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
#include "block-cache/block_cache.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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using namespace bcache;
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uint32_t const MD_BLOCK_SIZE = 4096;
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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enum mode {
READ_ONLY,
READ_WRITE,
CREATE
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};
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block_manager(std::string const &path,
block_address nr_blocks,
unsigned max_concurrent_locks,
mode m);
class read_ref {
public:
static uint32_t const BLOCK_SIZE = BlockSize;
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read_ref(block_cache::block &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;
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void const *data() const;
protected:
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block_cache::block &b_;
};
// 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_cache::block &b);
write_ref(block_cache::block &b, unsigned &ref_count);
write_ref(write_ref const &rhs);
~write_ref();
write_ref const &operator =(write_ref const &rhs);
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using read_ref::data;
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void *data();
private:
unsigned *ref_count_;
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};
// Locking methods
read_ref
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read_lock(block_address location,
typename validator::ptr v =
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typename validator::ptr(new bcache::noop_validator())) const;
write_ref
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write_lock(block_address location,
typename validator::ptr v =
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typename validator::ptr(new bcache::noop_validator()));
write_ref
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write_lock_zero(block_address location,
typename validator::ptr v =
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typename validator::ptr(new bcache::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 =
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typename validator::ptr(new bcache::noop_validator()));
write_ref superblock_zero(block_address b,
typename validator::ptr v =
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typename validator::ptr(new bcache::noop_validator()));
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block_address get_nr_blocks() const;
void prefetch(block_address b) 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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int open_or_create_block_file(std::string const &path, off_t file_size, mode m);
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void check(block_address b) const;
int fd_;
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mutable block_cache bc_;
unsigned superblock_ref_count_;
};
// A little utility to help build validators
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inline bcache::validator::ptr
mk_validator(bcache::validator *v) {
return bcache::validator::ptr(v);
}
}
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#include "block.tcc"
//----------------------------------------------------------------
#endif