summaryrefslogtreecommitdiffstats
path: root/cachecleaner.hh
blob: f3af11af7765aa4a466f394cbf59fb37fe57da84 (plain)
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
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
/*
 * This file is part of PowerDNS or dnsdist.
 * Copyright -- PowerDNS.COM B.V. and its contributors
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of version 2 of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * In addition, for the avoidance of any doubt, permission is granted to
 * link this program with OpenSSL and to (re)distribute the binaries
 * produced as the result of such linking.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
#pragma once

#include <boost/multi_index_container.hpp>

#include "dnsname.hh"
#include "lock.hh"

// this function can clean any cache that has a getTTD() method on its entries, a preRemoval() method and a 'sequence' index as its second index
// the ritual is that the oldest entries are in *front* of the sequence collection, so on a hit, move an item to the end
// on a miss, move it to the beginning
template <typename S, typename C, typename T> void pruneCollection(C& container, T& collection, size_t maxCached, size_t scanFraction = 1000)
{
  const time_t now = time(0);
  size_t toTrim = 0;
  const size_t cacheSize = collection.size();

  if (cacheSize > maxCached) {
    toTrim = cacheSize - maxCached;
  }

  auto& sidx = collection.template get<S>();

  // two modes - if toTrim is 0, just look through 1/scanFraction of all records 
  // and nuke everything that is expired
  // otherwise, scan first 5*toTrim records, and stop once we've nuked enough
  const size_t lookAt = toTrim ? 5 * toTrim : cacheSize / scanFraction;
  size_t tried = 0, erased = 0;

  for (auto iter = sidx.begin(); iter != sidx.end() && tried < lookAt ; ++tried) {
    if (iter->getTTD() < now) {
      iter = sidx.erase(iter);
      erased++;
    }
    else {
      ++iter;
    }

    if (toTrim && erased >= toTrim) {
      break;
    }
  }

  if (erased >= toTrim) { // done
    return;
  }

  toTrim -= erased;

  // just lob it off from the beginning
  auto iter = sidx.begin();
  for (size_t i = 0; i < toTrim && iter != sidx.end(); i++) {
    iter = sidx.erase(iter);
  }
}

// note: this expects iterator from first index
template <typename S, typename T> void moveCacheItemToFrontOrBack(T& collection, typename T::iterator& iter, bool front)
{
  typedef typename T::template index<S>::type sequence_t;
  sequence_t& sidx=collection.template get<S>();
  typename sequence_t::iterator si=collection.template project<S>(iter);
  if(front)
    sidx.relocate(sidx.begin(), si); // at the beginning of the delete queue
  else
    sidx.relocate(sidx.end(), si);  // back
}

template <typename S, typename T> void moveCacheItemToFront(T& collection, typename T::iterator& iter)
{
  moveCacheItemToFrontOrBack<S>(collection, iter, true);
}

template <typename S, typename T> void moveCacheItemToBack(T& collection, typename T::iterator& iter)
{
  moveCacheItemToFrontOrBack<S>(collection, iter, false);
}

template <typename S, typename T> uint64_t pruneLockedCollectionsVector(std::vector<T>& maps)
{
  uint64_t totErased = 0;
  time_t now = time(nullptr);

  for(auto& mc : maps) {
    auto map = mc.d_map.write_lock();

    uint64_t lookAt = (map->size() + 9) / 10; // Look at 10% of this shard
    uint64_t erased = 0;

    auto& sidx = boost::multi_index::get<S>(*map);
    for(auto i = sidx.begin(); i != sidx.end() && lookAt > 0; lookAt--) {
      if(i->ttd < now) {
        i = sidx.erase(i);
        erased++;
      } else {
        ++i;
      }
    }
    totErased += erased;
  }

  return totErased;
}

template <typename S, typename C, typename T> uint64_t pruneMutexCollectionsVector(C& container, std::vector<T>& maps, uint64_t maxCached, uint64_t cacheSize)
{
  time_t now = time(nullptr);
  uint64_t totErased = 0;
  uint64_t toTrim = 0;
  uint64_t lookAt = 0;

  // two modes - if toTrim is 0, just look through 10%  of the cache and nuke everything that is expired
  // otherwise, scan first 5*toTrim records, and stop once we've nuked enough
  if (cacheSize > maxCached) {
    toTrim = cacheSize - maxCached;
    lookAt = 5 * toTrim;
  } else {
    lookAt = cacheSize / 10;
  }

  uint64_t maps_size = maps.size();
  if (maps_size == 0) {
    return 0;
  }

  for (auto& content : maps) {
    auto mc = content.lock();
    mc->invalidate();
    auto& sidx = boost::multi_index::get<S>(mc->d_map);
    uint64_t erased = 0, lookedAt = 0;
    for (auto i = sidx.begin(); i != sidx.end(); lookedAt++) {
      if (i->getTTD() < now) {
        container.preRemoval(*mc, *i);
        i = sidx.erase(i);
        erased++;
        --content.d_entriesCount;
      } else {
        ++i;
      }

      if (toTrim && erased >= toTrim / maps_size)
        break;

      if (lookedAt > lookAt / maps_size)
        break;
    }
    totErased += erased;
    if (toTrim && totErased >= toTrim)
      break;
  }

  if (totErased >= toTrim) { // done
    return totErased;
  }

  toTrim -= totErased;

  while (true) {
    size_t pershard = toTrim / maps_size + 1;
    for (auto& content : maps) {
      auto mc = content.lock();
      mc->invalidate();
      auto& sidx = boost::multi_index::get<S>(mc->d_map);
      size_t removed = 0;
      for (auto i = sidx.begin(); i != sidx.end() && removed < pershard; removed++) {
        container.preRemoval(*mc, *i);
        i = sidx.erase(i);
        --content.d_entriesCount;
        totErased++;
        toTrim--;
        if (toTrim == 0) {
          return totErased;
        }
      }
    }
  }
  // Not reached
  return totErased;
}

template <typename T> uint64_t purgeLockedCollectionsVector(std::vector<T>& maps)
{
  uint64_t delcount=0;

  for(auto& mc : maps) {
    auto map = mc.d_map.write_lock();
    delcount += map->size();
    map->clear();
  }

  return delcount;
}

template <typename N, typename T> uint64_t purgeLockedCollectionsVector(std::vector<T>& maps, const std::string& match)
{
  uint64_t delcount=0;
  std::string prefix(match);
  prefix.resize(prefix.size()-1);
  DNSName dprefix(prefix);
  for(auto& mc : maps) {
    auto map = mc.d_map.write_lock();
    auto& idx = boost::multi_index::get<N>(*map);
    auto iter = idx.lower_bound(dprefix);
    auto start = iter;

    for(; iter != idx.end(); ++iter) {
      if(!iter->qname.isPartOf(dprefix)) {
        break;
      }
      delcount++;
    }
    idx.erase(start, iter);
  }

  return delcount;
}

template <typename N, typename T> uint64_t purgeExactLockedCollection(T& mc, const DNSName& qname)
{
  uint64_t delcount=0;
  auto map = mc.d_map.write_lock();
  auto& idx = boost::multi_index::get<N>(*map);
  auto range = idx.equal_range(qname);
  if(range.first != range.second) {
    delcount += distance(range.first, range.second);
    idx.erase(range.first, range.second);
  }

  return delcount;
}

template<typename S, typename Index>
bool lruReplacingInsert(Index& i, const typename Index::value_type& x)
{
  auto inserted = i.insert(x);
  if (!inserted.second) {
    moveCacheItemToBack<S>(i, inserted.first);
    i.replace(inserted.first, x);
    return false;
  }
  return true;
}