memgraph/src/storage/v2/constraints.cpp

404 lines
13 KiB
C++

#include "storage/v2/constraints.hpp"
#include <algorithm>
#include <cstring>
#include <map>
#include "storage/v2/mvcc.hpp"
#include "utils/logging.hpp"
namespace storage {
namespace {
/// Helper function that determines position of the given `property` in the
/// sorted `property_array` using binary search. In the case that `property`
/// cannot be found, `std::nullopt` is returned.
std::optional<size_t> FindPropertyPosition(const PropertyIdArray &property_array, PropertyId property) {
auto it = std::lower_bound(property_array.values, property_array.values + property_array.size, property);
if (it == property_array.values + property_array.size || *it != property) {
return std::nullopt;
}
return it - property_array.values;
}
/// Helper function for validating unique constraints on commit. Returns true if
/// the last committed version of the given vertex contains the given label and
/// set of property values. This function should be called when commit lock is
/// active.
bool LastCommittedVersionHasLabelProperty(const Vertex &vertex, LabelId label, const std::set<PropertyId> &properties,
const std::vector<PropertyValue> &value_array, const Transaction &transaction,
uint64_t commit_timestamp) {
MG_ASSERT(properties.size() == value_array.size(), "Invalid database state!");
PropertyIdArray property_array(properties.size());
bool current_value_equal_to_value[kUniqueConstraintsMaxProperties];
memset(current_value_equal_to_value, 0, sizeof(current_value_equal_to_value));
// Since the commit lock is active, any transaction that tries to write to
// a vertex which is part of the given `transaction` will result in a
// serialization error. But, note that the given `vertex`'s data does not have
// to be modified in the current `transaction`, meaning that a guard lock to
// access vertex's data is still necessary because another active transaction
// could modify it in the meantime.
Delta *delta;
bool deleted;
bool has_label;
{
std::lock_guard<utils::SpinLock> guard(vertex.lock);
delta = vertex.delta;
deleted = vertex.deleted;
has_label = utils::Contains(vertex.labels, label);
size_t i = 0;
for (const auto &property : properties) {
current_value_equal_to_value[i] = vertex.properties.IsPropertyEqual(property, value_array[i]);
property_array.values[i] = property;
i++;
}
}
while (delta != nullptr) {
auto ts = delta->timestamp->load(std::memory_order_acquire);
if (ts < commit_timestamp || ts == transaction.transaction_id) {
break;
}
switch (delta->action) {
case Delta::Action::SET_PROPERTY: {
auto pos = FindPropertyPosition(property_array, delta->property.key);
if (pos) {
current_value_equal_to_value[*pos] = delta->property.value == value_array[*pos];
}
break;
}
case Delta::Action::DELETE_OBJECT: {
MG_ASSERT(!deleted, "Invalid database state!");
deleted = true;
break;
}
case Delta::Action::RECREATE_OBJECT: {
MG_ASSERT(deleted, "Invalid database state!");
deleted = false;
break;
}
case Delta::Action::ADD_LABEL: {
if (delta->label == label) {
MG_ASSERT(!has_label, "Invalid database state!");
has_label = true;
break;
}
}
case Delta::Action::REMOVE_LABEL: {
if (delta->label == label) {
MG_ASSERT(has_label, "Invalid database state!");
has_label = false;
break;
}
}
case Delta::Action::ADD_IN_EDGE:
case Delta::Action::ADD_OUT_EDGE:
case Delta::Action::REMOVE_IN_EDGE:
case Delta::Action::REMOVE_OUT_EDGE:
break;
}
delta = delta->next.load(std::memory_order_acquire);
}
for (size_t i = 0; i < properties.size(); ++i) {
if (!current_value_equal_to_value[i]) {
return false;
}
}
return !deleted && has_label;
}
/// Helper function for unique constraint garbage collection. Returns true if
/// there's a reachable version of the vertex that has the given label and
/// property values.
