This change adds a fromXContent method to Settings that allows to read
the xcontent that is produced by toXContent. It also replaces the entire settings
loader infrastructure and removes the structured map representation. Future PRs will
also tackle the `getAsMap` that exposes the internal represenation of settings for
better encapsulation.
It is the exciting return of the global checkpoint background
sync. Long, long ago, in snapshot version far, far away we had and only
had a global checkpoint background sync. This sync would fire
periodically and send the global checkpoint from the primary shard to
the replicas so that they could update their local knowledge of the
global checkpoint. Later in time, as we sped ahead towards finalizing
the initial version of sequence IDs, we realized that we need the global
checkpoint updates to be inline. This means that on a replication
operation, the primary shard would piggy back the global checkpoint with
the replication operation to the replicas. The replicas would update
their local knowledge of the global checkpoint and reply with their
local checkpoint. However, this could allow the global checkpoint on the
primary to advance again and the replicas would fall behind in their
local knowledge of the global checkpoint. If another replication
operation never fired, then the replicas would be permanently behind. To
account for this, we added one more sync that would fire when the
primary shard fell idle. However, this has problems:
- the shard idle timer defaults to five minutes, a long time to wait
for the replicas to learn of the new global checkpoint
- if a replica missed the sync, there was no follow-up sync to catch
them up
- there is an inherent race condition where the primary shard could
fall idle mid-operation (after having sent the replication request to
the replicas); in this case, there would never be a background sync
after the operation completes
- tying the global checkpoint sync to the idle timer was never natural
To fix this, we add two additional changes for the global checkpoint to
be synced to the replicas. The first is that we add a post-operation
sync that only fires if there are no operations in flight and there is a
lagging replica. This gives us a chance to sync the global checkpoint to
the replicas immediately after an operation so that they are always kept
up to date. The second is that we add back a global checkpoint
background sync that fires on a timer. This timer fires every thirty
seconds, and is not configurable (for simplicity). This background sync
is smarter than what we had previously in the sense that it only sends a
sync if the global checkpoint on at least one replica is lagging that of
the primary. When the timer fires, we can compare the global checkpoint
on the primary to its knowledge of the global checkpoint on the replicas
and only send a sync if there is a shard behind.
Relates #26591
Removing several occurrences of this typo in the docs and javadocs, seems to be
a common mistake. Corrections turn up once in a while in PRs, better to correct
some of this in one sweep.
Today we have all non-plugin mappers in core. I'd like to start moving those
that neither map to json datatypes nor are very frequently used like `date` or
`ip` to a module.
This commit creates a new module called `mappers-extra` and moves the
`scaled_float` and `token_count` mappers to it. I'd like to eventually move
`range` fields there but it's more complicated due to their intimate
relationship with range queries.
Relates #10368
Today we don't have a pluggable way to validate if the cluster state
is compatible with the node that joins. We already apply some checks for index
compatibility that prevents nodes to join a cluster with indices it doesn't support
but for plugins this isn't possible. This change adds a cluster state validator that
allows plugins to prevent a join if the cluster-state is incompatible.
This test case was leftover from the static bwc tests. There was still
one use for checking we do not load old indices, but this PR moves the
legacy code needed for that directly into the test. I also opened a
follow up issue to completely remove the unsupported test: #26583.
When determining if a build is a snapshot build, we look for a field in
the JAR manifest. However, when running tests, we are not running with a
compiled core Elasticsearch JAR, we are running with the compiled core
classes on the classpath. We have a fallback for this, we always assume
such a situation is a snapshot build. However, when running builds with
-Dbuild.snapshot=false, this is not the case. As such, we need to
fallback to the value of build.snapshot. However, there are cases where
we are not running with a compiled core Elasticsearch JAR (e.g., when
the transport client is embedded in a web container) so we should only
do this fallback if we are in tests. To verify we are in tests, we check
if randomized runner is on the classpath.
Relates #26554
The percolator will add a `_percolator_document_slot` field to all percolator
hits to indicate with what document it has matched. This number matches with
the order in which the documents have been specified in the percolate query.
Also improved the support for multiple percolate queries in a search request.
We currently have a weird relationship between Transport,
TransportService, and TransportServiceAdaptor. At some point I think
that we would like to collapse these all into one concept as we only
support TCP transports.
This commit moves in that direction by eliminating the adaptor and just
passing the transport service to the transport.
The current script service has a script compilation limit for a one
minute window. This is set to a small default value of 15. Instead of
increasing that default value, this commit introduces a new setting
that allows to configure a rate per time unit, so that the script service can deal with bursts better.
The new setting is named `script.max_compilations_rate`,
requires a nonnegative number and a positive time value.
The default is `75/5m`, which is equivalent to the existing 15 per minute.
* Implement adaptive replica selection
This implements the selection algorithm described in the C3 paper for
determining which copy of the data a query should be routed to.
By using the service time EWMA, response time EWMA, and queue size EWMA we
calculate the score of a node by piggybacking these metrics with each search
request.
Since Elasticsearch lacks the "broadcast to every copy" behavior that Cassandra
has (as mentioned in the C3 paper) to update metrics after a node has been
highly weighted, this implementation adjusts a node's response stats using the
average of the its own and the "best" node's metrics. This is so that a long GC
or other activity that may cause a node's rank to increase dramatically does not
permanently keep a node from having requests routed to it, instead it will
eventually lower its score back to the realm where it is a potential candidate
for new queries.
This feature is off by default and can be turned on with the dynamic setting
`cluster.routing.use_adaptive_replica_selection`.
Relates to #24915, however instead of `b=3` I used `b=4` (after benchmarking)
* Randomly use adaptive replica selection for internal test cluster
* Use an action name *prefix* for retrieving pending requests
* Add unit test for replica selection
* don't use adaptive replica selection in SearchPreferenceIT
* Track client connections in a SearchTransportService instead of TransportService
* Bind `entry` pieces in local variables
* Add javadoc link to C3 paper and javadocs for stat adjustments
* Bind entry's key and value to local variables
* Remove unneeded actionNamePrefix parameter
* Use conns.longValue() instead of cached Long
* Add comments about removing entries from the map
* Pull out bindings for `entry` in IndexShardRoutingTable
* Use .compareTo instead of manually comparing
* add assert for connections not being null and gte to 1
* Copy map for pending search connections instead of "live" map
* Increase the number of pending search requests used for calculating rank when chosen
When a node gets chosen, this increases the number of search counts for the
winning node so that it will not be as likely to be chosen again for
non-concurrent search requests.
