rocksdb/utilities/transactions/optimistic_transaction_impl.cc
agiardullo ca8b85ac04 better document max_write_buffer_number_to_maintain
Test Plan: compile

Reviewers: igor, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D39285
2015-06-02 21:24:19 -07:00

351 lines
11 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"
#ifndef __STDC_FORMAT_MACROS
#define __STDC_FORMAT_MACROS
#endif
#include <inttypes.h>
#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"
namespace rocksdb {
struct WriteOptions;
OptimisticTransactionImpl::OptimisticTransactionImpl(
OptimisticTransactionDB* txn_db, const WriteOptions& write_options,
const OptimisticTransactionOptions& txn_options)
: txn_db_(txn_db),
db_(txn_db->GetBaseDB()),
write_options_(write_options),
snapshot_(nullptr),
write_batch_(txn_options.cmp, 0, true) {
if (txn_options.set_snapshot) {
SetSnapshot();
} else {
start_sequence_number_ = db_->GetLatestSequenceNumber();
}
}
OptimisticTransactionImpl::~OptimisticTransactionImpl() {
tracked_keys_.clear();
if (snapshot_ != nullptr) {
db_->ReleaseSnapshot(snapshot_);
}
}
void OptimisticTransactionImpl::SetSnapshot() {
if (snapshot_ != nullptr) {
db_->ReleaseSnapshot(snapshot_);
}
snapshot_ = db_->GetSnapshot();
start_sequence_number_ = snapshot_->GetSequenceNumber();
}
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()) {
tracked_keys_.clear();
write_batch_.Clear();
}
return s;
}
void OptimisticTransactionImpl::Rollback() {
tracked_keys_.clear();
write_batch_.Clear();
}
// Record this key so that we can check it for conflicts at commit time.
void OptimisticTransactionImpl::RecordOperation(
ColumnFamilyHandle* column_family, const Slice& key) {
uint32_t cfh_id = GetColumnFamilyID(column_family);
SequenceNumber seq;
if (snapshot_) {
seq = start_sequence_number_;
} else {
seq = db_->GetLatestSequenceNumber();
}
std::string key_str = key.ToString();
auto iter = tracked_keys_[cfh_id].find(key_str);
if (iter == tracked_keys_[cfh_id].end()) {
// key not yet seen, store it.
tracked_keys_[cfh_id].insert({std::move(key_str), seq});
} else {
SequenceNumber old_seq = iter->second;
if (seq < old_seq) {
// Snapshot has changed since we last saw this key, need to
// store the earliest seen sequence number.
tracked_keys_[cfh_id][key_str] = seq;
}
}
}
void OptimisticTransactionImpl::RecordOperation(
ColumnFamilyHandle* column_family, const SliceParts& key) {
size_t key_size = 0;
for (int i = 0; i < key.num_parts; ++i) {
key_size += key.parts[i].size();
}
std::string str;
str.reserve(key_size);
for (int i = 0; i < key.num_parts; ++i) {
str.append(key.parts[i].data(), key.parts[i].size());
}
RecordOperation(column_family, str);
}
Status OptimisticTransactionImpl::Get(const ReadOptions& read_options,
ColumnFamilyHandle* column_family,
const Slice& key, std::string* value) {
return write_batch_.GetFromBatchAndDB(db_, read_options, column_family, key,
value);
}
Status OptimisticTransactionImpl::GetForUpdate(
const ReadOptions& read_options, ColumnFamilyHandle* column_family,
const Slice& key, std::string* value) {
// Regardless of whether the Get succeeded, track this key.
RecordOperation(column_family, key);
return Get(read_options, column_family, key, value);
}
std::vector<Status> OptimisticTransactionImpl::MultiGet(
const ReadOptions& read_options,
const std::vector<ColumnFamilyHandle*>& column_family,
const std::vector<Slice>& keys, std::vector<std::string>* values) {
// Regardless of whether the MultiGet succeeded, track these keys.
size_t num_keys = keys.size();
values->resize(num_keys);
// TODO(agiardullo): optimize multiget?
std::vector<Status> stat_list(num_keys);
for (size_t i = 0; i < num_keys; ++i) {
std::string* value = &(*values)[i];
stat_list[i] = Get(read_options, column_family[i], keys[i], value);
}
return stat_list;
}
std::vector<Status> OptimisticTransactionImpl::MultiGetForUpdate(
const ReadOptions& read_options,
const std::vector<ColumnFamilyHandle*>& column_family,
const std::vector<Slice>& keys, std::vector<std::string>* values) {
// Regardless of whether the MultiGet succeeded, track these keys.
size_t num_keys = keys.size();
values->resize(num_keys);
// TODO(agiardullo): optimize multiget?
std::vector<Status> stat_list(num_keys);
for (size_t i = 0; i < num_keys; ++i) {
// Regardless of whether the Get succeeded, track this key.
