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rocksdb/db/arena_wrapped_db_iter.cc

158 lines
6.7 KiB

// 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).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "db/arena_wrapped_db_iter.h"
#include "memory/arena.h"
#include "rocksdb/env.h"
#include "rocksdb/iterator.h"
#include "rocksdb/options.h"
#include "table/internal_iterator.h"
#include "table/iterator_wrapper.h"
#include "util/user_comparator_wrapper.h"
namespace ROCKSDB_NAMESPACE {
Status ArenaWrappedDBIter::GetProperty(std::string prop_name,
std::string* prop) {
if (prop_name == "rocksdb.iterator.super-version-number") {
// First try to pass the value returned from inner iterator.
if (!db_iter_->GetProperty(prop_name, prop).ok()) {
*prop = std::to_string(sv_number_);
}
return Status::OK();
}
return db_iter_->GetProperty(prop_name, prop);
}
void ArenaWrappedDBIter::Init(
Env* env, const ReadOptions& read_options, const ImmutableOptions& ioptions,
const MutableCFOptions& mutable_cf_options, const Version* version,
const SequenceNumber& sequence, uint64_t max_sequential_skip_in_iteration,
uint64_t version_number, ReadCallback* read_callback, DBImpl* db_impl,
ColumnFamilyData* cfd, bool expose_blob_index, bool allow_refresh) {
auto mem = arena_.AllocateAligned(sizeof(DBIter));
db_iter_ =
new (mem) DBIter(env, read_options, ioptions, mutable_cf_options,
ioptions.user_comparator, /* iter */ nullptr, version,
sequence, true, max_sequential_skip_in_iteration,
read_callback, db_impl, cfd, expose_blob_index);
sv_number_ = version_number;
read_options_ = read_options;
allow_refresh_ = allow_refresh;
memtable_range_tombstone_iter_ = nullptr;
}
Status ArenaWrappedDBIter::Refresh() {
if (cfd_ == nullptr || db_impl_ == nullptr || !allow_refresh_) {
return Status::NotSupported("Creating renew iterator is not allowed.");
}
assert(db_iter_ != nullptr);
// TODO(yiwu): For last_seq_same_as_publish_seq_==false, this is not the
// correct behavior. Will be corrected automatically when we take a snapshot
// here for the case of WritePreparedTxnDB.
uint64_t cur_sv_number = cfd_->GetSuperVersionNumber();
TEST_SYNC_POINT("ArenaWrappedDBIter::Refresh:1");
TEST_SYNC_POINT("ArenaWrappedDBIter::Refresh:2");
auto reinit_internal_iter = [&]() {
Env* env = db_iter_->env();
db_iter_->~DBIter();
arena_.~Arena();
new (&arena_) Arena();
SuperVersion* sv = cfd_->GetReferencedSuperVersion(db_impl_);
SequenceNumber latest_seq = db_impl_->GetLatestSequenceNumber();
if (read_callback_) {
read_callback_->Refresh(latest_seq);
}
Init(env, read_options_, *(cfd_->ioptions()), sv->mutable_cf_options,
sv->current, latest_seq,
sv->mutable_cf_options.max_sequential_skip_in_iterations,
cur_sv_number, read_callback_, db_impl_, cfd_, expose_blob_index_,
allow_refresh_);
InternalIterator* internal_iter = db_impl_->NewInternalIterator(
read_options_, cfd_, sv, &arena_, latest_seq,
/* allow_unprepared_value */ true, /* db_iter */ this);
SetIterUnderDBIter(internal_iter);
};
while (true) {
if (sv_number_ != cur_sv_number) {
reinit_internal_iter();
break;
} else {
SequenceNumber latest_seq = db_impl_->GetLatestSequenceNumber();
// Refresh range-tombstones in MemTable
if (!read_options_.ignore_range_deletions) {
SuperVersion* sv = cfd_->GetThreadLocalSuperVersion(db_impl_);
auto t = sv->mem->NewRangeTombstoneIterator(
read_options_, latest_seq, false /* immutable_memtable */);
if (!t || t->empty()) {
// If memtable_range_tombstone_iter_ points to a non-empty tombstone
// iterator, then it means sv->mem is not the memtable that
// memtable_range_tombstone_iter_ points to, so SV must have changed
// after the sv_number_ != cur_sv_number check above. We will fall
// back to re-init the InternalIterator, and the tombstone iterator
// will be freed during db_iter destruction there.
if (memtable_range_tombstone_iter_) {
assert(!*memtable_range_tombstone_iter_ ||
sv_number_ != cfd_->GetSuperVersionNumber());
}
delete t;
} else { // current mutable memtable has range tombstones
if (!memtable_range_tombstone_iter_) {
delete t;
cfd_->ReturnThreadLocalSuperVersion(sv);
// The memtable under DBIter did not have range tombstone before
// refresh.
reinit_internal_iter();
break;
} else {
delete *memtable_range_tombstone_iter_;
*memtable_range_tombstone_iter_ = new TruncatedRangeDelIterator(
std::unique_ptr<FragmentedRangeTombstoneIterator>(t),
&cfd_->internal_comparator(), nullptr, nullptr);
}
}
cfd_->ReturnThreadLocalSuperVersion(sv);
}
// Refresh latest sequence number
db_iter_->set_sequence(latest_seq);
db_iter_->set_valid(false);
// Check again if the latest super version number is changed
uint64_t latest_sv_number = cfd_->GetSuperVersionNumber();
if (latest_sv_number != cur_sv_number) {
// If the super version number is changed after refreshing,
// fallback to Re-Init the InternalIterator
cur_sv_number = latest_sv_number;
continue;
}
break;
}
}
return Status::OK();
}
ArenaWrappedDBIter* NewArenaWrappedDbIterator(
Env* env, const ReadOptions& read_options, const ImmutableOptions& ioptions,
const MutableCFOptions& mutable_cf_options, const Version* version,
const SequenceNumber& sequence, uint64_t max_sequential_skip_in_iterations,
uint64_t version_number, ReadCallback* read_callback, DBImpl* db_impl,
ColumnFamilyData* cfd, bool expose_blob_index, bool allow_refresh) {
ArenaWrappedDBIter* iter = new ArenaWrappedDBIter();
iter->Init(env, read_options, ioptions, mutable_cf_options, version, sequence,
max_sequential_skip_in_iterations, version_number, read_callback,
db_impl, cfd, expose_blob_index, allow_refresh);
if (db_impl != nullptr && cfd != nullptr && allow_refresh) {
iter->StoreRefreshInfo(db_impl, cfd, read_callback, expose_blob_index);
}
return iter;
}
} // namespace ROCKSDB_NAMESPACE