blob: 3a38cdcea26da1e01364b5db17fa3c55f227fbe6 (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
|
// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include <vespa/searchcommon/attribute/i_document_meta_store_context.h>
#include <vespa/vespalib/stllike/hash_map.h>
#include <vespa/vespalib/stllike/string.h>
#include <memory>
#include <shared_mutex>
#include <atomic>
namespace search { class BitVector; }
namespace vespalib { class MemoryUsage; }
namespace search::attribute {
/**
* Class that caches posting lists (as bit vectors) for a set of search terms.
*
* Lifetime of cached bit vectors is controlled by calling clear() at regular intervals.
*/
class BitVectorSearchCache {
public:
using BitVectorSP = std::shared_ptr<BitVector>;
using ReadGuardSP = IDocumentMetaStoreContext::IReadGuard::SP;
struct Entry {
// We need to keep a document meta store read guard to ensure that no lids that are cached
// in the bit vector are re-used until the guard is released.
ReadGuardSP dmsReadGuard;
BitVectorSP bitVector;
uint32_t docIdLimit;
Entry(ReadGuardSP dmsReadGuard_, BitVectorSP bitVector_, uint32_t docIdLimit_) noexcept
: dmsReadGuard(std::move(dmsReadGuard_)), bitVector(std::move(bitVector_)), docIdLimit(docIdLimit_) {}
};
private:
using Cache = vespalib::hash_map<vespalib::string, std::shared_ptr<Entry>>;
mutable std::shared_mutex _mutex;
std::atomic<uint64_t> _size;
size_t _entries_extra_memory_usage;
Cache _cache;
public:
BitVectorSearchCache();
~BitVectorSearchCache();
void insert(const vespalib::string &term, std::shared_ptr<Entry> entry);
std::shared_ptr<Entry> find(const vespalib::string &term) const;
size_t size() const { return _size.load(std::memory_order_relaxed); }
vespalib::MemoryUsage get_memory_usage() const;
void clear();
};
}
|