RecordOperation(column_family[i], keys[i]);
std::string* value = &(*values)[i];
stat_list[i] = Get(read_options, column_family[i], keys[i], value);
}
return stat_list;
}
void OptimisticTransactionImpl::Put(ColumnFamilyHandle* column_family,
const Slice& key, const Slice& value) {
RecordOperation(column_family, key);
write_batch_.Put(column_family, key, value);
}
void OptimisticTransactionImpl::Put(ColumnFamilyHandle* column_family,
const SliceParts& key,
const SliceParts& value) {
RecordOperation(column_family, key);
write_batch_.Put(column_family, key, value);
}
void OptimisticTransactionImpl::Merge(ColumnFamilyHandle* column_family,
const Slice& key, const Slice& value) {
RecordOperation(column_family, key);
write_batch_.Merge(column_family, key, value);
}
void OptimisticTransactionImpl::Delete(ColumnFamilyHandle* column_family,
const Slice& key) {
RecordOperation(column_family, key);
write_batch_.Delete(column_family, key);
}
void OptimisticTransactionImpl::Delete(ColumnFamilyHandle* column_family,
const SliceParts& key) {
RecordOperation(column_family, key);
write_batch_.Delete(column_family, key);
}
void OptimisticTransactionImpl::PutUntracked(ColumnFamilyHandle* column_family,
const Slice& key,
const Slice& value) {
write_batch_.Put(column_family, key, value);
}
void OptimisticTransactionImpl::PutUntracked(ColumnFamilyHandle* column_family,
const SliceParts& key,
const SliceParts& value) {
write_batch_.Put(column_family, key, value);
}
void OptimisticTransactionImpl::MergeUntracked(
ColumnFamilyHandle* column_family, const Slice& key, const Slice& value) {
write_batch_.Merge(column_family, key, value);
}
void OptimisticTransactionImpl::DeleteUntracked(
ColumnFamilyHandle* column_family, const Slice& key) {
write_batch_.Delete(column_family, key);
}
void OptimisticTransactionImpl::DeleteUntracked(
ColumnFamilyHandle* column_family, const SliceParts& key) {
write_batch_.Delete(column_family, key);
}
void OptimisticTransactionImpl::PutLogData(const Slice& blob) {
write_batch_.PutLogData(blob);
}
WriteBatchWithIndex* OptimisticTransactionImpl::GetWriteBatch() {
return &write_batch_;
}
// 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.
Status OptimisticTransactionImpl::CheckTransactionForConflicts(DB* db) {
Status result;
assert(dynamic_cast<DBImpl*>(db) != nullptr);
auto db_impl = reinterpret_cast<DBImpl*>(db);
for (auto& tracked_keys_iter : tracked_keys_) {
uint32_t cf_id = tracked_keys_iter.first;
const auto& keys = tracked_keys_iter.second;
SuperVersion* sv = db_impl->GetAndRefSuperVersion(cf_id);
if (sv == nullptr) {
result =
Status::Busy("Could not access column family " + ToString(cf_id));
break;
}
SequenceNumber earliest_seq =
db_impl->GetEarliestMemTableSequenceNumber(sv, true);
// For each of the keys in this transaction, check to see if someone has
// written to this key since the start of the transaction.
for (const auto& key_iter : keys) {
const auto& key = key_iter.first;
const SequenceNumber key_seq = key_iter.second;
// Since it would be too slow to check the SST files, we will only use
// the memtables to check whether there have been any recent writes
// to this key after it was accessed in this transaction. But if the
// Memtables do not contain a long enough history, we must fail the
// transaction.
if (earliest_seq == kMaxSequenceNumber) {
// The age of this memtable is unknown. Cannot rely on it to check
// for recent writes. This error shouldn't happen often in practice as
// the
// Memtable should have a valid earliest sequence number except in some
// corner cases (such as error cases during recovery).
result = Status::Busy(
"Could not commit transaction with as the MemTable does not "
"countain a long enough history to check write at SequenceNumber: ",
ToString(key_seq));
} else if (key_seq < earliest_seq) {
// The age of this memtable is too new to use to check for recent
// writes.
char msg[255];
snprintf(
msg, sizeof(msg),
"Could not commit transaction with write at SequenceNumber %" PRIu64
" as the MemTable only contains changes newer than SequenceNumber "
"%" PRIu64
". Increasing the value of the "
"max_write_buffer_number_to_maintain option could reduce the "
"frequency "
"of this error.",
key_seq, earliest_seq);
result = Status::Busy(msg);
} else {
SequenceNumber seq = kMaxSequenceNumber;
Status s = db_impl->GetLatestSequenceForKeyFromMemtable(sv, key, &seq);
if (!s.ok()) {
result = s;
} else if (seq != kMaxSequenceNumber && seq > key_seq) {
result = Status::Busy();
}
}
if (!result.ok()) {
break;
}
}
db_impl->ReturnAndCleanupSuperVersion(cf_id, sv);
if (!result.ok()) {
break;
}
}
return result;
}
} // namespace rocksdb
#endif // ROCKSDB_LITE