Single header implementation of a function to determine the time in seconds that passed since the start of the current process. This differs from measuring time starting at main() because GetTimeSinceProcessStart() accounts for computations performed after the process creation, including OS loader activities, standard library initialization, memory allocation, DLL/DSO loading, and static symbol construction. This library is primarily designed to be called at the very first line of main() to measure the time spent initializing the process.. After that, add that time to other time measurement you retrieve using your favorite timer implementation. Do not use this library as a general purpose timer.
Developers focused on high-performance software who want to benchmark and optimize process startup times, for precise execution statistics reporting measured from the program itself. Typically, the process startup time is a few milliseconds quick, but sometimes your code, or some library, executes complex initialization, like the allocation of memory pools, or the computation of tables, or complex global objects... You don't want performance degradation to creep into the init of the executable, unaccounted for. Measure the initialization time, keep a record of it, benchmark it as your program evolves. If the measurement changes over time, profile the program form the start with your sampling profiler of choice, bisect the changes and figure out what can be done about it.
GetTimeSinceProcessStart currently has specific implementations for the main OSs including: Windows, Linux and Mac OSX. It can be called from C and C++ modules.
To use this library, define GTSPS_IMPLEMENTATION in a single C or C++ file before including this header to generate the implementation.
// Example: Including and using the library in a C++ file
#include <stdio.h>
#define GTSPS_IMPLEMENTATION
#include "GetTimeSinceProcessStart.h"In a C++ project you can place the content of the library in a namespace of your choice:
#define GTSPS_NAMESPACE YourCoolNamespaceThe implementation outputs any error to stderr using fprintf, but if you prefer to disable any logging define the following (the library returns 0.0 in case of error):
#define GTSPS_DONT_LOG_ERRORSIf instead you prefer to divert the errors logging to something else:
#define GTSPS_LOG_ERROR(str) YourCoolLoggingFunction(str)
// The default definition is:
// #define GTSPS_LOG_ERROR(str) fprintf(stderr, str)To test if the library works, temporarily insert some known wait time in the creation of a global symbol and compare against a normal run. For example:
#define GTSPS_IMPLEMENTATION
#include "GetTimeSinceProcessStart.h"
#warning remove me!!!
int sooooTiredAlready = usleep(5000000); //< Sleep fot 5 seconds
int main() {
double timeInSeconds = GetTimeSinceProcessStart();
printf("Startup time %f seconds\n", timeInSeconds);
[...]
}Beware the first measurement after recompiling an executable tends to be longer, due to caching, security scanning, and other OS checks. So, run the test several times.
Developed by Max Liani