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