thin-provisioning-tools/persistent-data/space-maps/recursive.cc

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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/>.
#include "persistent-data/space-maps/recursive.h"
#include "persistent-data/space-maps/subtracting_span_iterator.h"
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#include <list>
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using namespace persistent_data;
using namespace std;
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//----------------------------------------------------------------
namespace {
enum op {
INC,
SET
};
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struct block_op {
block_op(op o, uint32_t rc)
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: op_(o),
rc_(rc) {
}
op op_;
// I'm assuming the ref counts never get above 2^31, which is reasonable I think :)
int32_t rc_;
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};
// Aggregates two block_ops
block_op operator +(block_op const &lhs, block_op const &rhs) {
switch (lhs.op_) {
case INC:
switch (rhs.op_) {
case INC:
return block_op(INC, lhs.rc_ + rhs.rc_);
case SET:
return rhs;
}
break;
case SET:
switch (rhs.op_) {
case INC:
return block_op(SET, lhs.rc_ + rhs.rc_);
case SET:
return rhs;
}
break;
}
throw runtime_error("can't get here");
}
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class sm_recursive : public checked_space_map {
public:
sm_recursive(checked_space_map::ptr sm)
: sm_(sm),
depth_(0),
flush_in_progress_(false) {
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}
virtual block_address get_nr_blocks() const {
return sm_->get_nr_blocks();
}
virtual block_address get_nr_free() const {
return sm_->get_nr_free();
}
virtual ref_t get_count(block_address b) const {
recursing_const_lock lock(*this);
return modify_count(b, sm_->get_count(b));
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}
virtual void set_count(block_address b, ref_t c) {
if (depth_)
add_op(b, block_op(SET, c));
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else {
recursing_lock lock(*this);
return sm_->set_count(b, c);
}
}
virtual void commit() {
cant_recurse("commit");
sm_->commit();
}
virtual void inc(block_address b, ref_t count) override {
if (depth_)
add_op(b, block_op(INC, count));
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else {
recursing_lock lock(*this);
return sm_->inc(b, count);
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}
}
virtual void dec(block_address b, ref_t count) override {
if (depth_)
add_op(b, block_op(INC, -count));
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else {
recursing_lock lock(*this);
return sm_->dec(b, count);
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}
}
virtual maybe_block
find_free(span_iterator &it) {
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recursing_lock lock(*this);
subtracting_span_iterator filtered_it(get_nr_blocks(), it, allocated_blocks_);
return sm_->find_free(filtered_it);
}
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virtual bool count_possibly_greater_than_one(block_address b) const {
recursing_const_lock lock(*this);
bool gto = sm_->count_possibly_greater_than_one(b);
if (gto)
return true;
return modify_count(b, 1) > 1;
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}
virtual void extend(block_address extra_blocks) {
cant_recurse("extend");
recursing_lock lock(*this);
return sm_->extend(extra_blocks);
}
virtual void iterate(iterator &it) const {
sm_->iterate(it);
}
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virtual void count_metadata(block_counter &bc) const {
sm_->count_metadata(bc);
}
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virtual size_t root_size() const {
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cant_recurse("root_size");
recursing_const_lock lock(*this);
return sm_->root_size();
}
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virtual void copy_root(void *dest, size_t len) const {
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cant_recurse("copy_root");
recursing_const_lock lock(*this);
return sm_->copy_root(dest, len);
}
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virtual void visit(space_map_detail::visitor &v) const {
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cant_recurse("check");
recursing_const_lock lock(*this);
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return sm_->visit(v);
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}
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virtual checked_space_map::ptr clone() const {
return checked_space_map::ptr(new sm_recursive(sm_->clone()));
}
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void flush_ops() {
if (flush_in_progress_)
return;
flush_in_progress_ = true;
flush_ops_();
flush_in_progress_ = false;
}
private:
uint32_t modify_count(block_address b, uint32_t count) const {
auto ops_it = ops_.find(b);
if (ops_it != ops_.end()) {
auto const &op = ops_it->second;
switch (op.op_) {
case INC:
count += op.rc_;
break;
case SET:
count = op.rc_;
break;
}
}
return count;
}
void flush_ops_() {
recursing_lock lock(*this);
for (auto const &p : ops_) {
block_address b = p.first;
auto const &op = p.second;
switch (op.op_) {
case INC:
if (op.rc_ > 0)
sm_->inc(b, op.rc_);
else if (op.rc_ < 0)
sm_->dec(b, -op.rc_);
break;
case SET:
sm_->set_count(b, op.rc_);
break;
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}
}
ops_.clear();
allocated_blocks_.clear();
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}
void add_op(block_address b, block_op const &op) {
auto it = ops_.find(b);
if (it == ops_.end())
ops_.insert(make_pair(b, op));
else
it->second = it->second + op;
// FIXME: is this the best we can do?
if (op.rc_ > 0)
allocated_blocks_.add(b, b + 1);
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}
void cant_recurse(string const &method) const {
if (depth_)
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throw runtime_error("recursive '" + method + "' not supported");
}
struct recursing_lock {
recursing_lock(sm_recursive &smr)
: smr_(smr) {
smr_.depth_++;
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}
~recursing_lock() {
if (!--smr_.depth_)
smr_.flush_ops();
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}
private:
sm_recursive &smr_;
};
struct recursing_const_lock {
recursing_const_lock(sm_recursive const &smr)
: smr_(smr) {
smr_.depth_++;
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}
~recursing_const_lock() {
smr_.depth_--;
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}
private:
sm_recursive const &smr_;
};
checked_space_map::ptr sm_;
mutable int depth_;
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map<block_address, block_op> ops_;
subtracting_span_iterator::block_set allocated_blocks_;
bool flush_in_progress_;
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};
}
//----------------------------------------------------------------
checked_space_map::ptr
persistent_data::create_recursive_sm(checked_space_map::ptr sm)
{
return checked_space_map::ptr(new sm_recursive(sm));
}
//----------------------------------------------------------------