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write_cache.go
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write_cache.go
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package blockstore
import (
"github.com/ipfs/go-ipfs/Godeps/_workspace/src/github.com/hashicorp/golang-lru"
context "github.com/ipfs/go-ipfs/Godeps/_workspace/src/golang.org/x/net/context"
"github.com/ipfs/go-ipfs/blocks"
key "github.com/ipfs/go-ipfs/blocks/key"
)
// WriteCached returns a blockstore that caches up to |size| unique writes (bs.Put).
func WriteCached(bs Blockstore, size int) (Blockstore, error) {
c, err := lru.New(size)
if err != nil {
return nil, err
}
return &writecache{blockstore: bs, cache: c}, nil
}
type writecache struct {
cache *lru.Cache // pointer b/c Cache contains a Mutex as value (complicates copying)
blockstore Blockstore
}
func (w *writecache) DeleteBlock(k key.Key) error {
w.cache.Remove(k)
return w.blockstore.DeleteBlock(k)
}
func (w *writecache) Has(k key.Key) (bool, error) {
if _, ok := w.cache.Get(k); ok {
return true, nil
}
return w.blockstore.Has(k)
}
func (w *writecache) Get(k key.Key) (*blocks.Block, error) {
return w.blockstore.Get(k)
}
func (w *writecache) Put(b *blocks.Block) error {
if _, ok := w.cache.Get(b.Key()); ok {
return nil
}
w.cache.Add(b.Key(), struct{}{})
return w.blockstore.Put(b)
}
func (w *writecache) PutMany(bs []*blocks.Block) error {
var good []*blocks.Block
for _, b := range bs {
if _, ok := w.cache.Get(b.Key()); !ok {
good = append(good, b)
}
}
return w.blockstore.PutMany(good)
}
func (w *writecache) AllKeysChan(ctx context.Context) (<-chan key.Key, error) {
return w.blockstore.AllKeysChan(ctx)
}