Implementing DynamicIterator for TransformRepNoLock
Summary: What @haobo done with TransformRep, now in TransformRepNoLock. Similar implementation, except that I made DynamicIterator a subclass of Iterator which makes me have less iterator initializations. Test Plan: ./prefix_test. Seeing huge savings vs. TransformRep again! Reviewers: dhruba, haobo, sdong, kailiu Reviewed By: haobo CC: leveldb, haobo Differential Revision: https://reviews.facebook.net/D13953
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@ -93,9 +93,8 @@ class PrefixTest {
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auto prefix_extractor = NewFixedPrefixTransform(8);
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options.prefix_extractor = prefix_extractor;
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if (FLAGS_use_nolock_version) {
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options.memtable_factory =
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std::make_shared<rocksdb::PrefixHashRepNoLockFactory>(
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prefix_extractor, FLAGS_bucket_count);
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options.memtable_factory.reset(NewHashSkipListRepFactory(
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prefix_extractor, FLAGS_bucket_count));
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} else {
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options.memtable_factory =
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std::make_shared<rocksdb::PrefixHashRepFactory>(
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@ -63,6 +63,11 @@ class SkipList {
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// The returned iterator is not valid.
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explicit Iterator(const SkipList* list);
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// Change the underlying skiplist used for this iterator
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// This enables us not changing the iterator without deallocating
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// an old one and then allocating a new one
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void SetList(const SkipList* list);
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// Returns true iff the iterator is positioned at a valid node.
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bool Valid() const;
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@ -194,6 +199,11 @@ SkipList<Key,Comparator>::NewNode(const Key& key, int height) {
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template<typename Key, class Comparator>
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inline SkipList<Key,Comparator>::Iterator::Iterator(const SkipList* list) {
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SetList(list);
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}
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template<typename Key, class Comparator>
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inline void SkipList<Key,Comparator>::Iterator::SetList(const SkipList* list) {
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list_ = list;
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node_ = nullptr;
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}
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@ -260,67 +260,11 @@ public:
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}
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};
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// NO LOCKS VERSION
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// The same as TransformRepFactory except it doesn't use locks.
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// Experimental, will replace TransformRepFactory once we are sure
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// it performs better
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class TransformRepNoLockFactory : public MemTableRepFactory {
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public:
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explicit TransformRepNoLockFactory(const SliceTransform* transform,
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size_t bucket_count)
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: transform_(transform),
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bucket_count_(bucket_count) { }
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virtual ~TransformRepNoLockFactory() { delete transform_; }
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virtual std::shared_ptr<MemTableRep> CreateMemTableRep(
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MemTableRep::KeyComparator&, Arena*) override;
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virtual const char* Name() const override {
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return "TransformRepNoLockFactory";
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}
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const SliceTransform* GetTransform() { return transform_; }
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protected:
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const SliceTransform* transform_;
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const size_t bucket_count_;
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};
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// UnsortedReps bin user keys based on an identity function transform -- that
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// is, transform(key) = key. This optimizes for point look-ups.
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//
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// Parameters: See TransformRepNoLockFactory.
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class UnsortedRepNoLockFactory : public TransformRepNoLockFactory {
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public:
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explicit UnsortedRepNoLockFactory(size_t bucket_count = 1000000)
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: TransformRepNoLockFactory(NewNoopTransform(),
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bucket_count) { }
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virtual const char* Name() const override {
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return "UnsortedRepNoLockFactory";
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}
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};
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// PrefixHashReps bin user keys based on a fixed-size prefix. This optimizes for
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// short ranged scans over a given prefix.
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//
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// Parameters: See TransformRepNoLockFactory.
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class PrefixHashRepNoLockFactory : public TransformRepNoLockFactory {
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public:
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explicit PrefixHashRepNoLockFactory(const SliceTransform* prefix_extractor,
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size_t bucket_count = 1000000)
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: TransformRepNoLockFactory(prefix_extractor, bucket_count)
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{ }
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virtual std::shared_ptr<MemTableRep> CreateMemTableRep(
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MemTableRep::KeyComparator&, Arena*) override;
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virtual const char* Name() const override {
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return "PrefixHashRepNoLockFactory";
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}
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};
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extern MemTableRepFactory* NewHashSkipListRepFactory(
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const SliceTransform* transform, size_t bucket_count = 1000000);
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}
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@ -16,9 +16,9 @@
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namespace rocksdb {
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namespace {
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class TransformRepNoLock : public MemTableRep {
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class HashSkipListRep : public MemTableRep {
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public:
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TransformRepNoLock(MemTableRep::KeyComparator& compare, Arena* arena,
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HashSkipListRep(MemTableRep::KeyComparator& compare, Arena* arena,
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const SliceTransform* transform, size_t bucket_size);
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virtual void Insert(const char* key) override;
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@ -27,17 +27,21 @@ class TransformRepNoLock : public MemTableRep {
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virtual size_t ApproximateMemoryUsage() override;
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virtual ~TransformRepNoLock();
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virtual ~HashSkipListRep();
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virtual std::shared_ptr<MemTableRep::Iterator> GetIterator() override;
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virtual std::shared_ptr<MemTableRep::Iterator> GetIterator(
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const Slice& slice) override;
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std::shared_ptr<MemTableRep::Iterator> GetTransformIterator(
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const Slice& transformed);
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virtual std::shared_ptr<MemTableRep::Iterator> GetPrefixIterator(
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const Slice& prefix) override;
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virtual std::shared_ptr<MemTableRep::Iterator> GetDynamicPrefixIterator()
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override;
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private:
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friend class DynamicIterator;
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typedef SkipList<const char*, MemTableRep::KeyComparator&> Bucket;
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size_t bucket_size_;
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@ -76,50 +80,72 @@ class TransformRepNoLock : public MemTableRep {
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virtual ~Iterator() {
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// if we own the list, we should also delete it
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if (own_list_) {
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assert(list_ != nullptr);
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delete list_;
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}
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};
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}
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// Returns true iff the iterator is positioned at a valid node.
