[cppcon2016] c++ Practical Performance Practices -note

Practical Performance Practices

https://github.com/CppCon/CppCon2016/blob/master/Tutorials/Practical%20Performance%20Practices/Practical%20Performance%20Practices%20-%20Jason%20Turner%20-%20CppCon%202016.pdf

Make well-performing code 'by default'

Prefer containers in descendent order:

• std::array
• std::vector
• Then only differ if you need specific behavior.
  Make sure you understand what the library has to do.

 

Always const - Complex Initialization

• Use IIFE (Immediately-invoked Function Expressions), i.e lambda Expressions.
• Always Initialize When Const Isn't Practical.
• Don't Recalculate Values - Calculate on First Use.
• Branching is slower
• Atomic is even more slower
• Calculate At Construction

• Don't Disable Move Operations / Use Rule of 0
• Avoid Named Temporaries

• Avoid object copying
• Avoid ( shared_ptr ) Copies (use shared_ptr.get())
• Avoid Automatic Conversions (shared_ptr<Base> <-> shared_ptr<Derived>)
• Avoid automatic conversions
• Don't pass smart pointers
• Make conversion operations explicit
• Don't use std::endl => '\n' << std::flush

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Summarize:

• Avoid shared_ptr
• Avoid std::endl
• Always const
• Always initialize with meaningful values
• Don't recalculate immutable results

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Smaller Code Is Faster Code

• Common code in non-template base class.
• Prefer return unique_ptr<> from factories
• Avoid std::function<>
• Use Lambdas