Add a section to both the low level and high level client documentation on asynchronous usage and `Cancellable` added for #44802
Co-Authored-By: Lee Hinman <dakrone@users.noreply.github.com>
The low-level REST client exposes a `performRequestAsync` method that
allows to send async requests, but today it does not expose the ability
to cancel such requests. That is something that the underlying apache
async http client supports, and it makes sense for us to expose.
This commit adds a return value to the `performRequestAsync` method,
which is backwards compatible. A `Cancellable` object gets returned,
which exposes a `cancel` public method. When calling `cancel`, the
on-going request associated with the returned `Cancellable` instance
will be cancelled by calling its `abort` method. This works throughout
multiple retries, though some special care was needed for the case where
`cancel` is called between different attempts (when one attempt has
failed and the consecutive one has not been sent yet).
Note that cancelling a request on the client side does not automatically
translate to cancelling the server side execution of it. That needs to be
specifically implemented, which is on the work for the search API (see #43332).
Relates to #44802
As a follow-up to #38540 we can use lambda functions and method
references where convenient in the low-level REST client.
Also, we need to update the docs to state that the minimum java version
required is 1.8.
We have had various reports of problems caused by the maxRetryTimeout
setting in the low-level REST client. Such setting was initially added
in the attempts to not have requests go through retries if the request
already took longer than the provided timeout.
The implementation was problematic though as such timeout would also
expire in the first request attempt (see #31834), would leave the
request executing after expiration causing memory leaks (see #33342),
and would not take into account the http client internal queuing (see #25951).
Given all these issues, it seems that this custom timeout mechanism
gives little benefits while causing a lot of harm. We should rather rely
on connect and socket timeout exposed by the underlying http client
and accept that a request can overall take longer than the configured
timeout, which is the case even with a single retry anyways.
This commit removes the `maxRetryTimeout` setting and all of its usages.
We have made node selectors configurable per request, but all
of other language clients don't allow for that.
A good reason not to do so, is that having a different node selector
per request breaks round-robin. This commit makes NodeSelector
configurable only at client initialization. It also improves the docs
on this matter, important given that a single node selector can still
affect round-robin.
Add a `NodeSelector` so that users can filter the nodes that receive
requests based on node attributes.
I believe we'll need this to backport #30523 and we want it anyway.
I also added a bash script to help with rebuilding the sniffer parsing
test documents.
Allows users of the Low Level REST client to specify which hosts a
request should be run on. They implement the `NodeSelector` interface
or reuse a built in selector like `NOT_MASTER_ONLY` to chose which nodes
are valid. Using it looks like:
```
Request request = new Request("POST", "/foo/_search");
RequestOptions options = request.getOptions().toBuilder();
options.setNodeSelector(NodeSelector.NOT_MASTER_ONLY);
request.setOptions(options);
...
```
This introduces a new `Node` object which contains a `HttpHost` and the
metadata about the host. At this point that metadata is just `version`
and `roles` but I plan to add node attributes in a followup. The
canonical way to **get** this metadata is to use the `Sniffer` to pull
the information from the Elasticsearch cluster.
I've marked this as "breaking-java" because it breaks custom
implementations of `HostsSniffer` by renaming the interface to
`NodesSniffer` and by changing it from returning a `List<HttpHost>` to a
`List<Node>`. It *shouldn't* break anyone else though.
Because we expect to find it useful, this also implements `host_selector`
support to `do` statements in the yaml tests. Using it looks a little
like:
```
---
"example test":
- skip:
features: host_selector
- do:
host_selector:
version: " - 7.0.0" # same syntax as skip
apiname:
something: true
```
The `do` section parses the `version` string into a host selector that
uses the same version comparison logic as the `skip` section. When the
`do` section is executed it passed the off to the `RestClient`, using
the `ElasticsearchHostsSniffer` to sniff the required metadata.
The idea is to use this in mixed version tests to target a specific
version of Elasticsearch so we can be sure about the deprecation
logging though we don't currently have any examples that need it. We do,
however, have at least one open pull request that requires something
like this to properly test it.
Closes#21888
Adding headers rather than setting them all at once seems more
user-friendly and we already do it in a similar way for parameters
(see Request#addParameter).
Adds two new methods to `RestClient` that take a `Request` object. These
methods will allows us to add more per-request customizable options
without creating more and more and more overloads of the `performRequest`
and `performRequestAsync` methods. These new methods look like:
```
Response performRequest(Request request)
```
and
```
void performRequestAsync(Request request, ResponseListener responseListener)
```
This change doesn't add any actual features but enables adding things like
per request timeouts and per request node selectors. This change *does*
rework the `HighLevelRestClient` and its tests to use these new `Request`
objects and it does update the docs.
We publish javadocs to artifacts.elastic.co (and snapshots.elastic.co) for a while. This commit adds the link to them to the transport client, low level REST client, sniffer and high level REST client pages.
Closes#23761
It was brought up that our current client artifacts have generic names like 'rest' that may cause conflicts with other artifacts.
This commit renames:
- rest -> elasticsearch-rest-client
- sniffer -> elasticsearch-rest-client-sniffer
- rest-high-level -> elasticsearch-rest-high-level-client
A couple of small changes are also preparing the high level client for its first release.
Closes#20248
Using the infra that we now have in place, we can convert the low-level REST client docs so that they extract code snippets from real Java classes. This way we make sure that all the snippets properly compile. Compared to the high level REST client docs, in this case we don't run the tests themselves, as that would require depending on test-framework which requires java 8 while the low-level REST client is compatible with java 7. I think that compiling snippets is enough for now.
This commit converts the low level client and high level client chapters into two parts, which allows each high level client supported api to be on a separate page and show up in the index on the right.
The REST Client is split into 2 parts:
* Low level
* High level
The High level client has a main common section and the document delete API documentation as a start.
Jilles van Gurp
Luca Cavanna
Josh Soref
Kazuhiro Sera
Nik Everett
David Pilato
Christoph Büscher
Michael Basnight
Tanguy Leroux
javanna