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ccmap.go
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ccmap.go
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package cat
import (
"sync"
)
type ccMap struct {
count uint32
buckets []ccMapBucket
hasher ccMapHasher
}
type ccMapBucket struct {
mu sync.Mutex
data map[string]interface{}
}
type ccMapHasher func(name string) uint32
type ccMapCreator func(name string) interface{}
type ccMapComputer func(interface{}) error
func hasher(name string) uint32 {
var h uint32 = 0
if len(name) > 0 {
for i := 0; i < len(name); i++ {
h = 31*h + uint32(name[i])
}
}
return h
}
func newCCMap(count int) *ccMap {
var ccmap = &ccMap{
count: uint32(count),
buckets: make([]ccMapBucket, count),
hasher: hasher,
}
for i := 0; i < count; i++ {
ccmap.buckets[i] = ccMapBucket{
mu: sync.Mutex{},
data: make(map[string]interface{}),
}
}
return ccmap
}
func (p *ccMap) compute(key string, creator ccMapCreator, computer ccMapComputer) (err error) {
hash := p.hasher(key)
slot := hash % p.count
bucket := p.buckets[slot]
bucket.mu.Lock()
defer bucket.mu.Unlock()
return bucket.compute(key, creator, computer)
}
func (p *ccMapBucket) compute(key string, creator ccMapCreator, computer ccMapComputer) (err error) {
var item interface{}
var ok bool
if item, ok = p.data[key]; !ok {
p.data[key] = creator(key)
item = p.data[key]
}
err = computer(item)
return
}