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RcppClock

RcppClock is a simple wrapper for std::chrono::high_resolution_clock that makes benchmarking Rcpp code easy.

Install RcppClock from CRAN.

install.packages("RcppClock")
library(RcppClock)
?RcppClock

The Rcpp side of things

Load the RcppClock header into your R session using library(RcppClock), link it in your DESCRIPTION file or with //[[Rcpp::depends(RcppClock)]], and load the header library into individual .cpp files with #include <RcppClock.h>:

//[[Rcpp::depends(RcppClock)]]
#include <RcppClock.h>
#include <thread>

//[[Rcpp::export]]
void sleepy(){
  Rcpp::Clock clock;
  
  clock.tick("both_naps");
  
  clock.tick("short_nap");
  std::this_thread::sleep_for(std::chrono::milliseconds(10));  
  clock.tock("short_nap");
  
  clock.tick("long_nap");
  std::this_thread::sleep_for(std::chrono::milliseconds(100));  
  clock.tock("long_nap");

  clock.tock("both_naps");
  
  // send the times to the R global environment variable, named "naptimes"
  clock.stop("naptimes");
}

.tick(std::string) starts a new timer. Provide a name to record what is being timed.

.tock(std::string) stops a timer. It is important to use the same name as declared in .tick().

.stop(std::string) calculates the duration between all .tick() and .tock() timing results, and creates an object in the R environment with the name provided.

The R side of things

On the R end, we can now do stuff with the “naptimes” variable that was created in the above Rcpp function:

sleepy()
# global variable "naptimes" is now created in the environment
naptimes

summary(naptimes, units = "us")

plot(naptimes)

Timing multiple replicates

If a .tick() with the same name is called multiple times, RcppClock automatically groups the results.

The following code reproduces the ?fibonacci function example included in the RcppClock package:

int fib(int n) {
  return ((n <= 1) ? n : fib(n - 1) + fib(n - 2));
}

//[[Rcpp::export]]
void fibonacci(std::vector<int> n, int reps = 10) {
  Rcpp::Clock clock;
  
  while(reps-- > 0){
    for(auto number : n){
      clock.tick("fib" + std::to_string(number));
      fib(number);
      clock.tock("fib" + std::to_string(number));
    }
  }
  clock.stop("clock");
}

On the R end, we’ll get an object named “clock”:

fibonacci(n = 25:35, reps = 10)
# global variable "clock" is created in the R global environment
clock

plot(clock)

Limitations

• Not compatible with OpenMP parallelization.
• Processes taking less than a microsecond cannot be reliably timed.

These binaries (installable software) and packages are in development.
They may not be fully stable and should be used with caution. We make no claims about them.
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