Happened-before
RELATION BETWEEN THE RESULT OF TWO EVENTS, SUCH THAT IF ONE EVENT SHOULD HAPPEN BEFORE ANOTHER EVENT, THE RESULT MUST REFLECT THAT, EVEN IF THOSE EVENTS ARE IN REALITY EXECUTED OUT OF ORDER
Happened before; Lamport ordering; Happens-before
In computer science, the happened-before relation (denoted: \to \;) is a relation between the result of two events, such that if one event should happen before another event, the result must reflect that, even if those events are in reality executed out of order (usually to optimize program flow). This involves ordering events based on the potential causal relationship of pairs of events in a concurrent system, especially asynchronous distributed systems.