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
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
|
// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab
#pragma once
#include <boost/intrusive_ptr.hpp>
#include <boost/intrusive/set.hpp>
#include <boost/intrusive/list.hpp>
namespace ceph::common {
/**
* intrusive_lru: lru implementation with embedded map and list hook
*
* Note, this implementation currently is entirely thread-unsafe.
*/
template <typename K, typename V, typename VToK>
struct intrusive_lru_config {
using key_type = K;
using value_type = V;
using key_of_value = VToK;
};
template <typename Config>
class intrusive_lru;
template <typename Config>
class intrusive_lru_base;
template <typename Config>
void intrusive_ptr_add_ref(intrusive_lru_base<Config> *p);
template <typename Config>
void intrusive_ptr_release(intrusive_lru_base<Config> *p);
template <typename Config>
class intrusive_lru_base {
unsigned use_count = 0;
// null if unreferenced
intrusive_lru<Config> *lru = nullptr;
public:
boost::intrusive::set_member_hook<> set_hook;
boost::intrusive::list_member_hook<> list_hook;
using Ref = boost::intrusive_ptr<typename Config::value_type>;
using lru_t = intrusive_lru<Config>;
friend intrusive_lru<Config>;
friend void intrusive_ptr_add_ref<>(intrusive_lru_base<Config> *);
friend void intrusive_ptr_release<>(intrusive_lru_base<Config> *);
virtual ~intrusive_lru_base() {}
};
template <typename Config>
class intrusive_lru {
using base_t = intrusive_lru_base<Config>;
using K = typename Config::key_type;
using T = typename Config::value_type;
using TRef = typename base_t::Ref;
using lru_set_option_t = boost::intrusive::member_hook<
base_t,
boost::intrusive::set_member_hook<>,
&base_t::set_hook>;
using VToK = typename Config::key_of_value;
struct VToKWrapped {
using type = typename VToK::type;
const type &operator()(const base_t &obc) {
return VToK()(static_cast<const T&>(obc));
}
};
using lru_set_t = boost::intrusive::set<
base_t,
lru_set_option_t,
boost::intrusive::key_of_value<VToKWrapped>
>;
lru_set_t lru_set;
using lru_list_t = boost::intrusive::list<
base_t,
boost::intrusive::member_hook<
base_t,
boost::intrusive::list_member_hook<>,
&base_t::list_hook>>;
lru_list_t unreferenced_list;
size_t lru_target_size = 0;
void evict() {
while (!unreferenced_list.empty() &&
lru_set.size() > lru_target_size) {
auto &b = unreferenced_list.front();
assert(!b.lru);
unreferenced_list.pop_front();
lru_set.erase_and_dispose(
lru_set.iterator_to(b),
[](auto *p) { delete p; }
);
}
}
void access(base_t &b) {
if (b.lru)
return;
unreferenced_list.erase(lru_list_t::s_iterator_to(b));
b.lru = this;
}
void insert(base_t &b) {
assert(!b.lru);
lru_set.insert(b);
b.lru = this;
evict();
}
void unreferenced(base_t &b) {
assert(b.lru);
unreferenced_list.push_back(b);
b.lru = nullptr;
evict();
}
public:
/**
* Returns the TRef corresponding to k if it exists or
* creates it otherwise. Return is:
* std::pair(reference_to_val, found)
*/
std::pair<TRef, bool> get_or_create(const K &k) {
typename lru_set_t::insert_commit_data icd;
auto [iter, missing] = lru_set.insert_check(
k,
icd);
if (missing) {
auto ret = new T(k);
lru_set.insert_commit(*ret, icd);
insert(*ret);
return {TRef(ret), false};
} else {
access(*iter);
return {TRef(static_cast<T*>(&*iter)), true};
}
}
/*
* Clears unreferenced elements from the lru set [from, to]
*/
void clear_range(
const K& from,
const K& to) {
auto from_iter = lru_set.lower_bound(from);
auto to_iter = lru_set.upper_bound(to);
for (auto i = from_iter; i != to_iter; ) {
if (!(*i).lru) {
unreferenced_list.erase(lru_list_t::s_iterator_to(*i));
i = lru_set.erase_and_dispose(i, [](auto *p)
{ delete p; } );
} else {
i++;
}
}
}
template <class F>
void for_each(F&& f) {
for (auto& v : lru_set) {
access(v);
f(TRef{static_cast<T*>(&v)});
}
}
/**
* Returns the TRef corresponding to k if it exists or
* nullptr otherwise.
*/
TRef get(const K &k) {
if (auto iter = lru_set.find(k); iter != std::end(lru_set)) {
access(*iter);
return TRef(static_cast<T*>(&*iter));
} else {
return nullptr;
}
}
void set_target_size(size_t target_size) {
lru_target_size = target_size;
evict();
}
~intrusive_lru() {
set_target_size(0);
}
friend void intrusive_ptr_add_ref<>(intrusive_lru_base<Config> *);
friend void intrusive_ptr_release<>(intrusive_lru_base<Config> *);
};
template <typename Config>
void intrusive_ptr_add_ref(intrusive_lru_base<Config> *p) {
assert(p);
assert(p->lru);
p->use_count++;
}
template <typename Config>
void intrusive_ptr_release(intrusive_lru_base<Config> *p) {
assert(p);
assert(p->use_count > 0);
--p->use_count;
if (p->use_count == 0) {
p->lru->unreferenced(*p);
}
}
}
|
