Copyright 2013-2021 John Farrier Apache 2.0 License
Priori is a special base class which facilitates a very fast dynamic_cast<> alternative when dynamic_cast<> itself has shown to be a bottleneck. Specifically in the case where dynamic_cast<> from a base class to a derived class is impacting performance.
Priori is interesting, but not a wholesale replacement for dynamic_cast. There are very specific use cases when Priori should be considered to relieve a quantified bottle-neck. Benchmarking shows that the following scenarios show measurable improvements for non-threaded applications. Review the benchmark tables below to see if there is a measurable performance improvement for your specific use case. (There are several use cases which are slower than dynamic_cast, so consider this a highly-specialized micro-optimization.)
Priori uses CMake to provide cross-platform builds. It does require a modern compiler due to its use of C++11.
Given 10 levels of inheritance and benchmarked using Celero. (Start by looking at the "Baseline" number. Lower is better.)
For the non-thread-safe implementation:
Celero
Timer resolution: 0.100000 us
| Group | Experiment | Prob. Space | Samples | Iterations | Baseline | us/Iteration | Iterations/sec |
|:--------------:|:---------------:|:---------------:|:---------------:|:---------------:|:---------------:|:---------------:|:---------------:|
|priori_deep_fro | dynamic_cast | Null | 128 | 2000000 | 1.00000 | 0.01781 | 56143502.79 |
|priori_wide_fro | dynamic_cast | Null | 128 | 2000000 | 1.00000 | 0.01614 | 61973227.57 |
|priori_deep_toB | dynamic_cast | Null | 128 | 2000000 | 1.00000 | 0.00464 | 215331610.68 |
|priori_wide_toB | dynamic_cast | Null | 128 | 2000000 | 1.00000 | 0.00458 | 218150087.26 |
|priori_deep_toS | dynamic_cast | Null | 128 | 2000000 | 1.00000 | 0.00498 | 200702458.61 |
|priori_wide_toS | dynamic_cast | Null | 128 | 2000000 | 1.00000 | 0.00492 | 203417412.53 |
|rttiCosts | typeinfo | Null | 128 | 2000000 | 1.00000 | 0.00459 | 217983651.23 |
|priori_deep_fro | priori_cast | Null | 128 | 2000000 | 0.78115 | 0.01391 | 71872641.68 |
|priori_wide_fro | priori_cast | Null | 128 | 2000000 | 1.05311 | 0.01699 | 58847760.84 |
|priori_deep_toB | priori_cast | Null | 128 | 2000000 | 0.97782 | 0.00454 | 220215811.50 |
|priori_wide_toB | priori_cast | Null | 128 | 2000000 | 0.99247 | 0.00455 | 219804374.11 |
|priori_deep_toS | priori_cast | Null | 128 | 2000000 | 0.91159 | 0.00454 | 220167327.17 |
|priori_wide_toS | priori_cast | Null | 128 | 2000000 | 0.88314 | 0.00434 | 230335137.63 |
|rttiCosts | typeinfoHash | Null | 128 | 2000000 | 2.48262 | 0.01139 | 87804021.42 |
|rttiCosts | typeinfoName | Null | 128 | 2000000 | 1.39401 | 0.00639 | 156372165.75 |
For the thread-safe implementation:
Celero
Timer resolution: 0.100000 us
| Group | Experiment | Prob. Space | Samples | Iterations | Baseline | us/Iteration | Iterations/sec |
|:--------------:|:---------------:|:---------------:|:---------------:|:---------------:|:---------------:|:---------------:|:---------------:|
|priori_deep_fro | dynamic_cast | Null | 128 | 2000000 | 1.00000 | 0.01781 | 56154537.29 |
|priori_wide_fro | dynamic_cast | Null | 128 | 2000000 | 1.00000 | 0.01612 | 62034739.45 |
|priori_deep_toB | dynamic_cast | Null | 128 | 2000000 | 1.00000 | 0.00455 | 219973603.17 |
|priori_wide_toB | dynamic_cast | Null | 128 | 2000000 | 1.00000 | 0.00457 | 219034059.80 |
|priori_deep_toS | dynamic_cast | Null | 128 | 2000000 | 1.00000 | 0.00503 | 198925800.68 |
|priori_wide_toS | dynamic_cast | Null | 128 | 2000000 | 1.00000 | 0.00488 | 204918032.79 |
|rttiCosts | typeinfo | Null | 128 | 2000000 | 1.00000 | 0.00454 | 220312844.24 |
|priori_deep_fro | priori_cast | Null | 128 | 2000000 | 1.46114 | 0.02602 | 38431975.40 |
|priori_wide_fro | priori_cast | Null | 128 | 2000000 | 1.94498 | 0.03135 | 31894874.49 |
|priori_deep_toB | priori_cast | Null | 128 | 2000000 | 0.99890 | 0.00454 | 220215811.50 |
|priori_wide_toB | priori_cast | Null | 128 | 2000000 | 0.99660 | 0.00455 | 219780219.78 |
|priori_deep_toS | priori_cast | Null | 128 | 2000000 | 0.90302 | 0.00454 | 220288578.04 |
|priori_wide_toS | priori_cast | Null | 128 | 2000000 | 0.88648 | 0.00433 | 231160425.34 |
|rttiCosts | typeinfoHash | Null | 128 | 2000000 | 2.49251 | 0.01131 | 88389976.58 |
|rttiCosts | typeinfoName | Null | 128 | 2000000 | 1.41683 | 0.00643 | 155496812.32 |