Merge pull request #2885 from ipfs/feature/bloom-cache

Add ARC caching and bloom filter for blockstorage

Author: whyrusleeping

blocks/blockstore/bloom_cache.go

@@ -0,0 +1,181 @@
+package blockstore
+
+import (
+	"github.com/ipfs/go-ipfs/blocks"
+	key "github.com/ipfs/go-ipfs/blocks/key"
+	lru "gx/ipfs/QmVYxfoJQiZijTgPNHCHgHELvQpbsJNTg6Crmc3dQkj3yy/golang-lru"
+	bloom "gx/ipfs/QmWQ2SJisXwcCLsUXLwYCKSfyExXjFRW2WbBH5sqCUnwX5/bbloom"
+	context "gx/ipfs/QmZy2y8t9zQH2a1b8q2ZSLKp17ATuJoCNxxyMFG5qFExpt/go-net/context"
+	ds "gx/ipfs/QmfQzVugPq1w5shWRcLWSeiHF4a2meBX7yVD8Vw7GWJM9o/go-datastore"
+
+	"sync/atomic"
+)
+
+// BloomCached returns Blockstore that caches Has requests using Bloom filter
+// Size is size of bloom filter in bytes
+func BloomCached(bs Blockstore, bloomSize, lruSize int) (*bloomcache, error) {
+	bl, err := bloom.New(float64(bloomSize), float64(7))
+	if err != nil {
+		return nil, err
+	}
+	arc, err := lru.NewARC(lruSize)
+	if err != nil {
+		return nil, err
+	}
+	bc := &bloomcache{blockstore: bs, bloom: bl, arc: arc}
+	bc.Invalidate()
+	go bc.Rebuild()
+
+	return bc, nil
+}
+
+type bloomcache struct {
+	bloom  *bloom.Bloom
+	active int32
+
+	arc *lru.ARCCache
+	// This chan is only used for testing to wait for bloom to enable
+	rebuildChan chan struct{}
+	blockstore  Blockstore
+
+	// Statistics
+	hits   uint64
+	misses uint64
+}
+
+func (b *bloomcache) Invalidate() {
+	b.rebuildChan = make(chan struct{})
+	atomic.StoreInt32(&b.active, 0)
+}
+
+func (b *bloomcache) BloomActive() bool {
+	return atomic.LoadInt32(&b.active) != 0
+}
+
+func (b *bloomcache) Rebuild() {
+	ctx := context.TODO()
+	evt := log.EventBegin(ctx, "bloomcache.Rebuild")
+	defer evt.Done()
+
+	ch, err := b.blockstore.AllKeysChan(ctx)
+	if err != nil {
+		log.Errorf("AllKeysChan failed in bloomcache rebuild with: %v", err)
+		return
+	}
+	for key := range ch {
+		b.bloom.AddTS([]byte(key)) // Use binary key, the more compact the better
+	}
+	close(b.rebuildChan)
+	atomic.StoreInt32(&b.active, 1)
+}
+
+func (b *bloomcache) DeleteBlock(k key.Key) error {
+	if has, ok := b.hasCached(k); ok && !has {
+		return ErrNotFound
+	}
+
+	b.arc.Remove(k) // Invalidate cache before deleting.
+	err := b.blockstore.DeleteBlock(k)
+	switch err {
+	case nil:
+		b.arc.Add(k, false)
+	case ds.ErrNotFound, ErrNotFound:
+		b.arc.Add(k, false)
+	default:
+		return err
+	}
+	return nil
+}
+
+// if ok == false has is inconclusive
+// if ok == true then has respons to question: is it contained
+func (b *bloomcache) hasCached(k key.Key) (has bool, ok bool) {
+	if k == "" {
+		// Return cache invalid so call to blockstore
+		// in case of invalid key is forwarded deeper
+		return false, false
+	}
+	if b.BloomActive() {
+		blr := b.bloom.HasTS([]byte(k))
+		if blr == false { // not contained in bloom is only conclusive answer bloom gives
+			return false, true
+		}
+	}
+	h, ok := b.arc.Get(k)
+	if ok {
+		return h.(bool), ok
+	} else {
+		return false, false
+	}
+}
+
+func (b *bloomcache) Has(k key.Key) (bool, error) {
+	if has, ok := b.hasCached(k); ok {
+		return has, nil
+	}
+
+	res, err := b.blockstore.Has(k)
+	if err == nil {
+		b.arc.Add(k, res)
+	}
+	return res, err
+}
+
+func (b *bloomcache) Get(k key.Key) (blocks.Block, error) {
+	if has, ok := b.hasCached(k); ok && !has {
+		return nil, ErrNotFound
+	}
+
+	bl, err := b.blockstore.Get(k)
+	if bl == nil && err == ErrNotFound {
+		b.arc.Add(k, false)
+	} else if bl != nil {
+		b.arc.Add(k, true)
+	}
+	return bl, err
+}
+
+func (b *bloomcache) Put(bl blocks.Block) error {
+	if has, ok := b.hasCached(bl.Key()); ok && has {
+		return nil
+	}
+
+	err := b.blockstore.Put(bl)
+	if err == nil {
+		b.bloom.AddTS([]byte(bl.Key()))
+		b.arc.Add(bl.Key(), true)
+	}
+	return err
+}
+
+func (b *bloomcache) PutMany(bs []blocks.Block) error {
+	var good []blocks.Block
+	for _, block := range bs {
+		if has, ok := b.hasCached(block.Key()); !ok || (ok && !has) {
+			good = append(good, block)
+		}
+	}
+	err := b.blockstore.PutMany(bs)
+	if err == nil {
+		for _, block := range bs {
+			b.bloom.AddTS([]byte(block.Key()))
+		}
+	}
+	return err
+}
+
+func (b *bloomcache) AllKeysChan(ctx context.Context) (<-chan key.Key, error) {
+	return b.blockstore.AllKeysChan(ctx)
+}
+
+func (b *bloomcache) GCLock() Unlocker {
+	return b.blockstore.(GCBlockstore).GCLock()
+}
+
+func (b *bloomcache) PinLock() Unlocker {
+	return b.blockstore.(GCBlockstore).PinLock()
+}
+
+func (b *bloomcache) GCRequested() bool {
+	return b.blockstore.(GCBlockstore).GCRequested()
+}

blocks/blockstore/write_cache_test.go renamed to blocks/blockstore/bloom_cache_test.go

