Watchers

Watcher 让多个 enforcer 实例之间的策略保持同步。当一个 enforcer 更新策略时，它会（通过 etcd、Redis 或 Kafka 等消息总线）通知其他实例，其他实例随之重新加载或更新内存中的策略。这样你可以在负载均衡后面运行多个 enforcer，而不会出现过时的权限。

Watcher 和适配器一样，放在单独的包中实现。下面列出支持的后端。要添加新的后端，请提交 issue 或 PR。

Watcher	Type	Author	Description
PostgreSQL WatcherEx	Database	@IguteChung	WatcherEx for PostgreSQL
Redis WatcherEx	KV store	Casbin	WatcherEx for Redis
Redis Watcher	KV store	@billcobbler	Watcher for Redis
Etcd Watcher	KV store	Casbin	Watcher for etcd
TiKV Watcher	KV store	Casbin	Watcher for TiKV
Kafka Watcher	Messaging system	@wgarunap	Watcher for Apache Kafka
NATS Watcher	Messaging system	Soluto	Watcher for NATS
ZooKeeper Watcher	Messaging system	Grepsr	Watcher for Apache ZooKeeper
NATS, RabbitMQ, GCP Pub/Sub, AWS SNS & SQS, Kafka, InMemory	Messaging System	@rusenask	Watcher based on Go Cloud Dev Kit that works with leading cloud providers and self-hosted infrastructure
NATS, RabbitMQ, GCP Pub/Sub, AWS SNS & SQS, Kafka, InMemory	Messaging System	@bartventer	WatcherEx based on Go Cloud Dev Kit that works with leading cloud providers and self-hosted infrastructure
RocketMQ Watcher	Messaging system	@fmyxyz	Watcher for Apache RocketMQ

Watcher	Type	Author	Description
Etcd Adapter	KV store	@mapleafgo	Watcher for etcd
Redis Watcher	KV store	Casbin	Watcher for Redis
Redis WatcherEx	KV store	Casbin	WatcherEx for Redis
Lettuce-Based Redis Watcher	KV store	Casbin	Watcher for Redis based on Lettuce)
PostgreSQL Watcher	Database	Casbin	Watcher for PostgreSQL
Kafka Watcher	Messaging system	Casbin	Watcher for Apache Kafka
ZooKeeper Watcher	Messaging system	Casbin	Watcher for Apache ZooKeeper
RabbitMQ Watcher	Messaging system	Casbin	Watcher for RabbitMQ

Watcher	Type	Author	Description
Etcd Watcher	KV store	Casbin	Watcher for etcd
Redis Watcher	KV store	Casbin	Watcher for Redis
Pub/Sub Watcher	Messaging system	Casbin	Watcher for Google Cloud Pub/Sub
MongoDB Change Streams Watcher	Database	Casbin	Watcher for MongoDB Change Streams
Postgres Watcher	Database	@mcollina	Watcher for PostgreSQL

Watcher	Type	Author	Description
Etcd Watcher	KV store	Casbin	Watcher for etcd
Redis Watcher	KV store	Casbin	Watcher for Redis
Redis Watcher	KV store	ScienceLogic	Watcher for Redis
Redis Async Watcher	KV store	@kevinkelin	Watcher for Redis
PostgreSQL Watcher	Database	Casbin	Watcher for PostgreSQL
RabbitMQ Watcher	Messaging system	Casbin	Watcher for RabbitMQ
MongoDB Watcher	Database	@sanguinedab	Watcher for MongoDB

Watcher	Type	Author	Description
Redis Watcher	KV store	@Sbou	Watcher for Redis

Watcher	Type	Author	Description
Redis Watcher	KV store	CasbinRuby	Watcher for Redis
RabbitMQ Watcher	Messaging system	CasbinRuby	Watcher for RabbitMQ

Watcher	Type	Author	Description
Redis Watcher	KV store	@Tinywan	Watcher for Redis

Watcher	Type	Author	Description
Redis Watcher	KV store	Casbin	Watcher for Redis

WatcherEx

为支持多个实例之间的增量同步，我们提供了 WatcherEx 接口。这个接口可以在策略变化时通知其他实例，不过目前还没有 WatcherEx 的实现。建议使用 dispatcher 实现这一功能。

与 Watcher 接口相比，WatcherEx 可以区分收到的更新操作类型，例如 AddPolicy 和 RemovePolicy。

WatcherEx API：

API	描述
SetUpdateCallback(func(string)) error	SetUpdateCallback 设置回调函数，当数据库中的策略被其他实例修改时，watcher 会调用它。一个典型的回调是Enforcer.LoadPolicy()。
Update() error	Update 调用其他实例的更新回调，让它们同步策略。通常在修改数据库中的策略之后调用，例如 Enforcer.SavePolicy()、Enforcer.AddPolicy()、Enforcer.RemovePolicy() 等之后。
Close()	Close 停止并释放 watcher。之后不会再调用回调函数。
UpdateForAddPolicy(sec, ptype string, params ...string) error	UpdateForAddPolicy 调用其他实例的更新回调，让它们同步策略。在通过Enforcer.AddPolicy()，Enforcer.AddNamedPolicy()，Enforcer.AddGroupingPolicy()和Enforcer.AddNamedGroupingPolicy()添加策略后调用。
UpdateForRemovePolicy(sec, ptype string, params ...string) error	UpdateForRemovePolicy 调用其他实例的更新回调，让它们同步策略。在通过Enforcer.RemovePolicy()，Enforcer.RemoveNamedPolicy()，Enforcer.RemoveGroupingPolicy()和Enforcer.RemoveNamedGroupingPolicy()删除策略后调用。
UpdateForRemoveFilteredPolicy(sec, ptype string, fieldIndex int, fieldValues ...string) error	UpdateForRemoveFilteredPolicy 调用其他实例的更新回调，让它们同步策略。在Enforcer.RemoveFilteredPolicy()，Enforcer.RemoveFilteredNamedPolicy()，Enforcer.RemoveFilteredGroupingPolicy()和Enforcer.RemoveFilteredNamedGroupingPolicy()之后调用。
UpdateForSavePolicy(model model.Model) error	UpdateForSavePolicy 调用其他实例的更新回调，让它们同步策略。在 Enforcer.SavePolicy() 之后调用。
UpdateForAddPolicies(sec string, ptype string, rules ...[]string) error	UpdateForAddPolicies 调用其他实例的更新回调，让它们同步策略。在Enforcer.AddPolicies()，Enforcer.AddNamedPolicies()，Enforcer.AddGroupingPolicies()和Enforcer.AddNamedGroupingPolicies()之后调用。
UpdateForRemovePolicies(sec string, ptype string, rules ...[]string) error	UpdateForRemovePolicies 调用其他实例的更新回调，让它们同步策略。在 Enforcer.RemovePolicies()、Enforcer.RemoveNamedPolicies()、Enforcer.RemoveGroupingPolicies() 和 Enforcer.RemoveNamedGroupingPolicies() 之后调用。