bool AnyVersionHasLabelProperty(const Vertex &vertex, LabelId label, const std::set<PropertyId> &properties,
const std::vector<PropertyValue> &values, uint64_t timestamp) {
MG_ASSERT(properties.size() == values.size(), "Invalid database state!");
PropertyIdArray property_array(properties.size());
bool current_value_equal_to_value[kUniqueConstraintsMaxProperties];
memset(current_value_equal_to_value, 0, sizeof(current_value_equal_to_value));
bool has_label;
bool deleted;
Delta *delta;
{
std::lock_guard<utils::SpinLock> guard(vertex.lock);
has_label = utils::Contains(vertex.labels, label);
deleted = vertex.deleted;
delta = vertex.delta;
size_t i = 0;
for (const auto &property : properties) {
current_value_equal_to_value[i] = vertex.properties.IsPropertyEqual(property, values[i]);
property_array.values[i] = property;
i++;
}
}
{
bool all_values_match = true;
for (size_t i = 0; i < values.size(); ++i) {
if (!current_value_equal_to_value[i]) {
all_values_match = false;
break;
}
}
if (!deleted && has_label && all_values_match) {
return true;
}
}
while (delta != nullptr) {
auto ts = delta->timestamp->load(std::memory_order_acquire);
if (ts < timestamp) {
break;
}
switch (delta->action) {
case Delta::Action::ADD_LABEL:
if (delta->label == label) {
MG_ASSERT(!has_label, "Invalid database state!");
has_label = true;
}
break;
case Delta::Action::REMOVE_LABEL:
if (delta->label == label) {
MG_ASSERT(has_label, "Invalid database state!");
has_label = false;
}
break;
case Delta::Action::SET_PROPERTY: {
auto pos = FindPropertyPosition(property_array, delta->property.key);
if (pos) {
current_value_equal_to_value[*pos] = delta->property.value == values[*pos];
}
break;
}
case Delta::Action::RECREATE_OBJECT: {
MG_ASSERT(deleted, "Invalid database state!");
deleted = false;
break;
}
case Delta::Action::DELETE_OBJECT: {
MG_ASSERT(!deleted, "Invalid database state!");
deleted = true;
break;
}
case Delta::Action::ADD_IN_EDGE:
case Delta::Action::ADD_OUT_EDGE:
case Delta::Action::REMOVE_IN_EDGE:
case Delta::Action::REMOVE_OUT_EDGE:
break;
}
bool all_values_match = true;
for (size_t i = 0; i < values.size(); ++i) {
if (!current_value_equal_to_value[i]) {
all_values_match = false;
break;
}
}
if (!deleted && has_label && all_values_match) {
return true;
}
delta = delta->next.load(std::memory_order_acquire);
}
return false;
}
/// Helper function that, given the set of `properties`, extracts corresponding
/// property values from the `vertex`.
/// @throw std::bad_alloc
std::optional<std::vector<PropertyValue>> ExtractPropertyValues(const Vertex &vertex,
const std::set<PropertyId> &properties) {
std::vector<PropertyValue> value_array;
value_array.reserve(properties.size());
for (const auto &prop : properties) {
auto value = vertex.properties.GetProperty(prop);
if (value.IsNull()) {
return std::nullopt;
}
value_array.emplace_back(std::move(value));
}
return std::move(value_array);
}
} // namespace
bool operator==(const ConstraintViolation &lhs, const ConstraintViolation &rhs) {
return lhs.type == rhs.type && lhs.label == rhs.label && lhs.properties == rhs.properties;
}
bool UniqueConstraints::Entry::operator<(const Entry &rhs) {
if (values < rhs.values) {
return true;
}
if (rhs.values < values) {
return false;
}
return std::make_tuple(vertex, timestamp) < std::make_tuple(rhs.vertex, rhs.timestamp);
}
bool UniqueConstraints::Entry::operator==(const Entry &rhs) {
return values == rhs.values && vertex == rhs.vertex && timestamp == rhs.timestamp;
}
bool UniqueConstraints::Entry::operator<(const std::vector<PropertyValue> &rhs) { return values < rhs; }
bool UniqueConstraints::Entry::operator==(const std::vector<PropertyValue> &rhs) { return values == rhs; }
void UniqueConstraints::UpdateBeforeCommit(const Vertex *vertex, const Transaction &tx) {
for (auto &[label_props, storage] : constraints_) {
if (!utils::Contains(vertex->labels, label_props.first)) {
continue;
}
auto values = ExtractPropertyValues(*vertex, label_props.second);
if (values) {
auto acc = storage.access();
acc.insert(Entry{std::move(*values), vertex, tx.start_timestamp});
}
}
}
utils::BasicResult<ConstraintViolation, UniqueConstraints::CreationStatus> UniqueConstraints::CreateConstraint(
LabelId label, const std::set<PropertyId> &properties, utils::SkipList<Vertex>::Accessor vertices) {
if (properties.empty()) {
return CreationStatus::EMPTY_PROPERTIES;
}
if (properties.size() > kUniqueConstraintsMaxProperties) {
return CreationStatus::PROPERTIES_SIZE_LIMIT_EXCEEDED;
}
auto [constraint, emplaced] =
constraints_.emplace(std::piecewise_construct, std::forward_as_tuple(label, properties), std::forward_as_tuple());
if (!emplaced) {
// Constraint already exists.