* Remove unused HashMap import
* Rename rank -> rankShardsAndUpdateStats
* Rename rankedActiveInitializingShardsIt -> activeInitializingShardsRankedIt
* Instead of precalculating winning node, use "winning" shard from ranked list
* Sort null ranked nodes before nodes that have a rank
At current, we do not feel there is enough of a reason to shade the low
level rest client. It caused problems with commons logging and IDE's
during the brief time it was used. We did not know exactly how many
users will need this, and decided that leaving shading out until we
gather more information is best. Users can still shade the jar
themselves. For information and feeback, see issue #26366.
Closes#26328
This reverts commit 3a20922046.
This reverts commit 2c271f0f22.
This reverts commit 9d10dbea39.
This reverts commit e816ef89a2.
This allows plugins to plug rescore implementations into
Elasticsearch. While this is a fairly expert thing to do I've
done my best to point folks to the QueryRescorer as one that at
least documents the tradeoffs that it makes. I've attempted to
limit the API surface area by removing `SearchContext` from the
exposed interface, instead exposing just the IndexSearcher and
`QueryShardContext`. I also tried to make some of the class names
more consistent and do some general cleanup while I was there.
I entertained the notion of moving the `QueryRescorer` to module.
After all, it'd be a wonderful test to prove that you can plug
rescore implementation into Elasticsearch if the only built in
rescore implementation is in the module. But I decided against it
because the new module would require a client jar and it'd require
moving some more things around. I think if we really want to do
it, we should do it as a followup.
I did, on the other hand, create an "example" rescore plugin which
should both be a nice example for anyone wanting to plug in their
own rescore implementation and servers as a good integration test
to make sure that you can indeed plug one in.
Closes#26208
This PR begins the long journey to deprecating Streamable.
The idea here is to add additional method signatures that
support Writeable.Reader, so that the work to migrate objects TransportMessage to
implement Writeable and not Streamable.
One example conversion is done in this PR: SimulatePipelineRequest.
This commit makes the security code aware of the Java 9 FilePermission changes (see #21534) and allows us to remove the `jdk.io.permissionsUseCanonicalPath` system property.
This commit converts script query to use a new FilterScript context. The
new context returns a boolean, so the error that would have previously
happened at runtime if a non boolean was returned would now happen at
script compilation. Also, the leniency of supporting returning a number
and 0 mapping to false, non-zero to true is gone, but it was never
documented. With the new context compilation will now also fail if
special variables are used at compilation time, instead of runtime, eg
ctx.
Right now we use a custom future for the CloseFuture associated with a
channel. This is because we need special unwrapping logic to ensure that
exceptions from a future failure are a certain type (opposed to an
UncategorizedException). However, the current version is limiting
because we can only attach one listener.
This commit changes the CloseFuture to extend the
PlainListenableActionFuture. This change allows us to attach multiple
listeners.
The client sniffer depends on the low-level REST client, while the Java high-level REST client and the transport client depend on Elasticsearch itself. Javadoc are not that useful unless they have links to the Elasticsearch classes in the latter case, and to the low-level REST client in the sniffer javadoc. This commit adds those links.
This chance adds several random test infrastructure improvements that caused
issues in on-going developments but are generally useful. For instance is it impossible
to restart a node with a secure setting source since we close it after the node is started.
This change makes it cloneable such that we can reuse it for a restart.
The following token filters were moved: arabic_stem, brazilian_stem, czech_stem, dutch_stem, french_stem, german_stem and russian_stem.
Relates to #23658
In reindex APIs, when using the `slices` parameter to choose the number of slices, adds the option to specify `slices` as "auto" which will choose a reasonable number of slices. It uses the number of shards in the source index, up to a ceiling. If there is more than one source index, it uses the smallest number of shards among them.
This gives users an easy way to use slicing in these APIs without having to make decisions about how to configure it, as it provides a good-enough configuration for them out of the box. This may become the default behavior for these APIs in the future.
Today we have a `null` invariant on all `ClusterState.Custom`. This makes
several code paths complicated and requires complex state handling in some cases.
This change allows to register a custom supplier that is used to initialize the
initial clusterstate with these transient customs.
The build was ignoring suffixes like "beta1" and "rc1" on the version numbers which was causing the backwards compatibility packaging tests to fail because they expected to be upgrading from 6.0.0 even though they were actually upgrading from 6.0.0-beta1. This adds the suffixes to the information that the build scrapes from Version.java. It then uses those suffixes when it resolves artifacts build from the bwc branch and for testing.
Closes#26017
* Adds ToXContentFragment
This interface is meant for objects that implement `ToXContent` but are not complete objects. It is basically the opposite of `ToXContentObject`. It means that it will be easier to track the migration of classes over to the fragment/not fragment ToXContent model as it will be clear which classes are not migrated. When no classes directly implement `ToXContent` we can make `ToXContent` package private to be sure that all new classes must implement `ToXContentObject` or `ToXContentFragment`.
* review comments
* more review comments
* javadocs
* iter
* Adds tests
* iter
* adds toString test for aggs
* improves tests following review comments
* iter
* iter
We introduced a hack in #25885 to respect the cluster alias if available on the `_index` field. This is important if aggregations or other field data related operations are executed. Yet, we added a small hack that duplicated an implementation detail from the `_index` field data builder to make this work. This change adds a necessary but simple API change that allows us to remove the hack and only have a single implementation.
The goal of this similarity is to help users who would like to keep the
functionality of the `tf-idf` similarity that we want to remove, or to allow
for specific usec-cases (disabling idf, disabling tf, disabling length norm,
etc.) to not have to build a custom plugin and familiarize with the low-level
Lucene API.
Raw requests are supported only by the java yaml test runner and were introduced to test docs snippets. Some yaml tests ended up using them (see #23497) which causes failures for other language clients. This commit migrates those yaml tests to Java tests that send requests through the Java low-level REST client, and also moves the ability to send raw requests to a special client that's only available when testing docs snippets.
Closes#25694
When `refresh=wait_for` is set on an indexing request, we register a listener on the shards that are call during the next refresh. During the recover translog phase, when the engine is open, we have a window of time when indexing operations succeed and they can add their listeners. Those listeners will only be called when the recovery finishes as we do not refresh during recoveries (unless the indexing buffer is full). Next to being a bad user experience, it can also cause deadlocks with an ongoing peer recovery that may wait for those operations to mark the replica in sync (details below).
