예제 #1
0
파일: db_write.go 프로젝트: hsk81/goleveldb
// Write apply the given batch to the DB. The batch will be applied
// sequentially.
//
// It is safe to modify the contents of the arguments after Write returns.
func (d *DB) Write(b *Batch, wo *opt.WriteOptions) (err error) {
	err = d.ok()
	if err != nil || b == nil || b.len() == 0 {
		return
	}

	b.init(wo.GetSync())

	// The write happen synchronously.
	select {
	case _, _ = <-d.closeCh:
		return ErrClosed
	case d.writeCh <- b:
		return <-d.writeAckCh
	case d.writeLockCh <- struct{}{}:
	}

	merged := 0
	defer func() {
		<-d.writeLockCh
		for i := 0; i < merged; i++ {
			d.writeAckCh <- err
		}
	}()

	mem, err := d.flush()
	if err != nil {
		return
	}

	// Calculate maximum size of the batch.
	m := 1 << 20
	if x := b.size(); x <= 128<<10 {
		m = x + (128 << 10)
	}

	// Merge with other batch.
drain:
	for b.size() <= m && !b.sync {
		select {
		case nb := <-d.writeCh:
			b.append(nb)
			merged++
		default:
			break drain
		}
	}

	// Set batch first seq number relative from last seq.
	b.seq = d.seq + 1

	// Write journal concurrently if it is large enough.
	if b.size() >= (128 << 10) {
		// Push the write batch to the journal writer
		select {
		case _, _ = <-d.closeCh:
			err = ErrClosed
			return
		case d.journalCh <- b:
			// Write into memdb
			b.memReplay(mem)
		}
		// Wait for journal writer
		select {
		case _, _ = <-d.closeCh:
			err = ErrClosed
			return
		case err = <-d.journalAckCh:
			if err != nil {
				// Revert memdb if error detected
				b.revertMemReplay(mem)
				return
			}
		}
	} else {
		err = d.doWriteJournal(b)
		if err != nil {
			return
		}
		b.memReplay(mem)
	}

	// Set last seq number.
	d.addSeq(uint64(b.len()))
	return
}
예제 #2
0
// Write apply the given batch to the DB. The batch will be applied
// sequentially.
//
// It is safe to modify the contents of the arguments after Write returns.
func (db *DB) Write(b *Batch, wo *opt.WriteOptions) (err error) {
	err = db.ok()
	if err != nil || b == nil || b.len() == 0 {
		return
	}

	b.init(wo.GetSync())

	// The write happen synchronously.
retry:
	select {
	case db.writeC <- b:
		if <-db.writeMergedC {
			return <-db.writeAckC
		}
		goto retry
	case db.writeLockC <- struct{}{}:
	case _, _ = <-db.closeC:
		return ErrClosed
	}

	merged := 0
	defer func() {
		<-db.writeLockC
		for i := 0; i < merged; i++ {
			db.writeAckC <- err
		}
	}()

	mem, memFree, err := db.flush(b.size())
	if err != nil {
		return
	}

	// Calculate maximum size of the batch.
	m := 1 << 20
	if x := b.size(); x <= 128<<10 {
		m = x + (128 << 10)
	}
	m = minInt(m, memFree)

	// Merge with other batch.
drain:
	for b.size() < m && !b.sync {
		select {
		case nb := <-db.writeC:
			if b.size()+nb.size() <= m {
				b.append(nb)
				db.writeMergedC <- true
				merged++
			} else {
				db.writeMergedC <- false
				break drain
			}
		default:
			break drain
		}
	}

	// Set batch first seq number relative from last seq.
	b.seq = db.seq + 1

	// Write journal concurrently if it is large enough.
	if b.size() >= (128 << 10) {
		// Push the write batch to the journal writer
		select {
		case _, _ = <-db.closeC:
			err = ErrClosed
			return
		case db.journalC <- b:
			// Write into memdb
			b.memReplay(mem)
		}
		// Wait for journal writer
		select {
		case _, _ = <-db.closeC:
			err = ErrClosed
			return
		case err = <-db.journalAckC:
			if err != nil {
				// Revert memdb if error detected
				b.revertMemReplay(mem)
				return
			}
		}
	} else {
		err = db.writeJournal(b)
		if err != nil {
			return
		}
		b.memReplay(mem)
	}

	// Set last seq number.
	db.addSeq(uint64(b.len()))

	if b.size() >= memFree {
		db.rotateMem(0)
	}
	return
}