mirror of
https://github.com/chrislusf/seaweedfs
synced 2024-09-06 00:50:37 +02:00
67 lines
1.6 KiB
Go
67 lines
1.6 KiB
Go
package chunk_cache
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import (
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"github.com/karlseguin/ccache/v2"
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"time"
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)
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// a global cache for recently accessed file chunks
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type ChunkCacheInMemory struct {
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cache *ccache.Cache
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}
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func NewChunkCacheInMemory(maxEntries int64) *ChunkCacheInMemory {
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pruneCount := maxEntries >> 3
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if pruneCount <= 0 {
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pruneCount = 500
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}
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return &ChunkCacheInMemory{
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cache: ccache.New(ccache.Configure().MaxSize(maxEntries).ItemsToPrune(uint32(pruneCount))),
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}
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}
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func (c *ChunkCacheInMemory) GetChunk(fileId string) []byte {
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item := c.cache.Get(fileId)
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if item == nil {
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return nil
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}
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data := item.Value().([]byte)
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item.Extend(time.Hour)
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return data
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}
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func (c *ChunkCacheInMemory) getChunkSlice(fileId string, offset, length uint64) ([]byte, error) {
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item := c.cache.Get(fileId)
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if item == nil {
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return nil, nil
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}
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data := item.Value().([]byte)
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item.Extend(time.Hour)
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wanted := min(int(length), len(data)-int(offset))
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if wanted < 0 {
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return nil, ErrorOutOfBounds
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}
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return data[offset : int(offset)+wanted], nil
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}
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func (c *ChunkCacheInMemory) readChunkAt(buffer []byte, fileId string, offset uint64) (int, error) {
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item := c.cache.Get(fileId)
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if item == nil {
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return 0, nil
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}
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data := item.Value().([]byte)
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item.Extend(time.Hour)
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wanted := min(len(buffer), len(data)-int(offset))
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if wanted < 0 {
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return 0, ErrorOutOfBounds
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}
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n := copy(buffer, data[offset:int(offset)+wanted])
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return n, nil
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}
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func (c *ChunkCacheInMemory) SetChunk(fileId string, data []byte) {
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localCopy := make([]byte, len(data))
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copy(localCopy, data)
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c.cache.Set(fileId, localCopy, time.Hour)
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}
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