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BlockStore only writes changed data back if it actually was changed

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This commit is contained in:
Sebastian Messmer 2015-03-05 22:16:57 +01:00
parent d42bda0ca6
commit 2cb0f4e5de
4 changed files with 17 additions and 6 deletions
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11
implementations/ondisk/OnDiskBlock.cpp
View File

@ -20,15 +20,15 @@ namespace blockstore {
namespace ondisk { namespace ondisk {
OnDiskBlock::OnDiskBlock(const Key &key, const bf::path &filepath, size_t size) OnDiskBlock::OnDiskBlock(const Key &key, const bf::path &filepath, size_t size)
: Block(key), _filepath(filepath), _data(size) { : Block(key), _filepath(filepath), _data(size), _dataChanged(false) {
} }
OnDiskBlock::OnDiskBlock(const Key &key, const bf::path &filepath, Data &&data) OnDiskBlock::OnDiskBlock(const Key &key, const bf::path &filepath, Data &&data)
: Block(key), _filepath(filepath), _data(std::move(data)) { : Block(key), _filepath(filepath), _data(std::move(data)), _dataChanged(false) {
} }
OnDiskBlock::~OnDiskBlock() { OnDiskBlock::~OnDiskBlock() {
_storeToDisk(); flush();
} }
const void *OnDiskBlock::data() const { const void *OnDiskBlock::data() const {
@ -38,6 +38,7 @@ const void *OnDiskBlock::data() const {
void OnDiskBlock::write(const void *source, uint64_t offset, uint64_t size) { void OnDiskBlock::write(const void *source, uint64_t offset, uint64_t size) {
assert(offset <= _data.size() && offset + size <= _data.size()); //Also check offset < _data->size() because of possible overflow in the addition assert(offset <= _data.size() && offset + size <= _data.size()); //Also check offset < _data->size() because of possible overflow in the addition
std::memcpy((uint8_t*)_data.data()+offset, source, size); std::memcpy((uint8_t*)_data.data()+offset, source, size);
_dataChanged = true;
} }
size_t OnDiskBlock::size() const { size_t OnDiskBlock::size() const {
@ -61,6 +62,7 @@ unique_ptr<OnDiskBlock> OnDiskBlock::LoadFromDisk(const bf::path &rootdir, const
} }
unique_ptr<OnDiskBlock> OnDiskBlock::CreateOnDisk(const bf::path &rootdir, const Key &key, size_t size) { unique_ptr<OnDiskBlock> OnDiskBlock::CreateOnDisk(const bf::path &rootdir, const Key &key, size_t size) {
//TODO Only writeback, if data was actually changed (Block::write() was called)
auto filepath = rootdir / key.ToString(); auto filepath = rootdir / key.ToString();
if (bf::exists(filepath)) { if (bf::exists(filepath)) {
return nullptr; return nullptr;
@ -87,7 +89,10 @@ void OnDiskBlock::_storeToDisk() const {
} }
void OnDiskBlock::flush() { void OnDiskBlock::flush() {
if (_dataChanged) {
_storeToDisk(); _storeToDisk();
_dataChanged = false;
}
} }
} }

1
implementations/ondisk/OnDiskBlock.h
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@ -31,6 +31,7 @@ public:
private: private:
const boost::filesystem::path _filepath; const boost::filesystem::path _filepath;
Data _data; Data _data;
bool _dataChanged;
OnDiskBlock(const Key &key, const boost::filesystem::path &filepath, size_t size); OnDiskBlock(const Key &key, const boost::filesystem::path &filepath, size_t size);
OnDiskBlock(const Key &key, const boost::filesystem::path &filepath, Data &&data); OnDiskBlock(const Key &key, const boost::filesystem::path &filepath, Data &&data);

6
implementations/testfake/FakeBlock.cpp
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@ -15,7 +15,7 @@ namespace blockstore {
namespace testfake { namespace testfake {
FakeBlock::FakeBlock(FakeBlockStore *store, const Key &key, shared_ptr<Data> data) FakeBlock::FakeBlock(FakeBlockStore *store, const Key &key, shared_ptr<Data> data)
: Block(key), _store(store), _data(data) { : Block(key), _store(store), _data(data), _dataChanged(false) {
} }
FakeBlock::~FakeBlock() { FakeBlock::~FakeBlock() {
@ -29,6 +29,7 @@ const void *FakeBlock::data() const {
void FakeBlock::write(const void *source, uint64_t offset, uint64_t size) { void FakeBlock::write(const void *source, uint64_t offset, uint64_t size) {
assert(offset <= _data->size() && offset + size <= _data->size()); //Also check offset < _data->size() because of possible overflow in the addition assert(offset <= _data->size() && offset + size <= _data->size()); //Also check offset < _data->size() because of possible overflow in the addition
std::memcpy((uint8_t*)_data->data()+offset, source, size); std::memcpy((uint8_t*)_data->data()+offset, source, size);
_dataChanged = true;
} }
size_t FakeBlock::size() const { size_t FakeBlock::size() const {
@ -36,7 +37,10 @@ size_t FakeBlock::size() const {
} }
void FakeBlock::flush() { void FakeBlock::flush() {
if(_dataChanged) {
_store->updateData(key(), *_data); _store->updateData(key(), *_data);
_dataChanged = false;
}
} }
} }

1
implementations/testfake/FakeBlock.h
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@ -26,6 +26,7 @@ public:
private: private:
FakeBlockStore *_store; FakeBlockStore *_store;
std::shared_ptr<Data> _data; std::shared_ptr<Data> _data;
bool _dataChanged;
DISALLOW_COPY_AND_ASSIGN(FakeBlock); DISALLOW_COPY_AND_ASSIGN(FakeBlock);
}; };