In FS or single-node XL mode, there is no need to save listener
configuration to persistent storage. As there is only one server, if it
is restarted, any connected listenBucketAPI clients were disconnected
and will have to reconnect - so there is nothing to actually store.
This incidentally solves #3052 by avoiding the problem.
Don't close socket while re-initializing notify-listeners, as the rpc
client object is shared between notify-listeners and peer clients.
Also, improves SendRPC() readability by using GetPeerClient().
Fixes a serialisation bug - encoding/gob does not directly support
serializing `map[string]interface{}`, so we serialise to JSON and send a
byte array in the RPC call, and deserialize and update on the receiver.
* Implements a Peer RPC router that sends info to all Minio servers in the cluster.
* Bucket notifications are propagated to all nodes via this RPC router.
* Bucket listener configuration is persisted to separate object layer
file (`listener.json`) and peer RPCs are used to communicate changes
throughout the cluster.
* When events are generated, RPC calls to send them to other servers
where bucket listeners may be connected is implemented.
* Some bucket notification tests are now disabled as they cannot work in
the new design.
* Minor fix in `funcFromPC` to use `path.Join`
Aditya Manthramurthy
Harshavardhana
Krishna Srinivas
Anis Elleuch