Go 常用工具

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// 1. 仅下载源码
go get -d A
// 下载 A的特定版本，仅在 module-ware 模式下可用
go get -d A@version

// 2. 下载源码并编译安装
go get A

// 3. 更新依赖版本
go get -u A

// 4. 获取测试代码依赖的包
go get -t A

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// -x -v选项，go install会输出大量日志
$go install -x -v bitbucket.org/bigwhite/p

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go list  --help
usage: go list [-f format] [-json] [-m] [list flags] [build flags] [packages]
Run 'go help list' for details.

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# 1. 搜索路径
$go list
$go list ./...
$go list bitbucket.org/bigwhite/...
#  Go原生保留了几个代表特定包或包集合的路径关键字：main、all、cmd和std
#  这些保留的路径关键字不要用于Go包的构建中
$go list all
$go list std
$go list cmd

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$go list -f '{{.ImportPath}}'

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type PackagePublic struct {
    Dir           string `json:",omitempty"`  // 包含包源码的目录
    ImportPath    string `json:",omitempty"`  // dir下包的导入路径
    ImportComment string `json:",omitempty"`  // 包声明语句后面的注释中的路径
    Name          string `json:",omitempty"`  // 包名
    Doc           string `json:",omitempty"`  // 包文档字符串
    Target        string `json:",omitempty"`  // 该软件包的安装目标（可以是可执行的）
    ...

    TestGoFiles  []string `json:",omitempty"` // 包中的_test.go文件
    TestImports  []string `json:",omitempty"` // TestGoFiles导入的包
    XTestGoFiles []string `json:",omitempty"` // 包外的_test.go
    XTestImports []string `json:",omitempty"` // XTestGoFiles导入的包
}

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# 2. 输出详细信息
$go list -m    # 输出导出包的详细信息      
$go list -f '{{.ImportPath}}'
$ go list -json

# 3. 有关module的可用升级版本信息
$ go list -m -u all

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go build -gcflags[=标志应用的包范围]='空格分隔的标志选项列表'

go build -gcflags='-N -l'      # 仅将传递的编译选项应用于当前包
go build -gcflags=all='-N -l'  # 将传递的编译选项应用于当前包及其所有依赖包
go build -gcflags=std='-N -l'  # 仅将传递的编译选项应用于标准库包

# 一些选项还具有级别属性，即支持设定选项的作用级别或输出信息内容的详尽级别
go build -gcflags='-m'
go build -gcflags='-m -m'      // 输出比上一条命令更为详尽的逃逸分析过程信息
go build -gcflags='-m=2'       // 与上一条命令等价
go build -gcflags='-m -m -m'   // 输出最为详尽的逃逸分析过程信息
go build -gcflags='-m=3'       // 与上一条命令等价

