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// 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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#pragma once
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#ifndef ROCKSDB_LITE
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#include <limits>
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#include <string>
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#include <vector>
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#include "db/merge_context.h"
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#include "memtable/skiplist.h"
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#include "options/db_options.h"
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#include "port/port.h"
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#include "rocksdb/comparator.h"
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#include "rocksdb/iterator.h"
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#include "rocksdb/slice.h"
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#include "rocksdb/status.h"
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#include "rocksdb/utilities/write_batch_with_index.h"
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namespace ROCKSDB_NAMESPACE {
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class MergeContext;
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struct Options;
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// when direction == forward
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// * current_at_base_ <=> base_iterator > delta_iterator
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// when direction == backwards
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// * current_at_base_ <=> base_iterator < delta_iterator
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// always:
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// * equal_keys_ <=> base_iterator == delta_iterator
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class BaseDeltaIterator : public Iterator {
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public:
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BaseDeltaIterator(Iterator* base_iterator, WBWIIterator* delta_iterator,
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const Comparator* comparator,
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const ReadOptions* read_options = nullptr)
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: forward_(true),
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current_at_base_(true),
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equal_keys_(false),
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status_(Status::OK()),
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base_iterator_(base_iterator),
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delta_iterator_(delta_iterator),
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comparator_(comparator),
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iterate_upper_bound_(read_options ? read_options->iterate_upper_bound
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: nullptr) {}
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~BaseDeltaIterator() override {}
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bool Valid() const override {
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return status_.ok() ? (current_at_base_ ? BaseValid() : DeltaValid())
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: false;
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}
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void SeekToFirst() override {
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forward_ = true;
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base_iterator_->SeekToFirst();
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delta_iterator_->SeekToFirst();
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UpdateCurrent();
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}
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void SeekToLast() override {
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forward_ = false;
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base_iterator_->SeekToLast();
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delta_iterator_->SeekToLast();
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UpdateCurrent();
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}
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void Seek(const Slice& k) override {
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forward_ = true;
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base_iterator_->Seek(k);
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delta_iterator_->Seek(k);
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UpdateCurrent();
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}
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void SeekForPrev(const Slice& k) override {
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forward_ = false;
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base_iterator_->SeekForPrev(k);
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delta_iterator_->SeekForPrev(k);
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UpdateCurrent();
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}
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void Next() override {
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if (!Valid()) {
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status_ = Status::NotSupported("Next() on invalid iterator");
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return;
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}
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if (!forward_) {
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// Need to change direction
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// if our direction was backward and we're not equal, we have two states:
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// * both iterators are valid: we're already in a good state (current
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// shows to smaller)
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// * only one iterator is valid: we need to advance that iterator
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forward_ = true;
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equal_keys_ = false;
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if (!BaseValid()) {
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assert(DeltaValid());
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base_iterator_->SeekToFirst();
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} else if (!DeltaValid()) {
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delta_iterator_->SeekToFirst();
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} else if (current_at_base_) {
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// Change delta from larger than base to smaller
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AdvanceDelta();
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} else {
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// Change base from larger than delta to smaller
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AdvanceBase();
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}
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if (DeltaValid() && BaseValid()) {
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if (comparator_->Equal(delta_iterator_->Entry().key,
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base_iterator_->key())) {
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equal_keys_ = true;
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}
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}
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}
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Advance();
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}
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void Prev() override {
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if (!Valid()) {
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status_ = Status::NotSupported("Prev() on invalid iterator");
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return;
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}
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if (forward_) {
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// Need to change direction
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// if our direction was backward and we're not equal, we have two states:
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// * both iterators are valid: we're already in a good state (current
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// shows to smaller)
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// * only one iterator is valid: we need to advance that iterator
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forward_ = false;
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equal_keys_ = false;
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if (!BaseValid()) {
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assert(DeltaValid());
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base_iterator_->SeekToLast();
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} else if (!DeltaValid()) {
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delta_iterator_->SeekToLast();
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} else if (current_at_base_) {
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// Change delta from less advanced than base to more advanced
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AdvanceDelta();
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} else {
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// Change base from less advanced than delta to more advanced
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AdvanceBase();
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}
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if (DeltaValid() && BaseValid()) {
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if (comparator_->Equal(delta_iterator_->Entry().key,
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base_iterator_->key())) {
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equal_keys_ = true;
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}
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}
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}
