Godeps: update github.com/syndtr/goleveldb to 6b4daa5362

Godeps/Godeps.json

 {
 	"ImportPath": "github.com/ethereum/go-ethereum",
-	"GoVersion": "go1.5.2",
+	"GoVersion": "go1.7",
 	"GodepVersion": "v74",
 	"Packages": [
 		"./..."
@@ -110,6 +110,10 @@
 			"ImportPath": "github.com/rcrowley/go-metrics",
 			"Rev": "51425a2415d21afadfd55cd93432c0bc69e9598d"
 		},
+		{
+			"ImportPath": "github.com/rcrowley/go-metrics/exp",
+			"Rev": "51425a2415d21afadfd55cd93432c0bc69e9598d"
+		},
 		{
 			"ImportPath": "github.com/rjeczalik/notify",
 			"Rev": "f627deca7a510d96f0ef9388f2d0e8b16d21f87f"
@@ -152,51 +156,51 @@
 		},
 		{
 			"ImportPath": "github.com/syndtr/goleveldb/leveldb",
-			"Rev": "ab8b5dcf1042e818ab68e770d465112a899b668e"
+			"Rev": "6b4daa5362b502898ddf367c5c11deb9e7a5c727"
 		},
 		{
 			"ImportPath": "github.com/syndtr/goleveldb/leveldb/cache",
-			"Rev": "ab8b5dcf1042e818ab68e770d465112a899b668e"
+			"Rev": "6b4daa5362b502898ddf367c5c11deb9e7a5c727"
 		},
 		{
 			"ImportPath": "github.com/syndtr/goleveldb/leveldb/comparer",
-			"Rev": "ab8b5dcf1042e818ab68e770d465112a899b668e"
+			"Rev": "6b4daa5362b502898ddf367c5c11deb9e7a5c727"
 		},
 		{
 			"ImportPath": "github.com/syndtr/goleveldb/leveldb/errors",
-			"Rev": "ab8b5dcf1042e818ab68e770d465112a899b668e"
+			"Rev": "6b4daa5362b502898ddf367c5c11deb9e7a5c727"
 		},
 		{
 			"ImportPath": "github.com/syndtr/goleveldb/leveldb/filter",
-			"Rev": "ab8b5dcf1042e818ab68e770d465112a899b668e"
+			"Rev": "6b4daa5362b502898ddf367c5c11deb9e7a5c727"
 		},
 		{
 			"ImportPath": "github.com/syndtr/goleveldb/leveldb/iterator",
-			"Rev": "ab8b5dcf1042e818ab68e770d465112a899b668e"
+			"Rev": "6b4daa5362b502898ddf367c5c11deb9e7a5c727"
 		},
 		{
 			"ImportPath": "github.com/syndtr/goleveldb/leveldb/journal",
-			"Rev": "ab8b5dcf1042e818ab68e770d465112a899b668e"
+			"Rev": "6b4daa5362b502898ddf367c5c11deb9e7a5c727"
 		},
 		{
 			"ImportPath": "github.com/syndtr/goleveldb/leveldb/memdb",
-			"Rev": "ab8b5dcf1042e818ab68e770d465112a899b668e"
+			"Rev": "6b4daa5362b502898ddf367c5c11deb9e7a5c727"
 		},
 		{
 			"ImportPath": "github.com/syndtr/goleveldb/leveldb/opt",
-			"Rev": "ab8b5dcf1042e818ab68e770d465112a899b668e"
+			"Rev": "6b4daa5362b502898ddf367c5c11deb9e7a5c727"
 		},
 		{
 			"ImportPath": "github.com/syndtr/goleveldb/leveldb/storage",
-			"Rev": "ab8b5dcf1042e818ab68e770d465112a899b668e"
+			"Rev": "6b4daa5362b502898ddf367c5c11deb9e7a5c727"
 		},
 		{
 			"ImportPath": "github.com/syndtr/goleveldb/leveldb/table",
-			"Rev": "ab8b5dcf1042e818ab68e770d465112a899b668e"
+			"Rev": "6b4daa5362b502898ddf367c5c11deb9e7a5c727"
 		},
 		{
 			"ImportPath": "github.com/syndtr/goleveldb/leveldb/util",
-			"Rev": "ab8b5dcf1042e818ab68e770d465112a899b668e"
+			"Rev": "6b4daa5362b502898ddf367c5c11deb9e7a5c727"
 		},
 		{
 			"ImportPath": "golang.org/x/crypto/pbkdf2",

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/cache/cache.go

@@ -16,7 +16,7 @@ import (
 )
 
 // Cacher provides interface to implements a caching functionality.
-// An implementation must be goroutine-safe.
+// An implementation must be safe for concurrent use.
 type Cacher interface {
 	// Capacity returns cache capacity.
 	Capacity() int
@@ -511,18 +511,12 @@ func (r *Cache) EvictAll() {
 	}
 }
 
-// Close closes the 'cache map' and releases all 'cache node'.
+// Close closes the 'cache map' and forcefully releases all 'cache node'.
 func (r *Cache) Close() error {
 	r.mu.Lock()
 	if !r.closed {
 		r.closed = true
 
-		if r.cacher != nil {
-			if err := r.cacher.Close(); err != nil {
-				return err
-			}
-		}
-
 		h := (*mNode)(r.mHead)
 		h.initBuckets()
 
@@ -541,10 +535,37 @@ func (r *Cache) Close() error {
 				for _, f := range n.onDel {
 					f()
 				}
+				n.onDel = nil
 			}
 		}
 	}
 	r.mu.Unlock()
+
+	// Avoid deadlock.
+	if r.cacher != nil {
+		if err := r.cacher.Close(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// CloseWeak closes the 'cache map' and evict all 'cache node' from cacher, but
+// unlike Close it doesn't forcefully releases 'cache node'.
+func (r *Cache) CloseWeak() error {
+	r.mu.Lock()
+	if !r.closed {
+		r.closed = true
+	}
+	r.mu.Unlock()
+
+	// Avoid deadlock.
+	if r.cacher != nil {
+		r.cacher.EvictAll()
+		if err := r.cacher.Close(); err != nil {
+			return err
+		}
+	}
 	return nil
 }
 

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/comparer.go

@@ -6,7 +6,9 @@
 
 package leveldb
 
-import "github.com/syndtr/goleveldb/leveldb/comparer"
+import (
+	"github.com/syndtr/goleveldb/leveldb/comparer"
+)
 
 type iComparer struct {
 	ucmp comparer.Comparer
@@ -33,12 +35,12 @@ func (icmp *iComparer) Name() string {
 }
 
 func (icmp *iComparer) Compare(a, b []byte) int {
-	x := icmp.ucmp.Compare(internalKey(a).ukey(), internalKey(b).ukey())
+	x := icmp.uCompare(internalKey(a).ukey(), internalKey(b).ukey())
 	if x == 0 {
 		if m, n := internalKey(a).num(), internalKey(b).num(); m > n {
-			x = -1
+			return -1
 		} else if m < n {
-			x = 1
+			return 1
 		}
 	}
 	return x
@@ -46,30 +48,20 @@ func (icmp *iComparer) Compare(a, b []byte) int {
 
