thin-provisioning-tools/block.h
2011-12-06 13:53:05 +00:00

233 lines
5.8 KiB
C++

// Copyright (C) 20011 Red Hat, Inc. All rights reserved.
//
// This file is part of the thin-provisioning-tools source.
//
// thin-provisioning-tools is free software: you can redistribute it
// and/or modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation, either version 3 of
// the License, or (at your option) any later version.
//
// thin-provisioning-tools is distributed in the hope that it will be
// useful, but WITHOUT ANY WARRANTY; without even the implied warranty
// of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License along
// with thin-provisioning-tools. If not, see
// <http://www.gnu.org/licenses/>.
#ifndef BLOCK_H
#define BLOCK_H
#include "cache.h"
#include <stdint.h>
#include <map>
#include <vector>
#include <boost/noncopyable.hpp>
#include <boost/optional.hpp>
#include <boost/shared_ptr.hpp>
#include <string.h>
//----------------------------------------------------------------
namespace persistent_data {
uint32_t const MD_BLOCK_SIZE = 4096;
typedef uint64_t block_address;
template <uint32_t BlockSize>
class block_io : private boost::noncopyable {
public:
typedef boost::shared_ptr<block_io> ptr;
typedef unsigned char buffer[BlockSize];
typedef unsigned char const const_buffer[BlockSize];
block_io(std::string const &path, block_address nr_blocks, bool writeable = false);
~block_io();
block_address get_nr_blocks() const {
return nr_blocks_;
}
void read_buffer(block_address location, buffer &buf) const;
void write_buffer(block_address location, const_buffer &buf);
private:
int fd_;
block_address nr_blocks_;
bool writeable_;
};
template <uint32_t BlockSize = MD_BLOCK_SIZE>
class block_manager : private boost::noncopyable {
public:
typedef boost::shared_ptr<block_manager> ptr;
block_manager(std::string const &path,
block_address nr_blocks,
unsigned max_concurrent_locks,
bool writeable = false);
typedef unsigned char buffer[BlockSize];
typedef unsigned char const const_buffer[BlockSize];
class validator {
public:
typedef boost::shared_ptr<validator> ptr;
virtual ~validator() {}
virtual void check(const_buffer &b, block_address location) const = 0;
virtual void prepare(buffer &b, block_address location) const = 0;
};
class noop_validator : public validator {
public:
void check(const_buffer &b, block_address location) const {}
void prepare(buffer &b, block_address location) const {}
};
enum block_type {
BT_SUPERBLOCK,
BT_NORMAL
};
struct block {
typedef boost::shared_ptr<block> ptr;
block(typename block_io<BlockSize>::ptr io,
block_address location,
block_type bt,
typename validator::ptr v,
bool zero = false);
~block();
void check_read_lockable() const {
// FIXME: finish
}
void check_write_lockable() const {
// FIXME: finish
}
void flush();
typename block_io<BlockSize>::ptr io_;
block_address location_;
buffer data_;
typename validator::ptr validator_;
block_type bt_;
bool dirty_;
};
typedef typename block::ptr block_ptr;
class read_ref {
public:
read_ref(block_manager<BlockSize> const &bm,
block_ptr b);
read_ref(read_ref const &rhs);
virtual ~read_ref();
read_ref const &operator =(read_ref const &rhs);
block_address get_location() const;
const_buffer &data() const;
protected:
block_manager<BlockSize> const &bm_;
block_ptr block_;
unsigned *holders_;
};
// Inherited from read_ref, since you can read a block that's write
// locked.
class write_ref : public read_ref {
public:
write_ref(block_manager<BlockSize> const &bm,
typename block::ptr b);
using read_ref::data;
buffer &data();
};
// Locking methods
read_ref
read_lock(block_address location,
typename validator::ptr v =
typename validator::ptr(new noop_validator())) const;
write_ref
write_lock(block_address location,
typename validator::ptr v =
typename validator::ptr(new noop_validator()));
write_ref
write_lock_zero(block_address location,
typename validator::ptr v =
typename validator::ptr(new noop_validator()));
// The super block is the one that should be written last.
// Unlocking this block triggers the following events:
//
// i) synchronous write of all dirty blocks _except_ the
// superblock.
//
// ii) synchronous write of superblock
//
// If any locks are held at the time of the superblock
// being unlocked then an exception will be thrown.
write_ref superblock(block_address b,
typename validator::ptr v =
typename validator::ptr(new noop_validator()));
write_ref superblock_zero(block_address b,
typename validator::ptr v =
typename validator::ptr(new noop_validator()));
block_address get_nr_blocks() const;
void flush() const;
private:
void check(block_address b) const;
void write_block(block_ptr b) const;
enum lock_type {
READ_LOCK,
WRITE_LOCK
};
struct cache_traits {
typedef typename block::ptr value_type;
typedef block_address key_type;
static key_type get_key(value_type const &v) {
return v->location_;
}
};
typename block_io<BlockSize>::ptr io_;
mutable base::cache<cache_traits> cache_;
// FIXME: we need a dirty list as well as a cache
typedef std::map<block_address, std::pair<lock_type, unsigned> > held_map;
mutable held_map held_locks_;
};
// A little utility to help build validators
inline block_manager<>::validator::ptr
mk_validator(block_manager<>::validator *v) {
return block_manager<>::validator::ptr(v);
}
}
#include "block.tcc"
//----------------------------------------------------------------
#endif