Redis Subscriber

The cpp_redis::redis_subscriber is meant to be used for PUB/SUB communication with the Redis server.

Please do not use cpp_redis::redis_client to subscribe to some Redis channels as:

• the behavior is undefined
• cpp_redis::redis_client is not meant for that

Methods

connect

void connect(const std::string& host = "127.0.0.1", unsigned int port = 6379, const disconnection_handler& handler = nullptr)

Connects to the Redis Server. Connection is done synchronously. Throws redis_error in case of failure or if client if already connected.

Also sets the disconnection handler which is called whenever a disconnection has occurred. Disconnection handler is an std::function<void(redis_subscriber&)>.

disconnect

void disconnect(void)

Disconnects client from remote host. Throws redis_error if the client is not connected to any server.

is_connected

bool is_connected(void)

Returns whether the client is connected or not.

subscribe

redis_subscriber& subscribe(const std::string& channel, const subscribe_callback& callback)

Subscribes to the given channel and calls subscribe_callback each time a message is published in this channel. subscribe_callback is an std::function<void(const std::string&, const std::string&)>.

The command is not effectively sent immediately, but stored inside an internal buffer until commit() is called.

psubscribe

redis_subscriber& psubscribe(const std::string& pattern, const subscribe_callback& callback)

PSubscribes to the given pattern and calls subscribe_callback each time a message is published in a channel matching the pattern. subscribe_callback is an std::function<void(const std::string&, const std::string&)>.

The command is not effectively sent immediately, but stored inside an internal buffer until commit() is called.

unsubscribe

redis_subscriber& unsubscribe(const std::string& channel)

Unsubscribes from the given channel.

The command is not effectively sent immediately, but stored inside an internal buffer until commit() is called.

punsubscribe

redis_subscriber& punsubscribe(const std::string& pattern)

Unsubscribes from the given pattern.

The command is not effectively sent immediately, but stored inside an internal buffer until commit() is called.

commit

redis_subscriber& commit(void)

Sends all the commands that have been stored by calling send() since the last commit() call to the Redis server.

That is, pipelining is supported in a very simple and efficient way: sub.subscribe(...).psubscribe(...).unsubscribe(...).commit() will send the 3 commands at once (instead of sending 3 network requests, one for each command, as it would have been done without pipelining).

Pipelined commands are always removed from the buffer, even in case of error (for example, calling commit while the client is not connected, something that throws an exception).