Understanding Sys::Milliseconds

[illwieckz]

In src/shared/CommonProxies.cpp we have:

static Sys::SteadyClock::time_point baseTime;
int trap_Milliseconds()
{
	return std::chrono::duration_cast<std::chrono::milliseconds>(Sys::SteadyClock::now() - baseTime).count();
}

In src/common/System.cpp we have:

int Milliseconds() {
#ifdef BUILD_VM
	return trap_Milliseconds();
#else
	static Sys::SteadyClock::time_point baseTime = Sys::SteadyClock::now();
	return std::chrono::duration_cast<std::chrono::milliseconds>(Sys::SteadyClock::now() - baseTime).count();
#endif
}

What is the difference between what is done in engine and what is done in VM?

[illwieckz]

Also: is one of them faster?

[illwieckz]

We also have this in src/shared/CommonProxies.cpp:

namespace VM {

    void InitializeProxies(int milliseconds) {
        baseTime = Sys::SteadyClock::now() - std::chrono::milliseconds(milliseconds);
        Cmd::InitializeProxy();
        Cvar::InitializeProxy();
    }

Why is the VM one doing the first Sys::SteadyClock::now() in InitializeProxies?

[illwieckz]

For the engine one I forgot the first Sys::SteadyClock::now() is done when setting a static variable so maybe it's also only done once.

[illwieckz]

As an extra question, why is Milliseconds() so slow?

[slipher]

What is the difference between what is done in engine and what is done in VM?

The VM clock is initialized to the engine's current time, rather than 0. This is just for fun though, you can't count on them being synchronized.

As an extra question, why is Milliseconds() so slow?

On which platform?