Part of supporting KIP-213 ( https://cwiki.apache.org/confluence/display/KAFKA/KIP-213+Support+non-key+joining+in+KTable ). Murmur3 hash is used as a hashing mechanism in KIP-213 for the large range of uniqueness. The Murmur3 class and tests are ported directly from Apache Hive, with no alterations to the code or dependencies.
Author: Adam Bellemare <adam.bellemare@wishabi.com>
Reviewers: John Roesler <vvcephei@users.noreply.github.com>, Ismael Juma <ismael@juma.me.uk>, Guozhang Wang <wangguoz@gmail.com>
Closes#7271 from bellemare/murmur3hash
This PR makes two changes to code in the ReplicaManager.updateFollowerFetchState path, which is in the hot path for follower fetches. Although calling ReplicaManager.updateFollowerFetch state is inexpensive on its own, it is called once for each partition every time a follower fetch occurs.
1. updateFollowerFetchState no longer calls maybeExpandIsr when the follower is already in the ISR. This avoid repeated expansion checks.
2. Partition.maybeIncrementLeaderHW is also in the hot path for ReplicaManager.updateFollowerFetchState. Partition.maybeIncrementLeaderHW calls Partition.remoteReplicas four times each iteration, and it performs a toSet conversion. maybeIncrementLeaderHW now avoids generating any intermediate collections when updating the HWM.
**Benchmark results for Partition.updateFollowerFetchState on a r5.xlarge:**
Old:
```
1288.633 ±(99.9%) 1.170 ns/op [Average]
(min, avg, max) = (1287.343, 1288.633, 1290.398), stdev = 1.037
CI (99.9%): [1287.463, 1289.802] (assumes normal distribution)
```
New (when follower fetch offset is updated):
```
261.727 ±(99.9%) 0.122 ns/op [Average]
(min, avg, max) = (261.565, 261.727, 261.937), stdev = 0.114
CI (99.9%): [261.605, 261.848] (assumes normal distribution)
```
New (when follower fetch offset is the same):
```
68.484 ±(99.9%) 0.025 ns/op [Average]
(min, avg, max) = (68.446, 68.484, 68.520), stdev = 0.023
CI (99.9%): [68.460, 68.509] (assumes normal distribution)
```
Reviewers: Ismael Juma <ismael@juma.me.uk>, Jason Gustafson <jason@confluent.io>
This creates a test that generates sustained connections against Kafka. There
are three different components we can stress with this, KafkaConsumer,
KafkaProducer, and AdminClient. This test tries use minimal bandwidth per
connection to reduce overhead impacts.
This test works by creating a threadpool that creates connections and then
maintains a central pool of connections at a specified keepalive rate. The
keepalive action varies by which component is being stressed:
* KafkaProducer: Sends one single produce record. The configuration for
the produce request uses the same key/value generator as the ProduceBench
test.
* KafkaConsumer: Subscribes to a single partition, seeks to the end, and
then polls a minimal number of records. Each consumer connection is its
own consumer group, and defaults to 1024 bytes as FETCH_MAX_BYTES to keep
traffic to a minimum.
* AdminClient: Makes an API call to get the nodes in the cluster.
NOTE: This test is designed to be run alongside a ProduceBench test for a
specific topic, due to the way the Consumer test polls a single partition.
There may be no data returned by the consumer test if this is run on its own.
The connection should still be kept alive, but with no data returned.
Author: Scott Hendricks <scott.hendricks@confluent.io>
Reviewers: Stanislav Kozlovski, Gwen Shapira
Closes#7289 from scott-hendricks/trunk
This PR changes the TxnOffsetCommit protocol to auto-generated types, and add more unit test coverage to the plain OffsetCommit protocol.
Reviewers: Jason Gustafson <jason@confluent.io>
New Java Authorizer API and a new out-of-the-box authorizer (AclAuthorizer) that implements the new interface.
Reviewers: Manikumar Reddy <manikumar.reddy@gmail.com>
Prior to this change an NPE is raised when calling AssignedTasks.close
under the following conditions:
1. EOS is enabled
2. The task was in a suspended state
The cause for the NPE is that when a clean close is requested for a
StreamTask the StreamTask tries to commit. However, in the suspended
state there is no producer so ultimately an NPE is thrown for the
contained RecordCollector in flush.
The fix put forth in this commit is to have AssignedTasks call
closeSuspended when it knows the underlying StreamTask is suspended.
Note also that this test is quite involved. I could have just tested
that AssignedTasks calls closeSuspended when appropriate, but that is
testing, IMO, a detail of the implementation and doesn't actually verify
we reproduced the original problem as it was described. I feel much more
confident that we are reproducing the behavior - and we can test exactly
the conditions that lead to it - when testing across AssignedTasks and
StreamTask. I believe this is an additional support for the argument of
eventually consolidating the state split across classes.
Reviewers: Matthias J. Sax <matthias@confluent.io>, Guozhang Wang <wangguoz@gmail.com>
Add the AlterPartitionReassignments and ListPartitionReassignments APIs. Also remove an unused methodlength suppression for KafkaAdminClient.
Reviewers: Colin P. McCabe <cmccabe@apache.org>, Viktor Somogyi <viktorsomogyi@gmail.com>
Implement KIP-480, which specifies that the default partitioner should use a "sticky" partitioning strategy for records that have a null key.
Reviewers: Colin P. McCabe <cmccabe@apache.org>, Lucas Bradstreet <lucasbradstreet@gmail.com>, Stanislav Kozlovski <stanislav_kozlovski@outlook.com>, Jun Rao <junrao@gmail.com>, Kamal Chandraprakash <kamal.chandraprakash@gmail.com>
This patch is part of KIP-345. We are aiming to support batch leave group request issued from admin client. This diff is the first effort to bump leave group request version.
Reviewers: Guozhang Wang <wangguoz@gmail.com>, Jason Gustafson <jason@confluent.io>
ZkUtils was removed so we don't need this anymore.
Also:
* Fix ZkSecurityMigrator and ReplicaManagerTest not to
reference ZkClient classes.
* Remove references to zkclient in various `log4j.properties`
and `import-control.xml`.
Reviewers: Manikumar Reddy <manikumar.reddy@gmail.com>, Stanislav Kozlovski <stanislav_kozlovski@outlook.com>
This upgrade exposes a number of new options, including the WriteBufferManager which -- along with existing TableConfig options -- allows users to limit the total memory used by RocksDB across instances. This can alleviate some cascading OOM potential when, for example, a large number of stateful tasks are suddenly migrated to the same host.
The RocksDB docs guarantee backwards format compatibility across versions
Reviewers: Matthias J. Sax <mjsax@apache.org>, Bill Bejeck <bbejeck@gmail.com>,
Implementation to enable policy for Connector Client config overrides. This is
implemented per the KIP-458.
Reviewers: Randall Hauch <rhauch@gmail.com>
Fix registration of Connect REST extensions to prevent deadlocks when extensions get the list of connectors before the herder is available. Added integration test to check the behavior.
Author: Chris Egerton <cegerton@oberlin.edu>
Reviewers: Arjun Satish <arjun@confluent.io>, Randall Hauch <rhauch@gmail.com>
This is the first diff for the implementation of JoinGroup logic for static membership. The goal of this diff contains:
* Add group.instance.id to be unique identifier for consumer instances, provided by end user;
Modify group coordinator to accept JoinGroupRequest with/without static membership, refactor the logic for readability and code reusability.
* Add client side support for incorporating static membership changes, including new config for group.instance.id, apply stream thread client id by default, and new join group exception handling.
* Increase max session timeout to 30 min for more user flexibility if they are inclined to tolerate partial unavailability than burdening rebalance.
* Unit tests for each module changes, especially on the group coordinator logic. Crossing the possibilities like:
6.1 Dynamic/Static member
6.2 Known/Unknown member id
6.3 Group stable/unstable
6.4 Leader/Follower
The rest of the 345 change will be broken down to 4 separate diffs:
* Avoid kicking out members through rebalance.timeout, only do the kick out through session timeout.
* Changes around LeaveGroup logic, including version bumping, broker logic, client logic, etc.
* Admin client changes to add ability to batch remove static members
* Deprecate group.initial.rebalance.delay
Reviewers: Liquan Pei <liquanpei@gmail.com>, Stanislav Kozlovski <familyguyuser192@windowslive.com>, Jason Gustafson <jason@confluent.io>, Guozhang Wang <wangguoz@gmail.com>
Reviewers: Colin P. McCabe <cmccabe@apache.org>, Viktor Somogyi <viktorsomogyi@gmail.com>, Stanislav Kozlovski <stanislav_kozlovski@outlook.com>, Rajini Sivaram <rajinisivaram@googlemail.com>, Ismael Juma <ismael@juma.me.uk>
Currently close() only awaits completion of pending produce requests. If there is a transaction ongoing, it may be dropped. For example, if one thread is calling commitTransaction() and another calls close(), then the commit may never happen even if the caller is willing to wait for it (by using a long timeout). What's more, the thread blocking in commitTransaction() will be stuck since the result will not be completed once the producer has shutdown.
