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      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 #include <time.h>
     29 
     30 #ifdef WIN32
     31 #include "talk/base/win32.h"
     32 #endif
     33 
     34 #include "talk/base/common.h"
     35 #include "talk/base/diskcache.h"
     36 #include "talk/base/fileutils.h"
     37 #include "talk/base/pathutils.h"
     38 #include "talk/base/stream.h"
     39 #include "talk/base/stringencode.h"
     40 #include "talk/base/stringutils.h"
     41 
     42 #ifdef _DEBUG
     43 #define TRANSPARENT_CACHE_NAMES 1
     44 #else  // !_DEBUG
     45 #define TRANSPARENT_CACHE_NAMES 0
     46 #endif  // !_DEBUG
     47 
     48 namespace talk_base {
     49 
     50 class DiskCache;
     51 
     52 ///////////////////////////////////////////////////////////////////////////////
     53 // DiskCacheAdapter
     54 ///////////////////////////////////////////////////////////////////////////////
     55 
     56 class DiskCacheAdapter : public StreamAdapterInterface {
     57 public:
     58   DiskCacheAdapter(const DiskCache* cache, const std::string& id, size_t index,
     59                    StreamInterface* stream)
     60   : StreamAdapterInterface(stream), cache_(cache), id_(id), index_(index)
     61   { }
     62   virtual ~DiskCacheAdapter() {
     63     Close();
     64     cache_->ReleaseResource(id_, index_);
     65   }
     66 
     67 private:
     68   const DiskCache* cache_;
     69   std::string id_;
     70   size_t index_;
     71 };
     72 
     73 ///////////////////////////////////////////////////////////////////////////////
     74 // DiskCache
     75 ///////////////////////////////////////////////////////////////////////////////
     76 
     77 DiskCache::DiskCache() : max_cache_(0), total_size_(0), total_accessors_(0) {
     78 }
     79 
     80 DiskCache::~DiskCache() {
     81   ASSERT(0 == total_accessors_);
     82 }
     83 
     84 bool DiskCache::Initialize(const std::string& folder, size_t size) {
     85   if (!folder_.empty() || !Filesystem::CreateFolder(folder))
     86     return false;
     87 
     88   folder_ = folder;
     89   max_cache_ = size;
     90   ASSERT(0 == total_size_);
     91 
     92   if (!InitializeEntries())
     93     return false;
     94 
     95   return CheckLimit();
     96 }
     97 
     98 bool DiskCache::Purge() {
     99   if (folder_.empty())
    100     return false;
    101 
    102   if (total_accessors_ > 0) {
    103     LOG_F(LS_WARNING) << "Cache files open";
    104     return false;
    105   }
    106 
    107   if (!PurgeFiles())
    108     return false;
    109 
    110   map_.clear();
    111   return true;
    112 }
    113 
    114 bool DiskCache::LockResource(const std::string& id) {
    115   Entry* entry = GetOrCreateEntry(id, true);
    116   if (LS_LOCKED == entry->lock_state)
    117     return false;
    118   if ((LS_UNLOCKED == entry->lock_state) && (entry->accessors > 0))
    119     return false;
    120   if ((total_size_ > max_cache_) && !CheckLimit()) {
    121     LOG_F(LS_WARNING) << "Cache overfull";
    122     return false;
    123   }
    124   entry->lock_state = LS_LOCKED;
    125   return true;
    126 }
    127 
    128 StreamInterface* DiskCache::WriteResource(const std::string& id, size_t index) {
    129   Entry* entry = GetOrCreateEntry(id, false);
    130   if (LS_LOCKED != entry->lock_state)
    131     return NULL;
    132 
    133   size_t previous_size = 0;
    134   std::string filename(IdToFilename(id, index));
    135   FileStream::GetSize(filename, &previous_size);
    136   ASSERT(previous_size <= entry->size);
    137   if (previous_size > entry->size) {
    138     previous_size = entry->size;
    139   }
    140 
    141   scoped_ptr<FileStream> file(new FileStream);
    142   if (!file->Open(filename, "wb", NULL)) {
    143     LOG_F(LS_ERROR) << "Couldn't create cache file";
    144     return NULL;
    145   }
    146 
    147   entry->streams = stdmax(entry->streams, index + 1);
    148   entry->size -= previous_size;
    149   total_size_ -= previous_size;
    150 
    151   entry->accessors += 1;
    152   total_accessors_ += 1;
    153   return new DiskCacheAdapter(this, id, index, file.release());
    154 }
    155 
    156 bool DiskCache::UnlockResource(const std::string& id) {
    157   Entry* entry = GetOrCreateEntry(id, false);
    158   if (LS_LOCKED != entry->lock_state)
    159     return false;
    160 
    161   if (entry->accessors > 0) {
    162     entry->lock_state = LS_UNLOCKING;
    163   } else {
    164     entry->lock_state = LS_UNLOCKED;
    165     entry->last_modified = time(0);
    166     CheckLimit();
    167   }
    168   return true;
    169 }
    170 
    171 StreamInterface* DiskCache::ReadResource(const std::string& id,
    172                                          size_t index) const {
    173   const Entry* entry = GetEntry(id);
    174   if (LS_UNLOCKED != entry->lock_state)
    175     return NULL;
    176   if (index >= entry->streams)
    177     return NULL;
    178 
    179   scoped_ptr<FileStream> file(new FileStream);
    180   if (!file->Open(IdToFilename(id, index), "rb", NULL))
    181     return NULL;
    182 
    183   entry->accessors += 1;
    184   total_accessors_ += 1;
    185   return new DiskCacheAdapter(this, id, index, file.release());
    186 }
    187 
    188 bool DiskCache::HasResource(const std::string& id) const {
    189   const Entry* entry = GetEntry(id);
    190   return (NULL != entry) && (entry->streams > 0);
    191 }
    192 
    193 bool DiskCache::HasResourceStream(const std::string& id, size_t index) const {
    194   const Entry* entry = GetEntry(id);
    195   if ((NULL == entry) || (index >= entry->streams))
    196     return false;
    197 
    198   std::string filename = IdToFilename(id, index);
    199 
    200   return FileExists(filename);
    201 }
    202 
    203 bool DiskCache::DeleteResource(const std::string& id) {
    204   Entry* entry = GetOrCreateEntry(id, false);
    205   if (!entry)
    206     return true;
    207 
    208   if ((LS_UNLOCKED != entry->lock_state) || (entry->accessors > 0))
    209     return false;
    210 
    211   bool success = true;
    212   for (size_t index = 0; index < entry->streams; ++index) {
    213     std::string filename = IdToFilename(id, index);
    214 
    215     if (!FileExists(filename))
    216       continue;
    217 
    218     if (!DeleteFile(filename)) {
    219       LOG_F(LS_ERROR) << "Couldn't remove cache file: " << filename;
    220       success = false;
    221     }
    222   }
    223 
    224   total_size_ -= entry->size;
    225   map_.erase(id);
    226   return success;
    227 }
    228 
    229 bool DiskCache::CheckLimit() {
    230 #ifdef _DEBUG
    231   // Temporary check to make sure everything is working correctly.
    232   size_t cache_size = 0;
    233   for (EntryMap::iterator it = map_.begin(); it != map_.end(); ++it) {
    234     cache_size += it->second.size;
    235   }
    236   ASSERT(cache_size == total_size_);
    237 #endif  // _DEBUG
    238 
    239   // TODO: Replace this with a non-brain-dead algorithm for clearing out the
    240   // oldest resources... something that isn't O(n^2)
    241   while (total_size_ > max_cache_) {
    242     EntryMap::iterator oldest = map_.end();
    243     for (EntryMap::iterator it = map_.begin(); it != map_.end(); ++it) {
    244       if ((LS_UNLOCKED != it->second.lock_state) || (it->second.accessors > 0))
    245         continue;
    246       oldest = it;
    247       break;
    248     }
    249     if (oldest == map_.end()) {
    250       LOG_F(LS_WARNING) << "All resources are locked!";
    251       return false;
    252     }
    253     for (EntryMap::iterator it = oldest++; it != map_.end(); ++it) {
    254       if (it->second.last_modified < oldest->second.last_modified) {
    255         oldest = it;
    256       }
    257     }
    258     if (!DeleteResource(oldest->first)) {
    259       LOG_F(LS_ERROR) << "Couldn't delete from cache!";
    260       return false;
    261     }
    262   }
    263   return true;
    264 }
    265 
    266 std::string DiskCache::IdToFilename(const std::string& id, size_t index) const {
    267 #ifdef TRANSPARENT_CACHE_NAMES
    268   // This escapes colons and other filesystem characters, so the user can't open
    269   // special devices (like "COM1:"), or access other directories.
    270   size_t buffer_size = id.length()*3 + 1;
    271   char* buffer = new char[buffer_size];
    272   encode(buffer, buffer_size, id.data(), id.length(),
    273          unsafe_filename_characters(), '%');
    274   // TODO: ASSERT(strlen(buffer) < FileSystem::MaxBasenameLength());
    275 #else  // !TRANSPARENT_CACHE_NAMES
    276   // We might want to just use a hash of the filename at some point, both for
    277   // obfuscation, and to avoid both filename length and escaping issues.
    278   ASSERT(false);
    279 #endif  // !TRANSPARENT_CACHE_NAMES
    280 
    281   char extension[32];
    282   sprintfn(extension, ARRAY_SIZE(extension), ".%u", index);
    283 
    284   Pathname pathname;
    285   pathname.SetFolder(folder_);
    286   pathname.SetBasename(buffer);
    287   pathname.SetExtension(extension);
    288 
    289 #ifdef TRANSPARENT_CACHE_NAMES
    290   delete [] buffer;
    291 #endif  // TRANSPARENT_CACHE_NAMES
    292 
    293   return pathname.pathname();
    294 }
    295 
    296 bool DiskCache::FilenameToId(const std::string& filename, std::string* id,
    297                              size_t* index) const {
    298   Pathname pathname(filename);
    299   unsigned tempdex;
    300   if (1 != sscanf(pathname.extension().c_str(), ".%u", &tempdex))
    301     return false;
    302 
    303   *index = static_cast<size_t>(tempdex);
    304 
    305   size_t buffer_size = pathname.basename().length() + 1;
    306   char* buffer = new char[buffer_size];
    307   decode(buffer, buffer_size, pathname.basename().data(),
    308          pathname.basename().length(), '%');
    309   id->assign(buffer);
    310   delete [] buffer;
    311   return true;
    312 }
    313 
    314 DiskCache::Entry* DiskCache::GetOrCreateEntry(const std::string& id,
    315                                               bool create) {
    316   EntryMap::iterator it = map_.find(id);
    317   if (it != map_.end())
    318     return &it->second;
    319   if (!create)
    320     return NULL;
    321   Entry e;
    322   e.lock_state = LS_UNLOCKED;
    323   e.accessors = 0;
    324   e.size = 0;
    325   e.streams = 0;
    326   e.last_modified = time(0);
    327   it = map_.insert(EntryMap::value_type(id, e)).first;
    328   return &it->second;
    329 }
    330 
    331 void DiskCache::ReleaseResource(const std::string& id, size_t index) const {
    332   const Entry* entry = GetEntry(id);
    333   if (!entry) {
    334     LOG_F(LS_WARNING) << "Missing cache entry";
    335     ASSERT(false);
    336     return;
    337   }
    338 
    339   entry->accessors -= 1;
    340   total_accessors_ -= 1;
    341 
    342   if (LS_UNLOCKED != entry->lock_state) {
    343     // This is safe, because locked resources only issue WriteResource, which
    344     // is non-const.  Think about a better way to handle it.
    345     DiskCache* this2 = const_cast<DiskCache*>(this);
    346     Entry* entry2 = this2->GetOrCreateEntry(id, false);
    347 
    348     size_t new_size = 0;
    349     std::string filename(IdToFilename(id, index));
    350     FileStream::GetSize(filename, &new_size);
    351     entry2->size += new_size;
    352     this2->total_size_ += new_size;
    353 
    354     if ((LS_UNLOCKING == entry->lock_state) && (0 == entry->accessors)) {
    355       entry2->last_modified = time(0);
    356       entry2->lock_state = LS_UNLOCKED;
    357       this2->CheckLimit();
    358     }
    359   }
    360 }
    361 
    362 ///////////////////////////////////////////////////////////////////////////////
    363 
    364 } // namespace talk_base
    365