go - golang 中带有嵌入式锁的通用结构集合

Question

下面是一个嵌入另一个结构的示例。我试图弄清楚如何传递更具体的结构指针以存储在不太具体的结构指针中。您可以将其视为一个集合。包装在接口(interface)中似乎不起作用，因为这样做会制作副本，这对带锁的结构无效。想法？

package stackoverflow

import "sync"

type CoolerThingWithLock struct {
    fancyStuff string
    ThingWithLock
}

func NewCoolerThingWithLock() *CoolerThingWithLock {
    coolerThingWithLock := &CoolerThingWithLock{}
    coolerThingWithLock.InitThingWithLock()
    return coolerThingWithLock
}

type ThingWithLock struct {
    value    int
    lock     sync.Mutex
    children []*ThingWithLock
}

func (thingWithLock *ThingWithLock) InitThingWithLock() {
    thingWithLock.children = make([]*ThingWithLock, 0)
}

func NewThingWithLock() *ThingWithLock {
    newThingWithLock := &ThingWithLock{}
    newThingWithLock.InitThingWithLock()
    return newThingWithLock
}

func (thingWithLock *ThingWithLock) AddChild(newChild *ThingWithLock) {
    thingWithLock.children = append(thingWithLock.children, newChild)
}

func (thingWithLock *ThingWithLock) SetValue(newValue int) {
    thingWithLock.lock.Lock()
    defer thingWithLock.lock.Unlock()

    thingWithLock.value = newValue

    for _, child := range thingWithLock.children {
        child.SetValue(newValue)
    }
}

func main() {
    thingOne := NewThingWithLock()
    thingTwo := NewCoolerThingWithLock()
    thingOne.AddChild(thingTwo)

    thingOne.SetValue(42)
}

Error: cannot use thingTwo (type *CoolerThingWithLock) as type *ThingWithLock in argument to thingOne.AddChild

Answer 1

不可能将包装类型存储在 []*ThignWithLock 中，因为 go 没有结构子类型的概念。

您断言接口(interface)将导致复制 is incorrect ，您可以通过执行以下操作获得所需的效果:

type InterfaceOfThingThatParticipatesInAHierarchy interface {
    AddChild(InterfaceOfThingThatParticipatesInAHierarchy)
    SetValue(int)
}

type ThingWithLock struct {
    ...
    children []InterfaceOfThingThatParticipatesInAHierarchy
}

func (thingWithLock *ThingWithLock) AddChild(newChild InterfaceOfThingThatParticipatesInAHierarchy) { ... }

只要接口(interface)是在 *ThingWithLock 而不是 ThingWithLock 上实现的，就不会复制接收器结构本身，只有指向结构的指针会被复制到栈上。