fork of https://github.com/oxigraph/rocksdb and https://github.com/facebook/rocksdb for nextgraph and oxigraph
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442 lines
19 KiB
442 lines
19 KiB
// 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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#ifndef __STDC_FORMAT_MACROS
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#define __STDC_FORMAT_MACROS
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#endif
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#include <inttypes.h>
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#include <map>
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#include <set>
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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 "util/cast_util.h"
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#include "utilities/transactions/pessimistic_transaction.h"
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#include "utilities/transactions/write_prepared_txn_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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void WritePreparedTxn::Initialize(const TransactionOptions& txn_options) {
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PessimisticTransaction::Initialize(txn_options);
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prepare_batch_cnt_ = 0;
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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 = read_options.snapshot;
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auto snap_seq =
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snapshot != nullptr ? snapshot->GetSequenceNumber() : kMaxSequenceNumber;
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SequenceNumber min_uncommitted = 0; // by default disable the optimization
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if (snapshot != nullptr) {
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min_uncommitted =
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static_cast_with_check<const SnapshotImpl, const Snapshot>(snapshot)
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->min_uncommitted_;
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}
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WritePreparedTxnReadCallback callback(wpt_db_, snap_seq, min_uncommitted);
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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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Iterator* WritePreparedTxn::GetIterator(const ReadOptions& options) {
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// Make sure to get iterator from WritePrepareTxnDB, not the root db.
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Iterator* db_iter = wpt_db_->NewIterator(options);
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assert(db_iter);
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return write_batch_.NewIteratorWithBase(db_iter);
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}
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Iterator* WritePreparedTxn::GetIterator(const ReadOptions& options,
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ColumnFamilyHandle* column_family) {
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// Make sure to get iterator from WritePrepareTxnDB, not the root db.
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Iterator* db_iter = wpt_db_->NewIterator(options, column_family);
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assert(db_iter);
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return write_batch_.NewIteratorWithBase(column_family, db_iter);
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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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const bool WRITE_AFTER_COMMIT = true;
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WriteBatchInternal::MarkEndPrepare(GetWriteBatch()->GetWriteBatch(), name_,
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!WRITE_AFTER_COMMIT);
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// For each duplicate key we account for a new sub-batch
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prepare_batch_cnt_ = GetWriteBatch()->SubBatchCnt();
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// AddPrepared better to be called in the pre-release callback otherwise there
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// is a non-zero chance of max advancing prepare_seq and readers assume the
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// data as committed.
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// Also having it in the PreReleaseCallback allows in-order addition of
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// prepared entries to PrepareHeap and hence enables an optimization. Refer to
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// SmallestUnCommittedSeq for more details.
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AddPreparedCallback add_prepared_callback(
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wpt_db_, prepare_batch_cnt_,
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db_impl_->immutable_db_options().two_write_queues);
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const bool DISABLE_MEMTABLE = true;
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uint64_t seq_used = kMaxSequenceNumber;
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Status s = db_impl_->WriteImpl(
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write_options, GetWriteBatch()->GetWriteBatch(),
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/*callback*/ nullptr, &log_number_, /*log ref*/ 0, !DISABLE_MEMTABLE,
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&seq_used, prepare_batch_cnt_, &add_prepared_callback);
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assert(!s.ok() || seq_used != kMaxSequenceNumber);
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auto prepare_seq = seq_used;
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SetId(prepare_seq);
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return s;
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}
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Status WritePreparedTxn::CommitWithoutPrepareInternal() {
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// For each duplicate key we account for a new sub-batch
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const size_t batch_cnt = GetWriteBatch()->SubBatchCnt();
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return CommitBatchInternal(GetWriteBatch()->GetWriteBatch(), batch_cnt);
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}
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Status WritePreparedTxn::CommitBatchInternal(WriteBatch* batch,
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size_t batch_cnt) {
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return wpt_db_->WriteInternal(write_options_, batch, batch_cnt, this);
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}
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Status WritePreparedTxn::CommitInternal() {
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ROCKS_LOG_DETAILS(db_impl_->immutable_db_options().info_log,
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"CommitInternal prepare_seq: %" PRIu64, GetID());
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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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const bool empty = working_batch->Count() == 0;
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WriteBatchInternal::MarkCommit(working_batch, name_);
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const bool for_recovery = use_only_the_last_commit_time_batch_for_recovery_;
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if (!empty && for_recovery) {
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// When not writing to memtable, we can still cache the latest write batch.
