rocksdb/utilities/transactions/optimistic_transaction_impl.cc
agiardullo def74f8763 Deferred snapshot creation in transactions
Summary: Support for Transaction::CreateSnapshotOnNextOperation().  This is to fix a write-conflict race-condition that Yoshinori was running into when testing MyRocks with LinkBench.

Test Plan: New tests

Reviewers: yhchiang, spetrunia, rven, igor, yoshinorim, sdong

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D48099
2015-10-09 15:46:16 -07:00

112 lines
3.2 KiB
C++

// Copyright (c) 2015, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
#ifndef ROCKSDB_LITE
#include "utilities/transactions/optimistic_transaction_impl.h"
#include <algorithm>
#include <string>
#include <vector>
#include "db/column_family.h"
#include "db/db_impl.h"
#include "rocksdb/comparator.h"
#include "rocksdb/db.h"
#include "rocksdb/status.h"
#include "rocksdb/utilities/optimistic_transaction_db.h"
#include "util/string_util.h"
#include "utilities/transactions/transaction_util.h"
namespace rocksdb {
struct WriteOptions;
OptimisticTransactionImpl::OptimisticTransactionImpl(
OptimisticTransactionDB* txn_db, const WriteOptions& write_options,
const OptimisticTransactionOptions& txn_options)
: TransactionBaseImpl(txn_db->GetBaseDB(), write_options), txn_db_(txn_db) {
if (txn_options.set_snapshot) {
SetSnapshot();
}
}
OptimisticTransactionImpl::~OptimisticTransactionImpl() {
}
void OptimisticTransactionImpl::Clear() {
TransactionBaseImpl::Clear();
}
Status OptimisticTransactionImpl::Commit() {
// Set up callback which will call CheckTransactionForConflicts() to
// check whether this transaction is safe to be committed.
OptimisticTransactionCallback callback(this);
DBImpl* db_impl = dynamic_cast<DBImpl*>(db_->GetRootDB());
if (db_impl == nullptr) {
// This should only happen if we support creating transactions from
// a StackableDB and someone overrides GetRootDB().
return Status::InvalidArgument(
"DB::GetRootDB() returned an unexpected DB class");
}
Status s = db_impl->WriteWithCallback(
write_options_, write_batch_->GetWriteBatch(), &callback);
if (s.ok()) {
Clear();
}
return s;
}
void OptimisticTransactionImpl::Rollback() { Clear(); }
// Record this key so that we can check it for conflicts at commit time.
Status OptimisticTransactionImpl::TryLock(ColumnFamilyHandle* column_family,
const Slice& key, bool untracked) {
if (untracked) {
return Status::OK();
}
uint32_t cfh_id = GetColumnFamilyID(column_family);
SetSnapshotIfNeeded();
SequenceNumber seq;
if (snapshot_) {
seq = snapshot_->snapshot()->GetSequenceNumber();
} else {
seq = db_->GetLatestSequenceNumber();
}
std::string key_str = key.ToString();
TrackKey(cfh_id, key_str, seq);
// Always return OK. Confilct checking will happen at commit time.
return Status::OK();
}
// Returns OK if it is safe to commit this transaction. Returns Status::Busy
// if there are read or write conflicts that would prevent us from committing OR
// if we can not determine whether there would be any such conflicts.
//
// Should only be called on writer thread in order to avoid any race conditions
// in detecting
// write conflicts.
Status OptimisticTransactionImpl::CheckTransactionForConflicts(DB* db) {
Status result;
assert(dynamic_cast<DBImpl*>(db) != nullptr);
auto db_impl = reinterpret_cast<DBImpl*>(db);
return TransactionUtil::CheckKeysForConflicts(db_impl, GetTrackedKeys());
}
} // namespace rocksdb
#endif // ROCKSDB_LITE