85 lines
1.9 KiB
C++
85 lines
1.9 KiB
C++
#include "base/container_of.h"
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#include "thin-provisioning/cache_stream.h"
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#include "persistent-data/file_utils.h"
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#include <fcntl.h>
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using namespace thin_provisioning;
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using namespace std;
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using namespace persistent_data;
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//----------------------------------------------------------------
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cache_stream::cache_stream(string const &path,
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block_address block_size,
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size_t cache_mem)
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: block_size_(block_size),
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nr_blocks_(get_nr_blocks(path, block_size)),
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// hack because cache uses LRU rather than MRU
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cache_blocks_((cache_mem / block_size) / 2u),
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fd_(path, O_RDONLY | O_EXCL),
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v_(new bcache::noop_validator()),
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cache_(new block_cache(fd_, block_size / 512, nr_blocks_, cache_mem)),
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current_index_(0) {
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rewind();
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}
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block_address
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cache_stream::size() const
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{
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return nr_blocks_ * block_size_;
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}
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void
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cache_stream::rewind()
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{
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current_index_ = 0;
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for (block_address i = 1; i < min(cache_blocks_, nr_blocks_); i++)
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cache_->prefetch(i);
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}
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bool
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cache_stream::next(block_address count)
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{
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current_index_ = min(current_index_ + count, nr_blocks_);
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if (current_index_ + cache_blocks_ < nr_blocks_)
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cache_->prefetch(current_index_ + cache_blocks_);
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return !eof();
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}
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bool
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cache_stream::eof() const
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{
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return current_index_ >= nr_blocks_;
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}
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chunk const &
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cache_stream::get()
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{
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chunk_wrapper *w = new chunk_wrapper(*this);
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return w->c_; // wrapper will get freed by the put method
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}
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void
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cache_stream::put(chunk const &c)
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{
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chunk_wrapper *w = base::container_of(const_cast<chunk *>(&c), &chunk_wrapper::c_);
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delete w;
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}
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cache_stream::chunk_wrapper::chunk_wrapper(cache_stream &parent)
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: block_(parent.cache_->get(parent.current_index_, 0, parent.v_))
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{
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c_.offset_ = parent.current_index_ * parent.block_size_;
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c_.len_ = parent.block_size_;
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c_.mem_.begin = static_cast<uint8_t *>(block_.get_data());
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c_.mem_.end = c_.mem_.begin + parent.block_size_;
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}
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//----------------------------------------------------------------
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