rocksdb/utilities/transactions/transaction_base.h

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// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
#pragma once
#ifndef ROCKSDB_LITE
#include <stack>
#include <string>
#include <vector>
#include "db/write_batch_internal.h"
#include "rocksdb/db.h"
#include "rocksdb/slice.h"
#include "rocksdb/snapshot.h"
#include "rocksdb/status.h"
#include "rocksdb/types.h"
#include "rocksdb/utilities/transaction.h"
#include "rocksdb/utilities/transaction_db.h"
#include "rocksdb/utilities/write_batch_with_index.h"
refactor SavePoints (#5192) Summary: Savepoints are assumed to be used in a stack-wise fashion (only the top element should be used), so they were stored by `WriteBatch` in a member variable `save_points` using an std::stack. Conceptually this is fine, but the implementation had a few issues: - the `save_points_` instance variable was a plain pointer to a heap- allocated `SavePoints` struct. The destructor of `WriteBatch` simply deletes this pointer. However, the copy constructor of WriteBatch just copied that pointer, meaning that copying a WriteBatch with active savepoints will very likely have crashed before. Now a proper copy of the savepoints is made in the copy constructor, and not just a copy of the pointer - `save_points_` was an std::stack, which defaults to `std::deque` for the underlying container. A deque is a bit over the top here, as we only need access to the most recent savepoint (i.e. stack.top()) but never any elements at the front. std::deque is rather expensive to initialize in common environments. For example, the STL implementation shipped with GNU g++ will perform a heap allocation of more than 500 bytes to create an empty deque object. Although the `save_points_` container is created lazily by RocksDB, moving from a deque to a plain `std::vector` is much more memory-efficient. So `save_points_` is now a vector. - `save_points_` was changed from a plain pointer to an `std::unique_ptr`, making ownership more explicit. Pull Request resolved: https://github.com/facebook/rocksdb/pull/5192 Differential Revision: D15024074 Pulled By: maysamyabandeh fbshipit-source-id: 5b128786d3789cde94e46465c9e91badd07a25d7
2019-04-20 05:30:03 +02:00
#include "util/autovector.h"
#include "utilities/transactions/transaction_util.h"
namespace ROCKSDB_NAMESPACE {
class TransactionBaseImpl : public Transaction {
public:
TransactionBaseImpl(DB* db, const WriteOptions& write_options);
virtual ~TransactionBaseImpl();
// Remove pending operations queued in this transaction.
virtual void Clear();
void Reinitialize(DB* db, const WriteOptions& write_options);
// Called before executing Put, Merge, Delete, and GetForUpdate. If TryLock
// returns non-OK, the Put/Merge/Delete/GetForUpdate will be failed.
// do_validate will be false if called from PutUntracked, DeleteUntracked,
// MergeUntracked, or GetForUpdate(do_validate=false)
virtual Status TryLock(ColumnFamilyHandle* column_family, const Slice& key,
bool read_only, bool exclusive,
const bool do_validate = true,
const bool assume_tracked = false) = 0;
void SetSavePoint() override;
Status RollbackToSavePoint() override;
Status PopSavePoint() override;
using Transaction::Get;
Status Get(const ReadOptions& options, ColumnFamilyHandle* column_family,
const Slice& key, std::string* value) override;
Status Get(const ReadOptions& options, ColumnFamilyHandle* column_family,
const Slice& key, PinnableSlice* value) override;
Status Get(const ReadOptions& options, const Slice& key,
std::string* value) override {
return Get(options, db_->DefaultColumnFamily(), key, value);
}
using Transaction::GetForUpdate;
Status GetForUpdate(const ReadOptions& options,
ColumnFamilyHandle* column_family, const Slice& key,
std::string* value, bool exclusive,
const bool do_validate) override;
Status GetForUpdate(const ReadOptions& options,
ColumnFamilyHandle* column_family, const Slice& key,
PinnableSlice* pinnable_val, bool exclusive,
const bool do_validate) override;
Status GetForUpdate(const ReadOptions& options, const Slice& key,
std::string* value, bool exclusive,
const bool do_validate) override {
return GetForUpdate(options, db_->DefaultColumnFamily(), key, value,
exclusive, do_validate);
}
using Transaction::MultiGet;
std::vector<Status> MultiGet(
const ReadOptions& options,
const std::vector<ColumnFamilyHandle*>& column_family,
const std::vector<Slice>& keys,
std::vector<std::string>* values) override;
std::vector<Status> MultiGet(const ReadOptions& options,
const std::vector<Slice>& keys,
std::vector<std::string>* values) override {
return MultiGet(options, std::vector<ColumnFamilyHandle*>(
keys.size(), db_->DefaultColumnFamily()),
keys, values);
}
void MultiGet(const ReadOptions& options, ColumnFamilyHandle* column_family,
const size_t num_keys, const Slice* keys, PinnableSlice* values,
Status* statuses, const bool sorted_input = false) override;