 func (icmp *iComparer) Separator(dst, a, b []byte) []byte {
 	ua, ub := internalKey(a).ukey(), internalKey(b).ukey()
-	dst = icmp.ucmp.Separator(dst, ua, ub)
-	if dst == nil {
-		return nil
+	dst = icmp.uSeparator(dst, ua, ub)
+	if dst != nil && len(dst) < len(ua) && icmp.uCompare(ua, dst) < 0 {
+		// Append earliest possible number.
+		return append(dst, keyMaxNumBytes...)
 	}
-	if len(dst) < len(ua) && icmp.uCompare(ua, dst) < 0 {
-		dst = append(dst, keyMaxNumBytes...)
-	} else {
-		// Did not close possibilities that n maybe longer than len(ub).
-		dst = append(dst, a[len(a)-8:]...)
-	}
-	return dst
+	return nil
 }
 
 func (icmp *iComparer) Successor(dst, b []byte) []byte {
 	ub := internalKey(b).ukey()
-	dst = icmp.ucmp.Successor(dst, ub)
-	if dst == nil {
-		return nil
-	}
-	if len(dst) < len(ub) && icmp.uCompare(ub, dst) < 0 {
-		dst = append(dst, keyMaxNumBytes...)
-	} else {
-		// Did not close possibilities that n maybe longer than len(ub).
-		dst = append(dst, b[len(b)-8:]...)
+	dst = icmp.uSuccessor(dst, ub)
+	if dst != nil && len(dst) < len(ub) && icmp.uCompare(ub, dst) < 0 {
+		// Append earliest possible number.
+		return append(dst, keyMaxNumBytes...)
 	}
-	return dst
+	return nil
 }

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/db.go

@@ -53,14 +53,13 @@ type DB struct {
 	aliveSnaps, aliveIters int32
 
 	// Write.
-	writeC       chan *Batch
+	batchPool    sync.Pool
+	writeMergeC  chan writeMerge
 	writeMergedC chan bool
 	writeLockC   chan struct{}
 	writeAckC    chan error
 	writeDelay   time.Duration
 	writeDelayN  int
-	journalC     chan *Batch
-	journalAckC  chan error
 	tr           *Transaction
 
 	// Compaction.
@@ -94,12 +93,11 @@ func openDB(s *session) (*DB, error) {
 		// Snapshot
 		snapsList: list.New(),
 		// Write
-		writeC:       make(chan *Batch),
+		batchPool:    sync.Pool{New: newBatch},
+		writeMergeC:  make(chan writeMerge),
 		writeMergedC: make(chan bool),
 		writeLockC:   make(chan struct{}, 1),
 		writeAckC:    make(chan error),
-		journalC:     make(chan *Batch),
-		journalAckC:  make(chan error),
 		// Compaction
 		tcompCmdC:   make(chan cCmd),
 		tcompPauseC: make(chan chan<- struct{}),
@@ -144,10 +142,10 @@ func openDB(s *session) (*DB, error) {
 	if readOnly {
 		db.SetReadOnly()
 	} else {
-		db.closeW.Add(3)
+		db.closeW.Add(2)
 		go db.tCompaction()
 		go db.mCompaction()
-		go db.jWriter()
+		// go db.jWriter()
 	}
 
 	s.logf("db@open done T·%v", time.Since(start))
@@ -162,10 +160,10 @@ func openDB(s *session) (*DB, error) {
 // os.ErrExist error.
 //
 // Open will return an error with type of ErrCorrupted if corruption
-// detected in the DB. Corrupted DB can be recovered with Recover
-// function.
+// detected in the DB. Use errors.IsCorrupted to test whether an error is
+// due to corruption. Corrupted DB can be recovered with Recover function.
 //
-// The returned DB instance is goroutine-safe.
+// The returned DB instance is safe for concurrent use.
 // The DB must be closed after use, by calling Close method.
 func Open(stor storage.Storage, o *opt.Options) (db *DB, err error) {
 	s, err := newSession(stor, o)
@@ -202,13 +200,13 @@ func Open(stor storage.Storage, o *opt.Options) (db *DB, err error) {
 // os.ErrExist error.
 //
 // OpenFile uses standard file-system backed storage implementation as
-// desribed in the leveldb/storage package.
+// described in the leveldb/storage package.
 //
 // OpenFile will return an error with type of ErrCorrupted if corruption
-// detected in the DB. Corrupted DB can be recovered with Recover
-// function.
+// detected in the DB. Use errors.IsCorrupted to test whether an error is
+// due to corruption. Corrupted DB can be recovered with Recover function.
 //
-// The returned DB instance is goroutine-safe.
+// The returned DB instance is safe for concurrent use.
 // The DB must be closed after use, by calling Close method.
 func OpenFile(path string, o *opt.Options) (db *DB, err error) {
 	stor, err := storage.OpenFile(path, o.GetReadOnly())
@@ -229,7 +227,7 @@ func OpenFile(path string, o *opt.Options) (db *DB, err error) {
 // The DB must already exist or it will returns an error.
 // Also, Recover will ignore ErrorIfMissing and ErrorIfExist options.
 //
-// The returned DB instance is goroutine-safe.
+// The returned DB instance is safe for concurrent use.
 // The DB must be closed after use, by calling Close method.
 func Recover(stor storage.Storage, o *opt.Options) (db *DB, err error) {
 	s, err := newSession(stor, o)
@@ -255,10 +253,10 @@ func Recover(stor storage.Storage, o *opt.Options) (db *DB, err error) {
 // The DB must already exist or it will returns an error.
 // Also, Recover will ignore ErrorIfMissing and ErrorIfExist options.
 //
-// RecoverFile uses standard file-system backed storage implementation as desribed
+// RecoverFile uses standard file-system backed storage implementation as described
 // in the leveldb/storage package.
 //
-// The returned DB instance is goroutine-safe.
+// The returned DB instance is safe for concurrent use.
 // The DB must be closed after use, by calling Close method.
 func RecoverFile(path string, o *opt.Options) (db *DB, err error) {
 	stor, err := storage.OpenFile(path, false)
@@ -504,10 +502,11 @@ func (db *DB) recoverJournal() error {
 			checksum    = db.s.o.GetStrict(opt.StrictJournalChecksum)
 			writeBuffer = db.s.o.GetWriteBuffer()
 
-			jr    *journal.Reader
-			mdb   = memdb.New(db.s.icmp, writeBuffer)
-			buf   = &util.Buffer{}
-			batch = &Batch{}
+			jr       *journal.Reader
+			mdb      = memdb.New(db.s.icmp, writeBuffer)
+			buf      = &util.Buffer{}
+			batchSeq uint64
+			batchLen int
 		)
 
 		for _, fd := range fds {
@@ -526,7 +525,7 @@ func (db *DB) recoverJournal() error {
 			}
 
 			// Flush memdb and remove obsolete journal file.
-			if !ofd.Nil() {
+			if !ofd.Zero() {
 				if mdb.Len() > 0 {
 					if _, err := db.s.flushMemdb(rec, mdb, 0); err != nil {
 						fr.Close()
@@ -569,7 +568,8 @@ func (db *DB) recoverJournal() error {
 					fr.Close()
 					return errors.SetFd(err, fd)
 				}
-				if err := batch.memDecodeAndReplay(db.seq, buf.Bytes(), mdb); err != nil {
+				batchSeq, batchLen, err = decodeBatchToMem(buf.Bytes(), db.seq, mdb)
+				if err != nil {
 					if !strict && errors.IsCorrupted(err) {
 						db.s.logf("journal error: %v (skipped)", err)
 						// We won't apply sequence number as it might be corrupted.
@@ -581,7 +581,7 @@ func (db *DB) recoverJournal() error {
 				}
 
 				// Save sequence number.
-				db.seq = batch.seq + uint64(batch.Len())
+				db.seq = batchSeq + uint64(batchLen)
 
