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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include "bucketdatabase.h"
#include <memory>
namespace storage {
namespace bucketdb {
template <typename DataStoreTraitsT> class GenericBTreeBucketDatabase;
}
/*
* Bucket database implementation built around lock-free single-writer/multiple-readers B+tree.
*
* Since a distributor must be able to handle multiple replicas for a given bucket, these
* are handled via an ArrayStore indirection. A distributor bucket DB also includes state
* for the _entire bucket_ itself, not just the replicas; last timestamp of bucket GC. Since
* this is an uint32 we cheekily mangle it into the value, i.e. each bucket key maps to a
* composite key of (gc_timestamp_u32 << 32) | array_ref_u32.
*
* Readers from contexts that are not guaranteed to be the main distributor thread MUST
* only access the database via an acquired read guard.
* Writing MUST only take place from the main distributor thread.
*/
// TODO create and use a new DB interface with better bulk loading, snapshot and iteration support
class BTreeBucketDatabase : public BucketDatabase {
struct ReplicaValueTraits;
using ImplType = bucketdb::GenericBTreeBucketDatabase<ReplicaValueTraits>;
std::unique_ptr<ImplType> _impl;
public:
BTreeBucketDatabase();
~BTreeBucketDatabase() override;
void merge(MergingProcessor&) override;
// Ye olde bucket DB API:
Entry get(const document::BucketId& bucket) const override;
void remove(const document::BucketId& bucket) override;
void getParents(const document::BucketId& childBucket,
std::vector<Entry>& entries) const override;
void getAll(const document::BucketId& bucket,
std::vector<Entry>& entries) const override;
void update(const Entry& newEntry) override;
void process_update(const document::BucketId& bucket, EntryUpdateProcessor &processor, bool create_if_nonexisting) override;
void for_each_lower_bound(EntryProcessor&, const document::BucketId& at_or_after) const override;
void for_each_upper_bound(EntryProcessor&, const document::BucketId& after) const override;
Entry upperBound(const document::BucketId& value) const override;
uint64_t size() const override;
void clear() override;
document::BucketId getAppropriateBucket(
uint16_t minBits,
const document::BucketId& bid) override;
uint32_t childCount(const document::BucketId&) const override;
void print(std::ostream& out, bool verbose,
const std::string& indent) const override;
private:
class ReadGuardImpl;
friend class ReadGuardImpl;
public:
std::unique_ptr<bucketdb::ReadGuard<Entry, ConstEntryRef>> acquire_read_guard() const override;
vespalib::MemoryUsage memory_usage() const noexcept override;
};
}
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