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package chunk_cache
import ( "sync"
"github.com/chrislusf/seaweedfs/weed/glog" "github.com/chrislusf/seaweedfs/weed/storage/needle" )
const ( memCacheSizeLimit = 1024 * 1024 onDiskCacheSizeLimit0 = memCacheSizeLimit onDiskCacheSizeLimit1 = 4 * memCacheSizeLimit )
// a global cache for recently accessed file chunks
type ChunkCache struct { memCache *ChunkCacheInMemory diskCaches []*OnDiskCacheLayer sync.RWMutex }
func NewChunkCache(maxEntries int64, dir string, diskSizeMB int64) *ChunkCache {
c := &ChunkCache{ memCache: NewChunkCacheInMemory(maxEntries), } c.diskCaches = make([]*OnDiskCacheLayer, 3) c.diskCaches[0] = NewOnDiskCacheLayer(dir, "c0_1", diskSizeMB/4, 4) c.diskCaches[1] = NewOnDiskCacheLayer(dir, "c1_4", diskSizeMB/4, 4) c.diskCaches[2] = NewOnDiskCacheLayer(dir, "cache", diskSizeMB/2, 4)
return c }
func (c *ChunkCache) GetChunk(fileId string, chunkSize uint64) (data []byte) { if c == nil { return }
c.RLock() defer c.RUnlock()
return c.doGetChunk(fileId, chunkSize) }
func (c *ChunkCache) doGetChunk(fileId string, chunkSize uint64) (data []byte) {
if chunkSize < memCacheSizeLimit { if data = c.memCache.GetChunk(fileId); data != nil { return data } }
fid, err := needle.ParseFileIdFromString(fileId) if err != nil { glog.Errorf("failed to parse file id %s", fileId) return nil }
for _, diskCache := range c.diskCaches { data := diskCache.getChunk(fid.Key) if len(data) != 0 { return data } }
return nil
}
func (c *ChunkCache) SetChunk(fileId string, data []byte) { if c == nil { return } c.Lock() defer c.Unlock()
c.doSetChunk(fileId, data) }
func (c *ChunkCache) doSetChunk(fileId string, data []byte) {
if len(data) < memCacheSizeLimit { c.memCache.SetChunk(fileId, data) }
fid, err := needle.ParseFileIdFromString(fileId) if err != nil { glog.Errorf("failed to parse file id %s", fileId) return }
if len(data) < onDiskCacheSizeLimit0 { c.diskCaches[0].setChunk(fid.Key, data) } else if len(data) < onDiskCacheSizeLimit1 { c.diskCaches[1].setChunk(fid.Key, data) } else { c.diskCaches[2].setChunk(fid.Key, data) }
}
func (c *ChunkCache) Shutdown() { if c == nil { return } c.Lock() defer c.Unlock() for _, diskCache := range c.diskCaches { diskCache.shutdown() } }
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