blob: d8bb03350265bdf8afc254e569b4b2da8b6e2a41 (
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
56
57
|
// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include "constant_value.h"
#include <map>
#include <memory>
#include <mutex>
namespace vespalib {
namespace eval {
/**
* A cache enabling clients to share the constant values created by an
* underlying factory. The returned wrappers are used to ensure
* appropriate lifetime of created values. Used values are kept in the
* cache and unused values are evicted from the cache.
**/
class ConstantValueCache : public ConstantValueFactory
{
private:
struct Cache {
using SP = std::shared_ptr<Cache>;
using Key = std::pair<vespalib::string, vespalib::string>;
struct Value {
size_t num_refs;
ConstantValue::UP const_value;
Value(ConstantValue::UP const_value_in)
: num_refs(1), const_value(std::move(const_value_in)) {}
};
using Map = std::map<Key,Value>;
std::mutex lock;
Map cached;
};
struct Token : ConstantValue {
Cache::SP cache;
Cache::Map::iterator entry;
Token(Cache::SP cache_in, Cache::Map::iterator entry_in)
: cache(std::move(cache_in)), entry(entry_in) {}
const ValueType &type() const override { return entry->second.const_value->type(); }
const Value &value() const override { return entry->second.const_value->value(); }
~Token();
};
const ConstantValueFactory &_factory;
Cache::SP _cache;
public:
ConstantValueCache(const ConstantValueFactory &factory);
ConstantValue::UP create(const vespalib::string &path, const vespalib::string &type) const override;
~ConstantValueCache() override;
};
} // namespace vespalib::eval
} // namespace vespalib
|
