1 /*
2 * Copyright 2004 The WebRTC Project Authors. All rights reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10
11 #include <time.h>
12
13 #if defined(WEBRTC_WIN)
14 #include "webrtc/base/win32.h"
15 #endif
16
17 #include <algorithm>
18 #include "webrtc/base/arraysize.h"
19 #include "webrtc/base/common.h"
20 #include "webrtc/base/diskcache.h"
21 #include "webrtc/base/fileutils.h"
22 #include "webrtc/base/pathutils.h"
23 #include "webrtc/base/stream.h"
24 #include "webrtc/base/stringencode.h"
25 #include "webrtc/base/stringutils.h"
26
27 #if !defined(NDEBUG)
28 #define TRANSPARENT_CACHE_NAMES 1
29 #else
30 #define TRANSPARENT_CACHE_NAMES 0
31 #endif
32
33 namespace rtc {
34
35 class DiskCache;
36
37 ///////////////////////////////////////////////////////////////////////////////
38 // DiskCacheAdapter
39 ///////////////////////////////////////////////////////////////////////////////
40
41 class DiskCacheAdapter : public StreamAdapterInterface {
42 public:
DiskCacheAdapter(const DiskCache * cache,const std::string & id,size_t index,StreamInterface * stream)43 DiskCacheAdapter(const DiskCache* cache, const std::string& id, size_t index,
44 StreamInterface* stream)
45 : StreamAdapterInterface(stream), cache_(cache), id_(id), index_(index)
46 { }
~DiskCacheAdapter()47 ~DiskCacheAdapter() override {
48 Close();
49 cache_->ReleaseResource(id_, index_);
50 }
51
52 private:
53 const DiskCache* cache_;
54 std::string id_;
55 size_t index_;
56 };
57
58 ///////////////////////////////////////////////////////////////////////////////
59 // DiskCache
60 ///////////////////////////////////////////////////////////////////////////////
61
DiskCache()62 DiskCache::DiskCache() : max_cache_(0), total_size_(0), total_accessors_(0) {
63 }
64
~DiskCache()65 DiskCache::~DiskCache() {
66 ASSERT(0 == total_accessors_);
67 }
68
Initialize(const std::string & folder,size_t size)69 bool DiskCache::Initialize(const std::string& folder, size_t size) {
70 if (!folder_.empty() || !Filesystem::CreateFolder(folder))
71 return false;
72
73 folder_ = folder;
74 max_cache_ = size;
75 ASSERT(0 == total_size_);
76
77 if (!InitializeEntries())
78 return false;
79
80 return CheckLimit();
81 }
82
Purge()83 bool DiskCache::Purge() {
84 if (folder_.empty())
85 return false;
86
87 if (total_accessors_ > 0) {
88 LOG_F(LS_WARNING) << "Cache files open";
89 return false;
90 }
91
92 if (!PurgeFiles())
93 return false;
94
95 map_.clear();
96 return true;
97 }
98
LockResource(const std::string & id)99 bool DiskCache::LockResource(const std::string& id) {
100 Entry* entry = GetOrCreateEntry(id, true);
101 if (LS_LOCKED == entry->lock_state)
102 return false;
103 if ((LS_UNLOCKED == entry->lock_state) && (entry->accessors > 0))
104 return false;
105 if ((total_size_ > max_cache_) && !CheckLimit()) {
106 LOG_F(LS_WARNING) << "Cache overfull";
107 return false;
108 }
109 entry->lock_state = LS_LOCKED;
110 return true;
111 }
112
WriteResource(const std::string & id,size_t index)113 StreamInterface* DiskCache::WriteResource(const std::string& id, size_t index) {
114 Entry* entry = GetOrCreateEntry(id, false);
115 if (LS_LOCKED != entry->lock_state)
116 return NULL;
117
118 size_t previous_size = 0;
119 std::string filename(IdToFilename(id, index));
120 FileStream::GetSize(filename, &previous_size);
121 ASSERT(previous_size <= entry->size);
122 if (previous_size > entry->size) {
123 previous_size = entry->size;
124 }
125
126 scoped_ptr<FileStream> file(new FileStream);
127 if (!file->Open(filename, "wb", NULL)) {
128 LOG_F(LS_ERROR) << "Couldn't create cache file";
129 return NULL;
130 }
131
132 entry->streams = std::max(entry->streams, index + 1);
133 entry->size -= previous_size;
134 total_size_ -= previous_size;
135
136 entry->accessors += 1;
137 total_accessors_ += 1;