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Advance();
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}
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Slice key() const override {
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return current_at_base_ ? base_iterator_->key()
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: delta_iterator_->Entry().key;
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}
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Slice value() const override {
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return current_at_base_ ? base_iterator_->value()
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: delta_iterator_->Entry().value;
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}
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Status status() const override {
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if (!status_.ok()) {
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return status_;
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}
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if (!base_iterator_->status().ok()) {
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return base_iterator_->status();
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}
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return delta_iterator_->status();
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}
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void Invalidate(Status s) { status_ = s; }
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private:
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void AssertInvariants() {
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#ifndef NDEBUG
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bool not_ok = false;
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if (!base_iterator_->status().ok()) {
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assert(!base_iterator_->Valid());
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not_ok = true;
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}
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if (!delta_iterator_->status().ok()) {
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assert(!delta_iterator_->Valid());
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not_ok = true;
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}
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if (not_ok) {
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assert(!Valid());
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assert(!status().ok());
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return;
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}
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if (!Valid()) {
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return;
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}
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if (!BaseValid()) {
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assert(!current_at_base_ && delta_iterator_->Valid());
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return;
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}
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if (!DeltaValid()) {
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assert(current_at_base_ && base_iterator_->Valid());
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return;
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}
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// we don't support those yet
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assert(delta_iterator_->Entry().type != kMergeRecord &&
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delta_iterator_->Entry().type != kLogDataRecord);
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int compare = comparator_->Compare(delta_iterator_->Entry().key,
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base_iterator_->key());
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if (forward_) {
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// current_at_base -> compare < 0
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assert(!current_at_base_ || compare < 0);
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// !current_at_base -> compare <= 0
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assert(current_at_base_ && compare >= 0);
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} else {
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// current_at_base -> compare > 0
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assert(!current_at_base_ || compare > 0);
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// !current_at_base -> compare <= 0
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assert(current_at_base_ && compare <= 0);
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}
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// equal_keys_ <=> compare == 0
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assert((equal_keys_ || compare != 0) && (!equal_keys_ || compare == 0));
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#endif
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}
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void Advance() {
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if (equal_keys_) {
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assert(BaseValid() && DeltaValid());
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AdvanceBase();
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AdvanceDelta();
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} else {
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if (current_at_base_) {
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assert(BaseValid());
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AdvanceBase();
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} else {
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assert(DeltaValid());
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AdvanceDelta();
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}
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}
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UpdateCurrent();
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}
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void AdvanceDelta() {
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if (forward_) {
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delta_iterator_->Next();
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} else {
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delta_iterator_->Prev();
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}
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}
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void AdvanceBase() {
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if (forward_) {
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base_iterator_->Next();
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} else {
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base_iterator_->Prev();
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}
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}
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bool BaseValid() const { return base_iterator_->Valid(); }
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bool DeltaValid() const { return delta_iterator_->Valid(); }
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void UpdateCurrent() {
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// Suppress false positive clang analyzer warnings.
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#ifndef __clang_analyzer__
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status_ = Status::OK();
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while (true) {
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WriteEntry delta_entry;
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if (DeltaValid()) {
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assert(delta_iterator_->status().ok());
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delta_entry = delta_iterator_->Entry();
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} else if (!delta_iterator_->status().ok()) {
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// Expose the error status and stop.
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current_at_base_ = false;
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return;
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}
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equal_keys_ = false;
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if (!BaseValid()) {
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if (!base_iterator_->status().ok()) {
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// Expose the error status and stop.
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current_at_base_ = true;
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return;
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}
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// Base has finished.
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if (!DeltaValid()) {
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// Finished
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return;
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}
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if (iterate_upper_bound_) {
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if (comparator_->Compare(delta_entry.key, *iterate_upper_bound_) >=
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0) {
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// out of upper bound -> finished.
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return;
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}
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}
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if (delta_entry.type == kDeleteRecord ||
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delta_entry.type == kSingleDeleteRecord) {
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AdvanceDelta();
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} else {
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current_at_base_ = false;
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return;
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}
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} else if (!DeltaValid()) {
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// Delta has finished.
