/
group.go
66 lines (58 loc) 路 1.29 KB
/
group.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
// Package group provides a sample lazy load container.
// The group only creating a new object not until the object is needed by user.
// And it will cache all the objects to reduce the creation of object.
package group
import "sync"
// Group is a lazy load container.
type Group struct {
new func() interface{}
objs map[string]interface{}
sync.RWMutex
}
// NewGroup news a group container.
func NewGroup(new func() interface{}) *Group {
if new == nil {
panic("container.group: can't assign a nil to the new function")
}
return &Group{
new: new,
objs: make(map[string]interface{}),
}
}
// Get gets the object by the given key.
func (g *Group) Get(key string) interface{} {
g.RLock()
obj, ok := g.objs[key]
if ok {
g.RUnlock()
return obj
}
g.RUnlock()
// double check
g.Lock()
defer g.Unlock()
obj, ok = g.objs[key]
if ok {
return obj
}
// new a obj if not exist
obj = g.new()
g.objs[key] = obj
return obj
}
// Reset resets the new function and deletes all existing objects.
func (g *Group) Reset(new func() interface{}) {
if new == nil {
panic("container.group: can't assign a nil to the new function")
}
g.Lock()
g.new = new
g.Unlock()
g.Clear()
}
// Clear deletes all objects.
func (g *Group) Clear() {
g.Lock()
g.objs = make(map[string]interface{})
g.Unlock()
}