1 files changed, 152 insertions, 55 deletions

diff --git a/Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/db_state.go b/Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/db_state.go
index a13706142..d4db9d6dd 100644
--- a/Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/db_state.go
+++ b/Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/db_state.go
@@ -8,106 +8,203 @@ package leveldb
 
 import (
 	"sync/atomic"
+	"time"
 
 	"github.com/syndtr/goleveldb/leveldb/journal"
 	"github.com/syndtr/goleveldb/leveldb/memdb"
 )
 
+type memDB struct {
+	db  *DB
+	mdb *memdb.DB
+	ref int32
+}
+
+func (m *memDB) incref() {
+	atomic.AddInt32(&m.ref, 1)
+}
+
+func (m *memDB) decref() {
+	if ref := atomic.AddInt32(&m.ref, -1); ref == 0 {
+		// Only put back memdb with std capacity.
+		if m.mdb.Capacity() == m.db.s.o.GetWriteBuffer() {
+			m.mdb.Reset()
+			m.db.mpoolPut(m.mdb)
+		}
+		m.db = nil
+		m.mdb = nil
+	} else if ref < 0 {
+		panic("negative memdb ref")
+	}
+}
+
 // Get latest sequence number.
-func (d *DB) getSeq() uint64 {
-	return atomic.LoadUint64(&d.seq)
+func (db *DB) getSeq() uint64 {
+	return atomic.LoadUint64(&db.seq)
 }
 
 // Atomically adds delta to seq.
-func (d *DB) addSeq(delta uint64) {
-	atomic.AddUint64(&d.seq, delta)
+func (db *DB) addSeq(delta uint64) {
+	atomic.AddUint64(&db.seq, delta)
+}
+
+func (db *DB) sampleSeek(ikey iKey) {
+	v := db.s.version()
+	if v.sampleSeek(ikey) {
+		// Trigger table compaction.
+		db.compSendTrigger(db.tcompCmdC)
+	}
+	v.release()
+}
+
+func (db *DB) mpoolPut(mem *memdb.DB) {
+	defer func() {
+		recover()
+	}()
+	select {
+	case db.memPool <- mem:
+	default:
+	}
+}
+
+func (db *DB) mpoolGet() *memdb.DB {
+	select {
+	case mem := <-db.memPool:
+		return mem
+	default:
+		return nil
+	}
+}
+
+func (db *DB) mpoolDrain() {
+	ticker := time.NewTicker(30 * time.Second)
+	for {
+		select {
+		case <-ticker.C:
+			select {
+			case <-db.memPool:
+			default:
+			}
+		case _, _ = <-db.closeC:
+			close(db.memPool)
+			return
+		}
+	}
 }
 
 // Create new memdb and froze the old one; need external synchronization.
 // newMem only called synchronously by the writer.
-func (d *DB) newMem(n int) (mem *memdb.DB, err error) {
-	s := d.s
-
-	num := s.allocFileNum()
-	file := s.getJournalFile(num)
+func (db *DB) newMem(n int) (mem *memDB, err error) {
+	num := db.s.allocFileNum()
+	file := db.s.getJournalFile(num)
 	w, err := file.Create()
 	if err != nil {
-		s.reuseFileNum(num)
+		db.s.reuseFileNum(num)
 		return
 	}
-	d.memMu.Lock()
-	if d.journal == nil {
-		d.journal = journal.NewWriter(w)
+
+	db.memMu.Lock()
+	defer db.memMu.Unlock()
+
+	if db.frozenMem != nil {
+		panic("still has frozen mem")
+	}
+
+	if db.journal == nil {
+		db.journal = journal.NewWriter(w)
 	} else {
-		d.journal.Reset(w)
-		d.journalWriter.Close()
-		d.frozenJournalFile = d.journalFile
-	}
-	d.journalWriter = w
-	d.journalFile = file
-	d.frozenMem = d.mem
-	d.mem = memdb.New(s.icmp, maxInt(d.s.o.GetWriteBuffer(), n))
-	mem = d.mem
-	// The seq only incremented by the writer.
-	d.frozenSeq = d.seq
-	d.memMu.Unlock()
+		db.journal.Reset(w)
+		db.journalWriter.Close()
+		db.frozenJournalFile = db.journalFile
+	}
+	db.journalWriter = w
+	db.journalFile = file
+	db.frozenMem = db.mem
+	mdb := db.mpoolGet()
+	if mdb == nil || mdb.Capacity() < n {
+		mdb = memdb.New(db.s.icmp, maxInt(db.s.o.GetWriteBuffer(), n))
+	}
+	mem = &memDB{
+		db:  db,
+		mdb: mdb,
+		ref: 2,
+	}
+	db.mem = mem
+	// The seq only incremented by the writer. And whoever called newMem
+	// should hold write lock, so no need additional synchronization here.
+	db.frozenSeq = db.seq
 	return
 }
 
