thin-provisioning-tools/persistent-data/data-structures/btree_damage_visitor.h

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#ifndef PERSISTENT_DATA_DATA_STRUCTURES_DAMAGE_VISITOR_H
#define PERSISTENT_DATA_DATA_STRUCTURES_DAMAGE_VISITOR_H
#include "persistent-data/data-structures/btree.h"
#include "persistent-data/data-structures/btree_node_checker.h"
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#include "persistent-data/run.h"
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//----------------------------------------------------------------
namespace persistent_data {
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namespace btree_detail {
struct damage {
typedef boost::shared_ptr<damage> ptr;
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damage(run<uint64_t> lost_keys,
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std::string const &desc)
: lost_keys_(lost_keys),
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desc_(desc) {
}
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run<uint64_t> lost_keys_;
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std::string desc_;
};
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inline std::ostream &operator <<(std::ostream &out, damage const &d) {
out << "btree damage[lost_keys = " << d.lost_keys_
<< ", \"" << d.desc_ << "\"]";
return out;
}
class noop_damage_visitor {
public:
virtual void visit(btree_path const &path, damage const &d) {
}
};
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// Tracks damage in a single level btree. Use multiple
// trackers if you have a multilayer tree.
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class damage_tracker {
public:
damage_tracker()
: damaged_(false),
damage_begin_(0) {
}
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typedef run<uint64_t> run64;
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typedef boost::optional<run64> maybe_run64;
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void bad_node() {
damaged_ = true;
}
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maybe_run64 good_internal(block_address begin) {
maybe_run64 r;
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if (damaged_) {
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r = maybe_run64(run64(damage_begin_, begin));
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damaged_ = false;
}
damage_begin_ = begin;
return r;
}
// remember 'end' is the one-past-the-end value, so
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// take the last key in the leaf and add one.
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maybe_run64 good_leaf(block_address begin, block_address end) {
maybe_run64 r;
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if (damaged_) {
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r = maybe_run64(run64(damage_begin_, begin));
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damaged_ = false;
}
damage_begin_ = end;
return r;
}
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maybe_run64 end() {
maybe_run64 r;
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if (damaged_)
r = maybe_run64(damage_begin_);
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else
r = maybe_run64();
damaged_ = false;
damage_begin_ = 0;
return r;
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}
private:
bool damaged_;
block_address damage_begin_;
};
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// As we walk a btree we need to know if we've moved into a
// different sub tree (by looking at the btree_path).
class path_tracker {
public:
path_tracker() {
// We push an empty path, to ensure there
// is always a current_path.
paths_.push_back(btree_path());
}
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// returns the old path if the tree has changed.
btree_path const *next_path(btree_path const &p) {
if (p != current_path()) {
if (paths_.size() == 2)
paths_.pop_front();
paths_.push_back(p);
return &paths_.front();
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}
return NULL;
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}
btree_path const &current_path() const {
return paths_.back();
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}
private:
std::list<btree_path> paths_;
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};
//----------------------------------------------------------------
// This class implements consistency checking for the btrees. It
// also allows the caller to visit all accessible values.
// Derive from this if you want some additional checks. It's worth
// summarising what is checked:
//
// Implemented
// -----------
//
// - block_nr
// - nr_entries < max_entries
// - max_entries fits in block
// - max_entries is divisible by 3
// - nr_entries > minimum (except for root nodes)
//
// Not implemented
// ---------------
//
// - leaf | internal flags (this can be inferred from siblings)
//----------------------------------------------------------------
template <typename ValueVisitor, typename DamageVisitor, uint32_t Levels, typename ValueTraits>
class btree_damage_visitor : public btree<Levels, ValueTraits>::visitor {
public:
typedef btree_detail::node_location node_location;
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typedef run<block_address> run64;
typedef boost::optional<run64> maybe_run64;
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btree_damage_visitor(ValueVisitor &value_visitor,
DamageVisitor &damage_visitor)
: avoid_repeated_visits_(true),
value_visitor_(value_visitor),
damage_visitor_(damage_visitor) {
}
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bool visit_internal(node_location const &loc,
btree_detail::node_ref<block_traits> const &n) {
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update_path(loc.path);
return check_internal(loc, n);
}
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bool visit_internal_leaf(node_location const &loc,
btree_detail::node_ref<block_traits> const &n) {
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update_path(loc.path);
return check_leaf(loc, n);
}
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bool visit_leaf(node_location const &loc,
btree_detail::node_ref<ValueTraits> const &n) {
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update_path(loc.path);
bool r = check_leaf(loc, n);
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// If anything goes wrong with the checks, we skip
// the value visiting.
