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package util
import (
"sync"
)
// A mostly for read map, which can thread-safely
// initialize the map entries.
type ConcurrentReadMap struct {
rmutex sync.RWMutex
mutex sync.Mutex
Items map[string]interface{}
}
func NewConcurrentReadMap() *ConcurrentReadMap {
return &ConcurrentReadMap{Items: make(map[string]interface{})}
}
func (m *ConcurrentReadMap) initMapEntry(key string, newEntry func() interface{}) (value interface{}) {
m.mutex.Lock()
defer m.mutex.Unlock()
if value, ok := m.Items[key]; ok {
return value
}
value = newEntry()
m.Items[key] = value
return value
}
func (m *ConcurrentReadMap) Get(key string, newEntry func() interface{}) interface{} {
m.rmutex.RLock()
if value, ok := m.Items[key]; ok {
m.rmutex.RUnlock()
return value
}
m.rmutex.RUnlock()
return m.initMapEntry(key, newEntry)
}
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