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// The cached batch will be written to memtable in WriteRecoverableState
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// during FlushMemTable
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WriteBatchInternal::SetAsLastestPersistentState(working_batch);
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}
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auto prepare_seq = GetId();
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const bool includes_data = !empty && !for_recovery;
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assert(prepare_batch_cnt_);
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size_t commit_batch_cnt = 0;
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if (UNLIKELY(includes_data)) {
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ROCKS_LOG_WARN(db_impl_->immutable_db_options().info_log,
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"Duplicate key overhead");
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SubBatchCounter counter(*wpt_db_->GetCFComparatorMap());
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auto s = working_batch->Iterate(&counter);
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assert(s.ok());
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commit_batch_cnt = counter.BatchCount();
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}
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const bool disable_memtable = !includes_data;
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const bool do_one_write =
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!db_impl_->immutable_db_options().two_write_queues || disable_memtable;
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const bool publish_seq = do_one_write;
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// Note: CommitTimeWriteBatch does not need AddPrepared since it is written to
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// DB in one shot. min_uncommitted still works since it requires capturing
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// data that is written to DB but not yet committed, while
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// CommitTimeWriteBatch commits with PreReleaseCallback.
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WritePreparedCommitEntryPreReleaseCallback update_commit_map(
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wpt_db_, db_impl_, prepare_seq, prepare_batch_cnt_, commit_batch_cnt,
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publish_seq);
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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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size_t batch_cnt = UNLIKELY(commit_batch_cnt) ? commit_batch_cnt : 1;
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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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batch_cnt, &update_commit_map);
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assert(!s.ok() || seq_used != kMaxSequenceNumber);
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if (LIKELY(do_one_write || !s.ok())) {
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if (LIKELY(s.ok())) {
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// Note RemovePrepared should be called after WriteImpl that publishsed
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// the seq. Otherwise SmallestUnCommittedSeq optimization breaks.
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wpt_db_->RemovePrepared(prepare_seq, prepare_batch_cnt_);
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}
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return s;
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} // else do the 2nd write to publish seq
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// Note: the 2nd write comes with a performance penality. So if we have too
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// many of commits accompanied with ComitTimeWriteBatch and yet we cannot
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// enable use_only_the_last_commit_time_batch_for_recovery_ optimization,
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// two_write_queues should be disabled to avoid many additional writes here.
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class PublishSeqPreReleaseCallback : public PreReleaseCallback {
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public:
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explicit PublishSeqPreReleaseCallback(DBImpl* db_impl)
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: db_impl_(db_impl) {}
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virtual Status Callback(SequenceNumber seq, bool is_mem_disabled) override {
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#ifdef NDEBUG
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(void)is_mem_disabled;
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#endif
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assert(is_mem_disabled);
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assert(db_impl_->immutable_db_options().two_write_queues);
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db_impl_->SetLastPublishedSequence(seq);
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return Status::OK();
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}
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private:
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DBImpl* db_impl_;
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} publish_seq_callback(db_impl_);
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WriteBatch empty_batch;
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empty_batch.PutLogData(Slice());
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// In the absence of Prepare markers, use Noop as a batch separator
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WriteBatchInternal::InsertNoop(&empty_batch);
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const bool DISABLE_MEMTABLE = true;
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const size_t ONE_BATCH = 1;
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const uint64_t NO_REF_LOG = 0;
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s = db_impl_->WriteImpl(write_options_, &empty_batch, nullptr, nullptr,
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NO_REF_LOG, DISABLE_MEMTABLE, &seq_used, ONE_BATCH,
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&publish_seq_callback);
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assert(!s.ok() || seq_used != kMaxSequenceNumber);
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// Note RemovePrepared should be called after WriteImpl that publishsed the
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// seq. Otherwise SmallestUnCommittedSeq optimization breaks.