 				// Flush it if large enough.
 				if mdb.Size() >= writeBuffer {
@@ -624,7 +624,7 @@ func (db *DB) recoverJournal() error {
 	}
 
 	// Remove the last obsolete journal file.
-	if !ofd.Nil() {
+	if !ofd.Zero() {
 		db.s.stor.Remove(ofd)
 	}
 
@@ -661,9 +661,10 @@ func (db *DB) recoverJournalRO() error {
 		db.logf("journal@recovery RO·Mode F·%d", len(fds))
 
 		var (
-			jr    *journal.Reader
-			buf   = &util.Buffer{}
-			batch = &Batch{}
+			jr       *journal.Reader
+			buf      = &util.Buffer{}
+			batchSeq uint64
+			batchLen int
 		)
 
 		for _, fd := range fds {
@@ -703,7 +704,8 @@ func (db *DB) recoverJournalRO() error {
 					fr.Close()
 					return errors.SetFd(err, fd)
 				}
-				if err := batch.memDecodeAndReplay(db.seq, buf.Bytes(), mdb); err != nil {
+				batchSeq, batchLen, err = decodeBatchToMem(buf.Bytes(), db.seq, mdb)
+				if err != nil {
 					if !strict && errors.IsCorrupted(err) {
 						db.s.logf("journal error: %v (skipped)", err)
 						// We won't apply sequence number as it might be corrupted.
@@ -715,7 +717,7 @@ func (db *DB) recoverJournalRO() error {
 				}
 
 				// Save sequence number.
-				db.seq = batch.seq + uint64(batch.Len())
+				db.seq = batchSeq + uint64(batchLen)
 			}
 
 			fr.Close()
@@ -856,7 +858,7 @@ func (db *DB) Has(key []byte, ro *opt.ReadOptions) (ret bool, err error) {
 
 // NewIterator returns an iterator for the latest snapshot of the
 // underlying DB.
-// The returned iterator is not goroutine-safe, but it is safe to use
+// The returned iterator is not safe for concurrent use, but it is safe to use
 // multiple iterators concurrently, with each in a dedicated goroutine.
 // It is also safe to use an iterator concurrently with modifying its
 // underlying DB. The resultant key/value pairs are guaranteed to be
@@ -1062,6 +1064,8 @@ func (db *DB) Close() error {
 	if db.journal != nil {
 		db.journal.Close()
 		db.journalWriter.Close()
+		db.journal = nil
+		db.journalWriter = nil
 	}
 
 	if db.writeDelayN > 0 {
@@ -1077,15 +1081,11 @@ func (db *DB) Close() error {
 		if err1 := db.closer.Close(); err == nil {
 			err = err1
 		}
+		db.closer = nil
 	}
 
-	// NIL'ing pointers.
-	db.s = nil
-	db.mem = nil
-	db.frozenMem = nil
-	db.journal = nil
-	db.journalWriter = nil
-	db.closer = nil
+	// Clear memdbs.
+	db.clearMems()
 
 	return err
 }

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/db_compaction.go

@@ -96,7 +96,7 @@ noerr:
 			default:
 				goto haserr
 			}
-		case _, _ = <-db.closeC:
+		case <-db.closeC:
 			return
 		}
 	}
@@ -113,7 +113,7 @@ haserr:
 				goto hasperr
 			default:
 			}
-		case _, _ = <-db.closeC:
+		case <-db.closeC:
 			return
 		}
 	}
@@ -126,7 +126,7 @@ hasperr:
 		case db.writeLockC <- struct{}{}:
 			// Hold write lock, so that write won't pass-through.
 			db.compWriteLocking = true
-		case _, _ = <-db.closeC:
+		case <-db.closeC:
 			if db.compWriteLocking {
 				// We should release the lock or Close will hang.
 				<-db.writeLockC
@@ -195,7 +195,7 @@ func (db *DB) compactionTransact(name string, t compactionTransactInterface) {
 				db.logf("%s exiting (persistent error %q)", name, perr)
 				db.compactionExitTransact()
 			}
-		case _, _ = <-db.closeC:
+		case <-db.closeC:
 			db.logf("%s exiting", name)
 			db.compactionExitTransact()
 		}
@@ -224,7 +224,7 @@ func (db *DB) compactionTransact(name string, t compactionTransactInterface) {
 			}
 			select {
 			case <-backoffT.C:
-			case _, _ = <-db.closeC:
+			case <-db.closeC:
 				db.logf("%s exiting", name)
 				db.compactionExitTransact()
 			}
@@ -288,7 +288,7 @@ func (db *DB) memCompaction() {
 	case <-db.compPerErrC:
 		close(resumeC)
 		resumeC = nil
-	case _, _ = <-db.closeC:
+	case <-db.closeC:
 		return
 	}
 
@@ -337,7 +337,7 @@ func (db *DB) memCompaction() {
 		select {
 		case <-resumeC:
 			close(resumeC)
-		case _, _ = <-db.closeC:
+		case <-db.closeC:
 			return
 		}
 	}
@@ -378,7 +378,7 @@ func (b *tableCompactionBuilder) appendKV(key, value []byte) error {
 			select {
 			case ch := <-b.db.tcompPauseC:
 				b.db.pauseCompaction(ch)
-			case _, _ = <-b.db.closeC:
+			case <-b.db.closeC:
 				b.db.compactionExitTransact()
 			default:
 			}
@@ -643,7 +643,7 @@ func (db *DB) tableNeedCompaction() bool {
 func (db *DB) pauseCompaction(ch chan<- struct{}) {
 	select {
 	case ch <- struct{}{}:
-	case _, _ = <-db.closeC:
+	case <-db.closeC:
 		db.compactionExitTransact()
 	}
 }
@@ -697,14 +697,14 @@ func (db *DB) compTriggerWait(compC chan<- cCmd) (err error) {
 	case compC <- cAuto{ch}:
 	case err = <-db.compErrC:
 		return
-	case _, _ = <-db.closeC:
+	case <-db.closeC:
 		return ErrClosed
 	}
 	// Wait cmd.
 	select {
 	case err = <-ch:
 	case err = <-db.compErrC:
-	case _, _ = <-db.closeC:
+	case <-db.closeC:
 		return ErrClosed
 	}
 	return err
@@ -719,14 +719,14 @@ func (db *DB) compTriggerRange(compC chan<- cCmd, level int, min, max []byte) (e
 	case compC <- cRange{level, min, max, ch}:
 	case err := <-db.compErrC:
 		return err
-	case _, _ = <-db.closeC:
+	case <-db.closeC:
 		return ErrClosed
 	}
 	// Wait cmd.
 	select {
 	case err = <-ch:
 	case err = <-db.compErrC:
-	case _, _ = <-db.closeC:
+	case <-db.closeC:
 		return ErrClosed
 	}
 	return err
@@ -758,7 +758,7 @@ func (db *DB) mCompaction() {
 			default:
 				panic("leveldb: unknown command")
 			}
-		case _, _ = <-db.closeC:
+		case <-db.closeC:
 			return
 		}
 	}
@@ -791,7 +791,7 @@ func (db *DB) tCompaction() {
 			case ch := <-db.tcompPauseC:
 				db.pauseCompaction(ch)
 				continue
-			case _, _ = <-db.closeC:
+			case <-db.closeC:
 				return
 			default:
 			}
@@ -806,7 +806,7 @@ func (db *DB) tCompaction() {
 			case ch := <-db.tcompPauseC:
 				db.pauseCompaction(ch)
 				continue
-			case _, _ = <-db.closeC:
+			case <-db.closeC:
 				return
 			}
 		}

