Summary: Implement the rollback of WritePrepared txns. For each modified value, it reads the value before the txn and write it back. This would cancel out the effect of transaction. It also remove the rolled back txn from prepared heap. Closes https://github.com/facebook/rocksdb/pull/2946 Differential Revision: D5937575 Pulled By: maysamyabandeh fbshipit-source-id: a6d3c47f44db3729f44b287a80f97d08dc4e888d
199 lines
7.5 KiB
C++
199 lines
7.5 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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#ifndef ROCKSDB_LITE
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#include "utilities/transactions/write_prepared_txn.h"
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#include <map>
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#include "db/column_family.h"
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#include "db/db_impl.h"
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#include "rocksdb/db.h"
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#include "rocksdb/status.h"
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#include "rocksdb/utilities/transaction_db.h"
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#include "utilities/transactions/pessimistic_transaction.h"
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#include "utilities/transactions/pessimistic_transaction_db.h"
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namespace rocksdb {
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struct WriteOptions;
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WritePreparedTxn::WritePreparedTxn(WritePreparedTxnDB* txn_db,
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const WriteOptions& write_options,
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const TransactionOptions& txn_options)
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: PessimisticTransaction(txn_db, write_options, txn_options),
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wpt_db_(txn_db) {
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PessimisticTransaction::Initialize(txn_options);
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}
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Status WritePreparedTxn::Get(const ReadOptions& read_options,
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ColumnFamilyHandle* column_family,
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const Slice& key, PinnableSlice* pinnable_val) {
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auto snapshot = GetSnapshot();
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auto snap_seq =
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snapshot != nullptr ? snapshot->GetSequenceNumber() : kMaxSequenceNumber;
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WritePreparedTxnReadCallback callback(wpt_db_, snap_seq);
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return write_batch_.GetFromBatchAndDB(db_, read_options, column_family, key,
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pinnable_val, &callback);
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}
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Status WritePreparedTxn::PrepareInternal() {
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WriteOptions write_options = write_options_;
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write_options.disableWAL = false;
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WriteBatchInternal::MarkEndPrepare(GetWriteBatch()->GetWriteBatch(), name_);
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const bool disable_memtable = true;
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uint64_t seq_used = kMaxSequenceNumber;
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Status s =
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db_impl_->WriteImpl(write_options, GetWriteBatch()->GetWriteBatch(),
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/*callback*/ nullptr, &log_number_, /*log ref*/ 0,
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!disable_memtable, &seq_used);
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assert(seq_used != kMaxSequenceNumber);
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auto prepare_seq = seq_used;
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SetId(prepare_seq);
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wpt_db_->AddPrepared(prepare_seq);
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return s;
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}
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Status WritePreparedTxn::CommitWithoutPrepareInternal() {
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return CommitBatchInternal(GetWriteBatch()->GetWriteBatch());
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}
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Status WritePreparedTxn::CommitBatchInternal(WriteBatch* batch) {
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// In the absense of Prepare markers, use Noop as a batch separator
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WriteBatchInternal::InsertNoop(batch);
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const bool disable_memtable = true;
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const uint64_t no_log_ref = 0;
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uint64_t seq_used = kMaxSequenceNumber;
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auto s = db_impl_->WriteImpl(write_options_, batch, nullptr, nullptr,
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no_log_ref, !disable_memtable, &seq_used);
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assert(seq_used != kMaxSequenceNumber);
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uint64_t& prepare_seq = seq_used;
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uint64_t& commit_seq = seq_used;
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// TODO(myabandeh): skip AddPrepared
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wpt_db_->AddPrepared(prepare_seq);
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wpt_db_->AddCommitted(prepare_seq, commit_seq);
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return s;
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}
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Status WritePreparedTxn::CommitInternal() {
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// We take the commit-time batch and append the Commit marker.
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// The Memtable will ignore the Commit marker in non-recovery mode
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WriteBatch* working_batch = GetCommitTimeWriteBatch();
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// TODO(myabandeh): prevent the users from writing to txn after the prepare
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// phase
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assert(working_batch->Count() == 0);
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WriteBatchInternal::MarkCommit(working_batch, name_);
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// any operations appended to this working_batch will be ignored from WAL
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working_batch->MarkWalTerminationPoint();
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const bool disable_memtable = true;
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uint64_t seq_used = kMaxSequenceNumber;
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// Since the prepared batch is directly written to memtable, there is already
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// a connection between the memtable and its WAL, so there is no need to
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// redundantly reference the log that contains the prepared data.