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wpt_db_->RemovePrepared(prepare_seq, prepare_batch_cnt_);
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return s;
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}
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Status WritePreparedTxn::RollbackInternal() {
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ROCKS_LOG_WARN(db_impl_->immutable_db_options().info_log,
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"RollbackInternal prepare_seq: %" PRIu64, GetId());
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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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auto cf_map_shared_ptr = wpt_db_->GetCFHandleMap();
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auto cf_comp_map_shared_ptr = wpt_db_->GetCFComparatorMap();
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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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std::map<uint32_t, const Comparator*>& comparators_;
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std::map<uint32_t, ColumnFamilyHandle*>& handles_;
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using CFKeys = std::set<Slice, SetComparator>;
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std::map<uint32_t, CFKeys> keys_;
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bool rollback_merge_operands_;
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RollbackWriteBatchBuilder(
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DBImpl* db, WritePreparedTxnDB* wpt_db, SequenceNumber snap_seq,
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WriteBatch* dst_batch,
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std::map<uint32_t, const Comparator*>& comparators,
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std::map<uint32_t, ColumnFamilyHandle*>& handles,
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bool rollback_merge_operands)
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: db_(db),
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callback(wpt_db, snap_seq,
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0), // 0 disables min_uncommitted optimization
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rollback_batch_(dst_batch),
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comparators_(comparators),
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handles_(handles),
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rollback_merge_operands_(rollback_merge_operands) {}
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Status Rollback(uint32_t cf, const Slice& key) {
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Status s;
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CFKeys& cf_keys = keys_[cf];
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if (cf_keys.size() == 0) { // just inserted
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auto cmp = comparators_[cf];
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keys_[cf] = CFKeys(SetComparator(cmp));
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}
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auto it = cf_keys.insert(key);
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if (it.second ==
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false) { // second is false if a element already existed.
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return s;
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}
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PinnableSlice pinnable_val;
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bool not_used;
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auto cf_handle = handles_[cf];
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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,
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const Slice& /*val*/) override {
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if (rollback_merge_operands_) {
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return Rollback(cf, key);
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} else {
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return Status::OK();
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}
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}
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Status MarkNoop(bool) override { return Status::OK(); }
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Status MarkBeginPrepare(bool) 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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protected:
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virtual bool WriteAfterCommit() const override { return false; }
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} rollback_handler(db_impl_, wpt_db_, last_visible_txn, &rollback_batch,
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*cf_comp_map_shared_ptr.get(), *cf_map_shared_ptr.get(),
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wpt_db_->txn_db_options_.rollback_merge_operands);
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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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// The Rollback marker will be used as a batch separator
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WriteBatchInternal::MarkRollback(&rollback_batch, name_);
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bool do_one_write = !db_impl_->immutable_db_options().two_write_queues;
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const bool DISABLE_MEMTABLE = true;
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const uint64_t NO_REF_LOG = 0;
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uint64_t seq_used = kMaxSequenceNumber;
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const size_t ONE_BATCH = 1;
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// We commit the rolled back prepared batches. ALthough this is
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// counter-intuitive, i) it is safe to do so, since the prepared batches are
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// already canceled out by the rollback batch, ii) adding the commit entry to
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// CommitCache will allow us to benefit from the existing mechanism in
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// CommitCache that keeps an entry evicted due to max advance and yet overlaps
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// with a live snapshot around so that the live snapshot properly skips the
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// entry even if its prepare seq is lower than max_evicted_seq_.
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WritePreparedCommitEntryPreReleaseCallback update_commit_map(
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wpt_db_, db_impl_, GetId(), prepare_batch_cnt_, ONE_BATCH);
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// Note: the rollback batch does not need AddPrepared since it is written to
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// DB in one shot. min_uncommitted still works since it requires capturing
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// data that is written to DB but not yet committed, while
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// the roolback batch commits with PreReleaseCallback.
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s = db_impl_->WriteImpl(write_options_, &rollback_batch, nullptr, nullptr,
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NO_REF_LOG, !DISABLE_MEMTABLE, &seq_used, ONE_BATCH,
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do_one_write ? &update_commit_map : nullptr);
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assert(!s.ok() || seq_used != kMaxSequenceNumber);
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if (!s.ok()) {
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return s;
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}
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if (do_one_write) {
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wpt_db_->RemovePrepared(GetId(), prepare_batch_cnt_);
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return s;
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} // else do the 2nd write for commit
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uint64_t& prepare_seq = seq_used;
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ROCKS_LOG_DETAILS(db_impl_->immutable_db_options().info_log,
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"RollbackInternal 2nd write prepare_seq: %" PRIu64,
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prepare_seq);
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// Commit the batch by writing an empty batch to the queue that will release
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// the commit sequence number to readers.
