Connection timeout

[lutovich]

Added ability to enforce max connection timeout. It is applied to new connections and makes them terminate connection attempt after configured number of milliseconds. Feature is needed because connect part might take minutes in some environments.

NodeJS channel uses net.Socket when non-encrypted and it's subclass tls.TLSSocket when encrypted. Connection timeout is implemented using socket.setTimeout() function which triggers a callback after configured millis of inactivity. We first initiate a connection attempt and them set the timeout. If connection establishes before the timeout then later is canceled. Otherwise timeout event is fired and socket is destroyed.

WebSocket channel used in browser does not have built-in timeout functionality. That is why we simply use setTimeout() that closes WebSocket if it does not connect in time. Successful connection cancels the timeout.

Feature is turned of by default and can be configured using connectionTimeout property in the config. Example:

const driver = neo4j.driver(
                    'bolt://localhost',
                    neo4j.auth.basic('neo4j', 'pwd'),
                    {connectionTimeout: 5000 /* 5 seconds */ });