138 return new DiskCacheAdapter(this, id, index, file.release());
139 }
140
UnlockResource(const std::string & id)141 bool DiskCache::UnlockResource(const std::string& id) {
142 Entry* entry = GetOrCreateEntry(id, false);
143 if (LS_LOCKED != entry->lock_state)
144 return false;
145
146 if (entry->accessors > 0) {
147 entry->lock_state = LS_UNLOCKING;
148 } else {
149 entry->lock_state = LS_UNLOCKED;
150 entry->last_modified = time(0);
151 CheckLimit();
152 }
153 return true;
154 }
155
ReadResource(const std::string & id,size_t index) const156 StreamInterface* DiskCache::ReadResource(const std::string& id,
157 size_t index) const {
158 const Entry* entry = GetEntry(id);
159 if (LS_UNLOCKED != entry->lock_state)
160 return NULL;
161 if (index >= entry->streams)
162 return NULL;
163
164 scoped_ptr<FileStream> file(new FileStream);
165 if (!file->Open(IdToFilename(id, index), "rb", NULL))
166 return NULL;
167
168 entry->accessors += 1;
169 total_accessors_ += 1;
170 return new DiskCacheAdapter(this, id, index, file.release());
171 }
172
HasResource(const std::string & id) const173 bool DiskCache::HasResource(const std::string& id) const {
174 const Entry* entry = GetEntry(id);
175 return (NULL != entry) && (entry->streams > 0);
176 }
177
HasResourceStream(const std::string & id,size_t index) const178 bool DiskCache::HasResourceStream(const std::string& id, size_t index) const {
179 const Entry* entry = GetEntry(id);
180 if ((NULL == entry) || (index >= entry->streams))
181 return false;
182
183 std::string filename = IdToFilename(id, index);
184
185 return FileExists(filename);
186 }
187
DeleteResource(const std::string & id)188 bool DiskCache::DeleteResource(const std::string& id) {
189 Entry* entry = GetOrCreateEntry(id, false);
190 if (!entry)
191 return true;
192
193 if ((LS_UNLOCKED != entry->lock_state) || (entry->accessors > 0))
194 return false;
195
196 bool success = true;
197 for (size_t index = 0; index < entry->streams; ++index) {
198 std::string filename = IdToFilename(id, index);
199
200 if (!FileExists(filename))
201 continue;
202
203 if (!DeleteFile(filename)) {
204 LOG_F(LS_ERROR) << "Couldn't remove cache file: " << filename;
205 success = false;
206 }
207 }
208
209 total_size_ -= entry->size;
210 map_.erase(id);
211 return success;
212 }
213
CheckLimit()214 bool DiskCache::CheckLimit() {
215 #if !defined(NDEBUG)
216 // Temporary check to make sure everything is working correctly.
217 size_t cache_size = 0;
218 for (EntryMap::iterator it = map_.begin(); it != map_.end(); ++it) {
219 cache_size += it->second.size;
220 }
221 ASSERT(cache_size == total_size_);
222 #endif
223
224 // TODO: Replace this with a non-brain-dead algorithm for clearing out the
225 // oldest resources... something that isn't O(n^2)
226 while (total_size_ > max_cache_) {
227 EntryMap::iterator oldest = map_.end();
228 for (EntryMap::iterator it = map_.begin(); it != map_.end(); ++it) {
229 if ((LS_UNLOCKED != it->second.lock_state) || (it->second.accessors > 0))
230 continue;
231 oldest = it;
232 break;
233 }
234 if (oldest == map_.end()) {
235 LOG_F(LS_WARNING) << "All resources are locked!";
236 return false;
237 }
238 for (EntryMap::iterator it = oldest++; it != map_.end(); ++it) {
239 if (it->second.last_modified < oldest->second.last_modified) {
240 oldest = it;
241 }
242 }
243 if (!DeleteResource(oldest->first)) {
244 LOG_F(LS_ERROR) << "Couldn't delete from cache!";
245 return false;
246 }
247 }
248 return true;
249 }
250
IdToFilename(const std::string & id,size_t index) const251 std::string DiskCache::IdToFilename(const std::string& id, size_t index) const {
252 #ifdef TRANSPARENT_CACHE_NAMES
253 // This escapes colons and other filesystem characters, so the user can't open
254 // special devices (like "COM1:"), or access other directories.
