4 posts tagged with "golang"

func Main(archInit func(*Arch)) {
    	lines := parseFiles(flag.Args())  // lex and parse
        ...
        	typecheckok = true

	// Process top-level declarations in phases.

	// Phase 1: const, type, and names and types of funcs.
	//   This will gather all the information about types
	//   and methods but doesn't depend on any of it.
	//
	//   We also defer type alias declarations until phase 2
	//   to avoid cycles like #18640.
	//   TODO(gri) Remove this again once we have a fix for #25838.

	// Don't use range--typecheck can add closures to xtop.
	timings.Start("fe", "typecheck", "top1")
	for i := 0; i < len(xtop); i++ {
		n := xtop[i]
		if op := n.Op; op != ODCL && op != OAS && op != OAS2 && (op != ODCLTYPE || !n.Left.Name.Param.Alias) {
			xtop[i] = typecheck(n, ctxStmt)
		}
	}

	// Phase 2: Variable assignments.
	//   To check interface assignments, depends on phase 1.

	// Don't use range--typecheck can add closures to xtop.
	timings.Start("fe", "typecheck", "top2")
	for i := 0; i < len(xtop); i++ {
		n := xtop[i]
		if op := n.Op; op == ODCL || op == OAS || op == OAS2 || op == ODCLTYPE && n.Left.Name.Param.Alias {
			xtop[i] = typecheck(n, ctxStmt)
		}
	}

	// Phase 3: Type check function bodies.
	// Don't use range--typecheck can add closures to xtop.
	timings.Start("fe", "typecheck", "func")
	var fcount int64
	for i := 0; i < len(xtop); i++ {
		n := xtop[i]
		if op := n.Op; op == ODCLFUNC || op == OCLOSURE {
			Curfn = n
			decldepth = 1
			saveerrors()
			typecheckslice(Curfn.Nbody.Slice(), ctxStmt)
			checkreturn(Curfn)
			if nerrors != 0 {
				Curfn.Nbody.Set(nil) // type errors; do not compile
			}
			// Now that we've checked whether n terminates,
			// we can eliminate some obviously dead code.
			deadcode(Curfn)
			fcount++
		}
	}
	// With all types checked, it's now safe to verify map keys. One single
	// check past phase 9 isn't sufficient, as we may exit with other errors
	// before then, thus skipping map key errors.
}

(gdb) bt
#0  cmd/go/internal/load.LoadImport (path=..., srcDir=..., parent=0xc000147200, stk=0xc0001db698, importPos=..., mode=1, ~r6=<optimized out>) at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:530
#1  0x000000000079fa1b in cmd/go/internal/load.(*Package).load (p=0xc000147200, stk=0xc0001db698, bp=0xc0001b8a80, err=...) at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:1707
#2  0x0000000000799827 in cmd/go/internal/load.loadImport (pre=0x0, path=..., srcDir=..., parent=0xc000146d80, stk=0xc0001db698, importPos=..., mode=1, ~r7=<optimized out>)
    at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:578
#3  0x000000000079890a in cmd/go/internal/load.LoadImport (path=..., srcDir=..., parent=0xc000146d80, stk=0xc0001db698, importPos=..., mode=1, ~r6=<optimized out>) at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:531
#4  0x000000000079fa1b in cmd/go/internal/load.(*Package).load (p=0xc000146d80, stk=0xc0001db698, bp=0xc0001b8700, err=...) at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:1707
#5  0x0000000000799827 in cmd/go/internal/load.loadImport (pre=0x0, path=..., srcDir=..., parent=0xc000146900, stk=0xc0001db698, importPos=..., mode=1, ~r7=<optimized out>)
    at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:578
#6  0x000000000079890a in cmd/go/internal/load.LoadImport (path=..., srcDir=..., parent=0xc000146900, stk=0xc0001cf698, importPos=..., mode=1, ~r6=<optimized out>) at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:531
#7  0x000000000079fa1b in cmd/go/internal/load.(*Package).load (p=0xc000146900, stk=0xc0001db698, bp=0xc0001b8380, err=...) at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:1707
#8  0x00000000007a4c66 in cmd/go/internal/load.GoFilesPackage (gofiles=..., ~r1=<optimized out>) at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:2230
#9  0x00000000007a3c54 in cmd/go/internal/load.PackagesAndErrors (patterns=..., ~r1=...) at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:2056
#10 0x00000000007a417d in cmd/go/internal/load.PackagesForBuild (args=..., ~r1=...) at /home/dinosaur/newgo/go/src/cmd/go/internal/load/pkg.go:2123
#11 0x0000000000842528 in cmd/go/internal/work.runBuild (cmd=<optimized out>, args=...) at /home/dinosaur/newgo/go/src/cmd/go/internal/work/build.go:348
#12 0x0000000000932219 in main.main () at /home/dinosaur/newgo/go/src/cmd/go/main.go:189

