ch3.8: 增加例子代码

examples/ch3.8/ch3.8-1/main.go

@@ -0,0 +1,5 @@
+package main
+
+func main() {
+	panic("goid")
+}

examples/ch3.8/ch3.8-2/main.go

@@ -0,0 +1,9 @@
+package main
+
+import "runtime"
+
+func main() {
+	var buf = make([]byte, 64)
+	var stk = buf[:runtime.Stack(buf, false)]
+	println(string(stk))
+}

examples/ch3.8/ch3.8-3/main.go

@@ -0,0 +1,34 @@
+package main
+
+import (
+	"fmt"
+	"runtime"
+	"strconv"
+	"strings"
+	"time"
+)
+
+func main() {
+	println("a:", GetGoid())
+	go func() {
+		println("b:", GetGoid())
+	}()
+
+	time.Sleep(time.Second)
+}
+
+func GetGoid() int64 {
+	var (
+		buf [64]byte
+		n   = runtime.Stack(buf[:], false)
+		stk = strings.TrimPrefix(string(buf[:n]), "goroutine ")
+	)
+
+	idField := strings.Fields(stk)[0]
+	id, err := strconv.Atoi(idField)
+	if err != nil {
+		panic(fmt.Errorf("can not get goroutine id: %v", err))
+	}
+
+	return int64(id)
+}

examples/ch3.8/ch3.8-4/main.go

@@ -0,0 +1,19 @@
+package main
+
+import (
+	"unsafe"
+)
+
+func getg() unsafe.Pointer
+
+const g_goid_offset = 152 // Go1.8/Go1.9/Go1.10/Go1.11/Go1.12/Go1.13
+
+func GetGroutineId() int64 {
+	g := getg()
+	p := (*int64)(unsafe.Pointer(uintptr(g) + g_goid_offset))
+	return *p
+}
+
+func main() {
+	println(GetGroutineId())
+}

examples/ch3.8/ch3.8-4/main_amd64.s

@@ -0,0 +1,7 @@
+#include "textflag.h"
+
+// func getg() unsafe.Pointer
+TEXT ·getg(SB), NOSPLIT, $0-8
+	MOVQ (TLS), AX
+	MOVQ AX, ret+0(FP)
+	RET

examples/ch3.8/ch3.8-5/main.go

@@ -0,0 +1,34 @@
+package main
+
+import (
+	"reflect"
+	"time"
+)
+
+func getg() interface{}
+
+type eface struct {
+	_type, elem uintptr
+}
+
+//go:nosplit
+func runtime_convT2E_hack(_type, elem uintptr) eface {
+	return eface{
+		_type: _type,
+		elem:  elem,
+	}
+}
+
+func GetGoid() int64 {
+	g := getg()
+	goid := reflect.ValueOf(g).FieldByName("goid").Int()
+	return goid
+}
+func main() {
+	println("a:", GetGoid())
+	go func() {
+		println("b:", GetGoid())
+	}()
+
+	time.Sleep(time.Second)
+}

examples/ch3.8/ch3.8-5/main_amd64.s

@@ -0,0 +1,20 @@
+#include "textflag.h"
+
+// func getg() interface{}
+TEXT ·getg(SB), NOSPLIT, $32-16
+	// get runtime.g
+	MOVQ (TLS), AX
+	// get runtime.g type
+	MOVQ $type·runtime·g(SB), BX
+
+	// convert (*g) to interface{}
+	MOVQ AX, 8(SP)
+	MOVQ BX, 0(SP)
+	CALL ·runtime_convT2E_hack(SB)
+	MOVQ 16(SP), AX
+	MOVQ 24(SP), BX
+
+	// return interface{}
+	MOVQ AX, ret+0(FP)
+	MOVQ BX, ret+8(FP)
+	RET

examples/ch3.8/ch3.8-6/gls/gls.go

@@ -0,0 +1,43 @@
+package gls
+
+import "sync"
+
+var gls struct {
+	m map[int64]map[interface{}]interface{}
+	sync.Mutex
+}
+
+func init() {
+	gls.m = make(map[int64]map[interface{}]interface{})
+}
+
+func getMap() map[interface{}]interface{} {
+	gls.Lock()
+	defer gls.Unlock()
+
+	goid := GetGoid()
+	if m, _ := gls.m[goid]; m != nil {
+		return m
+	}
+
+	m := make(map[interface{}]interface{})
+	gls.m[goid] = m
+	return m
+}
+
+func Get(key interface{}) interface{} {
+	return getMap()[key]
+}
+func Put(key interface{}, v interface{}) {
+	getMap()[key] = v
+}
+func Delete(key interface{}) {
+	delete(getMap(), key)
+}
+
+func Clean() {
+	gls.Lock()
+	defer gls.Unlock()
+
+	delete(gls.m, GetGoid())
+}

examples/ch3.8/ch3.8-6/gls/goid.go

@@ -0,0 +1,25 @@
+package gls
+
+import (
+	"reflect"
+)
+
+func getg() interface{}
+
+type eface struct {
+	_type, elem uintptr
+}
+
+//go:nosplit
+func runtime_convT2E_hack(_type, elem uintptr) eface {
+	return eface{
+		_type: _type,
+		elem:  elem,
+	}
+}
+
+func GetGoid() int64 {
+	g := getg()
+	goid := reflect.ValueOf(g).FieldByName("goid").Int()
+	return goid
+}

examples/ch3.8/ch3.8-6/gls/goid_amd64.s

@@ -0,0 +1,20 @@
+#include "textflag.h"
+
+// func getg() interface{}
+TEXT ·getg(SB), NOSPLIT, $32-16
+	// get runtime.g
+	MOVQ (TLS), AX
+	// get runtime.g type
+	MOVQ $type·runtime·g(SB), BX
+
+	// convert (*g) to interface{}
+	MOVQ AX, 8(SP)
+	MOVQ BX, 0(SP)
+	CALL ·runtime_convT2E_hack(SB)
+	MOVQ 16(SP), AX
+	MOVQ 24(SP), BX
+
+	// return interface{}
+	MOVQ AX, ret+0(FP)
+	MOVQ BX, ret+8(FP)
+	RET

examples/ch3.8/ch3.8-6/go.mod

@@ -0,0 +1,3 @@
+module gobook/ch3.8-6
+
+go 1.13

examples/ch3.8/ch3.8-6/main.go

@@ -0,0 +1,25 @@
+package main
+
+import (
+	"fmt"
+	"sync"
+
+	"gobook/ch3.8-6/gls"
+)
+
+func main() {
+	var wg sync.WaitGroup
+	for i := 0; i < 5; i++ {
+		wg.Add(1)
+		go func(idx int) {
+			defer wg.Done()
+			defer gls.Clean()
+
+			defer func() {
+				fmt.Printf("%d: number = %d\n", idx, gls.Get("number"))
+			}()
+			gls.Put("number", idx+100)
+		}(i)
+	}
+	wg.Wait()
+}