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package chunk_cache
import (
"fmt"
"path"
"sort"
"sync"
"github.com/chrislusf/seaweedfs/weed/glog"
"github.com/chrislusf/seaweedfs/weed/storage"
"github.com/chrislusf/seaweedfs/weed/storage/needle"
)
// a global cache for recently accessed file chunks
type ChunkCache struct {
memCache *ChunkCacheInMemory
diskCaches []*ChunkCacheVolume
sync.RWMutex
}
func NewChunkCache(maxEntries int64, dir string, diskSizeMB int64, segmentCount int) *ChunkCache {
c := &ChunkCache{
memCache: NewChunkCacheInMemory(maxEntries),
}
volumeCount, volumeSize := int(diskSizeMB/30000), int64(30000)
if volumeCount < segmentCount {
volumeCount, volumeSize = segmentCount, diskSizeMB/int64(segmentCount)
}
for i := 0; i < volumeCount; i++ {
fileName := path.Join(dir, fmt.Sprintf("cache_%d", i))
diskCache, err := LoadOrCreateChunkCacheVolume(fileName, volumeSize*1024*1024)
if err != nil {
glog.Errorf("failed to add cache %s : %v", fileName, err)
} else {
c.diskCaches = append(c.diskCaches, diskCache)
}
}
// keep newest cache to the front
sort.Slice(c.diskCaches, func(i, j int) bool {
return c.diskCaches[i].lastModTime.After(c.diskCaches[j].lastModTime)
})
return c
}
func (c *ChunkCache) GetChunk(fileId string) (data []byte) {
if c == nil {
return
}
c.RLock()
defer c.RUnlock()
return c.doGetChunk(fileId)
}
func (c *ChunkCache) doGetChunk(fileId string) (data []byte) {
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, err = diskCache.GetNeedle(fid.Key)
if err == storage.ErrorNotFound {
continue
}
if err != nil {
glog.Errorf("failed to read cache file %s id %s", diskCache.fileName, fileId)
continue
}
if len(data) != 0 {
return
}
}
return nil
}
func (c *ChunkCache) SetChunk(fileId string, data []byte) {
if c == nil {
return
}
c.Lock()
defer c.Unlock()
if existingData := c.doGetChunk(fileId); len(existingData)==0{
c.doSetChunk(fileId, data)
}
}
func (c *ChunkCache) doSetChunk(fileId string, data []byte) {
c.memCache.SetChunk(fileId, data)
if len(c.diskCaches) == 0 {
return
}
if c.diskCaches[0].fileSize+int64(len(data)) > c.diskCaches[0].sizeLimit {
t, resetErr := c.diskCaches[len(c.diskCaches)-1].Reset()
if resetErr != nil {
glog.Errorf("failed to reset cache file %s", c.diskCaches[len(c.diskCaches)-1].fileName)
return
}
for i := len(c.diskCaches) - 1; i > 0; i-- {
c.diskCaches[i] = c.diskCaches[i-1]
}
c.diskCaches[0] = t
}
fid, err := needle.ParseFileIdFromString(fileId)
if err != nil {
glog.Errorf("failed to parse file id %s", fileId)
return
}
c.diskCaches[0].WriteNeedle(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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