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current_at_base_ = true;
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return;
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} else {
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int compare =
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(forward_ ? 1 : -1) *
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comparator_->Compare(delta_entry.key, base_iterator_->key());
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if (compare <= 0) { // delta bigger or equal
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if (compare == 0) {
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equal_keys_ = true;
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}
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if (delta_entry.type != kDeleteRecord &&
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delta_entry.type != kSingleDeleteRecord) {
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current_at_base_ = false;
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return;
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}
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// Delta is less advanced and is delete.
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AdvanceDelta();
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if (equal_keys_) {
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AdvanceBase();
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}
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} else {
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current_at_base_ = true;
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return;
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}
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}
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}
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AssertInvariants();
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#endif // __clang_analyzer__
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}
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bool forward_;
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bool current_at_base_;
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bool equal_keys_;
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Status status_;
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std::unique_ptr<Iterator> base_iterator_;
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std::unique_ptr<WBWIIterator> delta_iterator_;
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const Comparator* comparator_; // not owned
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const Slice* iterate_upper_bound_;
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};
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// Key used by skip list, as the binary searchable index of WriteBatchWithIndex.
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struct WriteBatchIndexEntry {
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WriteBatchIndexEntry(size_t o, uint32_t c, size_t ko, size_t ksz)
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: offset(o),
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column_family(c),
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key_offset(ko),
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key_size(ksz),
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search_key(nullptr) {}
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// Create a dummy entry as the search key. This index entry won't be backed
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// by an entry from the write batch, but a pointer to the search key. Or a
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// special flag of offset can indicate we are seek to first.
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// @_search_key: the search key
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// @_column_family: column family
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// @is_forward_direction: true for Seek(). False for SeekForPrev()
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// @is_seek_to_first: true if we seek to the beginning of the column family
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// _search_key should be null in this case.
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WriteBatchIndexEntry(const Slice* _search_key, uint32_t _column_family,
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bool is_forward_direction, bool is_seek_to_first)
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// For SeekForPrev(), we need to make the dummy entry larger than any
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// entry who has the same search key. Otherwise, we'll miss those entries.
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: offset(is_forward_direction ? 0 : port::kMaxSizet),
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column_family(_column_family),
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key_offset(0),
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key_size(is_seek_to_first ? kFlagMinInCf : 0),
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search_key(_search_key) {
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assert(_search_key != nullptr || is_seek_to_first);
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}
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// If this flag appears in the key_size, it indicates a
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// key that is smaller than any other entry for the same column family.
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static const size_t kFlagMinInCf = port::kMaxSizet;
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bool is_min_in_cf() const {
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assert(key_size != kFlagMinInCf ||
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(key_offset == 0 && search_key == nullptr));
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return key_size == kFlagMinInCf;
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}
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// offset of an entry in write batch's string buffer. If this is a dummy
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// lookup key, in which case search_key != nullptr, offset is set to either
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// 0 or max, only for comparison purpose. Because when entries have the same
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// key, the entry with larger offset is larger, offset = 0 will make a seek
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// key small or equal than all the entries with the seek key, so that Seek()
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// will find all the entries of the same key. Similarly, offset = MAX will
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// make the entry just larger than all entries with the search key so
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// SeekForPrev() will see all the keys with the same key.
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size_t offset;
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uint32_t column_family; // c1olumn family of the entry.
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size_t key_offset; // offset of the key in write batch's string buffer.
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size_t key_size; // size of the key. kFlagMinInCf indicates
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// that this is a dummy look up entry for
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// SeekToFirst() to the beginning of the column
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// family. We use the flag here to save a boolean
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// in the struct.
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const Slice* search_key; // if not null, instead of reading keys from
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// write batch, use it to compare. This is used
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// for lookup key.
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};
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class ReadableWriteBatch : public WriteBatch {
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public:
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explicit ReadableWriteBatch(size_t reserved_bytes = 0, size_t max_bytes = 0)
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: WriteBatch(reserved_bytes, max_bytes) {}
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// Retrieve some information from a write entry in the write batch, given
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// the start offset of the write entry.
