libcryfs/implementations/caching/CachingBlockStore.cpp
2015-10-14 14:40:45 +02:00

93 lines
2.8 KiB
C++

#include "CachedBlock.h"
#include "NewBlock.h"
#include "CachingBlockStore.h"
#include "../../interface/Block.h"
#include <algorithm>
#include <messmer/cpp-utils/pointer/cast.h>
#include <messmer/cpp-utils/assert/assert.h>
using cpputils::dynamic_pointer_move;
using cpputils::Data;
using boost::optional;
using cpputils::unique_ref;
using cpputils::make_unique_ref;
using boost::none;
namespace blockstore {
namespace caching {
CachingBlockStore::CachingBlockStore(cpputils::unique_ref<BlockStore> baseBlockStore)
:_baseBlockStore(std::move(baseBlockStore)), _cache(), _numNewBlocks(0) {
}
Key CachingBlockStore::createKey() {
return _baseBlockStore->createKey();
}
optional<unique_ref<Block>> CachingBlockStore::tryCreate(const Key &key, Data data) {
ASSERT(_cache.pop(key) == none, "Key already exists in cache");
//TODO Shouldn't we return boost::none if the key already exists?
//TODO Key can also already exist but not be in the cache right now.
++_numNewBlocks;
return unique_ref<Block>(make_unique_ref<CachedBlock>(make_unique_ref<NewBlock>(key, std::move(data), this), this));
}
optional<unique_ref<Block>> CachingBlockStore::load(const Key &key) {
optional<unique_ref<Block>> optBlock = _cache.pop(key);
//TODO an optional<> class with .getOrElse() would make this code simpler. boost::optional<>::value_or_eval didn't seem to work with unique_ptr members.
if (optBlock != none) {
return optional<unique_ref<Block>>(make_unique_ref<CachedBlock>(std::move(*optBlock), this));
} else {
auto block = _baseBlockStore->load(key);
if (block == none) {
return none;
} else {
return optional<unique_ref<Block>>(make_unique_ref<CachedBlock>(std::move(*block), this));
}
}
}
void CachingBlockStore::remove(cpputils::unique_ref<Block> block) {
auto cached_block = dynamic_pointer_move<CachedBlock>(block);
ASSERT(cached_block != none, "Passed block is not a CachedBlock");
auto baseBlock = (*cached_block)->releaseBlock();
auto baseNewBlock = dynamic_pointer_move<NewBlock>(baseBlock);
if (baseNewBlock != none) {
if(!(*baseNewBlock)->alreadyExistsInBaseStore()) {
--_numNewBlocks;
}
(*baseNewBlock)->remove();
} else {
_baseBlockStore->remove(std::move(baseBlock));
}
}
uint64_t CachingBlockStore::numBlocks() const {
return _baseBlockStore->numBlocks() + _numNewBlocks;
}
void CachingBlockStore::release(unique_ref<Block> block) {
Key key = block->key();
_cache.push(key, std::move(block));
}
optional<unique_ref<Block>> CachingBlockStore::tryCreateInBaseStore(const Key &key, Data data) {
auto block = _baseBlockStore->tryCreate(key, std::move(data));
if (block != none) {
--_numNewBlocks;
}
return block;
}
void CachingBlockStore::removeFromBaseStore(cpputils::unique_ref<Block> block) {
_baseBlockStore->remove(std::move(block));
}
void CachingBlockStore::flush() {
_cache.flush();
}
}
}