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virtual bool Valid() const {
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return iter_.Valid();
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return list_ != nullptr && 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 {
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assert(Valid());
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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() {
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assert(Valid());
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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() {
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assert(Valid());
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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 char* target) {
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if (list_ != nullptr) {
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iter_.Seek(target);
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}
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}
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// Position at the first entry in collection.
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// Final state of iterator is Valid() iff collection is not empty.
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virtual void SeekToFirst() {
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if (list_ != nullptr) {
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iter_.SeekToFirst();
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}
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}
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// Position at the last entry in collection.
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// Final state of iterator is Valid() iff collection is not empty.
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virtual void SeekToLast() {
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if (list_ != nullptr) {
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iter_.SeekToLast();
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}
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}
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protected:
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void Reset(Bucket* list) {
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if (own_list_) {
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assert(list_ != nullptr);
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delete list_;
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}
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list_ = list;
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iter_.SetList(list);
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own_list_ = false;
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}
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private:
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// if list_ is nullptr, we should NEVER call any methods on iter_
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// if list_ is nullptr, this Iterator is not Valid()
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Bucket* list_;
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Bucket::Iterator iter_;
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// here we track if we own list_. If we own it, we are also
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@ -127,6 +153,40 @@ class TransformRepNoLock : public MemTableRep {
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bool own_list_;
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};
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class DynamicIterator : public HashSkipListRep::Iterator {
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public:
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explicit DynamicIterator(const HashSkipListRep& memtable_rep)
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: HashSkipListRep::Iterator(nullptr, false),
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memtable_rep_(memtable_rep) {}
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// Advance to the first entry with a key >= target
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virtual void Seek(const char* target) {
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auto transformed = memtable_rep_.transform_->Transform(
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memtable_rep_.UserKey(target));
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Reset(memtable_rep_.GetBucket(transformed));
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HashSkipListRep::Iterator::Seek(target);
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}
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// Position at the first entry in collection.
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// Final state of iterator is Valid() iff collection is not empty.
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virtual void SeekToFirst() {
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// Prefix iterator does not support total order.
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// We simply set the iterator to invalid state
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Reset(nullptr);
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}
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// Position at the last entry in collection.
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// Final state of iterator is Valid() iff collection is not empty.
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virtual void SeekToLast() {
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// Prefix iterator does not support total order.
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// We simply set the iterator to invalid state
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Reset(nullptr);
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}
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private:
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// the underlying memtable
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const HashSkipListRep& memtable_rep_;
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};
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class EmptyIterator : public MemTableRep::Iterator {
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// This is used when there wasn't a bucket. It is cheaper than
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// instantiating an empty bucket over which to iterate.
