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Speed up block loading/storing by issuing only one read/write syscall to the base file system

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This commit is contained in:
Sebastian Messmer 2016-07-06 15:35:51 -07:00
parent 7348f7c64d
commit 0d860fa4f0
2 changed files with 14 additions and 32 deletions
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44
src/blockstore/implementations/ondisk/OnDiskBlock.cpp
View File

@ -99,56 +99,38 @@ void OnDiskBlock::RemoveFromDisk(const bf::path &rootdir, const Key &key) {
} }
void OnDiskBlock::_storeToDisk() const { void OnDiskBlock::_storeToDisk() const {
std::ofstream file(_filepath.c_str(), std::ios::binary | std::ios::trunc); Data fileContent(formatVersionHeaderSize() + _data.size());
if (!file.good()) { std::memcpy(fileContent.data(), FORMAT_VERSION_HEADER.c_str(), formatVersionHeaderSize());
throw std::runtime_error("Could not open file for writing"); std::memcpy(fileContent.dataOffset(formatVersionHeaderSize()), _data.data(), _data.size());
} fileContent.StoreToFile(_filepath);
file.write(FORMAT_VERSION_HEADER.c_str(), formatVersionHeaderSize());
if (!file.good()) {
throw std::runtime_error("Error writing block header");
}
_data.StoreToStream(file);
if (!file.good()) {
throw std::runtime_error("Error writing block data");
}
} }
optional<Data> OnDiskBlock::_loadFromDisk(const bf::path &filepath) { optional<Data> OnDiskBlock::_loadFromDisk(const bf::path &filepath) {
//If it isn't a file, ifstream::good() would return false. We still need this extra check auto fileContent = Data::LoadFromFile(filepath);
//upfront, because ifstream::good() doesn't crash if we give it the path of a directory if (fileContent == none) {
//instead the path of a file.
if(!bf::is_regular_file(filepath)) {
return none; return none;
} }
ifstream file(filepath.c_str(), ios::binary); return _checkAndRemoveHeader(std::move(*fileContent));
if (!file.good()) {
return none;
}
_checkHeader(&file);
Data result = Data::LoadFromStream(file);
//TODO With newer compilers, "return result;" would be enough
return boost::optional<Data>(std::move(result));
} }
void OnDiskBlock::_checkHeader(istream *str) { Data OnDiskBlock::_checkAndRemoveHeader(Data data) {
Data header(formatVersionHeaderSize()); if (!_isAcceptedCryfsHeader(data)) {
str->read(reinterpret_cast<char*>(header.data()), formatVersionHeaderSize()); if (_isOtherCryfsHeader(data)) {
if (!_isAcceptedCryfsHeader(header)) {
if (_isOtherCryfsHeader(header)) {
throw std::runtime_error("This block is not supported yet. Maybe it was created with a newer version of CryFS?"); throw std::runtime_error("This block is not supported yet. Maybe it was created with a newer version of CryFS?");
} else { } else {
throw std::runtime_error("This is not a valid block."); throw std::runtime_error("This is not a valid block.");
} }
} }
Data result(data.size() - formatVersionHeaderSize());
std::memcpy(result.data(), data.dataOffset(formatVersionHeaderSize()), result.size());
return result;
} }
bool OnDiskBlock::_isAcceptedCryfsHeader(const Data &data) { bool OnDiskBlock::_isAcceptedCryfsHeader(const Data &data) {
ASSERT(data.size() == formatVersionHeaderSize(), "We extracted the wrong header size from the block.");
return 0 == std::memcmp(data.data(), FORMAT_VERSION_HEADER.c_str(), formatVersionHeaderSize()); return 0 == std::memcmp(data.data(), FORMAT_VERSION_HEADER.c_str(), formatVersionHeaderSize());
} }
bool OnDiskBlock::_isOtherCryfsHeader(const Data &data) { bool OnDiskBlock::_isOtherCryfsHeader(const Data &data) {
ASSERT(data.size() >= FORMAT_VERSION_HEADER_PREFIX.size(), "We extracted the wrong header size from the block.");
return 0 == std::memcmp(data.data(), FORMAT_VERSION_HEADER_PREFIX.c_str(), FORMAT_VERSION_HEADER_PREFIX.size()); return 0 == std::memcmp(data.data(), FORMAT_VERSION_HEADER_PREFIX.c_str(), FORMAT_VERSION_HEADER_PREFIX.size());
} }

2
src/blockstore/implementations/ondisk/OnDiskBlock.h
View File

@ -40,7 +40,7 @@ private:
static bool _isAcceptedCryfsHeader(const cpputils::Data &data); static bool _isAcceptedCryfsHeader(const cpputils::Data &data);
static bool _isOtherCryfsHeader(const cpputils::Data &data); static bool _isOtherCryfsHeader(const cpputils::Data &data);
static void _checkHeader(std::istream *str); static cpputils::Data _checkAndRemoveHeader(cpputils::Data data);
static boost::filesystem::path _getFilepath(const boost::filesystem::path &rootdir, const Key &key); static boost::filesystem::path _getFilepath(const boost::filesystem::path &rootdir, const Key &key);
const boost::filesystem::path _filepath; const boost::filesystem::path _filepath;