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segment.go
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segment.go
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package cmap
import (
"fmt"
"sync"
"sync/atomic"
)
type Segment interface {
Put(p Pair) (bool, error)
Get(key string) Pair
GetWithHash(key string, keyHash uint64) Pair
Delete(key string) bool
Size() uint64
}
type segment struct {
buckets []Bucket
bucketLen int
pairTotal uint64
pairRedistributor PairRedistributor
lock sync.Mutex
}
func newSegment(bucketNumber int, pairRedistributor PairRedistributor) Segment {
if bucketNumber <= 0 {
bucketNumber = DEFAULT_BUCKET_NUMBER
}
if pairRedistributor == nil {
pairRedistributor = newDefautlPairRedistributor(DEFAULT_BUCKET_LOAD_FACTOR,
bucketNumber)
}
buckets := make([]Bucket, bucketNumber)
for i := 0; i < bucketNumber; i ++ {
buckets[i] = newBucket()
}
return &segment{
buckets: buckets,
bucketLen: bucketNumber,
pairRedistributor: pairRedistributor,
}
}
func (s *segment) Put(p Pair) (bool, error) {
s.lock.Lock()
defer s.lock.Unlock()
b := s.buckets[int(p.Hash() % uint64(s.bucketLen))]
ok, err := b.Put(p, nil)
if ok {
newTotal := atomic.AddUint64(&s.pairTotal, 1)
s.redistribute(newTotal, b.Size())
}
return ok, err
}
func (s *segment) Get(key string) Pair {
return s.GetWithHash(key, hash(key))
}
func (s *segment) GetWithHash(key string, keyHash uint64) Pair {
s.lock.Lock()
bs := s.buckets[int(keyHash % uint64(s.bucketLen))]
s.lock.Unlock()
return bs.Get(key)
}
func (s *segment) Size() uint64 {
return atomic.LoadUint64(&s.pairTotal)
}
func (s *segment) Delete(key string) bool {
s.lock.Lock()
b := s.buckets[int(hash(key) % uint64(s.bucketLen))]
ok := b.Delete(key, nil)
if ok {
newTotal := atomic.AddUint64(&s.pairTotal, ^uint64(0))
s.redistribute(newTotal, b.Size())
}
s.lock.Unlock()
return ok
}
func (s *segment) redistribute(pairTotal uint64, bucketSize uint64) (err error) {
defer func() {
if p := recover(); p != nil {
if pErr, ok := p.(error); ok {
err = newPairRedistributorError(pErr.Error())
} else {
err = newPairRedistributorError(fmt.Sprintf("%s", p))
}
}
}()
s.pairRedistributor.UpdateThreshold(pairTotal, s.bucketLen)
bucketStatus := s.pairRedistributor.CheckBucketStatus(pairTotal, bucketSize)
newBuckets, changed := s.pairRedistributor.Redistribe(bucketStatus, s.buckets )
if changed {
s.buckets = newBuckets
s.bucketLen = len(s.buckets)
}
return nil
}