Now that search templates always get converted to json, we don't need to try and auto-detect their content-type, which anyways didn't work as expected before given that only json was really working.
Elasticsearch accepts multiple content-type formats, hence scripts can be stored/provided in json, yaml, cbor or smile. Yet the format that should be used internally is json. This is a problem mainly around search templates, as they only support json out of the four content-types, so instead of maintaining the content-type of the request we should rather convert the scripts/templates to json.
Binary formats were not previously supported. If you stored a template in yaml format, you'd get back an error "No encoder found for MIME type [application/yaml]" when trying to execute it. With this commit the request content-type is independent from the template, which always gets converted to json internally. That is transparent to users and doesn't affect the content type of the response obtained when executing the template.
Fixes Painless to properly implement scripts that return primitives
and void. Adds some simple tests that we emit sane opcodes and some
other tests that we implement primitives as expected.
Mostly this is just a fix following up from #22983 but there is one
thing I did really worth talking about, I think. So, before this script
Painless scripts could only ever return Object and they did would always
return null for paths that didn't return any values. Now that they
can return primitives the question is "what should Painless return
from paths that don't return any values?" And I answered that with
"whatever the JLS default value is". So 0/0L/0f/0d/false.
Generalizes three previously hard coded things in painless into
generic concepts:
1. The "main method" is no longer hardcoded to:
```
public abstract Object execute(Map<String, Object> params,
Scorer scorer, LeafDocLookup doc, Object value);
```
Instead Painless's compiler takes an interface and implements it. It looks like:
```
public interface SomeScript {
// Argument names we expose to Painless scripts
String[] ARGUMENTS = new String[] {"a", "b"};
// Method implemented by Painless script. Must be named execute but can have any parameters or return any value.
Object execute(String a, int b);
// Is the "a" argument used by the script?
boolean uses$a();
}
SomeScript script = scriptEngine.compile(SomeScript.class, null, "the_script_here", emptyMap());
Object result = script.execute("a", 1);
```
`PainlessScriptEngine` now compiles all scripts to the new
`GenericElasticsearchScript` interface by default for compatibility
with the rest of Elasticsearch until it is able to use this new
ability.
2. `_score` and `ctx` are no longer hardcoded to be extracted from
`#score` and `params` respectively. Instead Painless's default
implementation of Elasticsearch scripts uses the `uses$_score` and
`uses$ctx` methods to determine if it is used and gives them
dummy values if they are not used.
3. Throwing the `ScriptException` is now handled by the Painless
script itself. That way Painless doesn't have to leak the metadata
that is required to build the fancy stack trace. And all painless scripts
get the fancy stack trace.
Previously we calculated Netty' receive predictor size for HTTP and transport
traffic based on available memory and worker nodes. This resulted in a receive
predictor size between 64kb and 512kb. In our benchmarks this leads to increased
GC pressure.
With this commit we set Netty's receive predictor size to 32kb. This value is in
a sweet spot between heap memory waste (-> GC pressure) and effect on request
metrics (achieved throughput and latency numbers).
Closes#23185
This commit enforces the requirement of Content-Type for the REST layer and removes the deprecated methods in transport
requests and their usages.
While doing this, it turns out that there are many places where *Entity classes are used from the apache http client
libraries and many of these usages did not specify the content type. The methods that do not specify a content type
explicitly have been added to forbidden apis to prevent more of these from entering our code base.
Relates #19388
Get HEAD requests incorrectly return a content-length header of 0. This
commit addresses this by removing the special handling for get HEAD
requests, and just relying on the general mechanism that exists for
handling HEAD requests in the REST layer.
Relates #23186
Get source HEAD requests incorrectly return a content-length header of
0. This commit addresses this by removing the special handling for get
source HEAD requests, and just relying on the general mechanism that
exists for handling HEAD requests in the REST layer.
Relates #23151
Today all search phases are inner classes of AbstractSearchAsyncAction or one of it's
subclasses. This makes unit testing of these classes practically impossible. This commit
Extracts `DfsQueryPhase` and `FetchSearchPhase` or of the code that composes the actual
query execution types and moves most of the fan-out and collect code into an `InitialSearchPhase`
class that can be used to build initial search phases (phases that retry on shards). This will
make modification to these classes simpler and allows to easily compose or add new search phases
down the road if additional roundtrips are required.