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$ go tool compile -help
usage: compile [options] file.go...
  -% int
    	debug non-static initializers
  -+	compiling runtime
  -B	disable bounds checking
  -C	disable printing of columns in error messages
  -D path
    	set relative path for local imports
  -E	debug symbol export
  -G	accept generic code (default 3)
  -I directory
    	add directory to import search path
  -K	debug missing line numbers
  -L	show full file names in error messages
  -N	disable optimizations
  -S	print assembly listing
  -V	print version and exit
  -W	debug parse tree after type checking
  -asan
    	build code compatible with C/C++ address sanitizer
  -asmhdr file
    	write assembly header to file
  -bench file
    	append benchmark times to file
  -blockprofile file
    	write block profile to file
  -buildid id
    	record id as the build id in the export metadata
  -c int
    	concurrency during compilation (1 means no concurrency) (default 1)
  -clobberdead
    	clobber dead stack slots (for debugging)
  -clobberdeadreg
    	clobber dead registers (for debugging)
  -complete
    	compiling complete package (no C or assembly)
  -cpuprofile file
    	write cpu profile to file
  -d value
    	enable debugging settings; try -d help
  -dwarf
    	generate DWARF symbols (default true)
  -dwarfbasentries
    	use base address selection entries in DWARF (default true)
  -dwarflocationlists
    	add location lists to DWARF in optimized mode (default true)
  -dynlink
    	support references to Go symbols defined in other shared libraries
  -e	no limit on number of errors reported
  -embedcfg file
    	read go:embed configuration from file
  -gendwarfinl int
    	generate DWARF inline info records (default 2)
  -goversion string
    	required version of the runtime
  -h	halt on error
  -importcfg file
    	read import configuration from file
  -importmap definition
    	add definition of the form source=actual to import map
  -installsuffix suffix
    	set pkg directory suffix
  -j	debug runtime-initialized variables
  -json string
    	version,file for JSON compiler/optimizer detail output
  -l	disable inlining
  -lang string
    	Go language version source code expects
  -linkobj file
    	write linker-specific object to file
  -linkshared
    	generate code that will be linked against Go shared libraries
  -live
    	debug liveness analysis
  -m	print optimization decisions
  -memprofile file
    	write memory profile to file
  -memprofilerate rate
    	set runtime.MemProfileRate to rate
  -msan
    	build code compatible with C/C++ memory sanitizer
  -mutexprofile file
    	write mutex profile to file
  -nolocalimports
    	reject local (relative) imports
  -o file
    	write output to file
  -p path
    	set expected package import path
  -pack
    	write to file.a instead of file.o
  -r	debug generated wrappers
  -race
    	enable race detector
  -shared
    	generate code that can be linked into a shared library
  -smallframes
    	reduce the size limit for stack allocated objects
  -spectre list
    	enable spectre mitigations in list (all, index, ret)
  -std
    	compiling standard library
  -symabis file
    	read symbol ABIs from file
  -t	enable tracing for debugging the compiler
  -traceprofile file
    	write an execution trace to file
  -trimpath prefix
    	remove prefix from recorded source file paths
  -v	increase debug verbosity
  -w	debug type checking
  -wb
    	enable write barrier (default true)

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go build -ldflags='空格分隔的标志选项列表'
go build -ldflags "-X main.version=v0.7.0 -s -w" -o linker_x_flag_without_symboltable_and_dwarf linker_x_flag.go

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$go version
go version go1.14 darwin/amd64

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var (
    version string
)

func main() {
    if os.Args[1] == "version" {
        fmt.Println("version:", version)
        return
    }
}

// 构建这个程序，在构建时为version这个string类型变量动态地注入新值：
$go build -ldflags "-X main.version=v0.7.0" linker_x_flag.go
$./linker_x_flag version
version: v0.7.0

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$ go tool link -help
usage: link [options] main.o
  -B note
    	add an ELF NT_GNU_BUILD_ID note when using ELF
  -E entry
    	set entry symbol name
  -H type
    	set header type
  -I linker
    	use linker as ELF dynamic linker
  -L directory
    	add specified directory to library path
  -R quantum
    	set address rounding quantum (default -1)
  -T address
    	set text segment address (default -1)
  -V	print version and exit
  -X definition
    	add string value definition of the form importpath.name=value
  -a	no-op (deprecated)
  -asan
    	enable ASan interface
  -aslr
    	enable ASLR for buildmode=c-shared on windows (default true)
  -benchmark string
    	set to 'mem' or 'cpu' to enable phase benchmarking
  -benchmarkprofile base
    	emit phase profiles to base_phase.{cpu,mem}prof
  -buildid id
    	record id as Go toolchain build id
  -buildmode mode
    	set build mode
  -c	dump call graph
  -compressdwarf
    	compress DWARF if possible (default true)
  -cpuprofile file
    	write cpu profile to file
  -d	disable dynamic executable
  -debugtextsize int
    	debug text section max size
  -debugtramp int
    	debug trampolines
  -dumpdep
    	dump symbol dependency graph
  -extar string
    	archive program for buildmode=c-archive
  -extld linker
    	use linker when linking in external mode
  -extldflags flags
    	pass flags to external linker
  -f	ignore version mismatch
  -g	disable go package data checks
  -h	halt on error
  -importcfg file
    	read import configuration from file
  -installsuffix suffix
    	set package directory suffix
  -k symbol
    	set field tracking symbol
  -libgcc string
    	compiler support lib for internal linking; use "none" to disable
  -linkmode mode
    	set link mode
  -linkshared
    	link against installed Go shared libraries
  -memprofile file
    	write memory profile to file
  -memprofilerate rate
    	set runtime.MemProfileRate to rate
  -msan
    	enable MSan interface
  -n	dump symbol table
  -o file
    	write output to file
  -pluginpath string
    	full path name for plugin
  -r path
    	set the ELF dynamic linker search path to dir1:dir2:...
  -race
    	enable race detector
  -s	disable symbol table
  -strictdups int
    	sanity check duplicate symbol contents during object file reading (1=warn 2=err).
  -tmpdir directory
    	use directory for temporary files
  -v	print link trace
  -w	disable DWARF generation

