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64 lines
1.3 KiB
64 lines
1.3 KiB
// Package group provides a sample lazy load container.
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// The group only creating a new object not until the object is needed by user.
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// And it will cache all the objects to reduce the creation of object.
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package group
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import "sync"
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// Group is a lazy load container.
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type Group struct {
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new func() interface{}
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vals map[string]interface{}
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sync.RWMutex
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}
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// NewGroup news a group container.
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func NewGroup(new func() interface{}) *Group {
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if new == nil {
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panic("container.group: can't assign a nil to the new function")
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}
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return &Group{
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new: new,
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vals: make(map[string]interface{}),
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}
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}
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// Get gets the object by the given key.
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func (g *Group) Get(key string) interface{} {
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g.RLock()
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v, ok := g.vals[key]
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if ok {
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g.RUnlock()
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return v
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}
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g.RUnlock()
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// slow path for group don`t have specified key value
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g.Lock()
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defer g.Unlock()
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v, ok = g.vals[key]
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if ok {
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return v
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}
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v = g.new()
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g.vals[key] = v
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return v
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}
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// Reset resets the new function and deletes all existing objects.
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func (g *Group) Reset(new func() interface{}) {
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if new == nil {
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panic("container.group: can't assign a nil to the new function")
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}
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g.Lock()
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g.new = new
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g.Unlock()
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g.Clear()
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}
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// Clear deletes all objects.
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func (g *Group) Clear() {
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g.Lock()
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g.vals = make(map[string]interface{})
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g.Unlock()
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}
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