When Netty decodes a bad HTTP request, it marks the decoder result on
the HTTP request as a failure, and reroutes the request to GET
/bad-request. This either leads to puzzling responses when a bad request
is sent to Elasticsearch (if an index named "bad-request" does not exist
then it produces an index not found exception and otherwise responds
with the index settings for the index named "bad-request"). This commit
addresses this by inspecting the decoder result on the HTTP request and
dispatching the request to a bad request handler preserving the initial
cause of the bad request and providing an error message to the client.
Relates #23153
This commit adds a new method to the TransportChannel that provides access to the version of the
remote node that the response is being sent on and that the request came from. This is helpful
for serialization of data attached as headers.
Template HEAD requests incorrectly return a content-length header of
0. This commit addresses this by removing the special handling for
template HEAD requests, and just relying on the general mechanism that
exists for handling HEAD requests in the REST layer.
Relates #23130
Index HEAD requests incorrectly return a content-length header of
0. This commit addresses this by removing the special handling for index
HEAD requests, and just relying on the general mechanism that exists for
handling HEAD requests in the REST layer.
Relates #23112
Alias HEAD requests incorrectly return a content-length header of
0. This commit addresses this by removing the special handling for alias
HEAD requests, and just relying on the general mechanism that exists for
handling HEAD requests in the REST layer.
Relates #23094
This pull request reuses the typed_keys parameter added in #22965, but this time it applies it to suggesters. When set to true, the suggester names in the search response will be prefixed with a prefix that reflects their type.
Netty 4.1.8 wraps connect and accept operations in doPrivileged blocks.
This means that we not need to give permissions to the entire transport
module. Additionally this commit deletes the privileged socket channel
and privileged server socket chanel.
This pull request adds a new parameter to the REST Search API named `typed_keys`. When set to true, the aggregation names in the search response will be prefixed with a prefix that reflects the internal type of the aggregation.
Here is a simple example:
```
GET /_search?typed_keys
{
"aggs": {
"tweets_per_user": {
"terms": {
"field": "user"
}
}
},
"size": 0
}
```
And the response:
```
{
"aggs": {
"sterms:tweets_per_user": {
...
}
}
}
```
This parameter is intended to make life easier for REST clients that could parse back the prefix and could detect the type of the aggregation to parse. It could also be implemented for suggesters.
We have a bunch of interfaces that have only a single implementation
for 6 years now. These interfaces are pretty useless from a SW development
perspective and only add unnecessary abstractions. They also require
lots of casting in many places where we expect that there is only one
concrete implementation. This change removes the interfaces, makes
all of the classes final and removes the duplicate `foo` `getFoo` accessors
in favor of `getFoo` from these classes.
This is related to #22116. This commit adds calls that require
SocketPermission connect to forbidden APIs.
The following calls are now forbidden:
- java.net.URL#openStream()
- java.net.URLConnection#connect()
- java.net.URLConnection#getInputStream()
- java.net.Socket#connect(java.net.SocketAddress)
- java.net.Socket#connect(java.net.SocketAddress, int)
- java.nio.channels.SocketChannel#open(java.net.SocketAddress)
- java.nio.channels.SocketChannel#connect(java.net.SocketAddress)
#22194 gave us the ability to open low level temporary connections to remote node based on their address. With this use case out of the way, actual full blown connections should validate the node on the other side, making sure we speak to who we think we speak to. This helps in case where multiple nodes are started on the same host and a quick node restart causes them to swap addresses, which in turn can cause confusion down the road.
As part of #22116 we are going to forbid usage of api
java.net.URL#openStream(). However in a number of places across the
we use this method to read files from the local filesystem. This commit
introduces a helper method openFileURLStream(URL url) to read files
from URLs. It does specific validation to only ensure that file:/
urls are read.
Additionlly, this commit removes unneeded method
FileSystemUtil.newBufferedReader(URL, Charset). This method used the
openStream () method which will soon be forbidden. Instead we use the
Files.newBufferedReader(Path, Charset).
This commit adds support for the newline delimited JSON Content-Type, which is how
the bulk, multi-search, and multi-search template APIs expect data to be formatted. The
`elasticsearch-js` client has also been using this content type for these types of requests.