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$go build -tags="tag1,tag2,..." ...

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// +build aix darwin dragonfly freebsd js,wasm linux netbsd openbsd solaris

package os

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$go build -o gctrace gctrace.go
$GODEBUG='gctrace=1' GOGC=100 ./gctrace
gc 1 @0.008s 3%: 0.005+2.7+0.017 ms clock, 0.042+0.056/3.6/3.7+0.14 ms cpu, 5->5->4 MB, 6 MB goal, 8 P
gc 2 @0.028s 5%: 0.007+8.4+0.024 ms clock, 0.057+0.074/11/11+0.19 ms cpu, 9->9->8 MB, 10 MB goal, 8 P
gc 3 @0.067s 5%: 0.005+14+0.023 ms clock, 0.040+0.38/19/18+0.18 ms cpu, 19->19->16 MB, 20 MB goal, 8 P
gc 4 @0.141s 6%: 0.011+25+0.021 ms clock, 0.093+0.26/46/82+0.17 ms cpu, 38->38->33 MB, 39 MB goal, 8 P
gc 5 @0.256s 6%: 0.003+34+0.016 ms clock, 0.031+0.40/67/61+0.13 ms cpu, 77->77->66 MB, 78 MB goal, 8 P
gc 6 @0.448s 6%: 0.004+58+0.017 ms clock, 0.033+0.49/113/185+0.14 ms cpu, 154->154->133 MB, 155 MB goal, 8 P
gc 7 @0.868s 6%: 0.004+116+0.017 ms clock, 0.032+0.64/231/574+0.13 ms cpu, 307->308->266 MB, 308 MB goal, 8 P
gc 8 @1.793s 7%: 0.003+368+0.016 ms clock, 0.025+0.95/734/1812+0.13 ms cpu, 615->616->533 MB, 616 MB goal, 8 P
gc 9 @3.715s 7%: 0.003+692+0.021 ms clock, 0.028+34/1384/3436+0.17 ms cpu, 1231->1232->1066 MB, 1232 MB goal, 8 P

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$ GODEBUG=schedtrace=1000 godoc -http=:6060
SCHED 0ms: gomaxprocs=4 idleprocs=3 threads=3 spinningthreads=0 idlethreads=0 runqueue=0 [0 0 0 0]
SCHED 1001ms: gomaxprocs=4 idleprocs=0 threads=9 spinningthreads=0 idlethreads=3 runqueue=2 [8 14 5 2]
SCHED 2006ms: gomaxprocs=4 idleprocs=0 threads=25 spinningthreads=0 idlethreads=19 runqueue=12 [0 0 4 0]
SCHED 3006ms: gomaxprocs=4 idleprocs=0 threads=26 spinningthreads=0 idlethreads=8 runqueue=2 [0 1 1 0]
SCHED 4010ms: gomaxprocs=4 idleprocs=0 threads=26 spinningthreads=0 idlethreads=20 runqueue=12 [6 3 1 0]

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$ GODEBUG=schedtrace=1000,scheddetail=1 godoc -http=:6060

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func deadloop() {
    for {
    }
}

func main() {
    runtime.GOMAXPROCS(1)
    go deadloop()
    for {
        time.Sleep(time.Second * 1)
        fmt.Println("I got scheduled!")
    }
}

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$GODEBUG=asyncpreemptoff=1 go run preemption_scheduler.go // 这里不会输出I got scheduled!

