diff options
Diffstat (limited to 'Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/db_transaction.go')
-rw-r--r-- | Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/db_transaction.go | 289 |
1 files changed, 289 insertions, 0 deletions
diff --git a/Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/db_transaction.go b/Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/db_transaction.go new file mode 100644 index 000000000..527028756 --- /dev/null +++ b/Godeps/_workspace/src/github.com/syndtr/goleveldb/leveldb/db_transaction.go @@ -0,0 +1,289 @@ +// Copyright (c) 2016, Suryandaru Triandana <syndtr@gmail.com> +// All rights reserved. +// +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. + +package leveldb + +import ( + "errors" + "sync" + "time" + + "github.com/syndtr/goleveldb/leveldb/iterator" + "github.com/syndtr/goleveldb/leveldb/opt" + "github.com/syndtr/goleveldb/leveldb/util" +) + +var errTransactionDone = errors.New("leveldb: transaction already closed") + +// Transaction is the transaction handle. +type Transaction struct { + db *DB + lk sync.RWMutex + seq uint64 + mem *memDB + tables tFiles + ikScratch []byte + rec sessionRecord + stats cStatStaging + closed bool +} + +// Get gets the value for the given key. It returns ErrNotFound if the +// DB does not contains the key. +// +// The returned slice is its own copy, it is safe to modify the contents +// of the returned slice. +// It is safe to modify the contents of the argument after Get returns. +func (tr *Transaction) Get(key []byte, ro *opt.ReadOptions) ([]byte, error) { + tr.lk.RLock() + defer tr.lk.RUnlock() + if tr.closed { + return nil, errTransactionDone + } + return tr.db.get(tr.mem.DB, tr.tables, key, tr.seq, ro) +} + +// Has returns true if the DB does contains the given key. +// +// It is safe to modify the contents of the argument after Has returns. +func (tr *Transaction) Has(key []byte, ro *opt.ReadOptions) (bool, error) { + tr.lk.RLock() + defer tr.lk.RUnlock() + if tr.closed { + return false, errTransactionDone + } + return tr.db.has(tr.mem.DB, tr.tables, key, tr.seq, ro) +} + +// 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. +// It is also safe to use an iterator concurrently while writes to the +// transaction. The resultant key/value pairs are guaranteed to be consistent. +// +// Slice allows slicing the iterator to only contains keys in the given +// range. A nil Range.Start is treated as a key before all keys in the +// DB. And a nil Range.Limit is treated as a key after all keys in +// the DB. +// +// The iterator must be released after use, by calling Release method. +// +// Also read Iterator documentation of the leveldb/iterator package. +func (tr *Transaction) NewIterator(slice *util.Range, ro *opt.ReadOptions) iterator.Iterator { + tr.lk.RLock() + defer tr.lk.RUnlock() + if tr.closed { + return iterator.NewEmptyIterator(errTransactionDone) + } + tr.mem.incref() + return tr.db.newIterator(tr.mem, tr.tables, tr.seq, slice, ro) +} + +func (tr *Transaction) flush() error { + // Flush memdb. + if tr.mem.Len() != 0 { + tr.stats.startTimer() + iter := tr.mem.NewIterator(nil) + t, n, err := tr.db.s.tops.createFrom(iter) + iter.Release() + tr.stats.stopTimer() + if err != nil { + return err + } + if tr.mem.getref() == 1 { + tr.mem.Reset() + } else { + tr.mem.decref() + tr.mem = tr.db.mpoolGet(0) + tr.mem.incref() + } + tr.tables = append(tr.tables, t) + tr.rec.addTableFile(0, t) + tr.stats.write += t.size + tr.db.logf("transaction@flush created L0@%d N·%d S·%s %q:%q", t.fd.Num, n, shortenb(int(t.size)), t.imin, t.imax) + } + return nil +} + +func (tr *Transaction) put(kt kType, key, value []byte) error { + tr.ikScratch = makeIkey(tr.ikScratch, key, tr.seq+1, kt) + if tr.mem.Free() < len(tr.ikScratch)+len(value) { + if err := tr.flush(); err != nil { + return err + } + } + if err := tr.mem.Put(tr.ikScratch, value); err != nil { + return err + } + tr.seq++ + return nil +} + +// Put sets the value for the given key. It