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Status GetEntryFromDataOffset(size_t data_offset, WriteType* type, Slice* Key,
|
Modification of WriteBatch to support two phase commit
Summary: Adds three new WriteBatch data types: Prepare(xid), Commit(xid), Rollback(xid). Prepare(xid) should precede the (single) operation to which is applies. There can obviously be multiple Prepare(xid) markers. There should only be one Rollback(xid) or Commit(xid) marker yet not both. None of this logic is currently enforced and will most likely be implemented further up such as in the memtableinserter. All three markers are similar to PutLogData in that they are writebatch meta-data, ie stored but not counted. All three markers differ from PutLogData in that they will actually be written to disk. As for WriteBatchWithIndex, Prepare, Commit, Rollback are all implemented just as PutLogData and none are tested just as PutLogData.
Test Plan: single unit test in write_batch_test.
Reviewers: hermanlee4, sdong, anthony
Subscribers: leveldb, dhruba, vasilep, andrewkr
Differential Revision: https://reviews.facebook.net/D57867
9 years ago
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Slice* value, Slice* blob, Slice* xid) const;
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};
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class WriteBatchEntryComparator {
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public:
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WriteBatchEntryComparator(const Comparator* _default_comparator,
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const ReadableWriteBatch* write_batch)
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: default_comparator_(_default_comparator), write_batch_(write_batch) {}
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// Compare a and b. Return a negative value if a is less than b, 0 if they
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// are equal, and a positive value if a is greater than b
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int operator()(const WriteBatchIndexEntry* entry1,
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const WriteBatchIndexEntry* entry2) const;
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int CompareKey(uint32_t column_family, const Slice& key1,
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const Slice& key2) const;
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void SetComparatorForCF(uint32_t column_family_id,
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const Comparator* comparator) {
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if (column_family_id >= cf_comparators_.size()) {
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cf_comparators_.resize(column_family_id + 1, nullptr);
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}
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cf_comparators_[column_family_id] = comparator;
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}
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const Comparator* default_comparator() { return default_comparator_; }
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private:
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const Comparator* default_comparator_;
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std::vector<const Comparator*> cf_comparators_;
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const ReadableWriteBatch* write_batch_;
|
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};
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typedef SkipList<WriteBatchIndexEntry*, const WriteBatchEntryComparator&>
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WriteBatchEntrySkipList;
|
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|
|
class WBWIIteratorImpl : public WBWIIterator {
|
|
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|
public:
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|
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|
WBWIIteratorImpl(uint32_t column_family_id,
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|
|
|
WriteBatchEntrySkipList* skip_list,
|
|
|
|
const ReadableWriteBatch* write_batch,
|
|
|
|
WriteBatchEntryComparator* comparator)
|
|
|
|
: column_family_id_(column_family_id),
|
|
|
|
skip_list_iter_(skip_list),
|
|
|
|
write_batch_(write_batch),
|
|
|
|
comparator_(comparator) {}
|
|
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|
