BitTorrent tracker Wikipedia

True if we are computing a computation now, either first time or recompute. This matches TRACKER.active unless we are inside Tracker.nonreactive, which nullfies currentComputation even though an enclosing computation may still be running. This value is useful for data source implementations to determine whether they are being accessed reactively or not.

An Afrikaner veteran of the Boer War has just immigrated to New Zealand and is hired to track a man accused of killing a soldier. While hunting through the countryside he captures his fugitive, only to learn that he's innocent of the crime. When faced with the life-changing decision to turn him in or set him free only, one man will walk away alive. BitTorious is an open source, commercially supported tracker with integrated web-based management portal. Trackers are the primary reason for a damaged BitTorrent "swarm".

This example implements a weather data source with a simple getter and setter. The getter records that the current computation depends on the weatherDep dependency using depend(), while the setter signals the dependency to invalidate all dependent computations by calling changed(). Invalidating a computation sets its invalidated property to true and immediately calls all of the computation’s onInvalidatecallbacks. A flush will occur when the current code finishes running, or sooner if Tracker.flush is called. A change to a data dependency does not cause an immediate rerun, but rather “invalidates” the computation, causing it to rerun the next time a flush occurs. A flush will occur automatically as soon as the system is idle if there are invalidated computations.

Meteor has a simple dependency tracking system which allows it to automatically rerun templates and other computations wheneverSession variables, database queries, and other data sources change. Unlike most other systems, you don’t have to manually declare these dependencies — it “just works”. When you call a function that supports reactive updates , it automatically saves the current Computation object, if any . Later, when the data changes, the function can “invalidate” the Computation, causing it to rerun .

Get accurate data with an anti-surveillance time tracking solution that your employees are happy to use. Returns true if the computation is a new dependent of dependency rather than an existing one. If there is no current computation and depend() is called with no arguments, it does nothing and returns false. Invalidate all dependent computations immediately and remove them as dependents. True during the initial run of the computation at the time Tracker.autorun is called, and false on subsequent reruns and at other times. Stopping a computation is irreversible and guarantees that it will never be rerun.