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/db_snapshot.go

@@ -59,7 +59,7 @@ func (db *DB) releaseSnapshot(se *snapshotElement) {
 	}
 }
 
-// Gets minimum sequence that not being snapshoted.
+// Gets minimum sequence that not being snapshotted.
 func (db *DB) minSeq() uint64 {
 	db.snapsMu.Lock()
 	defer db.snapsMu.Unlock()
@@ -131,7 +131,7 @@ func (snap *Snapshot) Has(key []byte, ro *opt.ReadOptions) (ret bool, err error)
 }
 
 // NewIterator returns an iterator for the snapshot of the underlying DB.
-// The returned iterator is not goroutine-safe, but it is safe to use
+// The returned iterator is not safe for concurrent use, but it is safe to use
 // multiple iterators concurrently, with each in a dedicated goroutine.
 // It is also safe to use an iterator concurrently with modifying its
 // underlying DB. The resultant key/value pairs are guaranteed to be

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/db_state.go

@@ -67,12 +67,11 @@ func (db *DB) sampleSeek(ikey internalKey) {
 }
 
 func (db *DB) mpoolPut(mem *memdb.DB) {
-	defer func() {
-		recover()
-	}()
-	select {
-	case db.memPool <- mem:
-	default:
+	if !db.isClosed() {
+		select {
+		case db.memPool <- mem:
+		default:
+		}
 	}
 }
 
@@ -100,7 +99,13 @@ func (db *DB) mpoolDrain() {
 			case <-db.memPool:
 			default:
 			}
-		case _, _ = <-db.closeC:
+		case <-db.closeC:
+			ticker.Stop()
+			// Make sure the pool is drained.
+			select {
+			case <-db.memPool:
+			case <-time.After(time.Second):
+			}
 			close(db.memPool)
 			return
 		}
@@ -148,24 +153,26 @@ func (db *DB) newMem(n int) (mem *memDB, err error) {
 func (db *DB) getMems() (e, f *memDB) {
 	db.memMu.RLock()
 	defer db.memMu.RUnlock()
-	if db.mem == nil {
+	if db.mem != nil {
+		db.mem.incref()
+	} else if !db.isClosed() {
 		panic("nil effective mem")
 	}
-	db.mem.incref()
 	if db.frozenMem != nil {
 		db.frozenMem.incref()
 	}
 	return db.mem, db.frozenMem
 }
 
-// Get frozen memdb.
+// Get effective memdb.
 func (db *DB) getEffectiveMem() *memDB {
 	db.memMu.RLock()
 	defer db.memMu.RUnlock()
-	if db.mem == nil {
+	if db.mem != nil {
+		db.mem.incref()
+	} else if !db.isClosed() {
 		panic("nil effective mem")
 	}
-	db.mem.incref()
 	return db.mem
 }
 
@@ -200,6 +207,14 @@ func (db *DB) dropFrozenMem() {
 	db.memMu.Unlock()
 }
 
+// Clear mems ptr; used by DB.Close().
+func (db *DB) clearMems() {
+	db.memMu.Lock()
+	db.mem = nil
+	db.frozenMem = nil
+	db.memMu.Unlock()
+}
+
 // Set closed flag; return true if not already closed.
 func (db *DB) setClosed() bool {
 	return atomic.CompareAndSwapUint32(&db.closed, 0, 1)

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/db_transaction.go

@@ -59,8 +59,8 @@ func (tr *Transaction) Has(key []byte, ro *opt.ReadOptions) (bool, error) {
 }
 
 // NewIterator returns an iterator for the latest snapshot of the transaction.
-// The returned iterator is not goroutine-safe, but it is safe to use multiple
-// iterators concurrently, with each in a dedicated goroutine.
+// The returned iterator is not safe for concurrent use, but it is safe to use
+// multiple iterators concurrently, with each in a dedicated goroutine.
 // It is also safe to use an iterator concurrently while writes to the
 // transaction. The resultant key/value pairs are guaranteed to be consistent.
 //
@@ -167,8 +167,8 @@ func (tr *Transaction) Write(b *Batch, wo *opt.WriteOptions) error {
 	if tr.closed {
 		return errTransactionDone
 	}
-	return b.decodeRec(func(i int, kt keyType, key, value []byte) error {
-		return tr.put(kt, key, value)
+	return b.replayInternal(func(i int, kt keyType, k, v []byte) error {
+		return tr.put(kt, k, v)
 	})
 }
 
@@ -179,7 +179,8 @@ func (tr *Transaction) setDone() {
 	<-tr.db.writeLockC
 }
 
-// Commit commits the transaction.
+// Commit commits the transaction. If error is not nil, then the transaction is
+// not committed, it can then either be retried or discarded.
 //
 // Other methods should not be called after transaction has been committed.
 func (tr *Transaction) Commit() error {
@@ -192,24 +193,27 @@ func (tr *Transaction) Commit() error {
 	if tr.closed {
 		return errTransactionDone
 	}
-	defer tr.setDone()
 	if err := tr.flush(); err != nil {
-		tr.discard()
+		// Return error, lets user decide either to retry or discard
+		// transaction.
 		return err
 	}
 	if len(tr.tables) != 0 {
 		// Committing transaction.
 		tr.rec.setSeqNum(tr.seq)
 		tr.db.compCommitLk.Lock()
-		defer tr.db.compCommitLk.Unlock()
+		tr.stats.startTimer()
+		var cerr error
 		for retry := 0; retry < 3; retry++ {
-			if err := tr.db.s.commit(&tr.rec); err != nil {
-				tr.db.logf("transaction@commit error R·%d %q", retry, err)
+			cerr = tr.db.s.commit(&tr.rec)
+			if cerr != nil {
+				tr.db.logf("transaction@commit error R·%d %q", retry, cerr)
 				select {
 				case <-time.After(time.Second):
-				case _, _ = <-tr.db.closeC:
+				case <-tr.db.closeC:
 					tr.db.logf("transaction@commit exiting")
-					return err
+					tr.db.compCommitLk.Unlock()
+					return cerr
 				}
 			} else {
 				// Success. Set db.seq.
@@ -217,9 +221,26 @@ func (tr *Transaction) Commit() error {
 				break
 			}
 		}
+		tr.stats.stopTimer()
+		if cerr != nil {
+			// Return error, lets user decide either to retry or discard
+			// transaction.
+			return cerr
+		}
+
+		// Update compaction stats. This is safe as long as we hold compCommitLk.
+		tr.db.compStats.addStat(0, &tr.stats)
+
 		// Trigger table auto-compaction.
 		tr.db.compTrigger(tr.db.tcompCmdC)
+		tr.db.compCommitLk.Unlock()
+
+		// Additionally, wait compaction when certain threshold reached.
+		// Ignore error, returns error only if transaction can't be committed.
+		tr.db.waitCompaction()
 	}
+	// Only mark as done if transaction committed successfully.
+	tr.setDone()
 	return nil
 }
 