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|
|
~WBWIIteratorImpl() override {}
|
|
|
|
|
|
|
|
bool Valid() const override {
|
|
|
|
if (!skip_list_iter_.Valid()) {
|
|
|
|
return false;
|
|
|
|
}
|
|
|
|
const WriteBatchIndexEntry* iter_entry = skip_list_iter_.key();
|
|
|
|
return (iter_entry != nullptr &&
|
|
|
|
iter_entry->column_family == column_family_id_);
|
|
|
|
}
|
|
|
|
|
|
|
|
void SeekToFirst() override {
|
|
|
|
WriteBatchIndexEntry search_entry(
|
|
|
|
nullptr /* search_key */, column_family_id_,
|
|
|
|
true /* is_forward_direction */, true /* is_seek_to_first */);
|
|
|
|
skip_list_iter_.Seek(&search_entry);
|
|
|
|
}
|
|
|
|
|
|
|
|
void SeekToLast() override {
|
|
|
|
WriteBatchIndexEntry search_entry(
|
|
|
|
nullptr /* search_key */, column_family_id_ + 1,
|
|
|
|
true /* is_forward_direction */, true /* is_seek_to_first */);
|
|
|
|
skip_list_iter_.Seek(&search_entry);
|
|
|
|
if (!skip_list_iter_.Valid()) {
|
|
|
|
skip_list_iter_.SeekToLast();
|
|
|
|
} else {
|
|
|
|
skip_list_iter_.Prev();
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
void Seek(const Slice& key) override {
|
|
|
|
WriteBatchIndexEntry search_entry(&key, column_family_id_,
|
|
|
|
true /* is_forward_direction */,
|
|
|
|
false /* is_seek_to_first */);
|
|
|
|
skip_list_iter_.Seek(&search_entry);
|
|
|
|
}
|
|
|
|
|
|
|
|
void SeekForPrev(const Slice& key) override {
|
|
|
|
WriteBatchIndexEntry search_entry(&key, column_family_id_,
|
|
|
|
false /* is_forward_direction */,
|
|
|
|
false /* is_seek_to_first */);
|
|
|
|
skip_list_iter_.SeekForPrev(&search_entry);
|
|
|
|
}
|
|
|
|
|
|
|
|
void Next() override { skip_list_iter_.Next(); }
|
|
|
|
|
|
|
|
void Prev() override { skip_list_iter_.Prev(); }
|
|
|
|
|
|
|
|
WriteEntry Entry() const override;
|
|
|
|
|
|
|
|
Status status() const override {
|
|
|
|
// this is in-memory data structure, so the only way status can be non-ok is
|
|
|
|
// through memory corruption
|
|
|
|
return Status::OK();
|
|
|
|
}
|
|
|
|
|
|
|
|
const WriteBatchIndexEntry* GetRawEntry() const {
|
|
|
|
return skip_list_iter_.key();
|
|
|
|
}
|
|
|
|
|
|
|
|
bool MatchesKey(uint32_t cf_id, const Slice& key);
|
|
|
|
|
|
|
|
private:
|
|
|
|
uint32_t column_family_id_;
|
|
|
|
WriteBatchEntrySkipList::Iterator skip_list_iter_;
|
|
|
|
const ReadableWriteBatch* write_batch_;
|
|
|
|
WriteBatchEntryComparator* comparator_;
|
|
|
|
};
|
|
|
|
|
|
|
|
class WriteBatchWithIndexInternal {
|
|
|
|
public:
|
|
|
|
// For GetFromBatchAndDB or similar
|
|
|
|
explicit WriteBatchWithIndexInternal(DB* db,
|
|
|
|
ColumnFamilyHandle* column_family);
|
|
|
|
// For GetFromBatch or similar
|
|
|
|
explicit WriteBatchWithIndexInternal(const DBOptions* db_options,
|
|
|
|
ColumnFamilyHandle* column_family);
|
|
|
|
|
|
|
|
enum Result { kFound, kDeleted, kNotFound, kMergeInProgress, kError };
|
|
|
|
|
|
|
|
// If batch contains a value for key, store it in *value and return kFound.
|
|
|
|
// If batch contains a deletion for key, return Deleted.
|
|
|
|
// If batch contains Merge operations as the most recent entry for a key,
|
|
|
|
// and the merge process does not stop (not reaching a value or delete),
|
|
|
|
// prepend the current merge operands to *operands,
|
|
|
|
// and return kMergeInProgress
|
|
|
|
// If batch does not contain this key, return kNotFound
|
|
|
|
// Else, return kError on error with error Status stored in *s.
|
|
|
|
Result GetFromBatch(WriteBatchWithIndex* batch, const Slice& key,
|
|
|
|
std::string* value, bool overwrite_key, Status* s) {
|
|
|
|
return GetFromBatch(batch, key, &merge_context_, value, overwrite_key, s);
|
|
|
|
}
|
|
|
|
Result GetFromBatch(WriteBatchWithIndex* batch, const Slice& key,
|
|
|
|
MergeContext* merge_context, std::string* value,
|
|
|
|
bool overwrite_key, Status* s);
|
|
|
|
Status MergeKey(const Slice& key, const Slice* value, std::string* result,
|
|
|
|
Slice* result_operand = nullptr) {
|
|
|
|
return MergeKey(key, value, merge_context_, result, result_operand);
|
|
|
|
}
|
|
|
|
Status MergeKey(const Slice& key, const Slice* value, MergeContext& context,
|
|
|
|
std::string* result, Slice* result_operand = nullptr);
|
|
|
|
|
|
|
|
private:
|
|
|
|
DB* db_;
|
|
|
|
const DBOptions* db_options_;
|
|
|
|
ColumnFamilyHandle* column_family_;
|
|
|
|
MergeContext merge_context_;
|
|
|
|
};
|
|
|
|
|
|
|
|
} // namespace ROCKSDB_NAMESPACE
|
|
|
|
#endif // !ROCKSDB_LITE
|