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>>.
This commit is contained in:
WGH
2020-07-28 18:46:03 +03:00
committed by Felipe Zimmerle
parent 2cb7591eac
commit 21a63b296a
55 changed files with 264 additions and 376 deletions

View File

@@ -72,10 +72,9 @@ struct MyHash{
class AnchoredSetVariable : public std::unordered_multimap<std::string,
VariableValue *, MyHash, MyEqual> {
std::shared_ptr<const VariableValue>, MyHash, MyEqual> {
public:
AnchoredSetVariable(Transaction *t, const std::string &name);
~AnchoredSetVariable();
void unset();
@@ -93,18 +92,18 @@ class AnchoredSetVariable : public std::unordered_multimap<std::string,
void setCopy(std::string key, std::string value, size_t offset);
void resolve(std::vector<const VariableValue *> *l);
void resolve(std::vector<const VariableValue *> *l,
void resolve(std::vector<std::shared_ptr<const VariableValue>> *l);
void resolve(std::vector<std::shared_ptr<const VariableValue>> *l,
variables::KeyExclusions &ke);
void resolve(const std::string &key,
std::vector<const VariableValue *> *l);
std::vector<std::shared_ptr<const VariableValue>> *l);
void resolveRegularExpression(Utils::Regex *r,
std::vector<const VariableValue *> *l);
std::vector<std::shared_ptr<const VariableValue>> *l);
void resolveRegularExpression(Utils::Regex *r,
std::vector<const VariableValue *> *l,
std::vector<std::shared_ptr<const VariableValue>> *l,
variables::KeyExclusions &ke);
std::unique_ptr<std::string> resolveFirst(const std::string &key);