@@ -245,10 +266,20 @@ func (tr *Transaction) Discard() {
 	tr.lk.Unlock()
 }
 
+func (db *DB) waitCompaction() error {
+	if db.s.tLen(0) >= db.s.o.GetWriteL0PauseTrigger() {
+		return db.compTriggerWait(db.tcompCmdC)
+	}
+	return nil
+}
+
 // OpenTransaction opens an atomic DB transaction. Only one transaction can be
-// opened at a time. Write will be blocked until the transaction is committed or
-// discarded.
-// The returned transaction handle is goroutine-safe.
+// opened at a time. Subsequent call to Write and OpenTransaction will be blocked
+// until in-flight transaction is committed or discarded.
+// The returned transaction handle is safe for concurrent use.
+//
+// Transaction is expensive and can overwhelm compaction, especially if
+// transaction size is small. Use with caution.
 //
 // The transaction must be closed once done, either by committing or discarding
 // the transaction.
@@ -263,7 +294,7 @@ func (db *DB) OpenTransaction() (*Transaction, error) {
 	case db.writeLockC <- struct{}{}:
 	case err := <-db.compPerErrC:
 		return nil, err
-	case _, _ = <-db.closeC:
+	case <-db.closeC:
 		return nil, ErrClosed
 	}
 
@@ -278,6 +309,11 @@ func (db *DB) OpenTransaction() (*Transaction, error) {
 		}
 	}
 
+	// Wait compaction when certain threshold reached.
+	if err := db.waitCompaction(); err != nil {
+		return nil, err
+	}
+
 	tr := &Transaction{
 		db:  db,
 		seq: db.seq,

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/db_util.go

@@ -62,7 +62,7 @@ func (db *DB) checkAndCleanFiles() error {
 		case storage.TypeManifest:
 			keep = fd.Num >= db.s.manifestFd.Num
 		case storage.TypeJournal:
-			if !db.frozenJournalFd.Nil() {
+			if !db.frozenJournalFd.Zero() {
 				keep = fd.Num >= db.frozenJournalFd.Num
 			} else {
 				keep = fd.Num >= db.journalFd.Num

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/errors.go

@@ -10,6 +10,7 @@ import (
 	"github.com/syndtr/goleveldb/leveldb/errors"
 )
 
+// Common errors.
 var (
 	ErrNotFound         = errors.ErrNotFound
 	ErrReadOnly         = errors.New("leveldb: read-only mode")

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/errors/errors.go

@@ -15,6 +15,7 @@ import (
 	"github.com/syndtr/goleveldb/leveldb/util"
 )
 
+// Common errors.
 var (
 	ErrNotFound    = New("leveldb: not found")
 	ErrReleased    = util.ErrReleased
@@ -34,11 +35,10 @@ type ErrCorrupted struct {
 }
 
 func (e *ErrCorrupted) Error() string {
-	if !e.Fd.Nil() {
+	if !e.Fd.Zero() {
 		return fmt.Sprintf("%v [file=%v]", e.Err, e.Fd)
-	} else {
-		return e.Err.Error()
 	}
+	return e.Err.Error()
 }
 
 // NewErrCorrupted creates new ErrCorrupted error.

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/iterator/iter.go

@@ -21,13 +21,13 @@ var (
 // IteratorSeeker is the interface that wraps the 'seeks method'.
 type IteratorSeeker interface {
 	// First moves the iterator to the first key/value pair. If the iterator
-	// only contains one key/value pair then First and Last whould moves
+	// only contains one key/value pair then First and Last would moves
 	// to the same key/value pair.
 	// It returns whether such pair exist.
 	First() bool
 
 	// Last moves the iterator to the last key/value pair. If the iterator
-	// only contains one key/value pair then First and Last whould moves
+	// only contains one key/value pair then First and Last would moves
 	// to the same key/value pair.
 	// It returns whether such pair exist.
 	Last() bool
@@ -48,7 +48,7 @@ type IteratorSeeker interface {
 	Prev() bool
 }
 
-// CommonIterator is the interface that wraps common interator methods.
+// CommonIterator is the interface that wraps common iterator methods.
 type CommonIterator interface {
 	IteratorSeeker
 
@@ -71,14 +71,15 @@ type CommonIterator interface {
 
 // Iterator iterates over a DB's key/value pairs in key order.
 //
-// When encouter an error any 'seeks method' will return false and will
+// When encounter an error any 'seeks method' will return false and will
 // yield no key/value pairs. The error can be queried by calling the Error
 // method. Calling Release is still necessary.
 //
 // An iterator must be released after use, but it is not necessary to read
 // an iterator until exhaustion.
-// Also, an iterator is not necessarily goroutine-safe, but it is safe to use
-// multiple iterators concurrently, with each in a dedicated goroutine.
+// Also, an iterator is not necessarily safe for concurrent use, but it is
+// safe to use multiple iterators concurrently, with each in a dedicated
+// goroutine.
 type Iterator interface {
 	CommonIterator
 
@@ -98,7 +99,7 @@ type Iterator interface {
 //
 // ErrorCallbackSetter implemented by indexed and merged iterator.
 type ErrorCallbackSetter interface {
-	// SetErrorCallback allows set an error callback of the coresponding
+	// SetErrorCallback allows set an error callback of the corresponding
 	// iterator. Use nil to clear the callback.
 	SetErrorCallback(f func(err error))
 }

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/journal/journal.go

@@ -180,34 +180,37 @@ func (r *Reader) nextChunk(first bool) error {
 			checksum := binary.LittleEndian.Uint32(r.buf[r.j+0 : r.j+4])
 			length := binary.LittleEndian.Uint16(r.buf[r.j+4 : r.j+6])
 			chunkType := r.buf[r.j+6]
-
+			unprocBlock := r.n - r.j
 			if checksum == 0 && length == 0 && chunkType == 0 {
 				// Drop entire block.
-				m := r.n - r.j
 				r.i = r.n
 				r.j = r.n
-				return r.corrupt(m, "zero header", false)
-			} else {
-				m := r.n - r.j
-				r.i = r.j + headerSize
-				r.j = r.j + headerSize + int(length)
-				if r.j > r.n {
-					// Drop entire block.
-					r.i = r.n
-					r.j = r.n
-					return r.corrupt(m, "chunk length overflows block", false)
-				} else if r.checksum && checksum != util.NewCRC(r.buf[r.i-1:r.j]).Value() {
-					// Drop entire block.
-					r.i = r.n
-					r.j = r.n
-					return r.corrupt(m, "checksum mismatch", false)
-				}
+				return r.corrupt(unprocBlock, "zero header", false)
+			}
+			if chunkType < fullChunkType || chunkType > lastChunkType {
+				// Drop entire block.
+				r.i = r.n
+				r.j = r.n
+				return r.corrupt(unprocBlock, fmt.Sprintf("invalid chunk type %#x", chunkType), false)
+			}
+			r.i = r.j + headerSize
+			r.j = r.j + headerSize + int(length)
+			if r.j > r.n {
+				// Drop entire block.
+				r.i = r.n
+				r.j = r.n
+				return r.corrupt(unprocBlock, "chunk length overflows block", false)
+			} else if r.checksum && checksum != util.NewCRC(r.buf[r.i-1:r.j]).Value() {
+				// Drop entire block.
+				r.i = r.n
+				r.j = r.n
+				return r.corrupt(unprocBlock, "checksum mismatch", false)
 			}
 			if first && chunkType != fullChunkType && chunkType != firstChunkType {
-				m := r.j - r.i
+				chunkLength := (r.j - r.i) + headerSize
 				r.i = r.j
 				// Report the error, but skip it.
-				return r.corrupt(m+headerSize, "orphan chunk", true)
+				return r.corrupt(chunkLength, "orphan chunk", true)
 			}
 			r.last = chunkType == fullChunkType || chunkType == lastChunkType
 			return nil