To fix this, this PR changes refresh listeners to be a noop when the shard is not yet serving reads (implicitly covering the recovery period). It doesn't matter anyway.
Deadlock with recovery:
When finalizing a peer recovery we mark the peer as "in sync". To do so we wait until the peer's local checkpoint is at least as high as the global checkpoint. If an operation with `refresh=wait_for` is added as a listener on that peer during recovery, it is not completed from the perspective of the primary. The primary than may wait for it to complete before advancing the local checkpoint for that peer. Since that peer is not considered in sync, the global checkpoint on the primary can be higher, causing a deadlock. Operation waits for recovery to finish and a refresh to happen. Recovery waits on the operation.
* Adds mutate function to various tests
Relates to #25929
* fix test
* implements mutate function for all single bucket aggs
* review comments
* convert getMutateFunction to mutateIInstance
Currently there is an issue where the send listener is not called in the
nio transport when an exception is throw during channel flush. This
leads to memory leaks. This commit ensures that the listener is called
This commit adds the nio transport as an option in place of the mock tcp
transport for tests. Each test will only use one transport type. The
transport type is decided by a random boolean generated inside of the
`ESTestCase` class.
This commit updates the version for master to 7.0.0-alpha1. It also adds
the 6.1 version constant, and fixes many tests, as well as marking some
as awaits fix.
Closes#25893Closes#25870
ToXContentToBytes is used as a base class that adds toString and buildAsBytes method implementation to classes that implement ToXContent. With the ongoing cleanups, this class is limited and doesn't add a lot of value, given that buildAsBytes can be replaced with XContentHelper.toXContent and toString can be replaced with Strings.toString(this).
The plan would be to remove ToXContentToBytes entirely, and AbstractQueryBuilder is the first place where we can remove its usage.
During peer recoveries, we need to copy over lucene files and replay the operations they miss from the source translog. Guaranteeing that translog files are not cleaned up has seen many iterations overtime. Back in the old 1.0 days, recoveries went through the Engine and actively prevented both translog cleaning and lucene commits. We then moved to a notion called Translog Views, which allowed the recovery code to "acquire" a view into the translog which is then guaranteed to be kept around until the view is closed. The Engine code was free to commit lucene and do what it ever it wanted without coordinating with recoveries. Translog file deletion logic was based on reference counting on the file level. Those counters were incremented when a view was acquired but also when the view was used to create a `Snapshot` that allowed you to read operations from the files. At some point we removed the file based counting complexity in favor of constructs on the Translog level that just keep track of "open" views and the minimum translog generation they refer to. To do so, Views had to be kept around until the last snapshot that was made from them was consumed. This was fine in recovery code but lead to [a subtle bug](https://github.com/elastic/elasticsearch/pull/25862) in the [Primary Replica Resyncer](https://github.com/elastic/elasticsearch/pull/25862).
Concurrently, we have developed the notion of a `TranslogDeletionPolicy` which is responsible for the liveness aspect of translog files. This class makes it very simple to take translog Snapshot into account for keep translog files around, allowing people that just need a snapshot to just take a snapshot and not worry about views and such. Recovery code which actually does need a view can now prevent trimming by acquiring a simple retention lock (a `Closable`). This removes the need for the notion of a View.
* Improves AbstractWireSerializingTestCase equals test
`AbstractWireSerializingTestCase.testEqualsAndHashcode()` now uses `EqualsHashcodeTestUtils` to perform the hashCode and equals checks. To support this `AbstractWireSerializingTestCase` has two new methods: `getCopyFunction()` and `getMutateFunction` which are used when calling `EqualsHashcodeTestUtils`
* Adds TODO
* Makes equivalent changes to AbstractStreamableTestCase
* corrects javadoc error
The following token filters were moved: delimited_payload_filter, keep, keep_types, classic, apostrophe, decimal_digit, fingerprint, min_hash and scandinavian_folding.
Relates to #23658
The Writeble representation is less heavy to parse and that will benefit percolate performance and throughput.
The query builder's binary format has now the same bwc guarentees as the xcontent format.
Added a qa test that verifies that percolator queries written in older versions are still readable by the current version.
This commit fixes tests for environment-aware commands. A previous
change added a check that es.path.conf is not null. The problem is that
this system property is not being set in tests so this check trips every
single time. To fix this, we move the check into a method that can be
overridden, and then override this method in relevant places in tests to
avoid having to set the property in tests. We also add a test that this
check works as expected.
Today we expose `IndexFieldDataService` outside of IndexService to do maintenance
or lookup field data in different ways. Yet, we have a streamlined way to access IndexFieldData
via `QueryShardContext` that should encapsulate all access to it. This also ensures that we control all other functionality like cache clearing etc.
This change also removes the `recycler` option from `ClearIndicesCacheRequest` this option is a no-op and should have been removed long ago.
Currently, NioTransport does start normal socket selectors and the
client when the network server setting is set to false. This commit
makes it so that the client will be started even when the network server
is not enabled.
Additionally, it randomly introduces the NioTransport as an option for
the MockTransportClient throughout tests.
These two methods do do the same thing. The subtle difference between the two is that the former prints out pretty printed content by default while the latter doesn't. There are way more usages of the latter throughout the codebase hence I kept that variant although I do think that it would be much better to print out prettified content by default from a `toString`. That breaks quite some tests so I didn't make that change yet.
Also XContentHelper#toString was outdated as it didn't check the ToXContent#isFragment method to decide whether a new anonymous object has to be created or not. It would simply fail with any ToXContentObject.
Today when we aggregate on the `_index` field the cross cluster search
alias is not taken into account. Neither is it respected when we search
on the field. This change adds support for cluster alias when the cluster
alias is present on the `_index` field.
Closes#25606
Currently we have an option to interrupt the selector thread on close.
This option is not needed as we do not call this method and we should
not be blocking on the network thread. Instead we only need to ever call
wakeup() on the raw selector.
This commit removes all external dependencies from the rest client jar
and shades them in an 'org.elasticsearch.client' package within the jar
using shadowJar gradle plugin. All projects that depended on the
existing jar have been converted to using the 'org.elasticsearch.client'
package prefixes to interact with the rest client.
