redis4-发布与订阅

UBSCRIBE, UNSUBSCRIBE and PUBLISH implement the Publish/Subscribe messaging paradigm where senders (publishers) are not programmed to send their messages to specific receivers (subscribers). Rather, published messages are characterized into channels, without knowledge of what (if any) subscribers there may be. Subscribers express interest in one or more channels, and only receive messages that are of interest, without knowledge of what (if any) publishers there are.

Messages sent by other clients to these channels will be pushed by Redis to all the subscribed clients.

A client subscribed to one or more channels should not issue commands, although it can subscribe and unsubscribe to and from other channels. The replies to subscription and unsubscription operations are sent in the form of messages, so that the client can just read a coherent stream of messages where the first element indicates the type of message. The commands that are allowed in the context of a subscribed client are SUBSCRIBE, PSUBSCRIBE, UNSUBSCRIBE, PUNSUBSCRIBE, PING and QUIT.

Please note that redis-cli will not accept any commands once in subscribed mode and can only quit the mode with Ctrl-C.

channel订阅实现:在客户端结构体的pubsub_channels(为dict)添加key为订阅的channel的entry,在server结构体的pubsub_chanels（dict）添加key为channel的entry，该entry为所有订阅该channel的list

The Redis Pub/Sub implementation supports pattern matching. Clients may subscribe to glob-style patterns in order to receive all the messages sent to channel names matching a given pattern.

pattern订阅实现：在客户端结构体的pubsub_patterns(为list)添加node,该node的value为订阅的pattern(robj)，在server结构体的pubsub_patterns（为list）添加pubsubPattern Node,该node的client为订阅该pattern的客户端指针,该pattern为订阅pattern的robj.

订阅channel代码:

订阅pattern代码: