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* Copyright 2004--2005, Google Inc.
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#include "talk/base/win32.h"
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#include "talk/base/common.h"
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#include "talk/base/diskcache.h"
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#include "talk/base/fileutils.h"
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#include "talk/base/pathutils.h"
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#include "talk/base/stream.h"
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#include "talk/base/stringencode.h"
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#include "talk/base/stringutils.h"
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#define TRANSPARENT_CACHE_NAMES 1
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#define TRANSPARENT_CACHE_NAMES 0
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///////////////////////////////////////////////////////////////////////////////
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///////////////////////////////////////////////////////////////////////////////
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class DiskCacheAdapter : public StreamAdapterInterface {
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DiskCacheAdapter(const DiskCache* cache, const std::string& id, size_t index,
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StreamInterface* stream)
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: StreamAdapterInterface(stream), cache_(cache), id_(id), index_(index)
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virtual ~DiskCacheAdapter() {
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cache_->ReleaseResource(id_, index_);
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const DiskCache* cache_;
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///////////////////////////////////////////////////////////////////////////////
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///////////////////////////////////////////////////////////////////////////////
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DiskCache::DiskCache() : max_cache_(0), total_size_(0), total_accessors_(0) {
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DiskCache::~DiskCache() {
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ASSERT(0 == total_accessors_);
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bool DiskCache::Initialize(const std::string& folder, size_t size) {
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if (!folder_.empty() || !Filesystem::CreateFolder(folder))
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ASSERT(0 == total_size_);
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if (!InitializeEntries())
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bool DiskCache::Purge() {
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if (total_accessors_ > 0) {
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LOG_F(LS_WARNING) << "Cache files open";
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bool DiskCache::LockResource(const std::string& id) {
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Entry* entry = GetOrCreateEntry(id, true);
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if (LS_LOCKED == entry->lock_state)
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if ((LS_UNLOCKED == entry->lock_state) && (entry->accessors > 0))
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if ((total_size_ > max_cache_) && !CheckLimit()) {
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LOG_F(LS_WARNING) << "Cache overfull";
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entry->lock_state = LS_LOCKED;
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StreamInterface* DiskCache::WriteResource(const std::string& id, size_t index) {
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Entry* entry = GetOrCreateEntry(id, false);
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if (LS_LOCKED != entry->lock_state)
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size_t previous_size = 0;
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std::string filename(IdToFilename(id, index));
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FileStream::GetSize(filename, &previous_size);
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ASSERT(previous_size <= entry->size);
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if (previous_size > entry->size) {
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previous_size = entry->size;
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scoped_ptr<FileStream> file(new FileStream);
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if (!file->Open(filename, "wb", NULL)) {
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LOG_F(LS_ERROR) << "Couldn't create cache file";
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entry->streams = stdmax(entry->streams, index + 1);
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entry->size -= previous_size;
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total_size_ -= previous_size;
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entry->accessors += 1;
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total_accessors_ += 1;
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return new DiskCacheAdapter(this, id, index, file.release());
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bool DiskCache::UnlockResource(const std::string& id) {
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Entry* entry = GetOrCreateEntry(id, false);
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if (LS_LOCKED != entry->lock_state)
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if (entry->accessors > 0) {
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entry->lock_state = LS_UNLOCKING;
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entry->lock_state = LS_UNLOCKED;
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entry->last_modified = time(0);
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StreamInterface* DiskCache::ReadResource(const std::string& id,
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size_t index) const {
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const Entry* entry = GetEntry(id);
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if (LS_UNLOCKED != entry->lock_state)
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if (index >= entry->streams)
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scoped_ptr<FileStream> file(new FileStream);
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if (!file->Open(IdToFilename(id, index), "rb", NULL))
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entry->accessors += 1;
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total_accessors_ += 1;
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return new DiskCacheAdapter(this, id, index, file.release());
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bool DiskCache::HasResource(const std::string& id) const {
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const Entry* entry = GetEntry(id);
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return (NULL != entry) && (entry->streams > 0);
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bool DiskCache::HasResourceStream(const std::string& id, size_t index) const {
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const Entry* entry = GetEntry(id);
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if ((NULL == entry) || (index >= entry->streams))
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std::string filename = IdToFilename(id, index);
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return FileExists(filename);
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bool DiskCache::DeleteResource(const std::string& id) {
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Entry* entry = GetOrCreateEntry(id, false);
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if ((LS_UNLOCKED != entry->lock_state) || (entry->accessors > 0))
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for (size_t index = 0; index < entry->streams; ++index) {
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std::string filename = IdToFilename(id, index);
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if (!FileExists(filename))
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if (!DeleteFile(filename)) {
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LOG_F(LS_ERROR) << "Couldn't remove cache file: " << filename;
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total_size_ -= entry->size;
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bool DiskCache::CheckLimit() {
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// Temporary check to make sure everything is working correctly.