255 size_t buffer_size = id.length()*3 + 1;
256 char* buffer = new char[buffer_size];
257 encode(buffer, buffer_size, id.data(), id.length(),
258 unsafe_filename_characters(), '%');
259 // TODO: ASSERT(strlen(buffer) < FileSystem::MaxBasenameLength());
260 #else // !TRANSPARENT_CACHE_NAMES
261 // We might want to just use a hash of the filename at some point, both for
262 // obfuscation, and to avoid both filename length and escaping issues.
263 ASSERT(false);
264 #endif // !TRANSPARENT_CACHE_NAMES
265
266 char extension[32];
267 sprintfn(extension, arraysize(extension), ".%u", index);
268
269 Pathname pathname;
270 pathname.SetFolder(folder_);
271 pathname.SetBasename(buffer);
272 pathname.SetExtension(extension);
273
274 #ifdef TRANSPARENT_CACHE_NAMES
275 delete [] buffer;
276 #endif // TRANSPARENT_CACHE_NAMES
277
278 return pathname.pathname();
279 }
280
FilenameToId(const std::string & filename,std::string * id,size_t * index) const281 bool DiskCache::FilenameToId(const std::string& filename, std::string* id,
282 size_t* index) const {
283 Pathname pathname(filename);
284 unsigned tempdex;
285 if (1 != sscanf(pathname.extension().c_str(), ".%u", &tempdex))
286 return false;
287
288 *index = static_cast<size_t>(tempdex);
289
290 size_t buffer_size = pathname.basename().length() + 1;
291 char* buffer = new char[buffer_size];
292 decode(buffer, buffer_size, pathname.basename().data(),
293 pathname.basename().length(), '%');
294 id->assign(buffer);
295 delete [] buffer;
296 return true;
297 }
298
GetOrCreateEntry(const std::string & id,bool create)299 DiskCache::Entry* DiskCache::GetOrCreateEntry(const std::string& id,
300 bool create) {
301 EntryMap::iterator it = map_.find(id);
302 if (it != map_.end())
303 return &it->second;
304 if (!create)
305 return NULL;
306 Entry e;
307 e.lock_state = LS_UNLOCKED;
308 e.accessors = 0;
309 e.size = 0;
310 e.streams = 0;
311 e.last_modified = time(0);
312 it = map_.insert(EntryMap::value_type(id, e)).first;
313 return &it->second;
314 }
315
ReleaseResource(const std::string & id,size_t index) const316 void DiskCache::ReleaseResource(const std::string& id, size_t index) const {
317 const Entry* entry = GetEntry(id);
318 if (!entry) {
319 LOG_F(LS_WARNING) << "Missing cache entry";
320 ASSERT(false);
321 return;
322 }
323
324 entry->accessors -= 1;
325 total_accessors_ -= 1;
326
327 if (LS_UNLOCKED != entry->lock_state) {
328 // This is safe, because locked resources only issue WriteResource, which
329 // is non-const. Think about a better way to handle it.
330 DiskCache* this2 = const_cast<DiskCache*>(this);
331 Entry* entry2 = this2->GetOrCreateEntry(id, false);
332
333 size_t new_size = 0;
334 std::string filename(IdToFilename(id, index));
335 FileStream::GetSize(filename, &new_size);
336 entry2->size += new_size;
337 this2->total_size_ += new_size;
338
339 if ((LS_UNLOCKING == entry->lock_state) && (0 == entry->accessors)) {
340 entry2->last_modified = time(0);
341 entry2->lock_state = LS_UNLOCKED;
342 this2->CheckLimit();
343 }
344 }
345 }
346
347 ///////////////////////////////////////////////////////////////////////////////
348
349 } // namespace rtc
350