thin-provisioning-tools/persistent-data/block.h

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// Copyright (C) 2011 Red Hat, Inc. All rights reserved.
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//
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// 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
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#include "persistent-data/buffer.h"
#include "persistent-data/cache.h"
#include "persistent-data/lock_tracker.h"
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#include <stdint.h>
#include <map>
#include <vector>
#include <boost/noncopyable.hpp>
#include <boost/optional.hpp>
#include <boost/shared_ptr.hpp>
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#include <string>
//----------------------------------------------------------------
namespace persistent_data {
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uint32_t const MD_BLOCK_SIZE = 4096;
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typedef uint64_t block_address;
template <uint32_t BlockSize = MD_BLOCK_SIZE>
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class block_io : private boost::noncopyable {
public:
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typedef boost::shared_ptr<block_io> ptr;
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enum mode {
READ_ONLY,
READ_WRITE,
CREATE
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};
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block_io(std::string const &path, block_address nr_blocks, mode m);
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~block_io();
block_address get_nr_blocks() const {
return nr_blocks_;
}
void read_buffer(block_address location, buffer<BlockSize> &buf) const;
void write_buffer(block_address location, buffer<BlockSize> const &buf);
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private:
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int fd_;
block_address nr_blocks_;
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mode mode_;
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bool writeable_;
};
template <uint32_t BlockSize = MD_BLOCK_SIZE>
class block_manager : private boost::noncopyable {
public:
typedef boost::shared_ptr<block_manager> ptr;
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block_manager(std::string const &path,
block_address nr_blocks,
unsigned max_concurrent_locks,
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typename block_io<BlockSize>::mode m);
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class validator {
public:
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typedef boost::shared_ptr<validator> ptr;
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virtual ~validator() {}
virtual void check(buffer<BlockSize> const &b, block_address location) const = 0;
virtual void prepare(buffer<BlockSize> &b, block_address location) const = 0;
};
class noop_validator : public validator {
public:
void check(buffer<BlockSize> const &b, block_address location) const {}
void prepare(buffer<BlockSize> &b, block_address location) const {}
};
enum block_type {
BT_SUPERBLOCK,
BT_NORMAL
};
struct block : private boost::noncopyable {
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typedef boost::shared_ptr<block> ptr;
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block(typename block_io<BlockSize>::ptr io,
block_address location,
block_type bt,
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typename validator::ptr v,
bool zero = false);
~block();
void check_read_lockable() const {
// FIXME: finish
}
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void check_write_lockable() const {
// FIXME: finish
}
void flush();
void change_validator(typename block_manager<BlockSize>::validator::ptr v,
bool check = true);
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typename block_io<BlockSize>::ptr io_;
block_address location_;
std::auto_ptr<buffer<BlockSize> > data_;
typename validator::ptr validator_;
block_type bt_;
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bool dirty_;
};
class read_ref {
public:
static uint32_t const BLOCK_SIZE = BlockSize;
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read_ref(block_manager<BlockSize> const &bm,
typename block::ptr b);
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read_ref(read_ref const &rhs);
virtual ~read_ref();
read_ref const &operator =(read_ref const &rhs);
block_address get_location() const;
buffer<BlockSize> const &data() const;
protected:
block_manager<BlockSize> const *bm_;
typename block::ptr block_;
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unsigned *holders_;
};
// Inherited from read_ref, since you can read a block that's write
// locked.
class write_ref : public read_ref {
public:
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write_ref(block_manager<BlockSize> const &bm,
typename block::ptr b);
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using read_ref::data;
buffer<BlockSize> &data();
};
// Locking methods
read_ref
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read_lock(block_address location,
typename validator::ptr v =
typename validator::ptr(new noop_validator())) const;
write_ref
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write_lock(block_address location,
typename validator::ptr v =
typename validator::ptr(new noop_validator()));
write_ref
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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()));
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block_address get_nr_blocks() const;
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void flush() const;
// This is just for unit tests, don't call in application
// code.
bool is_locked(block_address b) const;
private:
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void check(block_address b) const;
void write_block(typename block::ptr b) const;
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enum lock_type {
READ_LOCK,
WRITE_LOCK
};
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struct cache_traits {
typedef typename block::ptr value_type;
typedef block_address key_type;
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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
mutable lock_tracker tracker_;
};
// A little utility to help build validators
inline block_manager<>::validator::ptr
mk_validator(block_manager<>::validator *v) {
return block_manager<>::validator::ptr(v);
}
}
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#include "block.tcc"
//----------------------------------------------------------------
#endif