henrike@webrtc.org | 0e118e7 | 2013-07-10 00:45:36 +0000 | [diff] [blame] | 1 | /* |
| 2 | * libjingle |
| 3 | * Copyright 2004--2005, Google Inc. |
| 4 | * |
| 5 | * Redistribution and use in source and binary forms, with or without |
| 6 | * modification, are permitted provided that the following conditions are met: |
| 7 | * |
| 8 | * 1. Redistributions of source code must retain the above copyright notice, |
| 9 | * this list of conditions and the following disclaimer. |
| 10 | * 2. Redistributions in binary form must reproduce the above copyright notice, |
| 11 | * this list of conditions and the following disclaimer in the documentation |
| 12 | * and/or other materials provided with the distribution. |
| 13 | * 3. The name of the author may not be used to endorse or promote products |
| 14 | * derived from this software without specific prior written permission. |
| 15 | * |
| 16 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED |
| 17 | * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF |
| 18 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO |
| 19 | * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 20 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| 21 | * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; |
| 22 | * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
| 23 | * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR |
| 24 | * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF |
| 25 | * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 26 | */ |
| 27 | |
| 28 | #ifndef TALK_BASE_DISKCACHE_H__ |
| 29 | #define TALK_BASE_DISKCACHE_H__ |
| 30 | |
| 31 | #include <map> |
| 32 | #include <string> |
| 33 | |
| 34 | #ifdef WIN32 |
| 35 | #undef UnlockResource |
| 36 | #endif // WIN32 |
| 37 | |
| 38 | namespace talk_base { |
| 39 | |
| 40 | class StreamInterface; |
| 41 | |
| 42 | /////////////////////////////////////////////////////////////////////////////// |
| 43 | // DiskCache - An LRU cache of streams, stored on disk. |
| 44 | // |
| 45 | // Streams are identified by a unique resource id. Multiple streams can be |
| 46 | // associated with each resource id, distinguished by an index. When old |
| 47 | // resources are flushed from the cache, all streams associated with those |
| 48 | // resources are removed together. |
| 49 | // DiskCache is designed to persist across executions of the program. It is |
| 50 | // safe for use from an arbitrary number of users on a single thread, but not |
| 51 | // from multiple threads or other processes. |
| 52 | /////////////////////////////////////////////////////////////////////////////// |
| 53 | |
| 54 | class DiskCache { |
| 55 | public: |
| 56 | DiskCache(); |
| 57 | virtual ~DiskCache(); |
| 58 | |
| 59 | bool Initialize(const std::string& folder, size_t size); |
| 60 | bool Purge(); |
| 61 | |
| 62 | bool LockResource(const std::string& id); |
| 63 | StreamInterface* WriteResource(const std::string& id, size_t index); |
| 64 | bool UnlockResource(const std::string& id); |
| 65 | |
| 66 | StreamInterface* ReadResource(const std::string& id, size_t index) const; |
| 67 | |
| 68 | bool HasResource(const std::string& id) const; |
| 69 | bool HasResourceStream(const std::string& id, size_t index) const; |
| 70 | bool DeleteResource(const std::string& id); |
| 71 | |
| 72 | protected: |
| 73 | virtual bool InitializeEntries() = 0; |
| 74 | virtual bool PurgeFiles() = 0; |
| 75 | |
| 76 | virtual bool FileExists(const std::string& filename) const = 0; |
| 77 | virtual bool DeleteFile(const std::string& filename) const = 0; |
| 78 | |
| 79 | enum LockState { LS_UNLOCKED, LS_LOCKED, LS_UNLOCKING }; |
| 80 | struct Entry { |
| 81 | LockState lock_state; |
| 82 | mutable size_t accessors; |
| 83 | size_t size; |
| 84 | size_t streams; |
| 85 | time_t last_modified; |
| 86 | }; |
| 87 | typedef std::map<std::string, Entry> EntryMap; |
| 88 | friend class DiskCacheAdapter; |
| 89 | |
| 90 | bool CheckLimit(); |
| 91 | |
| 92 | std::string IdToFilename(const std::string& id, size_t index) const; |
| 93 | bool FilenameToId(const std::string& filename, std::string* id, |
| 94 | size_t* index) const; |
| 95 | |
| 96 | const Entry* GetEntry(const std::string& id) const { |
| 97 | return const_cast<DiskCache*>(this)->GetOrCreateEntry(id, false); |
| 98 | } |
| 99 | Entry* GetOrCreateEntry(const std::string& id, bool create); |
| 100 | |
| 101 | void ReleaseResource(const std::string& id, size_t index) const; |
| 102 | |
| 103 | std::string folder_; |
| 104 | size_t max_cache_, total_size_; |
| 105 | EntryMap map_; |
| 106 | mutable size_t total_accessors_; |
| 107 | }; |
| 108 | |
| 109 | /////////////////////////////////////////////////////////////////////////////// |
| 110 | // CacheLock - Automatically manage locking and unlocking, with optional |
| 111 | // rollback semantics |
| 112 | /////////////////////////////////////////////////////////////////////////////// |
| 113 | |
| 114 | class CacheLock { |
| 115 | public: |
| 116 | CacheLock(DiskCache* cache, const std::string& id, bool rollback = false) |
| 117 | : cache_(cache), id_(id), rollback_(rollback) |
| 118 | { |
| 119 | locked_ = cache_->LockResource(id_); |
| 120 | } |
| 121 | ~CacheLock() { |
| 122 | if (locked_) { |
| 123 | cache_->UnlockResource(id_); |
| 124 | if (rollback_) { |
| 125 | cache_->DeleteResource(id_); |
| 126 | } |
| 127 | } |
| 128 | } |
| 129 | bool IsLocked() const { return locked_; } |
| 130 | void Commit() { rollback_ = false; } |
| 131 | |
| 132 | private: |
| 133 | DiskCache* cache_; |
| 134 | std::string id_; |
| 135 | bool rollback_, locked_; |
| 136 | }; |
| 137 | |
| 138 | /////////////////////////////////////////////////////////////////////////////// |
| 139 | |
| 140 | } // namespace talk_base |
| 141 | |
| 142 | #endif // TALK_BASE_DISKCACHE_H__ |