304 lines
6.4 KiB
C++
304 lines
6.4 KiB
C++
// 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.
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//
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// thin-provisioning-tools is free software: you can redistribute it
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// and/or modify it under the terms of the GNU General Public License
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// as published by the Free Software Foundation, either version 3 of
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// the License, or (at your option) any later version.
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//
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// thin-provisioning-tools is distributed in the hope that it will be
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// useful, but WITHOUT ANY WARRANTY; without even the implied warranty
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// of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License along
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// with thin-provisioning-tools. If not, see
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// <http://www.gnu.org/licenses/>.
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#include "persistent-data/space-maps/recursive.h"
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#include "persistent-data/space-maps/subtracting_span_iterator.h"
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#include <list>
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using namespace persistent_data;
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using namespace std;
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//----------------------------------------------------------------
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namespace {
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enum op {
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INC,
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SET
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};
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struct block_op {
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block_op(op o, uint32_t rc)
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: op_(o),
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rc_(rc) {
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}
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op op_;
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// I'm assuming the ref counts never get above 2^31, which is reasonable I think :)
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int32_t rc_;
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};
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// Aggregates two block_ops
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block_op operator +(block_op const &lhs, block_op const &rhs) {
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switch (lhs.op_) {
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case INC:
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switch (rhs.op_) {
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case INC:
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return block_op(INC, lhs.rc_ + rhs.rc_);
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case SET:
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return rhs;
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}
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break;
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case SET:
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switch (rhs.op_) {
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case INC:
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return block_op(SET, lhs.rc_ + rhs.rc_);
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case SET:
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return rhs;
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}
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break;
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}
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throw runtime_error("can't get here");
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}
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class sm_recursive : public checked_space_map {
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public:
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sm_recursive(checked_space_map::ptr sm)
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: sm_(sm),
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depth_(0),
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flush_in_progress_(false) {
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}
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virtual block_address get_nr_blocks() const {
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return sm_->get_nr_blocks();
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}
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virtual block_address get_nr_free() const {
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return sm_->get_nr_free();
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}
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virtual ref_t get_count(block_address b) const {
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recursing_const_lock lock(*this);
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return modify_count(b, sm_->get_count(b));
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}
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virtual void set_count(block_address b, ref_t c) {
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if (depth_)
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add_op(b, block_op(SET, c));
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else {
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recursing_lock lock(*this);
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// the inner set_count may trigger a find_free,
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// so it's important we update the allocated
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// blocks list before calling.
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allocated_blocks_.add(b, b + 1);
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return sm_->set_count(b, c);
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}
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}
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virtual void commit() {
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cant_recurse("commit");
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sm_->commit();
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}
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virtual void inc(block_address b, ref_t count) override {
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if (depth_)
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add_op(b, block_op(INC, count));
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else {
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recursing_lock lock(*this);
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// the inner inc() may trigger a find_free,
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// so it's important we update the allocated
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// blocks list before calling.
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allocated_blocks_.add(b, b + 1);
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return sm_->inc(b, count);
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}
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}
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virtual void dec(block_address b, ref_t count) override {
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if (depth_)
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add_op(b, block_op(INC, -count));
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else {
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recursing_lock lock(*this);
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return sm_->dec(b, count);
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}
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}
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virtual maybe_block
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find_free(span_iterator &it) {
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recursing_lock lock(*this);
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subtracting_span_iterator filtered_it(get_nr_blocks(), it, allocated_blocks_);
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return sm_->find_free(filtered_it);
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}
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virtual void extend(block_address extra_blocks) {
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cant_recurse("extend");
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recursing_lock lock(*this);
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return sm_->extend(extra_blocks);
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}
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virtual void iterate(iterator &it) const {
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sm_->iterate(it);
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}
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virtual void count_metadata(block_counter &bc) const {
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sm_->count_metadata(bc);
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}
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virtual size_t root_size() const {
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cant_recurse("root_size");
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recursing_const_lock lock(*this);
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return sm_->root_size();
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}
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virtual void copy_root(void *dest, size_t len) const {
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cant_recurse("copy_root");
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recursing_const_lock lock(*this);
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return sm_->copy_root(dest, len);
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}
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virtual void visit(space_map_detail::visitor &v) const {
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cant_recurse("check");
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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 {
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return checked_space_map::ptr(new sm_recursive(sm_->clone()));
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}
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void flush_ops() {
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if (flush_in_progress_)
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return;
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flush_in_progress_ = true;
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flush_ops_();
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flush_in_progress_ = false;
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}
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private:
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uint32_t modify_count(block_address b, uint32_t count) const {
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auto ops_it = ops_.find(b);
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if (ops_it != ops_.end()) {
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auto const &op = ops_it->second;
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switch (op.op_) {
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case INC:
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count += op.rc_;
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break;
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case SET:
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count = op.rc_;
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break;
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}
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}
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return count;
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}
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void flush_ops_() {
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recursing_lock lock(*this);
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while (!ops_.empty()) {
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auto p = ops_.begin();
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block_address b = p->first;
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auto op = p->second;
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ops_.erase(p);
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switch (op.op_) {
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case INC:
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if (op.rc_ > 0)
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sm_->inc(b, op.rc_);
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else if (op.rc_ < 0)
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sm_->dec(b, -op.rc_);
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break;
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case SET:
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sm_->set_count(b, op.rc_);
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break;
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}
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}
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allocated_blocks_.clear();
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}
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void add_op(block_address b, block_op const &op) {
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auto it = ops_.find(b);
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if (it == ops_.end())
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ops_.insert(make_pair(b, op));
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else
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it->second = it->second + op;
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// FIXME: is this the best we can do?
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if (op.rc_ > 0)
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allocated_blocks_.add(b, b + 1);
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}
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void cant_recurse(string const &method) const {
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if (depth_)
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throw runtime_error("recursive '" + method + "' not supported");
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}
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struct recursing_lock {
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recursing_lock(sm_recursive &smr)
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: smr_(smr) {
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smr_.depth_++;
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}
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~recursing_lock() {
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if (!--smr_.depth_)
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smr_.flush_ops();
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}
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private:
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sm_recursive &smr_;
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};
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struct recursing_const_lock {
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recursing_const_lock(sm_recursive const &smr)
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: smr_(smr) {
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smr_.depth_++;
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}
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~recursing_const_lock() {
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smr_.depth_--;
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}
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private:
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sm_recursive const &smr_;
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};
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checked_space_map::ptr sm_;
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mutable int depth_;
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map<block_address, block_op> ops_;
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subtracting_span_iterator::block_set allocated_blocks_;
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bool flush_in_progress_;
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};
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}
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//----------------------------------------------------------------
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checked_space_map::ptr
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persistent_data::create_recursive_sm(checked_space_map::ptr sm)
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{
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return checked_space_map::ptr(new sm_recursive(sm));
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}
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//----------------------------------------------------------------
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