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const size_t ZERO_COMMITS = 0;
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WritePreparedCommitEntryPreReleaseCallback update_commit_map_with_prepare(
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wpt_db_, db_impl_, prepare_seq, ONE_BATCH, ZERO_COMMITS);
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WriteBatch empty_batch;
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empty_batch.PutLogData(Slice());
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// In the absence of Prepare markers, use Noop as a batch separator
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WriteBatchInternal::InsertNoop(&empty_batch);
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s = db_impl_->WriteImpl(write_options_, &empty_batch, nullptr, nullptr,
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NO_REF_LOG, DISABLE_MEMTABLE, &seq_used, ONE_BATCH,
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&update_commit_map_with_prepare);
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assert(!s.ok() || seq_used != kMaxSequenceNumber);
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// Mark the txn as rolled back
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uint64_t& rollback_seq = seq_used;
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if (s.ok()) {
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// Note: it is safe to do it after PreReleaseCallback via WriteImpl since
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// all the writes by the prpared batch are already blinded by the rollback
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// batch. The only reason we commit the prepared batch here is to benefit
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// from the existing mechanism in CommitCache that takes care of the rare
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// cases that the prepare seq is visible to a snsapshot but max evicted seq
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// advances that prepare seq.
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for (size_t i = 0; i < prepare_batch_cnt_; i++) {
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wpt_db_->AddCommitted(GetId() + i, rollback_seq);
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}
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wpt_db_->RemovePrepared(GetId(), prepare_batch_cnt_);
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}
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return s;
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}
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Status WritePreparedTxn::ValidateSnapshot(ColumnFamilyHandle* column_family,
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const Slice& key,
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SequenceNumber* tracked_at_seq) {
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assert(snapshot_);
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SequenceNumber min_uncommitted =
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static_cast_with_check<const SnapshotImpl, const Snapshot>(
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snapshot_.get())
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->min_uncommitted_;
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SequenceNumber snap_seq = snapshot_->GetSequenceNumber();
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// tracked_at_seq is either max or the last snapshot with which this key was
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// trackeed so there is no need to apply the IsInSnapshot to this comparison
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// here as tracked_at_seq is not a prepare seq.
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if (*tracked_at_seq <= snap_seq) {
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// If the key has been previous validated at a sequence number earlier
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// than the curent snapshot's sequence number, we already know it has not
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// been modified.
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return Status::OK();
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}
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*tracked_at_seq = snap_seq;
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ColumnFamilyHandle* cfh =
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column_family ? column_family : db_impl_->DefaultColumnFamily();
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WritePreparedTxnReadCallback snap_checker(wpt_db_, snap_seq, min_uncommitted);
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return TransactionUtil::CheckKeyForConflicts(db_impl_, cfh, key.ToString(),
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snap_seq, false /* cache_only */,
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&snap_checker);
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}
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void WritePreparedTxn::SetSnapshot() {
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// Note: for this optimization setting the last sequence number and obtaining
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// the smallest uncommitted seq should be done atomically. However to avoid
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// the mutex overhead, we call SmallestUnCommittedSeq BEFORE taking the
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// snapshot. Since we always updated the list of unprepared seq (via
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// AddPrepared) AFTER the last sequence is updated, this guarantees that the
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// smallest uncommited seq that we pair with the snapshot is smaller or equal
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// the value that would be obtained otherwise atomically. That is ok since
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// this optimization works as long as min_uncommitted is less than or equal
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// than the smallest uncommitted seq when the snapshot was taken.
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auto min_uncommitted = wpt_db_->SmallestUnCommittedSeq();
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const bool FOR_WW_CONFLICT_CHECK = true;
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SnapshotImpl* snapshot = dbimpl_->GetSnapshotImpl(FOR_WW_CONFLICT_CHECK);
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assert(snapshot);
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wpt_db_->EnhanceSnapshot(snapshot, min_uncommitted);
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SetSnapshotInternal(snapshot);
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}
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Status WritePreparedTxn::RebuildFromWriteBatch(WriteBatch* src_batch) {
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auto ret = PessimisticTransaction::RebuildFromWriteBatch(src_batch);
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prepare_batch_cnt_ = GetWriteBatch()->SubBatchCnt();
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return ret;
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}
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} // namespace rocksdb
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#endif // ROCKSDB_LITE
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