Golang结构体知识

对golang稍微熟悉的兄弟姐妹们就不用看了！

在看Docker源码时，碰到了这个语句：

container.Lock()

看到上面直接对struct Container进行上锁时，我翻了一下这个结构体，发现没有定义任何锁啊，怎么上锁的咧。于是我就翻了一下这个结构
体的一些子属性，发现了State的定义

// container/container.gotype Container struct {    StreamConfig *stream.Config    //   for Container to support states directly.    *State          `json:"State"`          // Needed for Engine API version <= 1.11    Root            string                  `json:"-"` // Path to the "home" of the container, including  data.     FS          containerfs.ContainerFS `json:"-"` // interface containing graphdriver mount    RW           .RW            `json:"-"`    ....   }// container/state.gotype State struct {    sync.Mutex    // Note that `Running` and `Paused` are not mutually exclusive:    // When pausing a container (on Linux), the cgroups freezer is used to suspend    // all processes in the container. Freezing the process requires the process to    // be running. As a result, paused containers are both `Running` _and_ `Paused`.    Running           bool    Paused            bool    Restarting        bool    OOMKilled         bool    RemovalInProgress bool // Not need for this to be persistent on disk.    Dead              bool    Pid               int    ExitCodeValue     int    `json:"ExitCode"`    ErrorMsg          string `json:"Error"` // contains last known error during container start, stop, or remove    StartedAt         time.Time    FinishedAt        time.Time    Health            *Health    waitStop   chan struct{}    waitRemove chan struct{}}

当时看到这我就纳闷了(go没学过，没写过，完全新手)，咋就直接访问到State里面的内容了。
看到没，Container结构体里面定义了*State之后，就可以直接访问State里面的成员，这有点类似继承啥玩意的。接下来我们就做个测试，可以瞅瞅。

package mainimport (    "fmt"    "sync")type State struct {    sync.Mutex    Running bool    Paused bool}type Container struct {    *State    ID string}func NewState() *State {    return &State{        Running: false,        Paused: false,    }}func (c *Container) getInfo() error {    c.Lock()    defer c.Unlock()  // defer 可以另写一篇文章说一下    fmt.Println("container is locked")    return nil}func main() {    c := Container{State: NewState()}    c.getInfo()    c.Lock()    fmt.Println("second lock")    c.Unlock()}

运行上面的程序，就可以看到Container可以直接访问到State里面的锁。

参考：兔子哥哥