Closes#22943
In order to support the evolving GeoPoint encodings in Lucene 5 and 6, ES 2.x and 5.x implements an abstraction layer to the GeoPointFieldMapper classes. As of 5.x the geo_point field mapper settled on using Lucene's more performant LatLonPoint field type and deprecated all other encodings. In 6.0 all encodings except LatLonPoint have been removed rendering this abstraction layer useless. This commit removes the abstraction layer and renames the LatLonPointFieldMapper back to GeoPointFieldMapper to mantain consistency with ES field naming.
Painless can cast anything into the magic type `def` but it
really shouldn't try to cast **nothing** into `def`. That causes
the byte code generation library to freak out a little.
Closes#22908
This test was using initial count of slices instead of the count
of unfinished slices to pick the expected throttle. Unfortunely
due to race conditions the actual rethrottle count is between the
two. So we weaken the assertion from "the new throttle is exactly X"
to "the new throttle is between X and Y (inclusive)".
This is related to #22116. Core no longer needs `SocketPermission`
`connect`.
This permission is relegated to these modules/plugins:
- transport-netty4 module
- reindex module
- repository-url module
- discovery-azure-classic plugin
- discovery-ec2 plugin
- discovery-gce plugin
- repository-azure plugin
- repository-gcs plugin
- repository-hdfs plugin
- repository-s3 plugin
And for tests:
- mocksocket jar
- rest client
- httpcore-nio jar
- httpasyncclient jar
Versions of Elasticsearch prior to 2.0 would return a scroll id
even with the last scroll response. They'd then automatically
clear the scroll because it is empty. When terminating reindex
will attempt to clear the last scroll it received, regardless of
the remote version. This quiets the warning when the scroll cannot
be cleared for versions before 2.0.
Closes#22937
This commit upgrades the checkstyle configuration from version 5.9 to
version 7.5, the latest version as of today. The main enhancement
obtained via this upgrade is better detection of redundant modifiers.
Relates #22960
`UpdateByQueryWhileModifyingTests#testUpdateWhileReindexing`
runs update-by-query and concurrently updates, asserting that
the update-by-query never reverts any changes made by the update.
It is a smoke test for concurrent updates.
Now, it expects to hit a certain number of version conflicts
during the updates. This is normal as it is racing the
update-by-query. We have a maximum number of failures we
expect (10) and I'd never seen us come close until
https://elasticsearch-ci.elastic.co/job/elastic+elasticsearch+5.x+multijob-unix-compatibility/os=sles/495/console
This bumps the max failures from 10 to 50 and improves
logging a bit. If we continue to see this failure then we have
some other issue.
Closes#22938
This change adds a strict mode for xcontent parsing on the rest layer. The strict mode will be off by default for 5.x and in a separate commit will be enabled by default for 6.0. The strict mode, which can be enabled by setting `http.content_type.required: true` in 5.x, will require that all incoming rest requests have a valid and supported content type header before the request is dispatched. In the non-strict mode, the Content-Type header will be inspected and if it is not present or not valid, we will continue with auto detection of content like we have done previously.
The content type header is parsed to the matching XContentType value with the only exception being for plain text requests. This value is then passed on with the content bytes so that we can reduce the number of places where we need to auto-detect the content type.
As part of this, many transport requests and builders were updated to provide methods that
accepted the XContentType along with the bytes and the methods that would rely on auto-detection have been deprecated.
In the non-strict mode, deprecation warnings are issued whenever a request with body doesn't provide the Content-Type header.
See #19388
In 5.2 we stopped sending the source parameter if the user didn't
specify it. This was a mistake as versions before 2.0 look like
they don't always include the `_source`. This is because reindex
requests some metadata fields. Anyway, now we say `"_source": true`
if there isn't a `_source` configured in the reindex request.
Closes#22893
We were incorrectly resolving qualified method references at run
time when invoked on `def`. This lead to errors like
`The struct with name [org] has not been defined.` when attempting
```
doc.date.dates.stream().map(
org.joda.time.ReadableDateTime::centuryOfEra
).collect(Collectors.toList())
```
Implemented by wrapping an array of reused `ModuleDateTime`s that
we grow when needed. The `ModuleDateTime`s are reused when we
move to the next document.
Also improves the error message returned when attempting to modify
the `ScriptdocValues`, removes a couple of allocations, and documents
that the date functions are available in Painless.