Closes#25208
Currently we are failing to close socket channels when the initial bind
or connect operation fails. This leaves the file descriptor hanging
around. This closes the channel when an exception occurs during bind or
connect.
Currently an NioChannel is created and it is UNREGISTERED. At some point
it is registered with a selector. From that point on, the channel can
only be closed by the selector. The fact that a channel might not be
associated with a selector has significant implications for concurrency
and the channel shutdown process. The only thing that is simplified by
allowing channels to be in a state independent of a selector is some
testing scenarios.
This PR modifies channels so that they are given a selector at creation
time and are always associated with that selector. Only that selector
can close that channel. This simplifies the channel lifecycle and
closing intricacies.
Removes the primary term from the replication request and pushes it into the transport envelope. This makes it possible to remove the term from the ReplicationOperation universe. The primary term that is to be used for a replication operation is now determined in the reroute phase when the node decides to execute a primary action (and validated once the primary action gets to execute). This makes it possible to validate that the primary action was sent to the correct primary shard instance that it was meant to be sent to (currently we only validate primary actions using the allocation id, which can be reused for failed and reallocated primaries).
When a node tries to join a cluster, it goes through a validation step to make sure the node is compatible with the cluster. Currently we validation that the node can read the cluster state and that it is compatible with the indexes of the cluster. This PR adds validation that the joining node's version is compatible with the versions of existing nodes. Concretely we check that:
1) The node's min compatible version is higher or equal to any node in the cluster (this prevents a too-new node from joining)
2) The node's version is higher or equal to the min compat version of all cluster nodes (this prevents a too old join where, for example, the master is on 5.6, there's another 6.0 node in the cluster and a 5.4 node tries to join).
3) The node's major version is at least as higher as the lowest node in the cluster. This is important as we use the minimum version in the cluster to stop executing bwc code for operations that require multiple nodes. If the nodes are already operating in "new cluster mode", we should prevent nodes from the previous major to join (even if they are wire level compatible). This does mean that if you have a very unlucky partition during the upgrade which partitions all old nodes which are also a minority / data nodes only, the may not be able to re-join the cluster. We feel this edge case risk is well worth the simplification it brings to BWC layers only going one way. This restriction only holds if the cluster state has been recovered (i.e., the cluster has properly formed).
Also, the node join validation can now selectively fail specific nodes (previously the entire batch was failed). This is an important preparation for a follow up PR where we plan to have a rejected joining node die with dignity.
The `QueryRewriteContext` used to provide a client object that can
be used to fetch geo-shapes, terms or documents for percolation. Unfortunately
all client calls used to be blocking calls which can have significant impact on the
rewrite phase since it occupies an entire search thread until the resource is
received. In the case that the index the resource is fetched from isn't on the local
node this can have significant impact on query throughput.
Note: this doesn't fix MLT since it fetches stuff in doQuery which is a different beast. Yet, it is a huge step in the right direction
Today we have duplicated code that is quite complicated to iterate
over rewriteable (`QueryBuilders` mainly) This change introduces a
`Rewriteable` interface that allow to share code to do the rewriting as
well as encapsulation and composition of queries.
Setting a timeout or enforcing low-level search cancellation used to make us
wrap the collector and check either the current time or whether the search
task was cancelled for every collected document. This can be significant
overhead on cheap queries that match many documents.
This commit changes the approach to wrap the bulk scorer rather than the
collector and exponentially increase the interval between two consecutive
checks in order to reduce the overhead of those checks.
When a node tries to join a cluster, it goes through a validation step to make sure the node is compatible with the cluster. Currently we validation that the node can read the cluster state and that it is compatible with the indexes of the cluster. This PR adds validation that the joining node's version is compatible with the versions of existing nodes. Concretely we check that:
1) The node's min compatible version is higher or equal to any node in the cluster (this prevents a too-new node from joining)
2) The node's version is higher or equal to the min compat version of all cluster nodes (this prevents a too old join where, for example, the master is on 5.6, there's another 6.0 node in the cluster and a 5.4 node tries to join).
3) The node's major version is at least as higher as the lowest node in the cluster. This is important as we use the minimum version in the cluster to stop executing bwc code for operations that require multiple nodes. If the nodes are already operating in "new cluster mode", we should prevent nodes from the previous major to join (even if they are wire level compatible). This does mean that if you have a very unlucky partition during the upgrade which partitions all old nodes which are also a minority / data nodes only, the may not be able to re-join the cluster. We feel this edge case risk is well worth the simplification it brings to BWC layers only going one way.
Also, the node join validation can now selectively fail specific nodes (previously the entire batch was failed). This is an important preparation for a follow up PR where we plan to have a rejected joining node die with dignity.
* Register data node stats from info carried back in search responses
This is part of #24915, where we now calculate the EWMA of service time for
tasks in the search threadpool, and send that as well as the current queue size
back to the coordinating node. The coordinating node now tracks this information
for each node in the cluster.
This information will be used in the future the determining the best replica a
search request should be routed to. This change has no user-visible difference.
* Move response time timing into ResponseListenerWrapper
* Move ResponseListenerWrapper to ActionListener instead of SearchActionListener
Also removes the logger
* Move `requestIndex` back to private
* De-guice-ify ResponseCollectorService \o/
* Undo all changes to SearchQueryThenFetchAsyncAction
* Remove unneeded response collector from TransportSearchAction
* Undo all changes to SearchDfsQueryThenFetchAsyncAction
* Completely rewrite the inside of ResponseCollectorService's record keeping
* Documentation and cleanups for ResponseCollectorService
* Add unit test for collection of queue size and service time
* Fix Guice construction error
* Add basic unit tests for ResponseCollectorService
* Fix version constant for the master merge
* Fix test compilation after master merge
* Add a test for node removal on cluster changed event
* Remove integration test as there are now unit tests
* Rename ResponseListenerWrapper -> SearchExecutionStatsCollector
* Fix line-length
* Make classes private and final where appropriate
* Pass nodeId into SearchExecutionStatsCollector and use only ActionListener
* Get nodeId from connection so searchShardTarget can be private
* Remove threadpool from SearchContext, get it from IndexShard instead
* Add missing import
* Use BiFunction for responseWrapper rather than passing in collector service
The following token filters were moved: arabic_normalization, german_normalization, hindi_normalization, indic_normalization, persian_normalization, scandinavian_normalization, serbian_normalization, sorani_normalization, cjk_width and cjk_width
Relates to #23658
#25521 changed channel closing to be handled async on anything but transport stop. This means it may take a while before
calling `connection.close()` and the node being removed from the `connectedNodes` list (but the connection is immediately unusuable).
