一款好用的 Go 調用鏈可視化工具
作者：機器鈴砍菜刀
go-callvis 工具將 Go 程序函數調用關系通過圖形可視化出來，它能幫助開發人員更好地梳理程序脈絡。且 go-callvis 的使用非常簡單，可以開箱即用。
在接手他人代碼或調研一些開源項目時，如果能夠理清其中的代碼調用鏈路，這將加速我們對實現的理解。
本文介紹一款工具 go-callvis，它能夠將 Go 代碼的調用關系可視化出來，并提供了可交互式的 web 服務。
go-callvis 使用
依賴
- Go 1.17+
- Graphviz (可選，當工具指定了 ?
?-graphviz?? 時需要)
工具安裝
go get -u github.com/ofabry/go-callvis
# or
git clone https://github.com/ofabry/go-callvis.git
cd go-callvis && make install
示例
package main
import (
func main() {
// Part 1: create a listener
l, err := net.Listen("tcp", ":8000")
if err != nil {
log.Fatalf("Error listener returned: %s", err)
}
defer l.Close()
for {
// Part 2: accept new connection
c, err := l.Accept()
if err != nil {
log.Fatalf("Error to accept new connection: %s", err)
}
// Part 3: create a goroutine that reads and write back data
go func() {
log.Printf("TCP session open")
defer c.Close()
for {
d := make([]byte, 1024)
// Read from TCP buffer
_, err := c.Read(d)
if err != nil {
log.Printf("Error reading TCP session: %s", err)
break
}
log.Printf("reading data from client: %s\n", string(d))
// write back data to TCP client
_, err = c.Write(d)
if err != nil {
log.Printf("Error writing TCP session: %s", err)
break
}
}
}()
}
}
以上是一個簡單的TCP服務端代碼，通過 go-callvis 工具，可將其代碼調用關系梳理出來。
$ go-callvis main.go
2022/08/14 21:23:03 http serving at http://localhost:7878
2022/08/14 21:23:03 converting dot to svg..
2022/08/14 21:23:03 serving file: /var/folders/xk/gn46n46d503dsztbc6_9qb2h0000gn/T/go-callvis_export.svg
go-callvis 默認將代碼調用關系存儲成 svg 格式的圖形，并會在 http://localhost:7878 服務上進行展示。
在?瀏覽器界面上，如果點擊 log 單元，將會進入 log 模塊的代碼調用交互圖中。
使用參數
go-callvis 默認以 main 作為鏈路起點進行分析，因此 package 需要為 main 包。
go-callvis [flags] package
如果不想從 main 方法開始，那么需要使用 -tests 參數，并且在 yourpackage 下創建單元測試，在測試中調用你想要的起始點方法。
go-callvis -tests yourpackage
詳細使用說明可通過執行 go-callvis 命令查看
$ go-callvis
go-callvis: visualize call graph of a Go program.
Usage:
go-callvis [flags] package
Package should be main package, otherwise -tests flag must be used.
Flags:
-algo string
The algorithm used to construct the call graph. Possible values inlcude: "static", "cha", "rta", "pointer" (default "pointer")
-cacheDir string
Enable caching to avoid unnecessary re-rendering, you can force rendering by adding 'refresh=true' to the URL query or emptying the cache directory
-debug
Enable verbose log.
-file string
output filename - omit to use server mode
-focus string
Focus specific package using name or import path. (default "main")
-format string
output file format [svg | png | jpg | ...] (default "svg")
-graphviz
Use Graphviz's dot program to render images.
-group string
Grouping functions by packages and/or types [pkg, type] (separated by comma) (default "pkg")
-http string
HTTP service address. (default ":7878")
-ignore string
Ignore package paths containing given prefixes (separated by comma)
-include string
Include package paths with given prefixes (separated by comma)
-limit string
Limit package paths to given prefixes (separated by comma)
-minlen uint
Minimum edge length (for wider output). (default 2)
-nodesep float
Minimum space between two adjacent nodes in the same rank (for taller output). (default 0.35)
-nodeshape string
graph node shape (see graphvis manpage for valid values) (default "box")
-nodestyle string
graph node style (see graphvis manpage for valid values) (default "filled,rounded")
-nointer
Omit calls to unexported functions.
-nostd
Omit calls to/from packages in standard library.
-rankdir string
Direction of graph layout [LR | RL | TB | BT] (default "LR")
-skipbrowser
Skip opening browser.
-tags build tags
a list of build tags to consider satisfied during the build. For more information about build tags, see the description of build constraints in the documentation for the go/build package
-tests
Include test code.
-version
Show version and exit.
[slp@slpdeMacBook-Pro:] ~/repo/MongoShake/cmd/collector $ go-callvis --help
Usage of go-callvis:
-algo string
The algorithm used to construct the call graph. Possible values inlcude: "static", "cha", "rta", "pointer" (default "pointer")
-cacheDir string
Enable caching to avoid unnecessary re-rendering, you can force rendering by adding 'refresh=true' to the URL query or emptying the cache directory
-debug
Enable verbose log.
-file string
output filename - omit to use server mode
-focus string
Focus specific package using name or import path. (default "main")
-format string
output file format [svg | png | jpg | ...] (default "svg")
-graphviz
Use Graphviz's dot program to render images.
-group string
Grouping functions by packages and/or types [pkg, type] (separated by comma) (default "pkg")
-http string
HTTP service address. (default ":7878")
-ignore string
Ignore package paths containing given prefixes (separated by comma)
-include string
Include package paths with given prefixes (separated by comma)
-limit string
Limit package paths to given prefixes (separated by comma)
-minlen uint
Minimum edge length (for wider output). (default 2)
-nodesep float
Minimum space between two adjacent nodes in the same rank (for taller output). (default 0.35)
-nodeshape string
graph node shape (see graphvis manpage for valid values) (default "box")
-nodestyle string
graph node style (see graphvis manpage for valid values) (default "filled,rounded")
-nointer
Omit calls to unexported functions.
-nostd
Omit calls to/from packages in standard library.
-rankdir string
Direction of graph layout [LR | RL | TB | BT] (default "LR")
-skipbrowser
Skip opening browser.
-tags build tags
a list of build tags to consider satisfied during the build. For more information about build tags, see the description of build constraints in the documentation for the go/build package
-tests
Include test code.
-version
Show version and exit.
每個參數都有對應的說明，無需詳細介紹。
有幾個比較有用的參數可以注意：nostd?用以忽略標準庫的調用；group?用以對函數分類；include?、limit?、ignore參數則用以控制過濾或保留調用關系。
總結
go-callvis 工具將 Go 程序函數調用關系通過圖形可視化出來，它能幫助開發人員更好地梳理程序脈絡。且 go-callvis 的使用非常簡單，可以開箱即用。
之后同學們在接觸復雜項目時，不妨用 go-callvis 試試看。?
責任編輯：武曉燕
來源：
Golang技術分享