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/key.go

@@ -37,14 +37,14 @@ func (kt keyType) String() string {
 	case keyTypeVal:
 		return "v"
 	}
-	return "x"
+	return fmt.Sprintf("<invalid:%#x>", uint(kt))
 }
 
 // Value types encoded as the last component of internal keys.
 // Don't modify; this value are saved to disk.
 const (
-	keyTypeDel keyType = iota
-	keyTypeVal
+	keyTypeDel = keyType(0)
+	keyTypeVal = keyType(1)
 )
 
 // keyTypeSeek defines the keyType that should be passed when constructing an
@@ -79,11 +79,7 @@ func makeInternalKey(dst, ukey []byte, seq uint64, kt keyType) internalKey {
 		panic("leveldb: invalid type")
 	}
 
-	if n := len(ukey) + 8; cap(dst) < n {
-		dst = make([]byte, n)
-	} else {
-		dst = dst[:n]
-	}
+	dst = ensureBuffer(dst, len(ukey)+8)
 	copy(dst, ukey)
 	binary.LittleEndian.PutUint64(dst[len(ukey):], (seq<<8)|uint64(kt))
 	return internalKey(dst)
@@ -143,5 +139,5 @@ func (ik internalKey) String() string {
 	if ukey, seq, kt, err := parseInternalKey(ik); err == nil {
 		return fmt.Sprintf("%s,%s%d", shorten(string(ukey)), kt, seq)
 	}
-	return "<invalid>"
+	return fmt.Sprintf("<invalid:%#x>", []byte(ik))
 }

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/memdb/memdb.go

@@ -17,6 +17,7 @@ import (
 	"github.com/syndtr/goleveldb/leveldb/util"
 )
 
+// Common errors.
 var (
 	ErrNotFound     = errors.ErrNotFound
 	ErrIterReleased = errors.New("leveldb/memdb: iterator released")
@@ -385,7 +386,7 @@ func (p *DB) Find(key []byte) (rkey, value []byte, err error) {
 }
 
 // NewIterator returns an iterator of the DB.
-// The returned iterator is not goroutine-safe, but it is safe to use
+// The returned iterator is not safe for concurrent use, but it is safe to use
 // multiple iterators concurrently, with each in a dedicated goroutine.
 // It is also safe to use an iterator concurrently with modifying its
 // underlying DB. However, the resultant key/value pairs are not guaranteed
@@ -411,7 +412,7 @@ func (p *DB) Capacity() int {
 }
 
 // Size returns sum of keys and values length. Note that deleted
-// key/value will not be accouted for, but it will still consume
+// key/value will not be accounted for, but it will still consume
 // the buffer, since the buffer is append only.
 func (p *DB) Size() int {
 	p.mu.RLock()
@@ -453,11 +454,14 @@ func (p *DB) Reset() {
 	p.mu.Unlock()
 }
 
-// New creates a new initalized in-memory key/value DB. The capacity
+// New creates a new initialized in-memory key/value DB. The capacity
 // is the initial key/value buffer capacity. The capacity is advisory,
 // not enforced.
 //
-// The returned DB instance is goroutine-safe.
+// This DB is append-only, deleting an entry would remove entry node but not
+// reclaim KV buffer.
+//
+// The returned DB instance is safe for concurrent use.
 func New(cmp comparer.BasicComparer, capacity int) *DB {
 	p := &DB{
 		cmp:       cmp,

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/opt/options.go

@@ -312,6 +312,11 @@ type Options struct {
 	// The default is false.
 	NoSync bool
 
+	// NoWriteMerge allows disabling write merge.
+	//
+	// The default is false.
+	NoWriteMerge bool
+
 	// OpenFilesCacher provides cache algorithm for open files caching.
 	// Specify NoCacher to disable caching algorithm.
 	//
@@ -543,6 +548,13 @@ func (o *Options) GetNoSync() bool {
 	return o.NoSync
 }
 
+func (o *Options) GetNoWriteMerge() bool {
+	if o == nil {
+		return false
+	}
+	return o.NoWriteMerge
+}
+
 func (o *Options) GetOpenFilesCacher() Cacher {
 	if o == nil || o.OpenFilesCacher == nil {
 		return DefaultOpenFilesCacher
@@ -629,6 +641,11 @@ func (ro *ReadOptions) GetStrict(strict Strict) bool {
 // WriteOptions holds the optional parameters for 'write operation'. The
 // 'write operation' includes Write, Put and Delete.
 type WriteOptions struct {
+	// NoWriteMerge allows disabling write merge.
+	//
+	// The default is false.
+	NoWriteMerge bool
+
 	// Sync is whether to sync underlying writes from the OS buffer cache
 	// through to actual disk, if applicable. Setting Sync can result in
 	// slower writes.
@@ -644,6 +661,13 @@ type WriteOptions struct {
 	Sync bool
 }
 
+func (wo *WriteOptions) GetNoWriteMerge() bool {
+	if wo == nil {
+		return false
+	}
+	return wo.NoWriteMerge
+}
+
 func (wo *WriteOptions) GetSync() bool {
 	if wo == nil {
 		return false

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/session.go

@@ -18,7 +18,8 @@ import (
 	"github.com/syndtr/goleveldb/leveldb/storage"
 )
 
-// ErrManifestCorrupted records manifest corruption.
+// ErrManifestCorrupted records manifest corruption. This error will be
+// wrapped with errors.ErrCorrupted.
 type ErrManifestCorrupted struct {
 	Field  string
 	Reason string
@@ -42,7 +43,7 @@ type session struct {
 	stSeqNum         uint64 // last mem compacted seq; need external synchronization
 
 	stor     storage.Storage
-	storLock storage.Lock
+	storLock storage.Locker
 	o        *cachedOptions
 	icmp     *iComparer
 	tops     *tOps
@@ -87,12 +88,12 @@ func (s *session) close() {
 	}
 	s.manifest = nil
 	s.manifestWriter = nil
-	s.stVersion = nil
+	s.setVersion(&version{s: s, closing: true})
 }
 
 // Release session lock.
 func (s *session) release() {
-	s.storLock.Release()
+	s.storLock.Unlock()
 }
 
 // Create a new database session; need external synchronization.

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/session_util.go

@@ -50,6 +50,12 @@ func (s *session) version() *version {
 	return s.stVersion
 }
 
+func (s *session) tLen(level int) int {
+	s.vmu.Lock()
+	defer s.vmu.Unlock()
+	return s.stVersion.tLen(level)
+}
+
 // Set current version to v.
 func (s *session) setVersion(v *version) {
 	s.vmu.Lock()
@@ -197,7 +203,7 @@ func (s *session) newManifest(rec *sessionRecord, v *version) (err error) {
 			if s.manifestWriter != nil {
 				s.manifestWriter.Close()
 			}
-			if !s.manifestFd.Nil() {
+			if !s.manifestFd.Zero() {
 				s.stor.Remove(s.manifestFd)
 			}
 			s.manifestFd = fd

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/storage/file_storage.go

@@ -32,7 +32,7 @@ type fileStorageLock struct {
 	fs *fileStorage
 }
 
-func (lock *fileStorageLock) Release() {
+func (lock *fileStorageLock) Unlock() {
 	if lock.fs != nil {
 		lock.fs.mu.Lock()
 		defer lock.fs.mu.Unlock()
@@ -116,7 +116,7 @@ func OpenFile(path string, readOnly bool) (Storage, error) {
 	return fs, nil
 }
 