Fixes#25686
Currently replication and recovery are both coordinated through the latest cluster state available on the ClusterService as well as through the GlobalCheckpointTracker (to have consistent local/global checkpoint information), making it difficult to understand the relation between recovery and replication, and requiring some tricky checks in the recovery code to coordinate between the two. This commit makes the primary the single owner of its replication group, which simplifies the replication model and allows to clean up corner cases we have in our recovery code. It also reduces the dependencies in the code, so that neither RecoverySourceXXX nor ReplicationOperation need access to the latest state on ClusterService anymore. Finally, it gives us the property that in-sync shard copies won't receive global checkpoint updates which are above their local checkpoint (relates #25485).
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
We already use a per JVM port range in MockTransportService. Yet,
it's possible that if we are executing in the JVM with ordinal 0 that
other clusters reuse ports from the mock transport service and some tests
try to simulate disconnects etc. By using a non-defautl port range (starting at 10300)
we prevent internal test clusters from reusing any of the mock impls ports
Relates to #25301
Today if we search across a large amount of shards we hit every shard. Yet, it's quite
common to search across an index pattern for time based indices but filtering will exclude
all results outside a certain time range ie. `now-3d`. While the search can potentially hit
hundreds of shards the majority of the shards might yield 0 results since there is not document
that is within this date range. Kibana for instance does this regularly but used `_field_stats`
to optimize the indexes they need to query. Now with the deprecation of `_field_stats` and it's upcoming removal a single dashboard in kibana can potentially turn into searches hitting hundreds or thousands of shards and that can easily cause search rejections even though the most of the requests are very likely super cheap and only need a query rewriting to early terminate with 0 results.
This change adds a pre-filter phase for searches that can, if the number of shards are higher than a the `pre_filter_shard_size` threshold (defaults to 128 shards), fan out to the shards
and check if the query can potentially match any documents at all. While false positives are possible, a negative response means that no matches are possible. These requests are not subject to rejection and can greatly reduce the number of shards a request needs to hit. The approach here is preferable to the kibana approach with field stats since it correctly handles aliases and uses the correct threadpools to execute these requests. Further it's completely transparent to the user and improves scalability of elasticsearch in general on large clusters.
There is a bug when a call to `BytesReferenceStreamInput` skip is made
on a `BytesReference` that has an initial offset. The offset for the
current slice is added to the current index and then subtracted from the
length. This introduces the possibility of a negative number of bytes to
skip. This happens inside a loop, which leads to an infinte loop.
This commit correctly subtracts the current slice index from the
slice.length. Additionally, the `BytesArrayTests` are modified to test
instances that include an offset.
This is a protection mechanism to prevent a single search request from
hitting a large number of shards in the cluster concurrently. If a search is
executed against all indices in the cluster this can easily overload the cluster
causing rejections etc. which is not necessarily desirable. Instead this PR adds
a per request limit of `max_concurrent_shard_requests` that throttles the number of
concurrent initial phase requests to `256` by default. This limit can be increased per request
and protects single search requests from overloading the cluster. Subsequent PRs can introduces
addiontional improvemetns ie. limiting this on a `_msearch` level, making defaults a factor of
the number of nodes or sort shards iters such that we gain the best concurrency across nodes.
We lost the cluster alias due to some special caseing in inner hits
and due to the fact that we didn't pass on the alias to the shard request.
This change ensures that we have the cluster alias present on the shard to
ensure all SearchShardTarget reads preserve the alias.
Relates to #25606
Currently when we close a channel in Netty4Utils.closeChannels we
block until the closing is complete. This introduces the possibility
that a network selector thread will block while waiting until a
separate network selector thread closes a channel.
For instance: T1 closes channel 1 (which is assigned to a T1 selector).
Channel 1's close listener executes the closing of the node. That
means that T1 now tries to close channel 2. However, channel 2 is
assigned to a selector that is running on T2. T1 now must wait until T2
closes that channel at some point in the future.
This commit addresses this by adding a boolean to closeChannels
indicating if we should block on close. We only set this boolean to true
if we are closing down the server channels at shutdown. This call is
never made from a network thread. When we call the closeChannels method
with that boolean set to false, we do not block on close.
This change collapses some of the packages for the bucket aggregations into their parent packages. This was done for the following aggregations:
* The variants of the range aggregation (geo_distance, date and ip) were moved into the `o.e.s.a.bucket.range` package
* The `o.e.s.a.bucket.terms.support` package was removed and the classes were moved to `o.e.s.a.bucket.terms`
* The filter aggregation was moved to `o.e.s.a.bucket.filter`
Since this PR is already relatively large with only the above changes subsequent PRs will do similar operations on relevant metric and pipeline aggregations
Relates to #22868
We currently check whether translog files can be trimmed whenever we create a new translog generation or close a view. However #25294 added a long translog retention period (12h, max 512MB by default), which means translog files should potentially be cleaned up long after there isn't any indexing activity to trigger flushes/the creation of new translog files. We therefore need a scheduled background check to clean up those files once they are no longer needed.
Relates to #10708
This commit does two things:
- bumps the version from 6.0.0-alpha3 to 6.0.0-beta1
- renames the 6.0.0-alpha3 version constant to 6.0.0-beta1
Relates #25621
This commit adds cross-settings validation for the low/high/flood stage
disk watermark settings. This validation was enabled by the introduction
of multiple settings validation.
Relates #25600
This commit refactors the global checkpont tracker to make it more
resilient. The main idea is to make it more explicit what state is
actually captured and how that state is updated through
replication/cluster state updates etc. It also fixes the issue where the
local checkpoint information is not being updated when a shard becomes
primary. The primary relocation handoff becomes very simple too, we can
just verbatim copy over the internal state.
Relates #25468
* Improved REST endpoint exception handling, see #15335
Also improved OPTIONS http method handling to better conform with the
http spec.
* Tidied up formatting and comments
See #15335
* Tests for #15335
* Cleaned up comments, added section number
* Swapped out tab indents for space indents
* Test class now extends ESSingleNodeTestCase
* Capture RestResponse so it can be examined in test cases
Simple addition to surface the RestResponse object so we can run tests
against it (see issue #15335).
* Refactored class name, included feedback
See #15335.
