thin-provisioning-tools/block-cache/io_engine.h

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2016-04-14 13:24:32 +05:30
#ifndef BLOCK_CACHE_IO_ENGINE_H
#define BLOCK_CACHE_IO_ENGINE_H
#include "base/unique_handle.h"
#include <boost/optional.hpp>
#include <ctype.h>
#include <libaio.h>
#include <set>
#include <string>
//----------------------------------------------------------------
namespace bcache {
using sector_t = uint64_t;
//----------------
class control_block_set {
public:
control_block_set(unsigned nr);
iocb *alloc(unsigned context);
void free(iocb *);
unsigned context(iocb *) const;
private:
struct cblock {
unsigned context;
struct iocb cb;
};
std::set<unsigned> free_cbs_;
std::vector<cblock> cbs_;
};
//----------------
class io_engine {
public:
enum mode {
READ_ONLY,
READ_WRITE
};
enum dir {
READ,
WRITE
};
// max_io is the maximum nr of concurrent ios expected
io_engine(unsigned max_io);
~io_engine();
using handle = unsigned;
handle open_file(std::string const &path, mode m);
void close_file(handle h);
// returns false if there are insufficient resources to
// queue the IO
bool issue_io(handle h, dir d, sector_t b, sector_t e, void *data, unsigned context);
// returns (success, context)
std::pair<bool, unsigned> wait();
private:
std::list<base::unique_fd> descriptors_;
io_context_t aio_context_;
control_block_set cbs_;
std::vector<io_event> events_;
io_engine(io_engine const &) = delete;
io_engine &operator =(io_engine const &) = delete;
};
}
//----------------------------------------------------------------
#endif