58e1956d50
Summary: For prefix mem tables, encoding mem table key may be unnecessary if the prefix doesn't have any key. This patch is a little bit hacky but I want to try out the performance gain of removing this lazy initialization. In longer term, we might want to revisit the way we abstract mem tables implementations. Test Plan: make all check Reviewers: haobo, igor, kailiu Reviewed By: igor CC: leveldb Differential Revision: https://reviews.facebook.net/D14265
112 lines
3.3 KiB
C++
112 lines
3.3 KiB
C++
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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//
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#include "rocksdb/memtablerep.h"
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#include "db/memtable.h"
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#include "db/skiplist.h"
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namespace rocksdb {
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namespace {
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class SkipListRep : public MemTableRep {
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SkipList<const char*, MemTableRep::KeyComparator&> skip_list_;
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public:
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explicit SkipListRep(MemTableRep::KeyComparator& compare, Arena* arena)
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: skip_list_(compare, arena) {
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}
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// Insert key into the list.
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// REQUIRES: nothing that compares equal to key is currently in the list.
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virtual void Insert(const char* key) override {
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skip_list_.Insert(key);
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}
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// Returns true iff an entry that compares equal to key is in the list.
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virtual bool Contains(const char* key) const override {
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return skip_list_.Contains(key);
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}
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virtual size_t ApproximateMemoryUsage() override {
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// All memory is allocated through arena; nothing to report here
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return 0;
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}
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virtual ~SkipListRep() override { }
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// Iteration over the contents of a skip list
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class Iterator : public MemTableRep::Iterator {
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SkipList<const char*, MemTableRep::KeyComparator&>::Iterator iter_;
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public:
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// Initialize an iterator over the specified list.
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// The returned iterator is not valid.
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explicit Iterator(
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const SkipList<const char*, MemTableRep::KeyComparator&>* list
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) : iter_(list) { }
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virtual ~Iterator() override { }
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// Returns true iff the iterator is positioned at a valid node.
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virtual bool Valid() const override {
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return iter_.Valid();
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}
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// Returns the key at the current position.
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// REQUIRES: Valid()
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virtual const char* key() const override {
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return iter_.key();
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}
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// Advances to the next position.
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// REQUIRES: Valid()
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virtual void Next() override {
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iter_.Next();
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}
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// Advances to the previous position.
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// REQUIRES: Valid()
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virtual void Prev() override {
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iter_.Prev();
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}
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// Advance to the first entry with a key >= target
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virtual void Seek(const Slice& user_key, const char* memtable_key)
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override {
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if (memtable_key != nullptr) {
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iter_.Seek(memtable_key);
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} else {
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iter_.Seek(EncodeKey(&tmp_, user_key));
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}
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}
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// Position at the first entry in list.
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// Final state of iterator is Valid() iff list is not empty.
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virtual void SeekToFirst() override {
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iter_.SeekToFirst();
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}
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// Position at the last entry in list.
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// Final state of iterator is Valid() iff list is not empty.
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virtual void SeekToLast() override {
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iter_.SeekToLast();
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}
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protected:
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std::string tmp_; // For passing to EncodeKey
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};
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// Unhide default implementations of GetIterator
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using MemTableRep::GetIterator;
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virtual std::shared_ptr<MemTableRep::Iterator> GetIterator() override {
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return std::make_shared<SkipListRep::Iterator>(&skip_list_);
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}
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};
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}
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std::shared_ptr<MemTableRep> SkipListFactory::CreateMemTableRep (
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MemTableRep::KeyComparator& compare, Arena* arena) {
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return std::shared_ptr<MemTableRep>(new SkipListRep(compare, arena));
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}
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} // namespace rocksdb
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