* Unit test for REST error handling enhancements
Randomizing unit test for enhanced REST response error handling. See
issue #15335 for more details.
* Cleaned up formatting
* New constructor to set HTTP method
Constructor added to support RestController test cases.
* Refactored FakeRestRequest, streamlined test case.
* Cleaned up conflicts
* Tests for #15335
* Added functionality to ignore or include path wildcards
See #15335
* Further enhancements to request handling
Refactored executeHandler to prioritize explicit path matches. See
#15335 for more information.
* Cosmetic fixes
* Refactored method handlers
* Removed redundant import
* Updated integration tests
* Refactoring to address issue #17853
* Cleaned up test assertions
* Fixed edge case if OPTIONS method randomly selected as invalid method
In this test, an OPTIONS method request is valid, and should not return
a 405 error.
* Remove redundant static modifier
* Hook the multiple PathTrie attempts into RestHandler.dispatchRequest
* Add missing space
* Correctly retrieve new handler for each Trie strategy
* Only copy headers to threadcontext once
* Fix test after REST header copying moved higher up
* Restore original params when trying the next trie candidate
* Remove OPTIONS for invalidHttpMethodArray so a 405 is guaranteed in tests
* Re-add the fix I already added and got removed during merge :-/
* Add missing GET method to test
* Add documentation to migration guide about breaking 404 -> 405 changes
* Explain boolean response, pull into local var
* fixup! Explain boolean response, pull into local var
* Encapsulate multiple HTTP methods into PathTrie<MethodHandlers>
* Add PathTrie.retrieveAll where all matching modes can be retrieved
Then TrieMatchingMode can be package private and not leak into RestController
* Include body of error with 405 responses to give hint about valid methods
* Fix missing usageService handler addition
I accidentally removed this :X
* Initialize PathTrieIterator modes with Arrays.asList
* Use "== false" instead of !
* Missing paren :-/
Indexing ids in binary form should help with indexing speed since we would
have to compare fewer bytes upon sorting, should help with memory usage of
the live version map since keys will be shorter, and might help with disk
usage depending on how efficient the terms dictionary is at compressing
terms.
Since we can only expect base64 ids in the auto-generated case, this PR tries
to use an encoding that makes the binary id equal to the base64-decoded id in
the majority of cases (253 out of 256). It also specializes numeric ids, since
this seems to be common when content that is stored in Elasticsearch comes
from another database that uses eg. auto-increment ids.
Another option could be to require base64 ids all the time. It would make things
simpler but I'm not sure users would welcome this requirement.
This PR should bring some benefits, but I expect it to be mostly useful when
coupled with something like #24615.
Closes#18154
Transport profiles unfortunately have never been validated. Yet, it's very
easy to make a mistake when configuring profiles which will most likely stay
undetected since we don't validate the settings but allow almost everything
based on the wildcard in `transport.profiles.*`. This change removes the
settings subset based parsing of profiles but rather uses concrete affix settings
for the profiles which makes it easier to fall back to higher level settings since
the fallback settings are present when the profile setting is parsed. Previously, it was
unclear in the code which setting is used ie. if the profiles settings (with removed
prefixes) or the global node setting. There is no distinction anymore since we don't pull
prefix based settings.
Some tests use MockTransportService to do network based testing.
Yet, we run tests in multiple JVMs that means
concurrent tests could claim port that another JVM just released
and if that test tries to simulate a disconnect it might be smart
enough to re-connect depending on what is tested. To reduce the risk,
since this is very hard to debug we use a different default
port range per JVM unless the incoming settings overriding it.
Closes#25301
Today when we run out of disk all kinds of crazy things can happen
and nodes are becoming hard to maintain once out of disk is hit.
While we try to move shards away if we hit watermarks this might not
be possible in many situations. Based on the discussion in #24299
this change monitors disk utilization and adds a flood-stage watermark
that causes all indices that are allocated on a node hitting the flood-stage
mark to be switched read-only (with the option to be deleted). This allows users to react on the low disk
situation while subsequent write requests will be rejected. Users can switch
individual indices read-write once the situation is sorted out. There is no
automatic read-write switch once the node has enough space. This requires
user interaction.
The flood-stage watermark is set to `95%` utilization by default.
Closes#24299
All query builders written as self contained xContent objects, to we should mark
them accordingly using ToXContentObject. This also makes it possible to use
things like XContentHelper#toXContent to render query builders in tests.
QueryParseContext is currently only used as a wrapper for an XContentParser, so
this change removes it entirely and changes the appropriate APIs that use it so
far to only accept a parser instead.
This commit makes the use of the global network settings explicit instead
of implicit within NetworkService. It cleans up several places where we fall
back to the global settings while we should have used tcp or http ones.
In addition this change also removes unnecessary settings classes
We have various assertions that check we never block on transport
threads. This commit adds the thread names for the NioTransport to
these assertions.
With this change I had to fix two places where we were calling blocking
methods from the transport threads.
This commit adds additional protection to `ESSelector` and its
implementations to ensure that channels are not enqueued after the
selector is closed.
After a channel has been added to the queue, we check that the selector
is open. If it is not, then we remove the channel from the queue. If the
channel is removed successfully, we throw an `IllegalStateException`.
Our current TCPTransport logic assumes that we do not pass pings to
the TCPTransport level.
This commit fixes an issue where NioTransport was passing pings to
TCPTransport and leading to exceptions.
Currently QueryParseContext is only a thin wrapper around an XContentParser that
adds little functionality of its own. I provides helpers for long deprecated
field names which can be removed and two helper methods that can be made static
and moved to other classes. This is a first step in helping to remove
QueryParseContext entirely.
In SimpleNioTransportTests we assert that an IOException has a certain
message. This message appears that it is not dependible (and might
change based on platform).
Our other transport tests (mock and netty) do not make this assertion.
Instead they only assert on our application exception message. This
commit removes the IOException message assertion. And retains the
ConnectTransportException message assertion.
This commit introduces a nio based tcp transport into framework for
testing.
Currently Elasticsearch uses a simple blocking tcp transport for
testing purposes (MockTcpTransport). This diverges from production
where our current transport (netty) is non-blocking.
The point of this commit is to introduce a testing variant that more
closely matches the behavior of production instances.
This commit removes path.conf as a valid setting and replaces it with a
command-line flag for specifying a non-default path for configuration.