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@ -150,17 +210,7 @@ class TransformRepNoLock : public MemTableRep {
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std::shared_ptr<EmptyIterator> empty_iterator_;
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};
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class PrefixHashRepNoLock : public TransformRepNoLock {
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public:
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PrefixHashRepNoLock(MemTableRep::KeyComparator& compare, Arena* arena,
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const SliceTransform* transform, size_t bucket_size)
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: TransformRepNoLock(compare, arena, transform, bucket_size) { }
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virtual std::shared_ptr<MemTableRep::Iterator> GetPrefixIterator(
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const Slice& prefix) override;
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};
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TransformRepNoLock::TransformRepNoLock(MemTableRep::KeyComparator& compare,
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HashSkipListRep::HashSkipListRep(MemTableRep::KeyComparator& compare,
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Arena* arena, const SliceTransform* transform, size_t bucket_size)
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: bucket_size_(bucket_size),
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transform_(transform),
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@ -175,11 +225,11 @@ TransformRepNoLock::TransformRepNoLock(MemTableRep::KeyComparator& compare,
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}
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}
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TransformRepNoLock::~TransformRepNoLock() {
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HashSkipListRep::~HashSkipListRep() {
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delete[] buckets_;
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}
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TransformRepNoLock::Bucket* TransformRepNoLock::GetInitializedBucket(
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HashSkipListRep::Bucket* HashSkipListRep::GetInitializedBucket(
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const Slice& transformed) {
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size_t hash = GetHash(transformed);
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auto bucket = GetBucket(hash);
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@ -191,14 +241,14 @@ TransformRepNoLock::Bucket* TransformRepNoLock::GetInitializedBucket(
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return bucket;
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}
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void TransformRepNoLock::Insert(const char* key) {
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void HashSkipListRep::Insert(const char* key) {
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assert(!Contains(key));
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auto transformed = transform_->Transform(UserKey(key));
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auto bucket = GetInitializedBucket(transformed);
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bucket->Insert(key);
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}
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bool TransformRepNoLock::Contains(const char* key) const {
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bool HashSkipListRep::Contains(const char* key) const {
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auto transformed = transform_->Transform(UserKey(key));
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auto bucket = GetBucket(transformed);
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if (bucket == nullptr) {
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@ -207,11 +257,11 @@ bool TransformRepNoLock::Contains(const char* key) const {
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return bucket->Contains(key);
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}
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size_t TransformRepNoLock::ApproximateMemoryUsage() {
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size_t HashSkipListRep::ApproximateMemoryUsage() {
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return sizeof(buckets_);
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}
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std::shared_ptr<MemTableRep::Iterator> TransformRepNoLock::GetIterator() {
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std::shared_ptr<MemTableRep::Iterator> HashSkipListRep::GetIterator() {
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auto list = new Bucket(compare_, arena_);
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for (size_t i = 0; i < bucket_size_; ++i) {
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auto bucket = GetBucket(i);
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@ -225,38 +275,56 @@ std::shared_ptr<MemTableRep::Iterator> TransformRepNoLock::GetIterator() {
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return std::make_shared<Iterator>(list);
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}
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std::shared_ptr<MemTableRep::Iterator> TransformRepNoLock::GetTransformIterator(
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const Slice& transformed) {
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auto bucket = GetBucket(transformed);
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std::shared_ptr<MemTableRep::Iterator> HashSkipListRep::GetPrefixIterator(
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const Slice& prefix) {
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auto bucket = GetBucket(prefix);
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if (bucket == nullptr) {
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return empty_iterator_;
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}
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return std::make_shared<Iterator>(bucket, false);
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}
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std::shared_ptr<MemTableRep::Iterator> TransformRepNoLock::GetIterator(
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std::shared_ptr<MemTableRep::Iterator> HashSkipListRep::GetIterator(
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const Slice& slice) {
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auto transformed = transform_->Transform(slice);
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return GetTransformIterator(transformed);
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return GetPrefixIterator(transform_->Transform(slice));
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}
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std::shared_ptr<MemTableRep::Iterator>
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HashSkipListRep::GetDynamicPrefixIterator() {
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return std::make_shared<DynamicIterator>(*this);
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}
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} // anon namespace
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std::shared_ptr<MemTableRep> TransformRepNoLockFactory::CreateMemTableRep(
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MemTableRep::KeyComparator& compare, Arena* arena) {
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return std::make_shared<TransformRepNoLock>(compare, arena, transform_,
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bucket_count_);
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}
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class HashSkipListRepFactory : public MemTableRepFactory {
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public:
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explicit HashSkipListRepFactory(const SliceTransform* transform,
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size_t bucket_count = 1000000)
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: transform_(transform),
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bucket_count_(bucket_count) { }
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std::shared_ptr<MemTableRep> PrefixHashRepNoLockFactory::CreateMemTableRep(
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MemTableRep::KeyComparator& compare, Arena* arena) {
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return std::make_shared<PrefixHashRepNoLock>(compare, arena, transform_,
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bucket_count_);
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}
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virtual ~HashSkipListRepFactory() { delete transform_; }
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std::shared_ptr<MemTableRep::Iterator> PrefixHashRepNoLock::GetPrefixIterator(
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const Slice& prefix) {
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return TransformRepNoLock::GetTransformIterator(prefix);
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virtual std::shared_ptr<MemTableRep> CreateMemTableRep(
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MemTableRep::KeyComparator& compare, Arena* arena) override {
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return std::make_shared<HashSkipListRep>(compare, arena, transform_,
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bucket_count_);
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}
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virtual const char* Name() const override {
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return "HashSkipListRepFactory";
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}
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const SliceTransform* GetTransform() { return transform_; }
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private:
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const SliceTransform* transform_;
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const size_t bucket_count_;
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};
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MemTableRepFactory* NewHashSkipListRepFactory(
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const SliceTransform* transform, size_t bucket_count) {
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return new HashSkipListRepFactory(transform, bucket_count);
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}
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} // namespace rocksdb
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