a4a4a2dabd
Summary: Previously, a `ReadOptions` object was stored in every `BlockBasedTableIterator` and every `LevelIterator`. This redundancy consumes extra memory, resulting in the `Arena` making more allocations, and iteration observing worse cache performance. This PR migrates callers of `NewInternalIterator()` and `MakeInputIterator()` to provide a `ReadOptions` object guaranteed to outlive the returned iterator. When the iterator's lifetime will be managed by the user, this lifetime guarantee is achieved by storing the `ReadOptions` value in `ArenaWrappedDBIter`. Then, sub-iterators of `NewInternalIterator()` and `MakeInputIterator()` can hold a reference-to-const `ReadOptions`. Pull Request resolved: https://github.com/facebook/rocksdb/pull/7210 Test Plan: - `make check` under ASAN and valgrind - benchmark: on a DB with 2 L0 files and 3 L1+ levels, this PR reduced `Arena` allocation 4792 -> 4160 bytes. Reviewed By: anand1976 Differential Revision: D22861323 Pulled By: ajkr fbshipit-source-id: 54aebb3e89c872eeab0f5793b4b6e42878d093ce
109 lines
4.6 KiB
C++
109 lines
4.6 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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//
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// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#include "db/arena_wrapped_db_iter.h"
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#include "memory/arena.h"
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#include "rocksdb/env.h"
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#include "rocksdb/iterator.h"
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#include "rocksdb/options.h"
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#include "table/internal_iterator.h"
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#include "table/iterator_wrapper.h"
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#include "util/user_comparator_wrapper.h"
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namespace ROCKSDB_NAMESPACE {
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Status ArenaWrappedDBIter::GetProperty(std::string prop_name,
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std::string* prop) {
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if (prop_name == "rocksdb.iterator.super-version-number") {
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// First try to pass the value returned from inner iterator.
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if (!db_iter_->GetProperty(prop_name, prop).ok()) {
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*prop = ToString(sv_number_);
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}
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return Status::OK();
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}
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return db_iter_->GetProperty(prop_name, prop);
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}
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void ArenaWrappedDBIter::Init(Env* env, const ReadOptions& read_options,
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const ImmutableCFOptions& cf_options,
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const MutableCFOptions& mutable_cf_options,
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const SequenceNumber& sequence,
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uint64_t max_sequential_skip_in_iteration,
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uint64_t version_number,
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ReadCallback* read_callback, DBImpl* db_impl,
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ColumnFamilyData* cfd, bool allow_blob,
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bool allow_refresh) {
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auto mem = arena_.AllocateAligned(sizeof(DBIter));
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db_iter_ = new (mem) DBIter(env, read_options, cf_options, mutable_cf_options,
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cf_options.user_comparator, nullptr, sequence,
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true, max_sequential_skip_in_iteration,
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read_callback, db_impl, cfd, allow_blob);
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sv_number_ = version_number;
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read_options_ = read_options;
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allow_refresh_ = allow_refresh;
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}
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Status ArenaWrappedDBIter::Refresh() {
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if (cfd_ == nullptr || db_impl_ == nullptr || !allow_refresh_) {
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return Status::NotSupported("Creating renew iterator is not allowed.");
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}
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assert(db_iter_ != nullptr);
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// TODO(yiwu): For last_seq_same_as_publish_seq_==false, this is not the
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// correct behavior. Will be corrected automatically when we take a snapshot
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// here for the case of WritePreparedTxnDB.
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uint64_t cur_sv_number = cfd_->GetSuperVersionNumber();
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TEST_SYNC_POINT("ArenaWrappedDBIter::Refresh:1");
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TEST_SYNC_POINT("ArenaWrappedDBIter::Refresh:2");
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if (sv_number_ != cur_sv_number) {
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Env* env = db_iter_->env();
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db_iter_->~DBIter();
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arena_.~Arena();
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new (&arena_) Arena();
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SuperVersion* sv = cfd_->GetReferencedSuperVersion(db_impl_);
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SequenceNumber latest_seq = db_impl_->GetLatestSequenceNumber();
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if (read_callback_) {
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read_callback_->Refresh(latest_seq);
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}
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Init(env, read_options_, *(cfd_->ioptions()), sv->mutable_cf_options,
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latest_seq, sv->mutable_cf_options.max_sequential_skip_in_iterations,
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cur_sv_number, read_callback_, db_impl_, cfd_, allow_blob_,
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allow_refresh_);
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InternalIterator* internal_iter = db_impl_->NewInternalIterator(
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read_options_, cfd_, sv, &arena_, db_iter_->GetRangeDelAggregator(),
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latest_seq, /* allow_unprepared_value */ true);
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SetIterUnderDBIter(internal_iter);
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} else {
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db_iter_->set_sequence(db_impl_->GetLatestSequenceNumber());
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db_iter_->set_valid(false);
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}
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return Status::OK();
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}
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ArenaWrappedDBIter* NewArenaWrappedDbIterator(
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Env* env, const ReadOptions& read_options,
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const ImmutableCFOptions& cf_options,
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const MutableCFOptions& mutable_cf_options, const SequenceNumber& sequence,
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uint64_t max_sequential_skip_in_iterations, uint64_t version_number,
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ReadCallback* read_callback, DBImpl* db_impl, ColumnFamilyData* cfd,
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bool allow_blob, bool allow_refresh) {
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ArenaWrappedDBIter* iter = new ArenaWrappedDBIter();
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iter->Init(env, read_options, cf_options, mutable_cf_options, sequence,
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max_sequential_skip_in_iterations, version_number, read_callback,
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db_impl, cfd, allow_blob, allow_refresh);
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if (db_impl != nullptr && cfd != nullptr && allow_refresh) {
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iter->StoreRefreshInfo(db_impl, cfd, read_callback, allow_blob);
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}
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return iter;
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}
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} // namespace ROCKSDB_NAMESPACE
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