Relates #25392
The following token filters were moved: stemmer, stemmer_override, kstem, dictionary_decompounder, hyphenation_decompounder, reverse, elision and truncate.
Relates to #23658
While real secure settings (ie an ES keystore) cannot be merged
together, mocked secure settings can and need to be sometimes merged.
This commit adds a merge method to allow tests to merge together
multiple instances of secure settings.
OldIndexBackwardsCompatibilityIT#testOldClusterStates tested whether global and index metadata could be read from data directory,
this can also be tested in full cluster qa test that checks cluster state via api.
Relates to #24939
#25147 added the translog deletion policy but didn't enable it by default. This PR enables a default retention of 512MB (same maximum size of the current translog) and an age of 12 hours (i.e., after 12 hours all translog files will be deleted). This increases to chance to have an ops based recovery, even if the primary flushed or the replica was offline for a few hours.
In order to see which parts of the translog are committed into lucene the translog stats are extended to include information about uncommitted operations.
Views now include all translog ops and guarantee, as before, that those will not go away. Snapshotting a view allows to filter out generations that are not relevant based on a specific sequence number.
Relates to #10708
Most notable changes:
- better update concurrency: LUCENE-7868
- TopDocs.totalHits is now a long: LUCENE-7872
- QueryBuilder does not remove the boolean query around multi-term synonyms:
LUCENE-7878
- removal of Fields: LUCENE-7500
For the `TopDocs.totalHits` change, this PR relies on the fact that the encoding
of vInts and vLongs are compatible: you can write and read with any of them as
long as the value can be represented by a positive int.
MockTransportServices allows us to simulate network disruptions in our testing infra. Sadly it wasn't updated to the state of the art in Transport land. This PR brings it up to speed. Specifically:
1) Opening a connection is now also blocked (before only node connections were blocked)
2) Simplifies things using the latest connection based notification between TcpTransport and TransportService for when a disconnect happens.
3) By 2, it fixes a race condition where we may fail to respond to a sent request when it is sent concurrently with the closing of a connection. The old code relied on a node based bridge between tcp transport and transport service. Sadly, the following doesn't work any more:
```
if (transport.nodeConnected(node)) {
// this a connected node, disconnecting from it will be up the exception
transport.disconnectFromNode(node); <-- this may now be a noop and it doesn't mean that the transport service was notified of the disconnect between the nodeConnected check and here.
} else {
throw new ConnectTransportException(node, reason, e);
}
```
If secure settings are closed after the node has been constructed
no key-store access is permitted. We should also try to be as close as possible
to the real behavior if we mock secure settings. This change also adds
the same behavior as bootstrap has to InternalTestCluster to ensure we fail
if we try to read from secure settings after the node has been constructed.
In MockFSDirectory we should use the actual indexes settings to build
a new IndexMetaData settings object instead of the node settings.
Relates to #25297
I'm still trying to hunt down rare failures in the cancelation tests
for reindex and friends. Here is the latest:
https://elasticsearch-ci.elastic.co/job/elastic+elasticsearch+5.x+multijob-unix-compatibility/os=ubuntu/876/console
It doesn't show much, other than that one of the tasks didn't kill
itself when asked to cancel.
So I'm going a bit crazy with debug logging so that the next time this
comes up I can trace exactly what happened.
Additionally, this tweaks the logic around how rethrottles were
performed around cancel. Previously we set the `requestsPerSecond`
to `0` when we cancelled the task. That was the "old way" to set them
to inifity which was the intent. This switches that from `0` to
`Float.MAX_VALUE` which is the "new way" to set the `requestsPerSecond`
to infinity. I don't know that this is much better, but it feels better.
In tests, we sometimes create a random directory service and as part of that the IndexSettings get
built again. When we build them again, we need to make sure we do not set the secure settings on
the new IndexMetaData object that gets created as the node settings already have the secure
settings and the index settings and node settings will be combined. If both have secure settings,
the settings builder will throw an AlreadySetException.
Indexing or deleting documents through the IndexShard interface is quite complex and error-prone. It requires multiple calls, e.g. first prepareIndexOnPrimary, then do some checks if mapping updates have occurred, then do the actual indexing using index(...) etc. Currently each consumer of the interface (local recovery, peer recovery, replication) has additional custom checks built around it to deal with mapping updates, some of which are even inconsistent. This commit aims at reducing the complexity by exposing a simpler interface on IndexShard. There are no more prepare*** methods and the mapping complexity is also hidden, but still giving callers a possibility to implement custom logic to deal with mapping updates.
Today we maintain a map of open connections in order to close them when
a low level channel gets closed or handles a failure. We also spawn a thread due to some
tricky concurrency issues especially with respect to netty since they listener might
be called on a transport / boss thread. Executions on those threads must not be blocking
since otherwise we will likely deadlock the event processing which adds to the
complexity of the concurrency model in this class.
This change associates the connection with the close callback that every channel invokes
once it's closed which allows us to remove the connections map. A relaxed non-blocking
concurrency model in the connection close listener allows cleaning up connected nodes without
blocking on any lock.
This change adds tests for the aggregation parsing that try to simulate that we
can parse existing aggregations in a forward compatible way in the future,
ignoring potential newly added fields or substructures to the xContent response.
Today TcpTransport is the de-facto base-class for transport implementations.
The need for all the callbacks we have in TransportServiceAdaptor are not necessary
anymore since we can simply have the logic inside the base class itself. This change
moves the stats metrics directly into TcpTransport removing the need for low level
bytes send / received callbacks.
We use assertBusy in many places where the underlying code throw exceptions. Currently we need to wrap those exceptions in a RuntimeException which is ugly.
This snapshot has faster range queries on range fields (LUCENE-7828), more
accurate norms (LUCENE-7730) and the ability to use fake term frequencies
(LUCENE-7854).
This commit renames the needsScores method so as to make it
automatically generatable, based on the name of the `_score` variable
which is available in search scripts. It also adds documentation to
ScriptContext to explain the naming and signature of such methods.
In #25201, a setting was added to allow setting the retry timeout for the rest client under the
impression that this would allow requests to go longer than 30s. However, there is also a socket
timeout that needs to be set to greater than 30s, which this change adds a setting for.
Expose the experimental simplepattern and
simplepatternsplit tokenizers in the common
analysis plugin. They provide tokenization based
on regular expressions, using Lucene's
deterministic regex implementation that is usually
faster than Java's and has protections against
creating too-deep stacks during matching.