-func (fs *fileStorage) Lock() (Lock, error) {
+func (fs *fileStorage) Lock() (Locker, error) {
 	fs.mu.Lock()
 	defer fs.mu.Unlock()
 	if fs.open < 0 {
@@ -323,7 +323,7 @@ func (fs *fileStorage) GetMeta() (fd FileDesc, err error) {
 		}
 	}
 	// Don't remove any files if there is no valid CURRENT file.
-	if fd.Nil() {
+	if fd.Zero() {
 		if cerr != nil {
 			err = cerr
 		} else {

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/storage/mem_storage.go

@@ -18,7 +18,7 @@ type memStorageLock struct {
 	ms *memStorage
 }
 
-func (lock *memStorageLock) Release() {
+func (lock *memStorageLock) Unlock() {
 	ms := lock.ms
 	ms.mu.Lock()
 	defer ms.mu.Unlock()
@@ -43,7 +43,7 @@ func NewMemStorage() Storage {
 	}
 }
 
-func (ms *memStorage) Lock() (Lock, error) {
+func (ms *memStorage) Lock() (Locker, error) {
 	ms.mu.Lock()
 	defer ms.mu.Unlock()
 	if ms.slock != nil {
@@ -69,7 +69,7 @@ func (ms *memStorage) SetMeta(fd FileDesc) error {
 func (ms *memStorage) GetMeta() (FileDesc, error) {
 	ms.mu.Lock()
 	defer ms.mu.Unlock()
-	if ms.meta.Nil() {
+	if ms.meta.Zero() {
 		return FileDesc{}, os.ErrNotExist
 	}
 	return ms.meta, nil
@@ -78,7 +78,7 @@ func (ms *memStorage) GetMeta() (FileDesc, error) {
 func (ms *memStorage) List(ft FileType) ([]FileDesc, error) {
 	ms.mu.Lock()
 	var fds []FileDesc
-	for x, _ := range ms.files {
+	for x := range ms.files {
 		fd := unpackFile(x)
 		if fd.Type&ft != 0 {
 			fds = append(fds, fd)

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/storage/storage.go

@@ -11,12 +11,12 @@ import (
 	"errors"
 	"fmt"
 	"io"
-
-	"github.com/syndtr/goleveldb/leveldb/util"
 )
 
+// FileType represent a file type.
 type FileType int
 
+// File types.
 const (
 	TypeManifest FileType = 1 << iota
 	TypeJournal
@@ -40,6 +40,7 @@ func (t FileType) String() string {
 	return fmt.Sprintf("<unknown:%d>", t)
 }
 
+// Common error.
 var (
 	ErrInvalidFile = errors.New("leveldb/storage: invalid file for argument")
 	ErrLocked      = errors.New("leveldb/storage: already locked")
@@ -55,11 +56,10 @@ type ErrCorrupted struct {
 }
 
 func (e *ErrCorrupted) Error() string {
-	if !e.Fd.Nil() {
+	if !e.Fd.Zero() {
 		return fmt.Sprintf("%v [file=%v]", e.Err, e.Fd)
-	} else {
-		return e.Err.Error()
 	}
+	return e.Err.Error()
 }
 
 // Syncer is the interface that wraps basic Sync method.
@@ -83,11 +83,12 @@ type Writer interface {
 	Syncer
 }
 
-type Lock interface {
-	util.Releaser
+// Locker is the interface that wraps Unlock method.
+type Locker interface {
+	Unlock()
 }
 
-// FileDesc is a file descriptor.
+// FileDesc is a 'file descriptor'.
 type FileDesc struct {
 	Type FileType
 	Num  int64
@@ -108,12 +109,12 @@ func (fd FileDesc) String() string {
 	}
 }
 
-// Nil returns true if fd == (FileDesc{}).
-func (fd FileDesc) Nil() bool {
+// Zero returns true if fd == (FileDesc{}).
+func (fd FileDesc) Zero() bool {
 	return fd == (FileDesc{})
 }
 
-// FileDescOk returns true if fd is a valid file descriptor.
+// FileDescOk returns true if fd is a valid 'file descriptor'.
 func FileDescOk(fd FileDesc) bool {
 	switch fd.Type {
 	case TypeManifest:
@@ -126,43 +127,44 @@ func FileDescOk(fd FileDesc) bool {
 	return fd.Num >= 0
 }
 
-// Storage is the storage. A storage instance must be goroutine-safe.
+// Storage is the storage. A storage instance must be safe for concurrent use.
 type Storage interface {
 	// Lock locks the storage. Any subsequent attempt to call Lock will fail
 	// until the last lock released.
-	// After use the caller should call the Release method.
-	Lock() (Lock, error)
+	// Caller should call Unlock method after use.
+	Lock() (Locker, error)
 
 	// Log logs a string. This is used for logging.
 	// An implementation may write to a file, stdout or simply do nothing.
 	Log(str string)
 
-	// SetMeta sets to point to the given fd, which then can be acquired using
-	// GetMeta method.
-	// SetMeta should be implemented in such way that changes should happened
+	// SetMeta store 'file descriptor' that can later be acquired using GetMeta
+	// method. The 'file descriptor' should point to a valid file.
+	// SetMeta should be implemented in such way that changes should happen
 	// atomically.
 	SetMeta(fd FileDesc) error
 
-	// GetManifest returns a manifest file.
-	// Returns os.ErrNotExist if meta doesn't point to any fd, or point to fd
-	// that doesn't exist.
+	// GetMeta returns 'file descriptor' stored in meta. The 'file descriptor'
+	// can be updated using SetMeta method.
+	// Returns os.ErrNotExist if meta doesn't store any 'file descriptor', or
+	// 'file descriptor' point to nonexistent file.
 	GetMeta() (FileDesc, error)
 
-	// List returns fds that match the given file types.
+	// List returns file descriptors that match the given file types.
 	// The file types may be OR'ed together.
 	List(ft FileType) ([]FileDesc, error)
 
-	// Open opens file with the given fd read-only.
+	// Open opens file with the given 'file descriptor' read-only.
 	// Returns os.ErrNotExist error if the file does not exist.
 	// Returns ErrClosed if the underlying storage is closed.
 	Open(fd FileDesc) (Reader, error)
 
-	// Create creates file with the given fd, truncate if already exist and
-	// opens write-only.
+	// Create creates file with the given 'file descriptor', truncate if already
+	// exist and opens write-only.
 	// Returns ErrClosed if the underlying storage is closed.
 	Create(fd FileDesc) (Writer, error)
 
-	// Remove removes file with the given fd.
+	// Remove removes file with the given 'file descriptor'.
 	// Returns ErrClosed if the underlying storage is closed.
 	Remove(fd FileDesc) error
 

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/table.go

@@ -434,7 +434,7 @@ func (t *tOps) close() {
 	t.bpool.Close()
 	t.cache.Close()
 	if t.bcache != nil {
-		t.bcache.Close()
+		t.bcache.CloseWeak()
 	}
 }
 

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/table/reader.go

@@ -26,12 +26,15 @@ import (
 	"github.com/syndtr/goleveldb/leveldb/util"
 )
 
+// Reader errors.
 var (
 	ErrNotFound       = errors.ErrNotFound
 	ErrReaderReleased = errors.New("leveldb/table: reader released")
 	ErrIterReleased   = errors.New("leveldb/table: iterator released")
 )
 
