Updating system behavior dynamically using feature expressions and feature loops

摘要

Behavior of an online system is modified dynamically using feature expressions and feature loops. A feature expression can be expressed as a combination of other features or feature expressions, thereby allowing specification of complex features. The sets of feature expressions and policies of an online system can be modified while the online system is running. Feature loops aggregate values of a feature expression across a plurality of actions, for example, number of occurrences of an event over a time interval. The online system evaluates a set of feature expressions in response to actions performed by users. Feature expressions are used to specify policies that determine how the online system reacts to certain types of user actions. The ability to dynamically modify the feature expressions and policies of the online system allows the online system to adapt to attacks by malicious users in a timely manner.

主权项

1. A computer-implemented method comprising:
maintaining, in an online system, a set of feature loops, wherein a feature loop comprises an expression capable of being processed by a computer processor to map a set of input values to an output value, the expression evaluating to a value describing one or more entities in the online system, wherein evaluating the feature loop comprises aggregating values of the expression across a plurality of user actions; receiving information describing a modification to the set of feature loops, wherein the modification to the set of feature loops is performed while the online system is executing; responsive to the set of feature loops being modified, evaluating feature loops of the set of modified feature loops for a subsequent user action; and responding to the subsequent user action based on the values of feature loops from the set of modified feature loops.