: glog.Logger.Sugar().Errorf("认证失败!")
46: ctx.Send(JsonRspErr("auth failed"))
47: time.Sleep(time.Second)
48: } else {
49: ctx.Conn.SetProperty(protocol.Auth, "ok")
=> 50: ctx.Send(JsonRspOK("auth ok"))
51: }
52: }
(dlv) print ctx.Conn.property
map[string]string [
"auth": "ok",
]
(dlv) 至此，一个鉴权的全部过程都详细debug了
不得不说dlv这个调试工具非常强大