百万级事实评估：可扩展的规则执行服务

The Rule Executor Service at Myntra stands out as a pivotal tool in the domain of rule engine. While, at a glance, one might wonder what sets it apart from the myriad of rule engines available today, the difference is profound. In Myntra ecosystem, supporting numerous pricing use cases necessitated building a capability that is engineered to handle vast volumes of rules, processing millions of facts against similar scale in terms of rules for multiple tenants with high reliability, performance, availability and consistency. In order for the system to be performant and use as a broker for all Myntra systems preference was given to scalability, and ability to persist and evaluate large large number of rules with low latency evaluation window.

Myntra的规则执行服务在规则引擎领域中独树一帜。虽然乍一看，人们可能会想知道它与今天众多规则引擎的区别在哪里，但实际上差别很大。在Myntra生态系统中，支持众多定价用例需要构建一个能够处理大量规则、处理数百万个事实并具有高可靠性、高性能、高可用性和一致性的能力。为了使系统具有良好的性能并用作所有Myntra系统的代理，我们优先考虑了可扩展性、持久性和低延迟评估窗口来评估大量规则。

Let’s first delve into the functional and non-functional requirements that necessitate the creation of the Rule Executor Service.

让我们首先深入了解需要创建规则执行服务的功能和非功能要求。

Functional Requirements
功能要求

Dynamic Rule Management: The rule engine should be designed with adaptability as a core principle, enabling administrators or users to effortlessly update, introduce, or dynamically remove rules through the user interface as the landscape evolves.
动态规则管理：规则引擎应设计为以适应性为核心原则，使管理员或用户能够通过用户界面轻松更新、引入或动态删除规则，以适应环境的变化。
Immediate Rule Reflection: Following any changes to the rule set, the rule engine should ensure that all future fact evaluations reflect the latest rule standards with high degree of consistency. Once the creation, updating, or deletion of a rule has been confirmed as successful for the user, no subsequent fact evaluations should be conducted with the outdated rules from that timestamp onwards. This necessitates the updates to be immediately reflected in the knowledge base of the rule engine.
立即规则反射：在规则集发生任何更改后，规则引擎应确保所有未来的事实评估都反映最新的规则标准，并具有高度的一致性。一旦用户确认规则的创建、更新或删除成功，从那个时间点开始，不应再使用过时的规则进行...