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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).
//
// 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 "table/two_level_iterator.h"
#include "db/pinned_iterators_manager.h"
#include "memory/arena.h"
#include "rocksdb/options.h"
#include "rocksdb/table.h"
#include "table/block_based/block.h"
#include "table/format.h"
namespace ROCKSDB_NAMESPACE {
namespace {
class TwoLevelIndexIterator : public InternalIteratorBase<IndexValue> {
public:
explicit TwoLevelIndexIterator(
TwoLevelIteratorState* state,
InternalIteratorBase<IndexValue>* first_level_iter);
~TwoLevelIndexIterator() override {
first_level_iter_.DeleteIter(false /* is_arena_mode */);
second_level_iter_.DeleteIter(false /* is_arena_mode */);
delete state_;
}
void Seek(const Slice& target) override;
void SeekForPrev(const Slice& target) override;
void SeekToFirst() override;
void SeekToLast() override;
void Next() override;
void Prev() override;
bool Valid() const override { return second_level_iter_.Valid(); }
Slice key() const override {
assert(Valid());
return second_level_iter_.key();
}
Slice user_key() const override {
assert(Valid());
return second_level_iter_.user_key();
}
IndexValue value() const override {
assert(Valid());
return second_level_iter_.value();
}
Status status() const override {
if (!first_level_iter_.status().ok()) {
assert(second_level_iter_.iter() == nullptr);
return first_level_iter_.status();
} else if (second_level_iter_.iter() != nullptr &&
!second_level_iter_.status().ok()) {
return second_level_iter_.status();
} else {
return status_;
}
}
void SetPinnedItersMgr(
PinnedIteratorsManager* /*pinned_iters_mgr*/) override {}
bool IsKeyPinned() const override { return false; }
bool IsValuePinned() const override { return false; }
private:
void SaveError(const Status& s) {
if (status_.ok() && !s.ok()) status_ = s;
}
void SkipEmptyDataBlocksForward();
void SkipEmptyDataBlocksBackward();
void SetSecondLevelIterator(InternalIteratorBase<IndexValue>* iter);
void InitDataBlock();
TwoLevelIteratorState* state_;
IteratorWrapperBase<IndexValue> first_level_iter_;
IteratorWrapperBase<IndexValue> second_level_iter_; // May be nullptr
Status status_;
// If second_level_iter is non-nullptr, then "data_block_handle_" holds the
// "index_value" passed to block_function_ to create the second_level_iter.
BlockHandle data_block_handle_;
};
TwoLevelIndexIterator::TwoLevelIndexIterator(
TwoLevelIteratorState* state,
InternalIteratorBase<IndexValue>* first_level_iter)
: state_(state), first_level_iter_(first_level_iter) {}
void TwoLevelIndexIterator::Seek(const Slice& target) {
first_level_iter_.Seek(target);
InitDataBlock();
if (second_level_iter_.iter() != nullptr) {
second_level_iter_.Seek(target);
}
SkipEmptyDataBlocksForward();
}
void TwoLevelIndexIterator::SeekForPrev(const Slice& target) {
first_level_iter_.Seek(target);
InitDataBlock();
if (second_level_iter_.iter() != nullptr) {
second_level_iter_.SeekForPrev(target);
}
if (!Valid()) {
if (!first_level_iter_.Valid() && first_level_iter_.status().ok()) {
first_level_iter_.SeekToLast();
InitDataBlock();
if (second_level_iter_.iter() != nullptr) {
second_level_iter_.SeekForPrev(target);
}
}
SkipEmptyDataBlocksBackward();
}
}
void TwoLevelIndexIterator::SeekToFirst() {
first_level_iter_.SeekToFirst();
InitDataBlock();
if (second_level_iter_.iter() != nullptr) {
second_level_iter_.SeekToFirst();
}
SkipEmptyDataBlocksForward();
}
void TwoLevelIndexIterator::SeekToLast() {
first_level_iter_.SeekToLast();
InitDataBlock();
if (second_level_iter_.iter() != nullptr) {
second_level_iter_.SeekToLast();
}
SkipEmptyDataBlocksBackward();
}
void TwoLevelIndexIterator::Next() {
assert(Valid());
second_level_iter_.Next();
SkipEmptyDataBlocksForward();
}
void TwoLevelIndexIterator::Prev() {
assert(Valid());
second_level_iter_.Prev();
SkipEmptyDataBlocksBackward();
}
void TwoLevelIndexIterator::SkipEmptyDataBlocksForward() {
while (second_level_iter_.iter() == nullptr ||
(!second_level_iter_.Valid() && second_level_iter_.status().ok())) {
// Move to next block
if (!first_level_iter_.Valid()) {
SetSecondLevelIterator(nullptr);
return;
}
first_level_iter_.Next();
InitDataBlock();
if (second_level_iter_.iter() != nullptr) {
second_level_iter_.SeekToFirst();
}
}
}
void TwoLevelIndexIterator::SkipEmptyDataBlocksBackward() {
while (second_level_iter_.iter() == nullptr ||
(!second_level_iter_.Valid() && second_level_iter_.status().ok())) {
// Move to next block
if (!first_level_iter_.Valid()) {
SetSecondLevelIterator(nullptr);
return;
}
first_level_iter_.Prev();
InitDataBlock();
if (second_level_iter_.iter() != nullptr) {
second_level_iter_.SeekToLast();
}
}
}
void TwoLevelIndexIterator::SetSecondLevelIterator(
InternalIteratorBase<IndexValue>* iter) {
InternalIteratorBase<IndexValue>* old_iter = second_level_iter_.Set(iter);
delete old_iter;
}
void TwoLevelIndexIterator::InitDataBlock() {
if (!first_level_iter_.Valid()) {
SetSecondLevelIterator(nullptr);
} else {
BlockHandle handle = first_level_iter_.value().handle;
if (second_level_iter_.iter() != nullptr &&
!second_level_iter_.status().IsIncomplete() &&
handle.offset() == data_block_handle_.offset()) {
// second_level_iter is already constructed with this iterator, so
// no need to change anything
} else {
InternalIteratorBase<IndexValue>* iter =
state_->NewSecondaryIterator(handle);
data_block_handle_ = handle;
SetSecondLevelIterator(iter);
if (iter == nullptr) {
status_ = Status::Corruption("Missing block for partition " +
handle.ToString());
}
}
}
}
} // namespace
InternalIteratorBase<IndexValue>* NewTwoLevelIterator(
TwoLevelIteratorState* state,
InternalIteratorBase<IndexValue>* first_level_iter) {
return new TwoLevelIndexIterator(state, first_level_iter);
}
} // namespace ROCKSDB_NAMESPACE
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