Relates to #22162
Currently, stored scripts use a namespace of (lang, id) to be put, get, deleted, and executed. This is not necessary since the lang is stored with the stored script. A user should only have to specify an id to use a stored script. This change makes that possible while keeping backwards compatibility with the previous namespace of (lang, id). Anywhere the previous namespace is used will log deprecation warnings.
The new behavior is the following:
When a user specifies a stored script, that script will be stored under both the new namespace and old namespace.
Take for example script 'A' with lang 'L0' and data 'D0'. If we add script 'A' to the empty set, the scripts map will be ["A" -- D0, "A#L0" -- D0]. If a script 'A' with lang 'L1' and data 'D1' is then added, the scripts map will be ["A" -- D1, "A#L1" -- D1, "A#L0" -- D0].
When a user deletes a stored script, that script will be deleted from both the new namespace (if it exists) and the old namespace.
Take for example a scripts map with {"A" -- D1, "A#L1" -- D1, "A#L0" -- D0}. If a script is removed specified by an id 'A' and lang null then the scripts map will be {"A#L0" -- D0}. To remove the final script, the deprecated namespace must be used, so an id 'A' and lang 'L0' would need to be specified.
When a user gets/executes a stored script, if the new namespace is used then the script will be retrieved/executed using only 'id', and if the old namespace is used then the script will be retrieved/executed using 'id' and 'lang'
This moves the building blocks for delete by query into core. This
should enabled two thigns:
1. Plugins other than reindex to implement "bulk by scroll" style
operations.
2. Plugins to directly call delete by query. Those plugins should
be careful to make sure that task cancellation still works, but
this should be possible.
Notes:
1. I've mostly just moved classes and moved around tests methods.
2. I haven't been super careful about cohesion between these core
classes and reindex. They are quite interconnected because I wanted
to make the change as mechanical as possible.
Closes#22616
Adds "Appending B. Painless API Reference", a reference of all classes
and methods available from Painless. Removes links to java packages
because they contain methods that we don't expose and don't contain
methods that we do expose (the ones in Augmentation). Instead this
generates a list of every class and every exposed method using the same
type information available to the
interpreter/compiler/whatever-we-call-it. From there you can jump to
the relevant docs.
Right now you build all the asciidoc files by running
```
gradle generatePainlessApi
```
These files are expected to be committed because we build the docs
without running `gradle`.
Also changes the output of `Debug.explain` so that it is easy to
search for the class in the generated reference documentation.
You can also run it in an IDE safely if you pass the path to the
directory in which to generate the docs as the first parameter. It'll
blow away the entire directory an recreate it from scratch so be careful.
And then you can build the docs by running something like:
```
../docs/build_docs.pl --out ../built_docs/ --doc docs/reference/index.asciidoc --open
```
That is, if you have checked out https://github.com/elastic/docs in
`../docs`. Wait a minute or two and your browser will pop open in with
all of Elasticsearch's reference documentation. If you go to
`http://localhost:8000/painless-api-reference.html` you can see this
list. Or you can get there by following the links to `Modules` and
`Scripting` and `Painless` and then clicking the link in the paragraphs
below titled `Appendix B. Painless API Reference`.
I like having these in asciidoc because we can deep link to them from the
rest of the guide with constructs like
`<<painless-api-reference-Object-hashCode-0>>` and
`<<painless-api-reference->>` and we get link checking. Then the only
brittle link maintenance bit is the link generation for javadoc. Which
sucks. But I think it is important that we link to the methods directly
so they are easy to find.
Relates to #22720
This is related to #22116. URLRepository requires SocketPermission
connect. This commit introduces a new module called "repository-url"
where URLRepository will reside. With the new module, permissions can
be removed from core.
Beforehand, the DateProcessor constructs its joda pattern formatter during processor
construction. This led to newly ingested documents being defaulted to
the year that the pipeline was constructed, not that of processing.
Fixes#22547.
This adds the necessary `AuthCache` needed to support preemptive authorization. By adding every host to the cache, the automatically added `RequestAuthCache` interceptor will add credentials on the first pass rather than waiting to do it after _each_ anonymous request is rejected (thus always sending everything twice when basic auth is required).
move "es." internal headers to separate metadata set in ElasticsearchException and stop returning them as response headers
Closes#17593
* [TEST] remove ESExceptionTests, move its methods to ElasticsearchExceptionTests or ExceptionSerializationTests
* Add top hits collapsing to search request
The field collapsing is done with a custom top docs collector that "collapse" search hits with same field value.