Interface values are comparable. Two interface values are equal if they have identical dynamic types and equal dynamic values or if both have value nil.
A value x of non-interface type X and a value t of interface type T are comparable when values of type X are comparable and X implements T. They are equal if t's dynamic type is identical to X and t's dynamic value is equal to x.

A comparison of two interface values with identical dynamic types causes a run-time panic if values of that type are not comparable. This behavior applies not only to direct interface value comparisons but also when comparing arrays of interface values or structs with interface-valued fields.

// In Go 1.13, the ed25519 package was promoted to the standard library as
// crypto/ed25519, and this package became a wrapper for the standard library one.
//
// +build !go1.13

func lockFile(){
    name := "lockfiletest.lock"
    file, err := os.OpenFile(name, syscall.O_CREAT|syscall.O_RDWR|syscall.O_CLOEXEC, 0666)  //①打开文件
   　...
    err = syscall.FcntlFlock(file.Fd(), syscall.F_SETLK, &flockT)　　//②加锁
    ...
}
func main(){
    err :=lockFile()
    if err!=nil{
        os.Exit(2)  // ③加锁失败退出
    }
}

package main

import (
	"os"
	"log"
	"time"
	"runtime"
)

func openFile(path string) error {
	_, err := os.Open(path)
	return err
}

func main() {
	if err := openFile(os.Args[1]); err != nil {
		log.Fatal(err)
	}
	// trigger GC below will also recycle the non-referenced fd opened before
	runtime.GC()
	time.Sleep(time.Hour)
}

## 8808 就是我的nginx　的master 的pid
ll /proc/8808/fd/
total 0
dr-x------ 2 root root  0 8月  10 06:16 ./
dr-xr-xr-x 9 root root  0 8月   9 07:35 ../
lrwx------ 1 root root 64 8月  10 06:16 0 -> /dev/null
lrwx------ 1 root root 64 8月  10 06:16 1 -> /dev/null
l-wx------ 1 root root 64 8月  10 06:16 2 -> /usr/local/nginx/logs/error.log*
lrwx------ 1 root root 64 8月  10 06:16 3 -> socket:[78178946]
l-wx------ 1 root root 64 8月  10 06:16 4 -> /usr/local/nginx/logs/access.log*
l-wx------ 1 root root 64 8月  10 06:16 5 -> /usr/local/nginx/logs/error.log*
lrwx------ 1 root root 64 8月  10 06:16 6 -> socket:[78180730]
lrwx------ 1 root root 64 8月  10 06:16 7 -> socket:[78178947]

var file *File  // 加了一行变成全局变量
func lockFile(){
    name := "lockfiletest.lock"
    file, err := os.OpenFile(name, syscall.O_CREAT|syscall.O_RDWR|syscall.O_CLOEXEC, 0666)  //①打开文件
   　...
    err = syscall.FcntlFlock(file.Fd(), syscall.F_SETLK, &flockT)　　//②加锁
    ...
}