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# go tool vet help
vet is a tool for static analysis of Go programs.

vet examines Go source code and reports suspicious constructs,
such as Printf calls whose arguments do not align with the format
string. It uses heuristics that do not guarantee all reports are
genuine problems, but it can find errors not caught by the compilers.

Registered analyzers:

    asmdecl      report mismatches between assembly files and Go declarations
    assign       check for useless assignments
    atomic       check for common mistakes using the sync/atomic package
    bools        check for common mistakes involving boolean operators
    buildtag     check that +build tags are well-formed and correctly located
    cgocall      detect some violations of the cgo pointer passing rules
    composites   check for unkeyed composite literals
    copylocks    check for locks erroneously passed by value
    errorsas     report passing non-pointer or non-error values to errors.As
    framepointer report assembly that clobbers the frame pointer before saving it
    httpresponse check for mistakes using HTTP responses
    ifaceassert  detect impossible interface-to-interface type assertions
    loopclosure  check references to loop variables from within nested functions
    lostcancel   check cancel func returned by context.WithCancel is called
    nilfunc      check for useless comparisons between functions and nil
    printf       check consistency of Printf format strings and arguments
    shift        check for shifts that equal or exceed the width of the integer
    sigchanyzer  check for unbuffered channel of os.Signal
    stdmethods   check signature of methods of well-known interfaces
    stringintconv check for string(int) conversions
    structtag    check that struct field tags conform to reflect.StructTag.Get
    testinggoroutine report calls to (*testing.T).Fatal from goroutines started by a test.
    tests        check for common mistaken usages of tests and examples
    unmarshal    report passing non-pointer or non-interface values to unmarshal
    unreachable  check for unreachable code
    unsafeptr    check for invalid conversions of uintptr to unsafe.Pointer
    unusedresult check for unused results of calls to some functions

# 手动关闭其中一个或几个规则
$go vet -printf=false -buildtag=false vet_printf.go

# 如果显式开启某些检查，则其他检查规则将不生效
# 仅开启 buildtag 检查，其他检查均不开启
$go vet -buildtag=true vet_printf.go

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# 1. 安装
go install  github.com/golangci/golangci-lint/cmd/golangci-lint@latest

# 2. 开启或关闭特定检查
# 仅开启staticcheck
$golangci-lint linters --disable-all -E staticcheck

# 在默认开启的lint工具集合的基础上，再额外开启bodyclose和dupl
$golangci-lint linters -E bodyclose,dupl 

# 关闭unused和varcheck
$golangci-lint linters -D unused,varcheck

# 3. 执行检查
# 仅对当前目录下的vet_assign.go源文件进行staticcheck检查
$golangci-lint run --disable-all -E staticcheck vet_assign.go

# 对当前路径下的Go包进行默认lint工具集合的检查
$golangci-lint run

# 对当前路径及其子路径（递归）下的所有Go包进行默认开启的lint工具集合检查以及额外的dupl工具检查
$golangci-lint run -E dupl ./...

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go doc <pkg>
go doc <sym>[.<methodOrField>]
go doc [<pkg>.]<sym>[.<methodOrField>]
go doc [<pkg>.][<sym>.]<methodOrField>

// 查看标准库文档
go doc net/http
go doc net/http.Request.Form

// 查看当前路径下的包的文档：
$go doc
// 查看当前路径下包的导出元素的文档：
$go doc CmppActiveTestReqPktLen
// 通过-u选项，我们也可以查看当前路径下包的非导出元素的文档：
$go doc -u newPacketWriter

// 查看源码
go doc -src fmt.Printf

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// 查看当前版本文档
$godoc -http=localhost:6060

// 查看旧版本 go 文档
$godoc -goroot /Users/tonybai/.bin/go1.9 -http=localhost:6060

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$go get golang.org/x/blog

// Go官方博客单独存放在github.com/golang/blog仓库下，需要先将该仓库下载到本地，再切换到该路径下来启动blog服务程序
$git clone https://github.com/golang/blog.git
$cd blog
$blog

2020/10/31 05:14:47 Listening on addr localhost:8080

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go get golang.org/x/tools/cmd/present
$git clone https://github.com/golang/talks.git
$cd talks
$present