if (!r)
return false;
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visit_values(loc.path, n);
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return true;
}
void visit_complete() {
end_walk();
}
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typedef typename btree<Levels, ValueTraits>::visitor::error_outcome error_outcome;
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error_outcome error_accessing_node(node_location const &l, block_address b,
std::string const &what) {
update_path(l.path);
report_damage(what);
return btree<Levels, ValueTraits>::visitor::EXCEPTION_HANDLED;
}
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private:
void visit_values(btree_path const &path,
node_ref<ValueTraits> const &n) {
btree_path p2(path);
unsigned nr = n.get_nr_entries();
for (unsigned i = 0; i < nr; i++) {
p2.push_back(n.key_at(i));
value_visitor_.visit(p2, n.value_at(i));
p2.pop_back();
}
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}
bool check_internal(node_location const &loc,
btree_detail::node_ref<block_traits> const &n) {
if (already_visited(n))
return false;
else if (!checker_.check_block_nr(n) ||
!checker_.check_value_size(n) ||
!checker_.check_max_entries(n) ||
!checker_.check_nr_entries(n, loc.is_sub_root()) ||
!checker_.check_ordered_keys(n) ||
!checker_.check_parent_key(n, loc.is_sub_root() ? boost::optional<uint64_t>() : loc.key)) {
report_damage(checker_.get_last_error_string());
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return false;
}
if (loc.is_sub_root())
new_root(loc.level());
good_internal(n.key_at(0));
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return true;
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}
template <typename ValueTraits2>
bool check_leaf(node_location const &loc,
btree_detail::node_ref<ValueTraits2> const &n) {
if (already_visited(n))
return false;
else if (!checker_.check_block_nr(n) ||
!checker_.check_value_size(n) ||
!checker_.check_max_entries(n) ||
!checker_.check_nr_entries(n, loc.is_sub_root()) ||
!checker_.check_ordered_keys(n) ||
!checker_.check_parent_key(n, loc.is_sub_root() ? boost::optional<uint64_t>() : loc.key)) {
report_damage(checker_.get_last_error_string());
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return false;
}
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if (loc.is_sub_root())
new_root(loc.level());
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bool r = checker_.check_leaf_key(n, last_leaf_key_[loc.level()]);
if (!r)
report_damage(checker_.get_last_error_string());
else if (n.get_nr_entries() > 0) {
last_leaf_key_[loc.level()] = n.key_at(n.get_nr_entries() - 1);
good_leaf(n.key_at(0), n.key_at(n.get_nr_entries() - 1) + 1);
}
return r;
}
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template <typename node>
bool already_visited(node const &n) {
block_address b = n.get_location();
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if (avoid_repeated_visits_) {
if (seen_.count(b) > 0)
return true;
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seen_.insert(b);
}
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return false;
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}
void new_root(unsigned level) {
// we're starting a new subtree, so should
// reset the last_leaf value.
last_leaf_key_[level] = boost::optional<uint64_t>();
}
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//--------------------------------
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// damage tracking
void report_damage(std::string const &desc) {
damage_reasons_.push_back(desc);
dt_.bad_node();
}
void good_internal(block_address b) {
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maybe_run64 mr = dt_.good_internal(b);
if (mr)
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issue_damage(path_tracker_.current_path(), *mr);
}
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void good_leaf(block_address b, block_address e) {
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maybe_run64 mr = dt_.good_leaf(b, e);
if (mr)
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issue_damage(path_tracker_.current_path(), *mr);
}
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void end_walk() {
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maybe_issue_damage(path_tracker_.current_path());
}
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void issue_damage(btree_path const &path, run64 const &r) {
damage d(r, build_damage_desc());
clear_damage_desc();
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damage_visitor_.visit(path, d);
}
std::string build_damage_desc() const {
std::string r;
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std::list<std::string>::const_iterator it, end = damage_reasons_.end();
for (it = damage_reasons_.begin(); it != end; ++it)
r += *it;
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return r;
}
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void clear_damage_desc() {
damage_reasons_.clear();
}
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void maybe_issue_damage(btree_path const &path) {
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maybe_run64 mr = dt_.end();
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if (mr)
issue_damage(path, *mr);
}
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void update_path(btree_path const &path) {
btree_path const *old_path = path_tracker_.next_path(path);
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if (old_path)
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// we need to emit any errors that
// were accrued against the old
// path.
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maybe_issue_damage(*old_path);
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}
//--------------------------------
bool avoid_repeated_visits_;
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ValueVisitor &value_visitor_;
DamageVisitor &damage_visitor_;
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std::set<block_address> seen_;
boost::optional<uint64_t> last_leaf_key_[Levels];
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btree_node_checker checker_;
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path_tracker path_tracker_;
damage_tracker dt_;
std::list<std::string> damage_reasons_;
};
}
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template <unsigned Levels, typename ValueTraits, typename ValueVisitor, typename DamageVisitor>
void btree_visit_values(btree<Levels, ValueTraits> const &tree,
ValueVisitor &value_visitor,
DamageVisitor &damage_visitor) {
btree_detail::btree_damage_visitor<ValueVisitor, DamageVisitor, Levels, ValueTraits>
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v(value_visitor, damage_visitor);
tree.visit_depth_first(v);
}
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}
//----------------------------------------------------------------
#endif