ModSecurity/src/run_time_string.cc
WGH 47be22e62a
Use std::shared_ptr for variable resolution
AnchoredSetVariable::resolve is called for every rule
(see RuleWithOperator::evaluate). The previous implementation allocated
a new copy of every variable, which quickly added up. In my tests,
AnchoredSetVariable::resolve function consumed 7.8% of run time.

AnchoredSetVariable (which is a multimap) values are never changed,
only added. This means it's safe to store them in std::shared_ptr,
and make resolve return shared_ptr pointing to the same object.

Other resolve implementation could also use this optimization by not
allocating new objects, however, they are not hot spots, so this
optimization was not implemented there.

In my benchmark, this raises performance from 117 requests per second to
131 RPS, and overhead is lowered from 7.8% to 2.4%.

As a bonus, replacing plain pointer with smart pointers make code
cleaner, since using smart pointers makes manual deletes no longer necessary.

Additionally, VariableOrigin is now stored in plain std::vector,
since it's wasteful to store structure containing just two integer
values using std::list<std::unique_ptr<T>>.
2020-08-10 10:35:07 -03:00

68 lines
2.0 KiB
C++

/*
* ModSecurity, http://www.modsecurity.org/
* Copyright (c) 2015 - 2020 Trustwave Holdings, Inc. (http://www.trustwave.com/)
*
* You may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* If any of the files related to licensing are missing or if you have any
* other questions related to licensing please contact Trustwave Holdings, Inc.
* directly using the email address security@modsecurity.org.
*
*/
#include <memory>
#include "src/run_time_string.h"
#include "modsecurity/variable_value.h"
#include "modsecurity/transaction.h"
#include "src/variables/rule.h"
#include "src/variables/tx.h"
#include "src/variables/highest_severity.h"
#include "src/utils/string.h"
#include "src/variables/variable.h"
#include "src/rule_with_operator.h"
namespace modsecurity {
void RunTimeString::appendText(const std::string &text) {
std::unique_ptr<RunTimeElementHolder> r(new RunTimeElementHolder);
r->m_string = text;
m_elements.push_back(std::move(r));
}
void RunTimeString::appendVar(
std::unique_ptr<modsecurity::variables::Variable> var) {
std::unique_ptr<RunTimeElementHolder> r(new RunTimeElementHolder);
r->m_variable = std::move(var);
m_elements.push_back(std::move(r));
m_containsMacro = true;
}
std::string RunTimeString::evaluate(Transaction *transaction) {
std::string retString;
// FIXME: Educated guess the size of retString based on the size of the elements.
for (auto &element : m_elements) {
if (element->m_string.size() > 0) {
retString.append(element->m_string);
} else if (element->m_variable != nullptr && transaction != nullptr) {
std::vector<std::shared_ptr<const VariableValue>> l;
element->m_variable->evaluate(transaction, &l);
if (!l.empty()) {
retString.append(l[0]->getValue());
}
}
}
return retString;
}
} // namespace modsecurity