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const uint64_t zero_log_number = 0ull;
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auto s = db_impl_->WriteImpl(write_options_, working_batch, nullptr, nullptr,
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zero_log_number, disable_memtable, &seq_used);
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assert(seq_used != kMaxSequenceNumber);
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uint64_t& commit_seq = seq_used;
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// TODO(myabandeh): Reject a commit request if AddCommitted cannot encode
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// commit_seq. This happens if prep_seq <<< commit_seq.
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auto prepare_seq = GetId();
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wpt_db_->AddCommitted(prepare_seq, commit_seq);
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return s;
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}
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Status WritePreparedTxn::RollbackInternal() {
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WriteBatch rollback_batch;
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assert(GetId() != kMaxSequenceNumber);
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assert(GetId() > 0);
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// In the absense of Prepare markers, use Noop as a batch separator
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WriteBatchInternal::InsertNoop(&rollback_batch);
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// In WritePrepared, the txn is is the same as prepare seq
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auto last_visible_txn = GetId() - 1;
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struct RollbackWriteBatchBuilder : public WriteBatch::Handler {
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DBImpl* db_;
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ReadOptions roptions;
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WritePreparedTxnReadCallback callback;
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WriteBatch* rollback_batch_;
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RollbackWriteBatchBuilder(DBImpl* db, WritePreparedTxnDB* wpt_db,
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SequenceNumber snap_seq, WriteBatch* dst_batch)
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: db_(db), callback(wpt_db, snap_seq), rollback_batch_(dst_batch) {}
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Status Rollback(uint32_t cf, const Slice& key) {
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PinnableSlice pinnable_val;
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bool not_used;
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auto cf_handle = db_->GetColumnFamilyHandle(cf);
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auto s = db_->GetImpl(roptions, cf_handle, key, &pinnable_val, ¬_used,
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&callback);
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assert(s.ok() || s.IsNotFound());
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if (s.ok()) {
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s = rollback_batch_->Put(cf_handle, key, pinnable_val);
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assert(s.ok());
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} else if (s.IsNotFound()) {
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// There has been no readable value before txn. By adding a delete we
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// make sure that there will be none afterwards either.
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s = rollback_batch_->Delete(cf_handle, key);
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assert(s.ok());
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} else {
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// Unexpected status. Return it to the user.
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}
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return s;
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}
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Status PutCF(uint32_t cf, const Slice& key, const Slice& val) override {
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return Rollback(cf, key);
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}
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Status DeleteCF(uint32_t cf, const Slice& key) override {
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return Rollback(cf, key);
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}
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Status SingleDeleteCF(uint32_t cf, const Slice& key) override {
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return Rollback(cf, key);
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}
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Status MergeCF(uint32_t cf, const Slice& key, const Slice& val) override {
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return Rollback(cf, key);
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}
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Status MarkNoop(bool) override { return Status::OK(); }
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Status MarkBeginPrepare() override { return Status::OK(); }
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Status MarkEndPrepare(const Slice&) override { return Status::OK(); }
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Status MarkCommit(const Slice&) override { return Status::OK(); }
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Status MarkRollback(const Slice&) override {
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return Status::InvalidArgument();
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}
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} rollback_handler(db_impl_, wpt_db_, last_visible_txn, &rollback_batch);
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auto s = GetWriteBatch()->GetWriteBatch()->Iterate(&rollback_handler);
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assert(s.ok());
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if (!s.ok()) {
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return s;
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}
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WriteBatchInternal::MarkRollback(&rollback_batch, name_);
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const bool disable_memtable = true;
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const uint64_t no_log_ref = 0;
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uint64_t seq_used = kMaxSequenceNumber;
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s = db_impl_->WriteImpl(write_options_, &rollback_batch, nullptr, nullptr,
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no_log_ref, !disable_memtable, &seq_used);
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assert(seq_used != kMaxSequenceNumber);
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uint64_t& prepare_seq = seq_used;
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uint64_t& commit_seq = seq_used;
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// TODO(myabandeh): skip AddPrepared
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wpt_db_->AddPrepared(prepare_seq);
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wpt_db_->AddCommitted(prepare_seq, commit_seq);
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// Mark the txn as rolled back
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wpt_db_->RollbackPrepared(GetId(), commit_seq);
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return s;
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}
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} // namespace rocksdb
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#endif // ROCKSDB_LITE
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