LimitRule

LimitRule is a constraint used in computer systems to enforce limits on a metric or resource. It is commonly employed in rate limiting, data validation, and resource management to prevent abuse, protect availability, and ensure predictable behavior. A LimitRule typically specifies a target metric (for example requests per minute, memory usage, or transaction amount), a threshold value, a comparison operator, an enforcement action to take when the limit is reached, and an evaluation window or scope over which the rule applies. Rules can be static, using a fixed threshold for all contexts, or dynamic, adjusting thresholds based on factors such as user, time of day, or system load. Common implementations include sliding window counters, token bucket, and leaky bucket models for rate control, as well as quotas in data pipelines or task queues.

Enforcement actions range from delaying or rejecting requests, throttling processing, and triggering alerts, to initiating automatic scaling or resource reallocation. LimitRules are often defined in rule engines or policy frameworks and evaluated by a monitoring loop or event-driven trigger. They are designed to be composable with other rules to express complex constraints.

Typical applications include API gateways that cap requests per key, data ingestion pipelines that enforce throughput limits, and financial or safety-critical systems that cap transactions or operational parameters.

See also: rate limiting, quotas, constraint programming, rule engine.