perf: RBAC role building and Enforcer optimizations

[sheny1xuan]

Signed-off-by: stonex 1479765922@qq.com

Fixes #177

Description

• Rbac AddNamedGroupingPolicy build role link by add role.
• Enforcer hold a scope pointer rather than initalize scope when enforce.
• Remove bindings directory.

Screenshots/Testimonials

• Now, normal Enforce performance is almost determined by duktape.
  
• Current benchmark in my machine is below. Compared to before, it can improve approximately 1/3. Compared to before, RBAC model' performance problem maybe can't be solved by this pr. And I will do more profiling about RBAC model.
  

[casbin-bot]

@EmperorYP7 @divy9881 @noob20000405 please review

[EmperorYP7]

The only bottleneck we're left with is duktape itself. We may look into faster alternatives or a different approach altogether.

[EmperorYP7]

The props depend on config. It should be dynamic.

[sheny1xuan]

Thanks for your review. I move clean_scope as a private member function in enforecer, because it based on model's config. And I exposed DeletePropFromObject for Enforcer to edit object in duktape. In this way, the clean step will be dynamic.

[EmperorYP7]

Again, multiple definitions can be accommodated in a single config. eg: r1, r2, r3, p1, p2, p3 etc.

[EmperorYP7]

LGTM

[CLAassistant]

All committers have signed the CLA.

[github-actions]

🎉 This PR is included in version 1.44.1 🎉

The release is available on GitHub release

Your semantic-release bot 📦🚀

[hsluoyz]

@sheny1xuan plz sign: https://cla-assistant.io/casbin/casbin-cpp?pullRequest=178

[sheny1xuan]

@sheny1xuan plz sign: https://cla-assistant.io/casbin/casbin-cpp?pullRequest=178

Have done.

[sheny1xuan]

The only bottleneck we're left with is duktape itself. We may look into faster alternatives or a different approach altogether.

I have searched lightweight cpp evalator in google, but I can't find suitbale replacement of duktape. Exprtk is most methioned, but it doesn't support accessor operator. But we can wrapper it by parsing the matcher string to proper expression. For example, we can replace . to _ and define a object's properties as different variables. Or we can directly make a lightweight library like govaluate. And I have made a plan to for the eval expression, and I have done the string token parse in this repo. What do you think, do you have any suggestions. @EmperorYP7 @hsluoyz

[ArashPartow]

but it doesn't support accessor operator

That is not correct. What you call an "accessor" is merely adding a variable to the symbol_table by its given instance name.

For example if you have a struct called my data:

struct my_data
{
   double avalue;
   std::string astring;
};

then subsequently have an instance of my_data and use it in an expression like so:

typedef exprtk::symbol_table<T> symbol_table_t;
typedef exprtk::expression<T>   expression_t;
typedef exprtk::parser<T>       parser_t

my_data x;

symbol_table_t symbol_table;
symbol_table.add_variable("x.avalue" ,x.avalue);
symbol_table.add_string  ("x.astring",x.astring);

expression_t expression;
expression.register_symbol_table(symbol_table);

const std::string expression_string =
                  "(x.avalue /2 > 3) or (x.astring like '*cat on a mat*')";

parser_t parser;
parser.compile(expression_string,expression);

...

expression.value();

x.avalue = 17;

expression.value();

x.astring = "there is a cat on a mat with a hat";

expression.value();

[sheny1xuan]

x.avalue = 17;

Oh, thanks for your reply. I don't know this trick usage of Exprtk. I'll try to use it as the evalutor of casbin-cpp. Thanks for your reply and your great code.

[hsluoyz]

@ArashPartow the original author of Exprtk has shown up, kudos!

[ArashPartow]

@sheny1xuan More information and examples can be found here:

1. https://github.com/ArashPartow/exprtk/blob/master/readme.txt#L786
2. https://github.com/ArashPartow/exprtk/blob/master/exprtk_simple_example_01.cpp#L47