snapshot of https://github.com/seaweedfs/seaweedfs.git (master, 2026-09-16; blobs > 131072B omitted)

weed/util/chunk_cache/chunk_cache_in_memory.go

@@ -0,0 +1,73 @@
+package chunk_cache
+
+import (
+	"time"
+
+	"github.com/karlseguin/ccache/v2"
+)
+
+var (
+	_ ChunkCache = &ChunkCacheInMemory{}
+)
+
+// a global cache for recently accessed file chunks
+type ChunkCacheInMemory struct {
+	cache *ccache.Cache
+}
+
+func (c *ChunkCacheInMemory) ReadChunkAt(data []byte, fileId string, offset uint64) (n int, err error) {
+	return c.readChunkAt(data, fileId, offset)
+}
+
+func (c *ChunkCacheInMemory) IsInCache(fileId string, lockNeeded bool) (answer bool) {
+	item := c.cache.Get(fileId)
+	if item == nil {
+		return false
+	}
+	return true
+}
+
+func (c *ChunkCacheInMemory) GetMaxFilePartSizeInCache() (answer uint64) {
+	return 8 * 1024 * 1024
+}
+
+func NewChunkCacheInMemory(maxEntries int64) *ChunkCacheInMemory {
+	pruneCount := maxEntries >> 3
+	if pruneCount <= 0 {
+		pruneCount = 500
+	}
+	return &ChunkCacheInMemory{
+		cache: ccache.New(ccache.Configure().MaxSize(maxEntries).ItemsToPrune(uint32(pruneCount))),
+	}
+}
+
+func (c *ChunkCacheInMemory) GetChunk(fileId string) []byte {
+	item := c.cache.Get(fileId)
+	if item == nil {
+		return nil
+	}
+	data := item.Value().([]byte)
+	item.Extend(time.Hour)
+	return data
+}
+
+func (c *ChunkCacheInMemory) readChunkAt(buffer []byte, fileId string, offset uint64) (int, error) {
+	item := c.cache.Get(fileId)
+	if item == nil {
+		return 0, nil
+	}
+	data := item.Value().([]byte)
+	item.Extend(time.Hour)
+	wanted := min(len(buffer), len(data)-int(offset))
+	if wanted < 0 {
+		return 0, ErrorOutOfBounds
+	}
+	n := copy(buffer, data[offset:int(offset)+wanted])
+	return n, nil
+}
+
+func (c *ChunkCacheInMemory) SetChunk(fileId string, data []byte) {
+	localCopy := make([]byte, len(data))
+	copy(localCopy, data)
+	c.cache.Set(fileId, localCopy, time.Hour)
+}