return CreationStatus::ALREADY_EXISTS;
}
bool violation_found = false;
{
auto acc = constraint->second.access();
for (const Vertex &vertex : vertices) {
if (vertex.deleted || !utils::Contains(vertex.labels, label)) {
continue;
}
auto values = ExtractPropertyValues(vertex, properties);
if (!values) {
continue;
}
// Check whether there already is a vertex with the same values for the
// given label and property.
auto it = acc.find_equal_or_greater(*values);
if (it != acc.end() && it->values == *values) {
violation_found = true;
break;
}
acc.insert(Entry{std::move(*values), &vertex, 0});
}
}
if (violation_found) {
// In the case of the violation, storage for the current constraint has to
// be removed.
constraints_.erase(constraint);
return ConstraintViolation{ConstraintViolation::Type::UNIQUE, label, properties};
}
return CreationStatus::SUCCESS;
}
UniqueConstraints::DeletionStatus UniqueConstraints::DropConstraint(LabelId label,
const std::set<PropertyId> &properties) {
if (properties.empty()) {
return UniqueConstraints::DeletionStatus::EMPTY_PROPERTIES;
}
if (properties.size() > kUniqueConstraintsMaxProperties) {
return UniqueConstraints::DeletionStatus::PROPERTIES_SIZE_LIMIT_EXCEEDED;
}
if (constraints_.erase({label, properties}) > 0) {
return UniqueConstraints::DeletionStatus::SUCCESS;
}
return UniqueConstraints::DeletionStatus::NOT_FOUND;
}
std::optional<ConstraintViolation> UniqueConstraints::Validate(const Vertex &vertex, const Transaction &tx,
uint64_t commit_timestamp) const {
if (vertex.deleted) {
return std::nullopt;
}
for (const auto &[label_props, storage] : constraints_) {
const auto &label = label_props.first;
const auto &properties = label_props.second;
if (!utils::Contains(vertex.labels, label)) {
continue;
}
auto value_array = ExtractPropertyValues(vertex, properties);
if (!value_array) {
continue;
}
auto acc = storage.access();
auto it = acc.find_equal_or_greater(*value_array);
for (; it != acc.end(); ++it) {
if (*value_array < it->values) {
break;
}
// The `vertex` that is going to be committed violates a unique constraint
// if it's different than a vertex indexed in the list of constraints and
// has the same label and property value as the last committed version of
// the vertex from the list.
if (&vertex != it->vertex &&
LastCommittedVersionHasLabelProperty(*it->vertex, label, properties, *value_array, tx, commit_timestamp)) {
return ConstraintViolation{ConstraintViolation::Type::UNIQUE, label, properties};
}
}
}
return std::nullopt;
}
std::vector<std::pair<LabelId, std::set<PropertyId>>> UniqueConstraints::ListConstraints() const {
std::vector<std::pair<LabelId, std::set<PropertyId>>> ret;
ret.reserve(constraints_.size());
for (const auto &[label_props, _] : constraints_) {
ret.push_back(label_props);
}
return ret;
}
void UniqueConstraints::RemoveObsoleteEntries(uint64_t oldest_active_start_timestamp) {
for (auto &[label_props, storage] : constraints_) {
auto acc = storage.access();
for (auto it = acc.begin(); it != acc.end();) {
auto next_it = it;
++next_it;
if (it->timestamp >= oldest_active_start_timestamp) {
it = next_it;
continue;
}
if ((next_it != acc.end() && it->vertex == next_it->vertex && it->values == next_it->values) ||
!AnyVersionHasLabelProperty(*it->vertex, label_props.first, label_props.second, it->values,
oldest_active_start_timestamp)) {
acc.remove(*it);
}
it = next_it;
}
}
}
} // namespace storage