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![Chris Lu](/assets/img/avatar_default.png)
glide has its own requirements. My previous workaround caused me some code checkin errors. Need to fix this.
76 lines
1.8 KiB
Go
76 lines
1.8 KiB
Go
package storage
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import (
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"fmt"
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"os"
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"sync/atomic"
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"github.com/hashicorp/golang-lru"
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"github.com/chrislusf/seaweedfs/weed/util"
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)
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var (
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bytesCache *lru.Cache
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bytesPool *util.BytesPool
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)
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/*
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There are one level of caching, and one level of pooling.
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In pooling, all []byte are fetched and returned to the pool bytesPool.
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In caching, the string~[]byte mapping is cached
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*/
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func init() {
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bytesPool = util.NewBytesPool()
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bytesCache, _ = lru.NewWithEvict(512, func(key interface{}, value interface{}) {
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value.(*Block).decreaseReference()
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})
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}
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type Block struct {
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Bytes []byte
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refCount int32
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}
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func (block *Block) decreaseReference() {
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if atomic.AddInt32(&block.refCount, -1) == 0 {
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bytesPool.Put(block.Bytes)
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}
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}
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func (block *Block) increaseReference() {
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atomic.AddInt32(&block.refCount, 1)
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}
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// get bytes from the LRU cache of []byte first, then from the bytes pool
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// when []byte in LRU cache is evicted, it will be put back to the bytes pool
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func getBytesForFileBlock(r *os.File, offset int64, readSize int) (dataSlice []byte, block *Block, err error) {
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// check cache, return if found
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cacheKey := fmt.Sprintf("%d:%d:%d", r.Fd(), offset>>3, readSize)
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if obj, found := bytesCache.Get(cacheKey); found {
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block = obj.(*Block)
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block.increaseReference()
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dataSlice = block.Bytes[0:readSize]
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return dataSlice, block, nil
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}
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// get the []byte from pool
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b := bytesPool.Get(readSize)
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// refCount = 2, one by the bytesCache, one by the actual needle object
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block = &Block{Bytes: b, refCount: 2}
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dataSlice = block.Bytes[0:readSize]
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_, err = r.ReadAt(dataSlice, offset)
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bytesCache.Add(cacheKey, block)
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return dataSlice, block, err
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}
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func (n *Needle) ReleaseMemory() {
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if n.rawBlock != nil {
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n.rawBlock.decreaseReference()
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}
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}
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func ReleaseBytes(b []byte) {
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bytesPool.Put(b)
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}
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