overwrites any previous value +// for that key; a DB is not a multi-map. +// Please note that the transaction is not compacted until committed, so if you +// writes 10 same keys, then those 10 same keys are in the transaction. +// +// It is safe to modify the contents of the arguments after Put returns. +func (tr *Transaction) Put(key, value []byte, wo *opt.WriteOptions) error { + tr.lk.Lock() + defer tr.lk.Unlock() + if tr.closed { + return errTransactionDone + } + return tr.put(ktVal, key, value) +} + +// Delete deletes the value for the given key. +// Please note that the transaction is not compacted until committed, so if you +// writes 10 same keys, then those 10 same keys are in the transaction. +// +// It is safe to modify the contents of the arguments after Delete returns. +func (tr *Transaction) Delete(key []byte, wo *opt.WriteOptions) error { + tr.lk.Lock() + defer tr.lk.Unlock() + if tr.closed { + return errTransactionDone + } + return tr.put(ktDel, key, nil) +} + +// Write apply the given batch to the transaction. The batch will be applied +// sequentially. +// Please note that the transaction is not compacted until committed, so if you +// writes 10 same keys, then those 10 same keys are in the transaction. +// +// It is safe to modify the contents of the arguments after Write returns. +func (tr *Transaction) Write(b *Batch, wo *opt.WriteOptions) error { + if b == nil || b.Len() == 0 { + return nil + } + + tr.lk.Lock() + defer tr.lk.Unlock() + if tr.closed { + return errTransactionDone + } + return b.decodeRec(func(i int, kt kType, key, value []byte) error { + return tr.put(kt, key, value) + }) +} + +func (tr *Transaction) setDone() { + tr.closed = true + tr.db.tr = nil + tr.mem.decref() + <-tr.db.writeLockC +} + +// Commit commits the transaction. +// +// Other methods should not be called after transaction has been committed. +func (tr *Transaction) Commit() error { + if err := tr.db.ok(); err != nil { + return err + } + + tr.lk.Lock() + defer tr.lk.Unlock() + if tr.closed { + return errTransactionDone + } + defer tr.setDone() + if err := tr.flush(); err != nil { + tr.discard() + return err + } + if len(tr.tables) != 0 { + // Committing transaction. + tr.rec.setSeqNum(tr.seq) + tr.db.compCommitLk.Lock() + defer tr.db.compCommitLk.Unlock() + 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) + select { + case <-time.After(time.Second): + case _, _ = <-tr.db.closeC: + tr.db.logf("transaction@commit exiting") + return err + } + } else { + // Success. Set db.seq. + tr.db.setSeq(tr.seq) + break + } + } + // Trigger table auto-compaction. + tr.db.compTrigger(tr.db.tcompCmdC) + } + return nil +} + +func (tr *Transaction) discard() { + // Discard transaction. + for _, t := range tr.tables { + tr.db.logf("transaction@discard @%d", t.fd.Num) + if err1 := tr.db.s.stor.Remove(t.fd); err1 == nil { + tr.db.s.reuseFileNum(t.fd.Num) + } + } +} + +// Discard discards the transaction. +// +// Other methods should not be called after transaction has been discarded. +func (tr *Transaction) Discard() { + tr.lk.Lock() + if !tr.closed { + tr.discard() + tr.setDone() + } + tr.lk.Unlock() +} + +// 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. +// +// The transaction must be closed once done, either by committing or discarding +// the transaction. +// Closing the DB will discard open transaction. +func (db *DB) OpenTransaction() (*Transaction, error) { + if err := db.ok(); err != nil { + return nil, err + } + + // The write happen synchronously. + select { + case db.writeLockC <- struct{}{}: + case err := <-db.compPerErrC: + return nil, err + case _, _ = <-db.closeC: + return nil, ErrClosed + } + + if db.tr != nil { + panic("leveldb: has open transaction") + } + + // Flush current memdb. + if db.mem != nil && db.mem.Len() != 0 { + if _, err := db.rotateMem(0, true); err != nil { + return nil, err + } + } + + tr := &Transaction{ + db: db, + seq: db.seq, + mem: db.mpoolGet(0), + } + tr.mem.incref() + db.tr = tr + return tr, nil +} |