Go调用链可视化工具使用实例探究
作者:机器铃砍菜刀
本文介绍一款工具 go-callvis,它能够将 Go 代码的调用关系可视化出来,并提供了可交互式的 web 服务,在接手他人代码或调研一些开源项目时,如果能够理清其中的代码调用链路,这将加速我们对实现的理解
go-callvis 使用
依赖
- Go 1.17+
- Graphviz (可选,当工具指定了
-graphviz
时需要)
工具安装
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 } } }() } }
以上是一个简单的TCP服务端代码,通过 go-callvis 工具,可将其代码调用关系梳理出来。
$ 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 默认将代码调用关系存储成 svg 格式的图形,并会在 http://localhost:7878 服务上进行展示。
在浏览器界面上,如果点击 log 单元,将会进入 log 模块的代码调用交互图中。
使用参数
go-callvis 默认以 main 作为链路起点进行分析,因此 package 需要为 main 包。
go-callvis [flags] package
如果不想从 main 方法开始,那么需要使用 -tests 参数,并且在 yourpackage 下创建单元测试,在测试中调用你想要的起始点方法。
go-callvis -tests yourpackage
详细使用说明可通过执行 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.
每个参数都有对应的说明,无需详细介绍。
有几个比较有用的参数可以注意:nostd
用以忽略标准库的调用;group
用以对函数分类;include
、limit
、ignore
参数则用以控制过滤或保留调用关系。
总结
go-callvis 工具将 Go 程序函数调用关系通过图形可视化出来,它能帮助开发人员更好地梳理程序脉络。且 go-callvis 的使用非常简单,可以开箱即用。
之后同学们在接触复杂项目时,不妨用 go-callvis 试试看。
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