The distributed aspect is resolve using the two passes that the regular search uses. The first pass "collapse" the top hits, then the coordinating node merge/collapse the top hits from each shard.
```
GET _search
{
"collapse": {
"field": "category",
}
}
```
This change also adds an ExpandCollapseSearchResponseListener that intercepts the search response and expands collapsed hits using the CollapseBuilder#innerHit} options.
The retrieval of each inner_hits is done by sending a query to all shards filtered by the collapse key.
```
GET _search
{
"collapse": {
"field": "category",
"inner_hits": {
"size": 2
}
}
}
```
This commit adds a SpecialPermission constant and uses that constant
opposed to introducing new instances everywhere.
Additionally, this commit introduces a single static method to check that
the current code has permission. This avoids all the duplicated access
blocks that exist currently.
* Upgrade to Lucene 6.4.0
`ValueSource`s are now converted to `DoubleValueSource`s using the Lucene adapter made for the migration to the new API in 6.4.0.
There are presently 7 ctor args used in any rest handlers:
* `Settings`: Every handler uses it to initialize a logger and
some other strange things.
* `RestController`: Every handler registers itself with it.
* `ClusterSettings`: Used by `RestClusterGetSettingsAction` to
render the default values for cluster settings.
* `IndexScopedSettings`: Used by `RestGetSettingsAction` to get
the default values for index settings.
* `SettingsFilter`: Used by a few handlers to filter returned
settings so we don't expose stuff like passwords.
* `IndexNameExpressionResolver`: Used by `_cat/indices` to
filter the list of indices.
* `Supplier<DiscoveryNodes>`: Used to fill enrich the response
by handlers that list tasks.
We probably want to reduce these arguments over time but
switching construction away from guice gives us tighter
control over the list of available arguments.
These parameters are passed to plugins using
`ActionPlugin#initRestHandlers` which is expected to build and
return that handlers immediately. This felt simpler than
returning an reference to the ctors given all the different
possible args.
Breaks java plugins by moving rest handlers off of guice.
This is related to #22116. Core no longer needs SocketPermission
accept. This permission is relegated to the transport-netty4 module
and (for tests) to the mocksocket jar.
This commit adds a MessyRestTestPlugin to the gradle build. It extends
StandaloneRestTestPlugin. The main piece of functionality that it adds
is to copy plugin-metadata from dependencies into the
generated-resources for the current test source. This is necessary to
ensure that permissions for dependencies are applied when running the
tests.
A current limitation is that the permissions are applied differently
than in the distribution sources. When permissions are granted to all
depedencies for a module or plugin, the permissions are granted to all
dependencies on the classpath for tests besides a few hardcoded
exclusions:
- es core
- es test framework
- lucene test framework
- randomized runner
- junit library
We don't want to expose `String#getBytes` which is required for
`Base64.getEncoder.encode` to work because we're worried about
character sets. This adds `encodeBase64` and `decodeBase64`
methods to `String` in Painless that are duals of one another
such that:
`someString == someString.encodeBase64().decodeBase64()`.
Both methods work with the UTF-8 encoding of the string.
Closes#22648
Everything that extended `AbstractAsyncBulkByScrollAction` also
extended `AbstractAsyncBulkIndexByScrollAction` so this removes
`AbstractAsyncBulkIndexByScrollAction`, merging it into
`AbstractAsyncBulkByScrollAction`.
Changes the error message when `action.auto_create_index` or
`index.mapper.dynamic` forbids automatic creation of an index
from `no such index` to one of:
* `no such index and [action.auto_create_index] is [false]`
* `no such index and [index.mapper.dynamic] is [false]`
* `no such index and [action.auto_create_index] contains [-<pattern>] which forbids automatic creation of the index`
* `no such index and [action.auto_create_index] ([all patterns]) doesn't match`
This should make it more clear *why* there is `no such index`.
Closes#22435
Today we do not preserve response headers if they are present on a transport protocol
response. While preserving these headers is not always desired, in the most cases we
should pass on these headers to have consistent results for depreciation headers etc.
yet, this hasn't been much of a problem since most of the deprecations are detected early
ie. on the coordinating node such that this bug wasn't uncovered until #22647
This commit allow to optionally preserve headers when a context is restored and also streamlines
the context restore since it leaked frequently into the callers thread context when the callers
context wasn't restored again.
