golangスレッドの安全なSet構造を実現

同時アクセスのサポート

package main
import (
    "sync"
    "fmt"
)

type Set struct {
    m map[interface{}]bool
    sync.RWMutex
}

func New() *Set {
    return &Set{
        m :map[interface{}]bool{},
    }
}

func (s *Set) Add (item interface{}) {
    // 
    s.Lock()
    defer s.Unlock()
    s.m[item] = true
}

func (s *Set) Remove (item interface{}) {
    // 
    s.Lock()
    defer s.Unlock()
    delete(s.m, item)
}

func (s *Set) Has (item interface{}) bool {
    // 
    s.RLock()
    defer s.RUnlock()
    _, ok := s.m[item]
    return ok
}

func (s *Set) List() []interface{} {
    // 
    s.RLock()
    defer s.RUnlock()
    var outList []interface{}
    for value := range s.m {
        outList = append(outList, value)
    }
    return outList
}

func (s *Set) Len() int {
    return len(s.List())
}

func (s *Set) Clear() {
    s.Lock()
    defer s.Unlock()
    s.m = map[interface{}]bool{}
}

func (s *Set) IsEmpty() bool {
    if s.Len() == 0 {
        return true
    }
    return false
}

func main () {

    s := New()
    wait := sync.WaitGroup{}

    go func() {
        wait.Add(1)
        defer wait.Done()
        s.Add(1)
        s.Add("2")
        s.Add("3")
    }()

    go func() {
        wait.Add(1)
        defer wait.Done()
        s.Add(1)
        s.Add("2")
        s.Add("3")
    }()

    go func() {
        wait.Add(1)
        defer wait.Done()
        s.Add(3.1415926)
        //fmt.Println(s.List())
        s.Remove("2")
        //fmt.Println(s.List())
    }()

    go func() {
        wait.Add(1)
        defer wait.Done()
        if s.Has("2") {
            fmt.Println("2 exist")
        } else {
            fmt.Println("2 not exist")
        }
    }()

    go func() {
        wait.Add(1)
        defer wait.Done()
        if s.Has(3.1415926) {
            fmt.Println("3.1415926 exist")
        } else {
            fmt.Println("3.1415926 not exist")
        }
    }()

    for i:= 99; i< 999 ;i++ {
        s.Add(i)
    }

    fmt.Println("main gorotue :")
    fmt.Println("clear before ")
    fmt.Println("len == ", s.Len())
    fmt.Println("Is empty:", s.IsEmpty())
    s.Clear()
    fmt.Println("clear after")
    fmt.Println("is empty:", s.IsEmpty())
    fmt.Println("len == ", s.Len())
    wait.Wait()
}