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size_t cache_size = 0;
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for (EntryMap::iterator it = map_.begin(); it != map_.end(); ++it) {
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cache_size += it->second.size;
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ASSERT(cache_size == total_size_);
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// TODO: Replace this with a non-brain-dead algorithm for clearing out the
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// oldest resources... something that isn't O(n^2)
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while (total_size_ > max_cache_) {
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EntryMap::iterator oldest = map_.end();
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for (EntryMap::iterator it = map_.begin(); it != map_.end(); ++it) {
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if ((LS_UNLOCKED != it->second.lock_state) || (it->second.accessors > 0))
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if (oldest == map_.end()) {
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LOG_F(LS_WARNING) << "All resources are locked!";
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for (EntryMap::iterator it = oldest++; it != map_.end(); ++it) {
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if (it->second.last_modified < oldest->second.last_modified) {
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if (!DeleteResource(oldest->first)) {
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LOG_F(LS_ERROR) << "Couldn't delete from cache!";
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std::string DiskCache::IdToFilename(const std::string& id, size_t index) const {
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#ifdef TRANSPARENT_CACHE_NAMES
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// This escapes colons and other filesystem characters, so the user can't open
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// special devices (like "COM1:"), or access other directories.
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size_t buffer_size = id.length()*3 + 1;
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char* buffer = new char[buffer_size];
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encode(buffer, buffer_size, id.data(), id.length(),
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unsafe_filename_characters(), '%');
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// TODO: ASSERT(strlen(buffer) < FileSystem::MaxBasenameLength());
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#else // !TRANSPARENT_CACHE_NAMES
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// We might want to just use a hash of the filename at some point, both for
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// obfuscation, and to avoid both filename length and escaping issues.
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#endif // !TRANSPARENT_CACHE_NAMES
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sprintfn(extension, ARRAY_SIZE(extension), ".%u", index);
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pathname.SetFolder(folder_);
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pathname.SetBasename(buffer);
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pathname.SetExtension(extension);
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#ifdef TRANSPARENT_CACHE_NAMES
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#endif // TRANSPARENT_CACHE_NAMES
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return pathname.pathname();
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bool DiskCache::FilenameToId(const std::string& filename, std::string* id,
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size_t* index) const {
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Pathname pathname(filename);
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if (1 != sscanf(pathname.extension().c_str(), ".%u", &tempdex))
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*index = static_cast<size_t>(tempdex);
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size_t buffer_size = pathname.basename().length() + 1;
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char* buffer = new char[buffer_size];
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decode(buffer, buffer_size, pathname.basename().data(),
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pathname.basename().length(), '%');
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DiskCache::Entry* DiskCache::GetOrCreateEntry(const std::string& id,
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EntryMap::iterator it = map_.find(id);
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if (it != map_.end())
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e.lock_state = LS_UNLOCKED;
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e.last_modified = time(0);
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it = map_.insert(EntryMap::value_type(id, e)).first;
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void DiskCache::ReleaseResource(const std::string& id, size_t index) const {
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const Entry* entry = GetEntry(id);
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LOG_F(LS_WARNING) << "Missing cache entry";
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entry->accessors -= 1;
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total_accessors_ -= 1;
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if (LS_UNLOCKED != entry->lock_state) {
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// This is safe, because locked resources only issue WriteResource, which
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// is non-const. Think about a better way to handle it.
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DiskCache* this2 = const_cast<DiskCache*>(this);
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Entry* entry2 = this2->GetOrCreateEntry(id, false);
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std::string filename(IdToFilename(id, index));
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FileStream::GetSize(filename, &new_size);
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entry2->size += new_size;
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this2->total_size_ += new_size;
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if ((LS_UNLOCKING == entry->lock_state) && (0 == entry->accessors)) {
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entry2->last_modified = time(0);
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entry2->lock_state = LS_UNLOCKED;
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///////////////////////////////////////////////////////////////////////////////
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} // namespace talk_base