This patch ensures that 1) completing transactions are awaited, 2) ongoing transactions are aborted, and 3) pending callbacks are completed before close() returns.
Reviewers: Jason Gustafson <jason@confluent.io>
Extend Connect's integration test framework to add or remove workers to EmbeddedConnectCluster, and choosing whether to fail the test on ungraceful service shutdown. Also added more JavaDoc and other minor improvements.
Author: Konstantine Karantasis <konstantine@confluent.io>
Reviewers: Arjun Satish <arjun@confluent.io>, Randall Hauch <rhauch@gmail.com>
Closes#6342 from kkonstantine/KAFKA-8014
The test `org.apache.kafka.connect.runtime.rest.RestServerTest#testCORSEnabled` assumes Jersey client can send restricted HTTP headers(`Origin`).
Jersey client uses `sun.net.www.protocol.http.HttpURLConnection`.
`sun.net.www.protocol.http.HttpURLConnection` drops restricted headers(`Host`, `Keep-Alive`, `Origin`, etc) based on static property `allowRestrictedHeaders`.
This property is initialized in a static block by reading Java system property `sun.net.http.allowRestrictedHeaders`.
So, if classloader loads `HttpURLConnection` before we set `sun.net.http.allowRestrictedHeaders=true`, then all subsequent changes of this system property won't take any effect(which happens if `org.apache.kafka.connect.integration.ExampleConnectIntegrationTest` is executed before `RestServerTest`).
To prevent this, we have to either make sure we set `sun.net.http.allowRestrictedHeaders=true` as early as possible or do not rely on this system property at all.
This PR adds test dependency on `httpcomponents-client` which doesn't depend on `sun.net.http.allowRestrictedHeaders` system property. Thus none of existing tests should interfere with `RestServerTest`.
Author: Alex Diachenko <sansanichfb@gmail.com>
Reviewers: Randall Hauch, Konstantine Karantasis, Gwen Shapira
Closes#6236 from avocader/KAFKA-7799
Reviewers: Guozhang Wang <guozhang@confluent.io>, Ismael Juma <ismael@confluent.io>, Jorge Quilcate Otoya <quilcate.jorge@gmail.com>, John Roesler <john@confluent.io>, Bill Bejeck <bill@confluent.io>
See also KIP-183.
This implements the following algorithm:
AdminClient sends ElectPreferredLeadersRequest.
KafakApis receives ElectPreferredLeadersRequest and delegates to
ReplicaManager.electPreferredLeaders()
ReplicaManager delegates to KafkaController.electPreferredLeaders()
KafkaController adds a PreferredReplicaLeaderElection to the EventManager,
ReplicaManager.electPreferredLeaders()'s callback uses the
delayedElectPreferredReplicasPurgatory to wait for the results of the
election to appear in the metadata cache. If there are no results
because of errors, or because the preferred leaders are already leading
the partitions then a response is returned immediately.
In the EventManager work thread the preferred leader is elected as follows:
The EventManager runs PreferredReplicaLeaderElection.process()
process() calls KafkaController.onPreferredReplicaElectionWithResults()
KafkaController.onPreferredReplicaElectionWithResults()
calls the PartitionStateMachine.handleStateChangesWithResults() to
perform the election (asynchronously the PSM will send LeaderAndIsrRequest
to the new and old leaders and UpdateMetadataRequest to all brokers)
then invokes the callback.
Reviewers: Colin P. McCabe <cmccabe@apache.org>, Jun Rao <junrao@gmail.com>
* Allow the Trogdor agent to be started in "exec mode", where it simply
runs a single task and exits after it is complete.
* For AgentClient and CoordinatorClient, allow the user to pass the path
to a file containing JSON, instead of specifying the JSON object in the
command-line text itself. This means that we can get rid of the bash
scripts whose only function was to load task specs into a bash string
and run a Trogdor command.
* Print dates and times in a human-readable way, rather than as numbers
of milliseconds.
* When listing tasks or workers, output human-readable tables of
information.
* Allow the user to filter on task ID name, task ID pattern, or task
state.
* Support a --json flag to provide raw JSON output if desired.