 // Get all memdbs.
-func (d *DB) getMems() (e *memdb.DB, f *memdb.DB) {
-	d.memMu.RLock()
-	defer d.memMu.RUnlock()
-	return d.mem, d.frozenMem
+func (db *DB) getMems() (e, f *memDB) {
+	db.memMu.RLock()
+	defer db.memMu.RUnlock()
+	if db.mem == nil {
+		panic("nil effective mem")
+	}
+	db.mem.incref()
+	if db.frozenMem != nil {
+		db.frozenMem.incref()
+	}
+	return db.mem, db.frozenMem
 }
 
 // Get frozen memdb.
-func (d *DB) getEffectiveMem() *memdb.DB {
-	d.memMu.RLock()
-	defer d.memMu.RUnlock()
-	return d.mem
+func (db *DB) getEffectiveMem() *memDB {
+	db.memMu.RLock()
+	defer db.memMu.RUnlock()
+	if db.mem == nil {
+		panic("nil effective mem")
+	}
+	db.mem.incref()
+	return db.mem
 }
 
 // Check whether we has frozen memdb.
-func (d *DB) hasFrozenMem() bool {
-	d.memMu.RLock()
-	defer d.memMu.RUnlock()
-	return d.frozenMem != nil
+func (db *DB) hasFrozenMem() bool {
+	db.memMu.RLock()
+	defer db.memMu.RUnlock()
+	return db.frozenMem != nil
 }
 
 // Get frozen memdb.
-func (d *DB) getFrozenMem() *memdb.DB {
-	d.memMu.RLock()
-	defer d.memMu.RUnlock()
-	return d.frozenMem
+func (db *DB) getFrozenMem() *memDB {
+	db.memMu.RLock()
+	defer db.memMu.RUnlock()
+	if db.frozenMem != nil {
+		db.frozenMem.incref()
+	}
+	return db.frozenMem
 }
 
 // Drop frozen memdb; assume that frozen memdb isn't nil.
-func (d *DB) dropFrozenMem() {
-	d.memMu.Lock()
-	if err := d.frozenJournalFile.Remove(); err != nil {
-		d.s.logf("journal@remove removing @%d %q", d.frozenJournalFile.Num(), err)
+func (db *DB) dropFrozenMem() {
+	db.memMu.Lock()
+	if err := db.frozenJournalFile.Remove(); err != nil {
+		db.logf("journal@remove removing @%d %q", db.frozenJournalFile.Num(), err)
 	} else {
-		d.s.logf("journal@remove removed @%d", d.frozenJournalFile.Num())
+		db.logf("journal@remove removed @%d", db.frozenJournalFile.Num())
 	}
-	d.frozenJournalFile = nil
-	d.frozenMem = nil
-	d.memMu.Unlock()
+	db.frozenJournalFile = nil
+	db.frozenMem.decref()
+	db.frozenMem = nil
+	db.memMu.Unlock()
 }
 
 // Set closed flag; return true if not already closed.
-func (d *DB) setClosed() bool {
-	return atomic.CompareAndSwapUint32(&d.closed, 0, 1)
+func (db *DB) setClosed() bool {
+	return atomic.CompareAndSwapUint32(&db.closed, 0, 1)
 }
 
 // Check whether DB was closed.
-func (d *DB) isClosed() bool {
-	return atomic.LoadUint32(&d.closed) != 0
+func (db *DB) isClosed() bool {
+	return atomic.LoadUint32(&db.closed) != 0
 }
 
 // Check read ok status.
-func (d *DB) ok() error {
-	if d.isClosed() {
+func (db *DB) ok() error {
+	if db.isClosed() {
 		return ErrClosed
 	}
 	return nil