Instead of forcing each task to register all nodes where its children are running, this commit runs cancellation on all nodes. The task cancellation operation doesn't run too frequently, so this optimization doesn't seem to be worth additional complexity of the interface.
Previously, certain settings that could take multiple comma delimited
values would pick up incorrect values for all entries but the first if
each comma separated value was followed by a whitespace character. For
example, the multi-value "A,B,C" would be correctly parsed as
["A", "B", "C"] but the multi-value "A, B, C" would be incorrectly parsed
as ["A", " B", " C"].
This commit allows a comma separated list to have whitespace characters
after each entry. The specific settings that were affected by this are:
cluster.routing.allocation.awareness.attributes
index.routing.allocation.require.*
index.routing.allocation.include.*
index.routing.allocation.exclude.*
cluster.routing.allocation.require.*
cluster.routing.allocation.include.*
cluster.routing.allocation.exclude.*
http.cors.allow-methods
http.cors.allow-headers
For the allocation filtering related settings, this commit also provides
validation of each specified entry if the filtering is done by _ip,
_host_ip, or _publish_ip, to ensure that each entry is a valid IP
address.
Closes#22297
This commit tries to simplify the way ElasticsearchException are rendered to xcontent. It adds some documentation and renames and merges some methods. Current behavior is preserved, the goal is to be more readable and centralize everything in the ElasticsearchException class.
Today we have quite some abstractions that are essentially providing a simple
dispatch method to the plugins defining a `HttpServerTransport`. This commit
removes `HttpServer` and `HttpServerAdaptor` and introduces a simple `Dispatcher` functional
interface that delegate to `RestController` by default.
Relates to #18482
The IndexingOperationListener interface did not provide any
information about the shard id when a document was indexed.
This commit adds the shard id as the first parameter to all methods
in the IndexingOperationListener.
This is related to #22116. netty channels require socket `connect` and
`accept` privileges. Netty does not currently wrap these operations
with `doPrivileged` blocks. These changes extend the netty channels
and wrap calls to the relevant super methods in doPrivileged blocks.
Adds a message about how the remote is unlikely to be Elasticsearch.
This isn't as good as including the whole message from the remote but
we can't do that because we are stream parsing it and we don't want
to mark the whole request.
Closes#22330
Moves fetching the local node id into `NodeClient` which is a
fairly useful place to put it so you can generate task ids from
`NodeClient#executeLocally`.
It is no longer needed. It used to contain a lot of strings
used by serialization but those have since been removed. Now
it is just another thing to pass around that we don't really
need.
Reindex-from-remote had a race when it tried to clear the scroll. It
first starts the request to clear the scroll and then submits a task
to the generic threadpool to shutdown the client. These two things
race and, in my experience, closing the scroll generally loses. That
means that most of the time reindex-from-remote isn't clearing the
scrolls that it uses. This isn't the end of the world because we
flush old scroll contexts after a while but this isn't great.
Noticed while experimenting with #22514.
Reindex-from-remote was accepting source filtering in the request
but ignoring it and setting `_source=true` on the search URI. This
fixes the filtering so it is piped through to the remote node and
adds tests for that.
Closes#22507
Removes `AggregatorParsers`, replacing all of its functionality with
`XContentParser#namedObject`.
This is the third bit of payoff from #22003, one less thing to pass
around the entire application.
If the remote doesn't return a content type then reindex
tried to guess the content-type. This didn't work most
of the time and produced a rather useless error message.
Given that Elasticsearch always returns the content-type
we are dropping content-type detection in favor of just
failing the request if the remote didn't return a content-type.
Closes#22329
javanna
Nik Everett
Martijn van Groningen
Jack Conradson
Daniel Mitterdorfer
Jay Modi
Jason Tedor
Ryan Ernst
Simon Willnauer
jaymode
Adrien Grand
Tanguy Leroux
Tim Brooks
Boaz Leskes
Nicholas Knize
Christoph Büscher
Tal Levy
Chris Earle
Luca Cavanna
Jim Ferenczi
Igor Motov
Ali Beyad
Alexander Reelsen
Zachary Tong
Jack Conradson