Database asynchronous notification listener abstract class. More...

Public Types
using	MessageCallback = std::function<void(std::string, std::string)>

Public Member Functions
virtual void	listen (const std::string &channel, MessageCallback messageCallback) noexcept=0
	Listen to a channel.
virtual void	unlisten (const std::string &channel) noexcept=0
	Stop listening to channel.

Static Public Member Functions
static DbListenerPtr	newPgListener (const std::string &connInfo, trantor::EventLoop *loop=nullptr)
	Create a new postgresql notification listener.

Detailed Description

Database asynchronous notification listener abstract class.

Member Function Documentation

virtual void drogon::orm::DbListener::listen	(	const std::string &	channel,
		MessageCallback	messageCallback )

pure virtualnoexcept

Listen to a channel.

Parameters

channel	channel name to listen
messageCallback	callback when notification arrives on channel

Note: listen() can be called on the same channel multiple times. In this case, each messageCallback will be called when message arrives. However, a single unlisten() call will cancel all the callbacks.; If has connection issues, the listener will keep retrying until listen success. The listener will also re-listen to all channels after re-connection. However, if user passes an invalid channel string, the operation will fail with an error log without any other actions. (This behavior may change in future. A errorCallback may be added as a parameters.)

DbListenerPtr drogon::orm::DbListener::newPgListener	(	const std::string &	connInfo,
		trantor::EventLoop *	loop = nullptr )

static

Create a new postgresql notification listener.

Parameters

connInfo	Connection string, the same as DbClient::newPgClient()
loop	The eventloop this DbListener runs in. If empty, a new thread will be created.

virtual void drogon::orm::DbListener::unlisten ( const std::string & channel )

pure virtualnoexcept

Stop listening to channel.

Parameters

channel channel to stop listening

The documentation for this class was generated from the following file: