We keep the default async client behaviour like in BasicAsyncResponseConsumer, but we lower the maximum size of the buffer from Integer.MAX_VALUE (2GB) to 10 MB. This way users will realize they are buffering big responses in heap hence they'll know they have to do something about it, either write their own response consumer or increase the buffer size limit by providing their manually creeted instance of HeapBufferedAsyncResponseConsumer (constructor accept a bufferLimit int argument).
Also delayed call to HttpAsyncClient#start so that if something goes wrong while creating the RestClient, the http client threads don't linger. In fact, if the constructor fails it is not possible to call close against the RestClient.
HttpClientConfigCallback#customizeHttpClient now also returns the HttpClientBuilder so it can be completely replaced
RequestConfigCallback#customizeRequestConfig now also returns the HttpClientBuilder so it can be completely replaced
The new method accepts the usual parameters (method, endpoint, params, entity and headers) plus a response listener and an async response consumer. Shortcut methods are also added that don't require params, entity and the async response consumer optional.
There are a few relevant api changes as a consequence of the move to async client that affect sync methods:
- Response doesn't implement Closeable anymore, responses don't need to be closed
- performRequest throws Exception rather than just IOException, as that is the the exception that we get from the FutureCallback#failed method in the async http client
- ssl configuration is a bit simpler, one only needs to call setSSLStrategy from a custom HttpClientConfigCallback, that doesn't end up overridng any other default around connection pooling (it used to happen with the sync client and make ssl configuration more complex)
Relates to #19055
The callback replaces the ability to fully replace the http client instance. By doing that, one used to lose any default that the RestClient had set for the underlying http client. Given that you'd usually override one or two things only, like a couple of timeout values, the ssl factory or the default credentials providers, it is not uder friendly if by doing that users end up replacing the whole http client instance and lose any default set by us.
Users wanting to send a request by providing only its method and endpoint, effectively the only two required arguments, shouldn't need to pass in an empty map and a null entity for the body. While at it we can also add a variant to send requests by specifying only method, endpoint and params, but not body. Headers remain a vararg as last argument, so they can always optionally be provided.
Closes#19312
:client ---------> :client:rest
:client-sniffer -> :client:sniffer
:client-test ----> :client:test
This lines the client up with how we do things like modules and
plugins.
javanna
Tanguy Leroux
Nik Everett