rocksdb/utilities/transactions/write_prepared_txn.cc

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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).
#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, false),
wpt_db_(txn_db) {
// Call Initialize outside PessimisticTransaction constructor otherwise it
// would skip overridden functions in WritePreparedTxn since they are not
// defined yet in the constructor of PessimisticTransaction
Initialize(txn_options);
}
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();
// Having AddPrepared in the PreReleaseCallback allows in-order addition of
// prepared entries to PreparedHeap 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;
WritePreparedCommitEntryPreReleaseCallback update_commit_map(
wpt_db_, db_impl_, prepare_seq, prepare_batch_cnt_, commit_batch_cnt);
// This is to call AddPrepared on CommitTimeWriteBatch
AddPreparedCallback add_prepared_callback(
wpt_db_, commit_batch_cnt,
db_impl_->immutable_db_options().two_write_queues);
PreReleaseCallback* pre_release_callback;
if (do_one_write) {
pre_release_callback = &update_commit_map;
} else {
pre_release_callback = &add_prepared_callback;
}
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, pre_release_callback);
assert(!s.ok() || seq_used != kMaxSequenceNumber);
const SequenceNumber commit_batch_seq = seq_used;
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_);
}
if (UNLIKELY(!do_one_write)) {
wpt_db_->RemovePrepared(commit_batch_seq, commit_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.
const size_t kZeroData = 0;
// Update commit map only from the 2nd queue
WritePreparedCommitEntryPreReleaseCallback update_commit_map_with_aux_batch(
wpt_db_, db_impl_, prepare_seq, prepare_batch_cnt_, kZeroData,
commit_batch_seq, commit_batch_cnt);
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,
&update_commit_map_with_aux_batch);
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_);
wpt_db_->RemovePrepared(commit_batch_seq, commit_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();
auto read_at_seq = kMaxSequenceNumber;
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, &not_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:
bool WriteAfterCommit() const override { return false; }
} rollback_handler(db_impl_, wpt_db_, read_at_seq, &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_.
AddPreparedCallback add_prepared_callback(
wpt_db_, ONE_BATCH, db_impl_->immutable_db_options().two_write_queues);
WritePreparedCommitEntryPreReleaseCallback update_commit_map(
wpt_db_, db_impl_, GetId(), prepare_batch_cnt_, ONE_BATCH);
PreReleaseCallback* pre_release_callback;
if (do_one_write) {
pre_release_callback = &update_commit_map;
} else {
pre_release_callback = &add_prepared_callback;
}
// 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 rollback batch commits with PreReleaseCallback.
s = db_impl_->WriteImpl(write_options_, &rollback_batch, nullptr, nullptr,
NO_REF_LOG, !DISABLE_MEMTABLE, &seq_used, ONE_BATCH,
pre_release_callback);
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 rollback_seq = seq_used;
ROCKS_LOG_DETAILS(db_impl_->immutable_db_options().info_log,
"RollbackInternal 2nd write rollback_seq: %" PRIu64,
rollback_seq);
// Commit the batch by writing an empty batch to the queue that will release
// the commit sequence number to readers.
WritePrepared: fix two versions in compaction see different status for released snapshots (#4890) Summary: Fix how CompactionIterator::findEarliestVisibleSnapshots handles released snapshot. It fixing the two scenarios: Scenario 1: key1 has two values v1 and v2. There're two snapshots s1 and s2 taken after v1 and v2 are committed. Right after compaction output v2, s1 is released. Now findEarliestVisibleSnapshot may see s1 being released, and return the next snapshot, which is s2. That's larger than v2's earliest visible snapshot, which was s1. The fix: the only place we check against last snapshot and current key snapshot is when we decide whether to compact out a value if it is hidden by a later value. In the check if we see current snapshot is even larger than last snapshot, we know last snapshot is released, and we are safe to compact out current key. Scenario 2: key1 has two values v1 and v2. there are two snapshots s1 and s2 taken after v1 and v2 are committed. During compaction before we process the key, s1 is released. When compaction process v2, snapshot checker may return kSnapshotReleased, and the earliest visible snapshot for v2 become s2. When compaction process v1, snapshot checker may return kIsInSnapshot (for WritePrepared transaction, it could be because v1 is still in commit cache). The result will become inconsistent here. The fix: remember the set of released snapshots ever reported by snapshot checker, and ignore them when finding result for findEarliestVisibleSnapshot. Pull Request resolved: https://github.com/facebook/rocksdb/pull/4890 Differential Revision: D13705538 Pulled By: maysamyabandeh fbshipit-source-id: e577f0d9ee1ff5a6035f26859e56902ecc85a5a4
2019-01-19 02:20:13 +01:00
WritePreparedRollbackPreReleaseCallback update_commit_map_with_prepare(
wpt_db_, db_impl_, GetId(), rollback_seq, prepare_batch_cnt_);
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);
WritePrepared: fix two versions in compaction see different status for released snapshots (#4890) Summary: Fix how CompactionIterator::findEarliestVisibleSnapshots handles released snapshot. It fixing the two scenarios: Scenario 1: key1 has two values v1 and v2. There're two snapshots s1 and s2 taken after v1 and v2 are committed. Right after compaction output v2, s1 is released. Now findEarliestVisibleSnapshot may see s1 being released, and return the next snapshot, which is s2. That's larger than v2's earliest visible snapshot, which was s1. The fix: the only place we check against last snapshot and current key snapshot is when we decide whether to compact out a value if it is hidden by a later value. In the check if we see current snapshot is even larger than last snapshot, we know last snapshot is released, and we are safe to compact out current key. Scenario 2: key1 has two values v1 and v2. there are two snapshots s1 and s2 taken after v1 and v2 are committed. During compaction before we process the key, s1 is released. When compaction process v2, snapshot checker may return kSnapshotReleased, and the earliest visible snapshot for v2 become s2. When compaction process v1, snapshot checker may return kIsInSnapshot (for WritePrepared transaction, it could be because v1 is still in commit cache). The result will become inconsistent here. The fix: remember the set of released snapshots ever reported by snapshot checker, and ignore them when finding result for findEarliestVisibleSnapshot. Pull Request resolved: https://github.com/facebook/rocksdb/pull/4890 Differential Revision: D13705538 Pulled By: maysamyabandeh fbshipit-source-id: e577f0d9ee1ff5a6035f26859e56902ecc85a5a4
2019-01-19 02:20:13 +01:00
ROCKS_LOG_DETAILS(db_impl_->immutable_db_options().info_log,
"RollbackInternal (status=%s) commit: %" PRIu64,
s.ToString().c_str(), GetId());
if (s.ok()) {
wpt_db_->RemovePrepared(GetId(), prepare_batch_cnt_);
}
wpt_db_->RemovePrepared(rollback_seq, ONE_BATCH);
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, min_uncommitted);
}
void WritePreparedTxn::SetSnapshot() {
const bool kForWWConflictCheck = true;
SnapshotImpl* snapshot = wpt_db_->GetSnapshotInternal(kForWWConflictCheck);
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