92 lines
2.0 KiB
C++
92 lines
2.0 KiB
C++
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#include "thin-provisioning/cache_stream.h"
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#include "persistent-data/file_utils.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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namespace {
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int open_file(string const &path) {
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int fd = ::open(path.c_str(), O_RDONLY | O_DIRECT | O_EXCL, 0666);
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if (fd < 0)
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syscall_failed("open",
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"Note: you cannot run this tool with these options on live metadata.");
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return fd;
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}
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}
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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_(open_file(path)),
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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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load(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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block_address
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cache_stream::nr_chunks() const
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{
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return nr_blocks_;
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}
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void
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cache_stream::rewind()
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{
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load(0);
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}
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bool
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cache_stream::advance(block_address count)
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{
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if (current_index_ + count >= nr_blocks_)
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return false;
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current_index_ += count;
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load(current_index_);
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return true;
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}
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block_address
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cache_stream::index() const
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{
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return current_index_;
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}
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chunk const &
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cache_stream::get() const
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{
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return current_chunk_;
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}
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void
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cache_stream::load(block_address b)
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{
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current_index_ = b;
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current_block_ = cache_->get(current_index_, 0, v_);
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current_chunk_.offset_sectors_ = (b * block_size_) / 512;
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current_chunk_.mem_.clear();
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current_chunk_.mem_.push_back(mem(static_cast<uint8_t *>(current_block_.get_data()),
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static_cast<uint8_t *>(current_block_.get_data()) + block_size_));
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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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}
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//----------------------------------------------------------------
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