Create a new subproject called client-sniffer that contains the o.e.client.sniff package. Since it is going to go to a separate jar, due to its additional functionalities and dependency on jackson, it makes sense to have it as a separate project that depends on client. This way we make sure that client doesn't depend on it etc.
ElasticsearchResponseException, as well as ElasticsearchResponse, should only be created from o.e.client package.
RequestLogger should only be used from this package too.
Instead of having a Connection mutable object that holds the state of the connection to each host, we now have immutable objects only. We keep two sets, one with all the hosts, one with the blacklisted ones. Once we blacklist a host we associate it with a DeadHostState which keeps track of the number of failed attempts and when the host should be retried. A new state object is created each and every time the state of the host needs to be updated.
We still have a wrapper called RestTestClient that is very specific to Rest tests, as well as RestTestResponse etc. but all the low level bits around http connections etc. are now handled by RestClient.
The only small problem is that the response gets closed straightaway and its body read immediately into a string. Should be ok to load it all into memory eagerly though in case of errors. Otherwise it becomes cumbersome to have an exception implement Closeable...
The connection class can be greatly simplified now that we don't ping anymore. Pings required a special initial state (UNKNOWN) for connections, to indicate that they require pinging although they are not dead. At this point we don't need the State enum anymore, as connections can only be dead or alive based on the number of failed attempts. markResurrected is also not needed, as it was again a way to make pings required. RestClient can simply pick a dead connection now and use it, no need to change its state when picking the connection.
Given that we don't use streams anymore, we can check straightaway if the connection iterator is empty before returning it and resurrect a connection when needed directly in the connection pool, no lastResortConnection method required.
There are two implementations of connection pool, a static one that allows to enable/disable pings, and a sniffing one that sniffs nodes from the nodes info api.
Transport retrieves a stream of connections from the connection for each request and calls onSuccess or onFailure depending on the result of the request.
Transport also supports a max retry timeout to control the timeout for the request retries overall.
javanna
Simon Willnauer