using Transaction::MultiGetForUpdate;
std::vector<Status> MultiGetForUpdate(
const ReadOptions& options,
const std::vector<ColumnFamilyHandle*>& column_family,
const std::vector<Slice>& keys,
std::vector<std::string>* values) override;
std::vector<Status> MultiGetForUpdate(
const ReadOptions& options, const std::vector<Slice>& keys,
std::vector<std::string>* values) override {
return MultiGetForUpdate(options,
std::vector<ColumnFamilyHandle*>(
keys.size(), db_->DefaultColumnFamily()),
keys, values);
}
Iterator* GetIterator(const ReadOptions& read_options) override;
Iterator* GetIterator(const ReadOptions& read_options,
ColumnFamilyHandle* column_family) override;
Status Put(ColumnFamilyHandle* column_family, const Slice& key,
const Slice& value, const bool assume_tracked = false) override;
Status Put(const Slice& key, const Slice& value) override {
return Put(nullptr, key, value);
}
Status Put(ColumnFamilyHandle* column_family, const SliceParts& key,
const SliceParts& value,
const bool assume_tracked = false) override;
Status Put(const SliceParts& key, const SliceParts& value) override {
return Put(nullptr, key, value);
}
Status Merge(ColumnFamilyHandle* column_family, const Slice& key,
const Slice& value, const bool assume_tracked = false) override;
Status Merge(const Slice& key, const Slice& value) override {
return Merge(nullptr, key, value);
}
Status Delete(ColumnFamilyHandle* column_family, const Slice& key,
const bool assume_tracked = false) override;
Status Delete(const Slice& key) override { return Delete(nullptr, key); }
Status Delete(ColumnFamilyHandle* column_family, const SliceParts& key,
const bool assume_tracked = false) override;
Status Delete(const SliceParts& key) override { return Delete(nullptr, key); }
Status SingleDelete(ColumnFamilyHandle* column_family, const Slice& key,
const bool assume_tracked = false) override;
Status SingleDelete(const Slice& key) override {
return SingleDelete(nullptr, key);
}
Status SingleDelete(ColumnFamilyHandle* column_family, const SliceParts& key,
const bool assume_tracked = false) override;
Status SingleDelete(const SliceParts& key) override {
return SingleDelete(nullptr, key);
}
Status PutUntracked(ColumnFamilyHandle* column_family, const Slice& key,
const Slice& value) override;
Status PutUntracked(const Slice& key, const Slice& value) override {
return PutUntracked(nullptr, key, value);
}
Status PutUntracked(ColumnFamilyHandle* column_family, const SliceParts& key,
const SliceParts& value) override;
Status PutUntracked(const SliceParts& key, const SliceParts& value) override {
return PutUntracked(nullptr, key, value);
}
Status MergeUntracked(ColumnFamilyHandle* column_family, const Slice& key,
const Slice& value) override;
Status MergeUntracked(const Slice& key, const Slice& value) override {
return MergeUntracked(nullptr, key, value);
}
Status DeleteUntracked(ColumnFamilyHandle* column_family,
const Slice& key) override;
Status DeleteUntracked(const Slice& key) override {
return DeleteUntracked(nullptr, key);
}
Status DeleteUntracked(ColumnFamilyHandle* column_family,
const SliceParts& key) override;
Status DeleteUntracked(const SliceParts& key) override {
return DeleteUntracked(nullptr, key);
}
Status SingleDeleteUntracked(ColumnFamilyHandle* column_family,
const Slice& key) override;
Status SingleDeleteUntracked(const Slice& key) override {
return SingleDeleteUntracked(nullptr, key);
}
void PutLogData(const Slice& blob) override;
WriteBatchWithIndex* GetWriteBatch() override;
virtual void SetLockTimeout(int64_t /*timeout*/) override { /* Do nothing */
}
const Snapshot* GetSnapshot() const override {
return snapshot_ ? snapshot_.get() : nullptr;
}
virtual void SetSnapshot() override;
void SetSnapshotOnNextOperation(
std::shared_ptr<TransactionNotifier> notifier = nullptr) override;
void ClearSnapshot() override {
snapshot_.reset();
snapshot_needed_ = false;
snapshot_notifier_ = nullptr;
}
void DisableIndexing() override { indexing_enabled_ = false; }
void EnableIndexing() override { indexing_enabled_ = true; }
uint64_t GetElapsedTime() const override;
uint64_t GetNumPuts() const override;
uint64_t GetNumDeletes() const override;
uint64_t GetNumMerges() const override;
uint64_t GetNumKeys() const override;
void UndoGetForUpdate(ColumnFamilyHandle* column_family,
const Slice& key) override;
void UndoGetForUpdate(const Slice& key) override {
return UndoGetForUpdate(nullptr, key);
};
// Get list of keys in this transaction that must not have any conflicts
// with writes in other transactions.
const TransactionKeyMap& GetTrackedKeys() const { return tracked_keys_; }
WriteOptions* GetWriteOptions() override { return &write_options_; }
void SetWriteOptions(const WriteOptions& write_options) override {
write_options_ = write_options;
}
// Used for memory management for snapshot_
void ReleaseSnapshot(const Snapshot* snapshot, DB* db);
// iterates over the given batch and makes the appropriate inserts.