Reviewed-by: David Arthur <mumrah@gmail.com>, Stanislav Kozlovski <stanislav_kozlovski@outlook.com>
Expose a programmatic way to bring up a Kafka and Zk cluster through Java API to facilitate integration tests for framework level changes in Kafka Connect. The Kafka classes would be similar to KafkaEmbedded in streams. The new classes would reuse the kafka.server.KafkaServer classes from :core, and provide a simple interface to bring up brokers in integration tests.
Signed-off-by: Arjun Satish <arjunconfluent.io>
Author: Arjun Satish <arjun@confluent.io>
Author: Arjun Satish <wicknicks@users.noreply.github.com>
Reviewers: Randall Hauch <rhauch@gmail.com>, Konstantine Karantasis <konstantine@confluent.io>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5516 from wicknicks/connect-integration-test
Reviewers: Bill Bejeck <bill@confluent.io>, John Roesler <john@confluent.io>, Guozhang Wang <guozhang@confluent.io>, Ryanne Dolan <ryannedolan@gmail.com>, Ismael Juma <ismael@confuent.io>
This patch adds a framework to automatically generate the request/response classes for Kafka's protocol. The code will be updated to use the generated classes in follow-up patches. Below is a brief summary of the included components:
**buildSrc/src**
The message generator code is here. This code is automatically re-run by gradle when one of the schema files changes. The entire directory is processed at once to minimize the number of times we have to start a new JVM. We use Jackson to translate the JSON files into Java objects.
**clients/src/main/java/org/apache/kafka/common/protocol/Message.java**
This is the interface implemented by all automatically generated messages.
**clients/src/main/java/org/apache/kafka/common/protocol/MessageUtil.java**
Some utility functions used by the generated message code.
**clients/src/main/java/org/apache/kafka/common/protocol/Readable.java, Writable.java, ByteBufferAccessor.java**
The generated message code uses these classes for writing to a buffer.
**clients/src/main/message/README.md**
This README file explains how the JSON schemas work.
**clients/src/main/message/\*.json**
The JSON files in this directory implement every supported version of every Kafka API. The unit tests automatically validate that the generated schemas match the hand-written schemas in our code. Additionally, there are some things like request and response headers that have schemas here.
**clients/src/main/java/org/apache/kafka/common/utils/ImplicitLinkedHashSet.java**
I added an optimization here for empty sets. This is useful here because I want all messages to start with empty sets by default prior to being loaded with data. This is similar to the "empty list" optimizations in the `java.util.ArrayList` class.
Reviewers: Stanislav Kozlovski <stanislav_kozlovski@outlook.com>, Ismael Juma <ismael@juma.me.uk>, Bob Barrett <bob.barrett@outlook.com>, Jason Gustafson <jason@confluent.io>
KIP-368 implementation to enable periodic re-authentication of SASL clients. Also adds a broker configuration option to terminate client connections that do not re-authenticate within the configured interval.
Add CreatePartitionsRequest.PartitionDetails similar to CreateTopicsRequest.TopicDetails to avoid references from `common.requests` package to `clients`.
Reviewers: Ismael Juma <ismael@juma.me.uk>
Development of EasyMock and PowerMock has stagnated while Mockito
continues to be actively developed. With the new Java release cadence,
it's a problem to depend on libraries that do bytecode manipulation
and are not actively maintained. In addition, Mockito is also
easier to use.
While updating the tests, I attempted to go from failing test to
passing test. In cases where the updated test passed on the first
attempt, I artificially broke it to ensure the test was still doing its
job.
I included a few improvements that were helpful while making these
changes:
1. Better exception if there are no nodes in `leastLoadedNodes`
2. Always close the producer in `KafkaProducerTest`
3. requestsInFlight producer metric should not hold a reference to
`Sender`
Finally, `Metadata` is no longer final so that we don't need
`PowerMock` to mock it. It's an internal class, so it's OK.
Author: Ismael Juma <ismael@juma.me.uk>
Reviewers: Viktor Somogyi <viktorsomogyi@gmail.com>, Dong Lin <lindong28@gmail.com>
Closes#5691 from ijuma/kafka-7438-mockito
Modified several classes' `equals` methods and simplified a complex method to
reduce the NPath complexity so they could be removed from the checkstyle
suppressions that were required with the recent move to Java 8 and upgrade
of Checkstyle: https://github.com/apache/kafka/pull/5046.
Reviewers: Robert Yokota <rayokota@gmail.com>, Arjun Satish <arjun@confluent.io>, Ismael Juma <ismael@juma.me.uk>
A call to `kafka-consumer-groups --describe --group ...` can result in NullPointerException for two reasons:
1) `Fetcher.fetchOffsetsByTimes()` may return too early, without sending list offsets request for topic partitions that are not in cached metadata.