+// ErrCorrupted describes error due to corruption. This error will be wrapped
+// with errors.ErrCorrupted.
 type ErrCorrupted struct {
 	Pos    int64
 	Size   int64
@@ -61,7 +64,7 @@ type block struct {
 func (b *block) seek(cmp comparer.Comparer, rstart, rlimit int, key []byte) (index, offset int, err error) {
 	index = sort.Search(b.restartsLen-rstart-(b.restartsLen-rlimit), func(i int) bool {
 		offset := int(binary.LittleEndian.Uint32(b.data[b.restartsOffset+4*(rstart+i):]))
-		offset += 1                                 // shared always zero, since this is a restart point
+		offset++                                    // shared always zero, since this is a restart point
 		v1, n1 := binary.Uvarint(b.data[offset:])   // key length
 		_, n2 := binary.Uvarint(b.data[offset+n1:]) // value length
 		m := offset + n1 + n2
@@ -356,7 +359,7 @@ func (i *blockIter) Prev() bool {
 	i.value = nil
 	offset := i.block.restartOffset(ri)
 	if offset == i.offset {
-		ri -= 1
+		ri--
 		if ri < 0 {
 			i.dir = dirSOI
 			return false
@@ -783,8 +786,8 @@ func (r *Reader) getDataIterErr(dataBH blockHandle, slice *util.Range, verifyChe
 // table. And a nil Range.Limit is treated as a key after all keys in
 // the table.
 //
-// The returned iterator is not goroutine-safe and should be released
-// when not used.
+// The returned iterator is not safe for concurrent use and should be released
+// after use.
 //
 // Also read Iterator documentation of the leveldb/iterator package.
 func (r *Reader) NewIterator(slice *util.Range, ro *opt.ReadOptions) iterator.Iterator {
@@ -826,18 +829,21 @@ func (r *Reader) find(key []byte, filtered bool, ro *opt.ReadOptions, noValue bo
 
 	index := r.newBlockIter(indexBlock, nil, nil, true)
 	defer index.Release()
+
 	if !index.Seek(key) {
-		err = index.Error()
-		if err == nil {
+		if err = index.Error(); err == nil {
 			err = ErrNotFound
 		}
 		return
 	}
+
 	dataBH, n := decodeBlockHandle(index.Value())
 	if n == 0 {
 		r.err = r.newErrCorruptedBH(r.indexBH, "bad data block handle")
-		return
+		return nil, nil, r.err
 	}
+
+	// The filter should only used for exact match.
 	if filtered && r.filter != nil {
 		filterBlock, frel, ferr := r.getFilterBlock(true)
 		if ferr == nil {
@@ -847,30 +853,53 @@ func (r *Reader) find(key []byte, filtered bool, ro *opt.ReadOptions, noValue bo
 			}
 			frel.Release()
 		} else if !errors.IsCorrupted(ferr) {
-			err = ferr
-			return
+			return nil, nil, ferr
 		}
 	}
+
 	data := r.getDataIter(dataBH, nil, r.verifyChecksum, !ro.GetDontFillCache())
-	defer data.Release()
 	if !data.Seek(key) {
-		err = data.Error()
-		if err == nil {
-			err = ErrNotFound
+		data.Release()
+		if err = data.Error(); err != nil {
+			return
+		}
+
+		// The nearest greater-than key is the first key of the next block.
+		if !index.Next() {
+			if err = index.Error(); err == nil {
+				err = ErrNotFound
+			}
+			return
+		}
+
+		dataBH, n = decodeBlockHandle(index.Value())
+		if n == 0 {
+			r.err = r.newErrCorruptedBH(r.indexBH, "bad data block handle")
+			return nil, nil, r.err
+		}
+
+		data = r.getDataIter(dataBH, nil, r.verifyChecksum, !ro.GetDontFillCache())
+		if !data.Next() {
+			data.Release()
+			if err = data.Error(); err == nil {
+				err = ErrNotFound
+			}
+			return
 		}
-		return
 	}
-	// Don't use block buffer, no need to copy the buffer.
+
+	// Key doesn't use block buffer, no need to copy the buffer.
 	rkey = data.Key()
 	if !noValue {
 		if r.bpool == nil {
 			value = data.Value()
 		} else {
-			// Use block buffer, and since the buffer will be recycled, the buffer
-			// need to be copied.
+			// Value does use block buffer, and since the buffer will be
+			// recycled, it need to be copied.
 			value = append([]byte{}, data.Value()...)
 		}
 	}
+	data.Release()
 	return
 }
 
@@ -888,7 +917,7 @@ func (r *Reader) Find(key []byte, filtered bool, ro *opt.ReadOptions) (rkey, val
 	return r.find(key, filtered, ro, false)
 }
 
-// Find finds key that is greater than or equal to the given key.
+// FindKey finds key that is greater than or equal to the given key.
 // It returns ErrNotFound if the table doesn't contain such key.
 // If filtered is true then the nearest 'block' will be checked against
 // 'filter data' (if present) and will immediately return ErrNotFound if
@@ -987,7 +1016,7 @@ func (r *Reader) Release() {
 // NewReader creates a new initialized table reader for the file.
 // The fi, cache and bpool is optional and can be nil.
 //
-// The returned table reader instance is goroutine-safe.
+// The returned table reader instance is safe for concurrent use.
 func NewReader(f io.ReaderAt, size int64, fd storage.FileDesc, cache *cache.NamespaceGetter, bpool *util.BufferPool, o *opt.Options) (*Reader, error) {
 	if f == nil {
 		return nil, errors.New("leveldb/table: nil file")
@@ -1039,9 +1068,8 @@ func NewReader(f io.ReaderAt, size int64, fd storage.FileDesc, cache *cache.Name
 		if errors.IsCorrupted(err) {
 			r.err = err
 			return r, nil
-		} else {
-			return nil, err
 		}
+		return nil, err
 	}
 
 	// Set data end.
@@ -1086,9 +1114,8 @@ func NewReader(f io.ReaderAt, size int64, fd storage.FileDesc, cache *cache.Name
 			if errors.IsCorrupted(err) {
 				r.err = err
 				return r, nil
-			} else {
-				return nil, err
 			}
+			return nil, err
 		}
 		if r.filter != nil {
 			r.filterBlock, err = r.readFilterBlock(r.filterBH)

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/table/writer.go

@@ -349,7 +349,7 @@ func (w *Writer) Close() error {
 
 // NewWriter creates a new initialized table writer for the file.
 //
-// Table writer is not goroutine-safe.
+// Table writer is not safe for concurrent use.
 func NewWriter(f io.Writer, o *opt.Options) *Writer {
 	w := &Writer{
 		writer:          f,

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/util.go

@@ -89,3 +89,10 @@ func (p fdSorter) Swap(i, j int) {
 func sortFds(fds []storage.FileDesc) {
 	sort.Sort(fdSorter(fds))
 }
+
+func ensureBuffer(b []byte, n int) []byte {
+	if cap(b) < n {
+		return make([]byte, n)
+	}
+	return b[:n]
+}

Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/version.go

@@ -34,7 +34,8 @@ type version struct {
 
 	cSeek unsafe.Pointer
 
-	ref int
+	closing bool
+	ref     int
 	// Succeeding version.
 	next *version
 }
@@ -131,6 +132,10 @@ func (v *version) walkOverlapping(aux tFiles, ikey internalKey, f func(level int
 }
 
 func (v *version) get(aux tFiles, ikey internalKey, ro *opt.ReadOptions, noValue bool) (value []byte, tcomp bool, err error) {
+	if v.closing {
+		return nil, false, ErrClosed
+	}
+
 	ukey := ikey.ukey()
 
 	var (