// used for rebuilding prepared transactions after recovery.
virtual Status RebuildFromWriteBatch(WriteBatch* src_batch) override;
WriteBatch* GetCommitTimeWriteBatch() override;
protected:
// Add a key to the list of tracked keys.
//
// seqno is the earliest seqno this key was involved with this transaction.
// readonly should be set to true if no data was written for this key
void TrackKey(uint32_t cfh_id, const std::string& key, SequenceNumber seqno,
bool readonly, bool exclusive);
// Helper function to add a key to the given TransactionKeyMap
static void TrackKey(TransactionKeyMap* key_map, uint32_t cfh_id,
const std::string& key, SequenceNumber seqno,
bool readonly, bool exclusive);
// Called when UndoGetForUpdate determines that this key can be unlocked.
virtual void UnlockGetForUpdate(ColumnFamilyHandle* column_family,
const Slice& key) = 0;
std::unique_ptr<TransactionKeyMap> GetTrackedKeysSinceSavePoint();
// Sets a snapshot if SetSnapshotOnNextOperation() has been called.
void SetSnapshotIfNeeded();
// Initialize write_batch_ for 2PC by inserting Noop.
inline void InitWriteBatch(bool clear = false) {
if (clear) {
write_batch_.Clear();
}
assert(write_batch_.GetDataSize() == WriteBatchInternal::kHeader);
WriteBatchInternal::InsertNoop(write_batch_.GetWriteBatch());
}
DB* db_;
DBImpl* dbimpl_;
WriteOptions write_options_;
const Comparator* cmp_;
// Stores that time the txn was constructed, in microseconds.
uint64_t start_time_;
// Stores the current snapshot that was set by SetSnapshot or null if
// no snapshot is currently set.
std::shared_ptr<const Snapshot> snapshot_;
// Count of various operations pending in this transaction
uint64_t num_puts_ = 0;
uint64_t num_deletes_ = 0;
uint64_t num_merges_ = 0;
struct SavePoint {
std::shared_ptr<const Snapshot> snapshot_;
bool snapshot_needed_ = false;
std::shared_ptr<TransactionNotifier> snapshot_notifier_;
uint64_t num_puts_ = 0;
uint64_t num_deletes_ = 0;
uint64_t num_merges_ = 0;
// Record all keys tracked since the last savepoint
TransactionKeyMap new_keys_;
SavePoint(std::shared_ptr<const Snapshot> snapshot, bool snapshot_needed,
std::shared_ptr<TransactionNotifier> snapshot_notifier,
uint64_t num_puts, uint64_t num_deletes, uint64_t num_merges)
: snapshot_(snapshot),
snapshot_needed_(snapshot_needed),
snapshot_notifier_(snapshot_notifier),
num_puts_(num_puts),
num_deletes_(num_deletes),
num_merges_(num_merges) {}
SavePoint() = default;
};
// Records writes pending in this transaction
WriteBatchWithIndex write_batch_;
// Map from column_family_id to map of keys that are involved in this
// transaction.
// For Pessimistic Transactions this is the list of locked keys.
// Optimistic Transactions will wait till commit time to do conflict checking.
TransactionKeyMap tracked_keys_;
// Stack of the Snapshot saved at each save point. Saved snapshots may be
// nullptr if there was no snapshot at the time SetSavePoint() was called.
std::unique_ptr<std::stack<TransactionBaseImpl::SavePoint,
autovector<TransactionBaseImpl::SavePoint>>>
save_points_;
private:
friend class WritePreparedTxn;
// Extra data to be persisted with the commit. Note this is only used when
// prepare phase is not skipped.
WriteBatch commit_time_batch_;
// If true, future Put/Merge/Deletes will be indexed in the
// WriteBatchWithIndex.
// If false, future Put/Merge/Deletes will be inserted directly into the
// underlying WriteBatch and not indexed in the WriteBatchWithIndex.
bool indexing_enabled_;
// SetSnapshotOnNextOperation() has been called and the snapshot has not yet
// been reset.
bool snapshot_needed_ = false;
// SetSnapshotOnNextOperation() has been called and the caller would like
// a notification through the TransactionNotifier interface
std::shared_ptr<TransactionNotifier> snapshot_notifier_ = nullptr;
Status TryLock(ColumnFamilyHandle* column_family, const SliceParts& key,
bool read_only, bool exclusive, const bool do_validate = true,
const bool assume_tracked = false);
WriteBatchBase* GetBatchForWrite();
void SetSnapshotInternal(const Snapshot* snapshot);
};
} // namespace ROCKSDB_NAMESPACE
#endif // ROCKSDB_LITE