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comparison Core/Cache/MemoryObjectCache.h @ 3557:4d809b2e1141

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better cache toolbox: MemoryObjectCache
author Sebastien Jodogne <s.jodogne@gmail.com>
date Mon, 04 Nov 2019 15:18:38 +0100
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children fb759c9efd73
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3556:87940f7156e0 3557:4d809b2e1141
1 /**
2 * Orthanc - A Lightweight, RESTful DICOM Store
3 * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
4 * Department, University Hospital of Liege, Belgium
5 * Copyright (C) 2017-2019 Osimis S.A., Belgium
6 *
7 * This program is free software: you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as
9 * published by the Free Software Foundation, either version 3 of the
10 * License, or (at your option) any later version.
11 *
12 * In addition, as a special exception, the copyright holders of this
13 * program give permission to link the code of its release with the
14 * OpenSSL project's "OpenSSL" library (or with modified versions of it
15 * that use the same license as the "OpenSSL" library), and distribute
16 * the linked executables. You must obey the GNU General Public License
17 * in all respects for all of the code used other than "OpenSSL". If you
18 * modify file(s) with this exception, you may extend this exception to
19 * your version of the file(s), but you are not obligated to do so. If
20 * you do not wish to do so, delete this exception statement from your
21 * version. If you delete this exception statement from all source files
22 * in the program, then also delete it here.
23 *
24 * This program is distributed in the hope that it will be useful, but
25 * WITHOUT ANY WARRANTY; without even the implied warranty of
26 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
27 * General Public License for more details.
28 *
29 * You should have received a copy of the GNU General Public License
30 * along with this program. If not, see <http://www.gnu.org/licenses/>.
31 **/
32
33
34 #pragma once
35
36 #include "ICacheable.h"
37 #include "LeastRecentlyUsedIndex.h"
38
39 #if !defined(__EMSCRIPTEN__)
40 // Multithreading is not supported in WebAssembly
41 # include <boost/thread/shared_mutex.hpp>
42 #endif
43
44 #include <boost/date_time/posix_time/posix_time.hpp>
45
46
47 namespace Orthanc
48 {
49 class MemoryObjectCache : public boost::noncopyable
50 {
51 private:
52 class Item;
53
54 #if !defined(__EMSCRIPTEN__)
55 typedef boost::unique_lock<boost::shared_mutex> WriterLock;
56 typedef boost::shared_lock<boost::shared_mutex> ReaderLock;
57
58 // This mutex protects modifications to the structure of the cache (monitor)
59 boost::mutex cacheMutex_;
60
61 // This mutex protects modifications to the items that are stored in the cache
62 boost::shared_mutex contentMutex_;
63 #endif
64
65 size_t currentSize_;
66 size_t maxSize_;
67 LeastRecentlyUsedIndex<std::string, Item*> content_;
68
69 void Recycle(size_t targetSize);
70
71 public:
72 MemoryObjectCache();
73
74 ~MemoryObjectCache();
75
76 size_t GetMaximumSize();
77
78 void SetMaximumSize(size_t size);
79
80 void Acquire(const std::string& key,
81 ICacheable* value);
82
83 void Invalidate(const std::string& key);
84
85 class Reader : public boost::noncopyable
86 {
87 private:
88 #if !defined(__EMSCRIPTEN__)
89 ReaderLock contentLock_;
90 boost::mutex::scoped_lock cacheLock_;
91 #endif
92
93 Item* item_;
94
95 public:
96 Reader(MemoryObjectCache& cache,
97 const std::string& key);
98
99 bool IsValid() const
100 {
101 return item_ != NULL;
102 }
103
104 ICacheable& GetValue() const;
105
106 const boost::posix_time::ptime& GetTime() const;
107 };
108 };
109 }