Milliseconds from a monotonic clock when the runtime provides one.
Deadlines and embargoes compare differences of these values. A wall clock can
step backward, for example through an NTP correction, and a deadline armed
against it would then never pass. Values from this function are not epoch
times and must only be compared with each other.
The time source is selected on the first call and never changes after that.
Monotonic values and wall-clock values have different origins, so a switch
between sources would corrupt in-flight measurements. A runtime without a
performance global at the first call uses the wall clock from then on, even
if a polyfill appears later.
Milliseconds from a monotonic clock when the runtime provides one.
Deadlines and embargoes compare differences of these values. A wall clock can step backward, for example through an NTP correction, and a deadline armed against it would then never pass. Values from this function are not epoch times and must only be compared with each other.
The time source is selected on the first call and never changes after that. Monotonic values and wall-clock values have different origins, so a switch between sources would corrupt in-flight measurements. A runtime without a performance global at the first call uses the wall clock from then on, even if a polyfill appears later.