Both have a not-very-useful default pattern of the
empty string because all tokenizer factories must
be able to be instantiated at index creation time.
They should always be configured by the user
in practice.
This commit adds a setting to change the request timeout for the rest client. This is useful as the
default timeout is 30s, which is also the same default for calls like cluster health. If both are
the same then the response from the cluster health api will not be received as the client usually
times out first making test failures harder to debug.
Relates #25185
Today if a channel gets closed due to a disconnect we notify the response
handler that the connection is closed and the node is disconnected. Unfortunately
this is not a complete solution since it only works for published connections.
Connections that are unpublished ie. for discovery can indefinitely hang since we
never invoke their handers when we get a failure while a user is waiting for
the response. This change adds connection tracking to TcpTransport that ensures
we are notifying the corresponding connection if there is a failure on a channel.
When we disabled `_all` by default for indices created in 6.0, we missed adding
a layer that would handle the situation where `_all` was not enabled in 5.x and
then the cluster was updated to 6.0, this means that when the cluster was
updated the `_all` field would be disabled for 5.x indices and field values
would not be added to the `_all` field.
This adds a compatibility layer for 5.x indices where we treat the default
enabled value for the `_all` field to be `true` if unset on 5.x indices.
Resolves#25068
Test: randomVersionBetween works with unreleased
Modifies randomVersionBetween so that it works with unreleased
versions. This should make switching a version from unreleased
to released much simpler.
This commit refactors the query phase in order to be able
to automatically detect queries that can be early terminated.
If the index sort matches the query sort, the top docs collection is early terminated
on each segment and the computing of the total number of hits that match the query is delegated to a simple TotalHitCountCollector.
This change also adds a new parameter to the search request called `track_total_hits`.
It indicates if the total number of hits that match the query should be tracked.
If false, queries sorted by the index sort will not try to compute this information and
and will limit the collection to the first N documents per segment.
Aggregations are not impacted and will continue to see every document
even when the index sort matches the query sort and `track_total_hits` is false.
Relates #6720
This commit modifies query_string, simple_query_string and multi_match queries to always use a DisjunctionMaxQuery when a disjunction over multiple fields is built. The tiebreaker is set to 1 in order to behave like the boolean query in terms of scoring.
The removal of the coord factor in Lucene 7 made this change mandatory to correctly handle minimum_should_match.
Closes#23966
This commit moves the assumeFalse() calls that implement test skipping
and blacklisting out of the @Before method of ESClientYamlSuiteTestCase.
The problem with having them in the @Before method is that if an
assumption triggers then the @Before methods of classes that extend
ESClientYamlSuiteTestCase will not run, but their @After methods will.
This can lead to inconsistencies that cause assertions in the @After
methods and fail the test even though it was skipped/blacklisted.
Instead the assumeFalse() calls are now at the beginning of the test()
method, which runs after all @Before methods (including those in classes
that extend ESClientYamlSuiteTestCase) have completed. The only side
effect is that overridden test() methods in classes that extend
ESClientYamlSuiteTestCase which call super.test() and also do other things
must now be designed not to consume any InternalAssumptionViolatedException
that may be thrown by the super.test() call.
Relates elastic/x-pack-elasticsearch#1650
For the response parsing we want to be lenient when it comes to parsing
new xContent fields. In order to ensure this in our testing, this change
adds a utility method to XContentTestUtils that takes xContent bytes
representation as input and recursively a random field on each object
level.
Sometimes we also want to exclude a whole subtree from this treatment
(e.g. skipping "_source"), other times an element (e.g. "fields", "highlight"
in SearchHit) can have arbitraryly named objects. Those cases can be
specified as exceptions.
Splits TranslogRecoveryPerformer into three parts:
- the translog operation to engine operation converter
- the operation perfomer (that indexes the operation into the engine)
- the translog statistics (for which there is already RecoveryState.Translog)
This makes it possible for peer recovery to use the same IndexShard interface as bulk shard requests (i.e. Engine operations instead of Translog operations). It also pushes the "fail on bad mapping" logic outside of IndexShard. Future pull requests could unify the BulkShard and peer recovery path even more.
This change moves the parent_id query to the parent-join module and handles the case when only the parent-join field can be declared on an index (index with single type on).
If single type is off it uses the legacy parent join field mapper and switch to the new one otherwise (default in 6).
Relates #20257
Both gradle and java code attempt to infer the type of a each
Version constant in Version.java. It is super important that
they infer that each constant has the same type. If they disagree
we might accidentally not be testing backwards compatibility for
some version.
This adds a test to make sure that they agree, modulo known and
accepted differences (mostly around alphas). It also changes the
minimum wire compatible version from the released 5.4.0 to the
unreleased 5.5.0 as that lines up with the gradle logic.
Relates to #24798
Note that the gradle and java version logic doesn't actually match so
this contains a hack to make it *look* like it matches. Since this is a
start, I'm merging it and going to work on some followups to make the
logic actually match.....
This commit creates TemplateScript and associated classes so that
templates no longer need a special ScriptService.compileTemplate method.
The execute() method is equivalent to the old run() method.
relates #20426
Previously, when allocating bytes for a BigArray, the array was created
(or attempted to be created) and only then would the array be checked
for the amount of RAM used to see if the circuit breaker should trip.
This is problematic because for very large arrays, if creating or
resizing the array, it is possible to attempt to create/resize and get
an OOM error before the circuit breaker trips, because the allocation
happens before checking with the circuit breaker.
This commit ensures that the circuit breaker is checked before all big
array allocations (note, this does not effect the array allocations that
are less than 16kb which use the [Type]ArrayWrapper classes found in
BigArrays.java). If such an allocation or resizing would cause the
circuit breaker to trip, then the breaker trips before attempting to
allocate and potentially running into an OOM error from the JVM.
Closes#24790
After every REST test we wait for the list of pending cluster tasks
to empty before moving on to the next task. If the list doesn't
empty in 10 second we fail the test. This improves the error message
when we fail the test to include the list of running tasks.
For comparing actual and parsed object equality for the response parsing we
currently rely on comparing the original xContent and the output of the parsed
object. Currently we only have cryptic error messages if this comparison fails
which are hard to read also because we recursively compare lists and maps of
the xContent structures we compare.
This commits leverages the existing NotEqualMessageBuilder for providing error
messages that are more detailed and useful for debugging if an error occurs.