thin-provisioning-tools/persistent-data/space_map.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 SPACE_MAP_H
#define SPACE_MAP_H
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#include "persistent-data/block.h"
#include "persistent-data/block_counter.h"
#include "persistent-data/run.h"
#include <boost/optional.hpp>
#include <functional>
//----------------------------------------------------------------
namespace persistent_data {
typedef uint32_t ref_t;
// FIXME: document these methods
class space_map {
public:
typedef std::shared_ptr<space_map> ptr;
virtual ~space_map() {};
virtual block_address get_nr_blocks() const = 0;
virtual block_address get_nr_free() const = 0;
virtual ref_t get_count(block_address b) const = 0;
virtual void set_count(block_address b, ref_t c) = 0;
virtual void commit() = 0;
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virtual void inc(block_address b) = 0;
virtual void dec(block_address b) = 0;
// slow default implementation
virtual void inc(block_address b, uint32_t count) {
for (uint32_t i = 0; i < count; i++)
inc(b);
}
virtual void dec(block_address b, uint32_t count) {
for (uint32_t i = 0; i < count; i++)
dec(b);
}
// FIXME: change these to return an optional, failure is
// not that rare if we're restricting the area that's
// searched.
typedef boost::optional<block_address> maybe_block;
typedef std::pair<block_address, block_address> span;
typedef boost::optional<span> maybe_span;
struct span_iterator {
typedef boost::optional<span> maybe_span;
virtual maybe_span first() = 0;
virtual maybe_span next() = 0;
};
struct single_span_iterator : public span_iterator {
single_span_iterator(span const &s)
: s_(s) {
}
virtual maybe_span first() {
return maybe_span(s_);
}
virtual maybe_span next() {
return maybe_span();
}
private:
span s_;
};
// deliberately not virtual
maybe_block new_block() {
single_span_iterator it(span(0, get_nr_blocks()));
return new_block(it);
}
virtual maybe_block find_free(span_iterator &it) = 0;
virtual bool count_possibly_greater_than_one(block_address b) const = 0;
virtual void extend(block_address extra_blocks) = 0;
struct iterator {
virtual ~iterator() {}
virtual void operator() (block_address b, ref_t c) = 0;
};
virtual void iterate(iterator &it) const {
throw std::runtime_error("iterate() not implemented");
}
// This is a concrete method
maybe_block new_block(span_iterator &it) {
maybe_block mb = find_free(it);
if (mb)
inc(*mb);
return mb;
}
};
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//--------------------------------
namespace space_map_detail {
class damage {
public:
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virtual ~damage() {}
};
class missing_counts : public damage {
public:
missing_counts(base::run<block_address> &lost);
};
class visitor {
public:
virtual ~visitor() {}
virtual void visit(missing_counts const &mc) = 0;
virtual void visit(block_address b, uint32_t count) = 0;
};
}
//--------------------------------
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class persistent_space_map : public space_map {
public:
typedef std::shared_ptr<persistent_space_map> ptr;
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virtual void count_metadata(block_counter &bc) const = 0;
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virtual size_t root_size() const = 0;
virtual void copy_root(void *dest, size_t len) const = 0;
};
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class checked_space_map : public persistent_space_map {
public:
typedef std::shared_ptr<checked_space_map> ptr;
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virtual void visit(space_map_detail::visitor &v) const {
throw std::runtime_error("space_map.visit not implemented");
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}
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// FIXME: should this be in the base space_map class?
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virtual ptr clone() const = 0;
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};
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class sm_adjust {
public:
sm_adjust(space_map::ptr sm, block_address b, int delta)
: sm_(sm),
b_(b),
delta_(delta) {
adjust_count(delta_);
}
~sm_adjust() {
adjust_count(-delta_);
}
void release() {
delta_ = 0;
}
private:
void adjust_count(int delta) {
if (delta == 1)
sm_->inc(b_);
else if (delta == -1)
sm_->dec(b_);
else
sm_->set_count(b_, sm_->get_count(b_) + delta);
}
space_map::ptr sm_;
block_address b_;
int delta_;
};
class sm_decrementer {
public:
sm_decrementer(space_map::ptr sm, block_address b);
~sm_decrementer();
void dont_bother();
private:
space_map::ptr sm_;
block_address b_;
bool released_;
};
}
//----------------------------------------------------------------
#endif