@@ -1,34 +1,44 @@
 package blockstore
 
 import (
+	"fmt"
+	"sync"
 	"testing"
+	"time"
 
 	"github.com/ipfs/go-ipfs/blocks"
+
 	ds "gx/ipfs/QmfQzVugPq1w5shWRcLWSeiHF4a2meBX7yVD8Vw7GWJM9o/go-datastore"
 	dsq "gx/ipfs/QmfQzVugPq1w5shWRcLWSeiHF4a2meBX7yVD8Vw7GWJM9o/go-datastore/query"
 	syncds "gx/ipfs/QmfQzVugPq1w5shWRcLWSeiHF4a2meBX7yVD8Vw7GWJM9o/go-datastore/sync"
 )
 
 func TestReturnsErrorWhenSizeNegative(t *testing.T) {
 	bs := NewBlockstore(syncds.MutexWrap(ds.NewMapDatastore()))
-	_, err := WriteCached(bs, -1)
-	if err != nil {
-		return
+	_, err := BloomCached(bs, 100, -1)
+	if err == nil {
+		t.Fail()
+	}
+	_, err = BloomCached(bs, -1, 100)
+	if err == nil {
+		t.Fail()
 	}
-	t.Fail()
 }
 
 func TestRemoveCacheEntryOnDelete(t *testing.T) {
 	b := blocks.NewBlock([]byte("foo"))
 	cd := &callbackDatastore{f: func() {}, ds: ds.NewMapDatastore()}
 	bs := NewBlockstore(syncds.MutexWrap(cd))
-	cachedbs, err := WriteCached(bs, 1)
+	cachedbs, err := BloomCached(bs, 1, 1)
 	if err != nil {
 		t.Fatal(err)
 	}
 	cachedbs.Put(b)
 
+	cd.Lock()
 	writeHitTheDatastore := false
+	cd.Unlock()
+
 	cd.SetFunc(func() {
 		writeHitTheDatastore = true
 	})
@@ -43,7 +53,7 @@ func TestRemoveCacheEntryOnDelete(t *testing.T) {
 func TestElideDuplicateWrite(t *testing.T) {
 	cd := &callbackDatastore{f: func() {}, ds: ds.NewMapDatastore()}
 	bs := NewBlockstore(syncds.MutexWrap(cd))
-	cachedbs, err := WriteCached(bs, 1)
+	cachedbs, err := BloomCached(bs, 1, 1)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -56,36 +66,78 @@ func TestElideDuplicateWrite(t *testing.T) {
 	})
 	cachedbs.Put(b1)
 }
+func TestHasIsBloomCached(t *testing.T) {
+	cd := &callbackDatastore{f: func() {}, ds: ds.NewMapDatastore()}
+	bs := NewBlockstore(syncds.MutexWrap(cd))
+
+	for i := 0; i < 1000; i++ {
+		bs.Put(blocks.NewBlock([]byte(fmt.Sprintf("data: %d", i))))
+	}
+	cachedbs, err := BloomCached(bs, 256*1024, 128)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	select {
+	case <-cachedbs.rebuildChan:
+	case <-time.After(1 * time.Second):
+		t.Fatalf("Timeout wating for rebuild: %d", cachedbs.bloom.ElementsAdded())
+	}
+
+	cacheFails := 0
+	cd.SetFunc(func() {
+		cacheFails++
+	})
+
+	for i := 0; i < 1000; i++ {
+		cachedbs.Has(blocks.NewBlock([]byte(fmt.Sprintf("data: %d", i+2000))).Key())
+	}
+
+	if float64(cacheFails)/float64(1000) > float64(0.05) {
+		t.Fatal("Bloom filter has cache miss rate of more than 5%")
+	}
+}
 
 type callbackDatastore struct {
+	sync.Mutex
 	f  func()
 	ds ds.Datastore
 }
 
-func (c *callbackDatastore) SetFunc(f func()) { c.f = f }
+func (c *callbackDatastore) SetFunc(f func()) {
+	c.Lock()
+	defer c.Unlock()
+	c.f = f
+}
+
+func (c *callbackDatastore) CallF() {
+	c.Lock()
+	defer c.Unlock()
+	c.f()
+}
 
 func (c *callbackDatastore) Put(key ds.Key, value interface{}) (err error) {
-	c.f()
+	c.CallF()
 	return c.ds.Put(key, value)
 }
 
 func (c *callbackDatastore) Get(key ds.Key) (value interface{}, err error) {
-	c.f()
+	c.CallF()
 	return c.ds.Get(key)
 }
 
 func (c *callbackDatastore) Has(key ds.Key) (exists bool, err error) {
-	c.f()
+	c.CallF()
 	return c.ds.Has(key)
 }
 
 func (c *callbackDatastore) Delete(key ds.Key) (err error) {
-	c.f()
+	c.CallF()
 	return c.ds.Delete(key)
 }
 
 func (c *callbackDatastore) Query(q dsq.Query) (dsq.Results, error) {
-	c.f()
+	c.CallF()
 	return c.ds.Query(q)
 }