2) `ConsumerGroupCommand.getLogEndOffsets()` and `getLogStartOffsets()` assumed that endOffsets()/beginningOffsets() which eventually call Fetcher.fetchOffsetsByTimes(), would return a map with all the topic partitions passed to endOffsets()/beginningOffsets() and that values are not null. Because of (1), null values were possible if some of the topic partitions were already known (in metadata cache) and some not (metadata cache did not have entries for some of the topic partitions). However, even with fixing (1), endOffsets()/beginningOffsets() may return a map with some topic partitions missing, when list offset request returns a non-retriable error. This happens in corner cases such as message format on broker is before 0.10, or maybe in cases of some other errors.
Testing:
-- added unit test to verify fix in Fetcher.fetchOffsetsByTimes()
-- did some manual testing with `kafka-consumer-groups --describe`, causing NPE. Was not able to reproduce any NPE cases with DescribeConsumerGroupTest.scala,
Reviewers: Jason Gustafson <jason@confluent.io>
Previously, we depicted creating a Jackson serde for every pojo class, which becomes a burden in practice. There are many ways to avoid this and just have a single serde, so we've decided to model this design choice instead.
Reviewers: Viktor Somogyi <viktorsomogyi@gmail.com>, Bill Bejeck <bill@confluent.io>, Guozhang Wang <wangguoz@gmail.com>
Relative paths in Gradle break when the Gradle daemon is used
unless user.dir can be changed while the process is running.
Java 11 disallows this, so we use project paths instead.
Verified that rat and checkstyle work with Java 11 after these
changes.
Reviewers: Dong Lin <lindong28@gmail.com>
We need to use the same lock for metric update and read to avoid NPE and concurrent modification exceptions. Sensor add/remove/update are synchronized on Sensor since they access lists and maps that are not thread-safe. Reporters are notified of metrics add/remove while holding (Sensor, Metrics) locks and reporters may synchronize on the reporter lock. Metric read may be invoked by metrics reporters while holding a reporter lock. So read/update cannot be synchronized using Sensor since that could lead to deadlock. This PR introduces a new lock in Sensor for update/read.
Locking order:
- Sensor#add: Sensor -> Metrics -> MetricsReporter
- Metrics#removeSensor: Sensor -> Metrics -> MetricsReporter
- KafkaMetric#metricValue: MetricsReporter -> Sensor#metricLock
- Sensor#record: Sensor -> Sensor#metricLock
Reviewers: Jun Rao <junrao@gmail.com>, Guozhang Wang <wangguoz@gmail.com>
- Removed Scala consumers (`SimpleConsumer` and `ZooKeeperConsumerConnector`)
and their tests.
- Removed Scala request/response/message classes.
- Removed any mention of new consumer or new producer in the code
with the exception of MirrorMaker where the new.consumer option was
never deprecated so we have to keep it for now. The non-code
documentation has not been updated either, that will be done
separately.
- Removed a number of tools that only made sense in the context
of the Scala consumers (see upgrade notes).
- Updated some tools that worked with both Scala and Java consumers
so that they only support the latter (see upgrade notes).
- Removed `BaseConsumer` and related classes apart from `BaseRecord`
which is used in `MirrorMakerMessageHandler`. The latter is a pluggable
interface so effectively public API.
- Removed `ZkUtils` methods that were only used by the old consumers.
- Removed `ZkUtils.registerBroker` and `ZKCheckedEphemeral` since
the broker now uses the methods in `KafkaZkClient` and no-one else
should be using that method.
- Updated system tests so that they don't use the Scala consumers except
for multi-version tests.
- Updated LogDirFailureTest so that the consumer offsets topic would
continue to be available after all the failures. This was necessary for it
to work with the Java consumer.
- Some multi-version system tests had not been updated to include
recently released Kafka versions, fixed it.
- Updated findBugs and checkstyle configs not to refer to deleted
classes and packages.
Reviewers: Dong Lin <lindong28@gmail.com>, Manikumar Reddy <manikumar.reddy@gmail.com>
Reviewers: Colin Patrick McCabe <colin@cmccabe.xyz>, Jun Rao <junrao@gmail.com>
Co-authored-by: Piyush Vijay <pvijay@apple.com>
Co-authored-by: Andy Coates <big-andy-coates@users.noreply.github.com>
This commit allows secrets in Connect configs to be externalized and replaced with variable references of the form `${provider:[path:]key}`, where the "path" is optional.
There are 2 main additions to `org.apache.kafka.common.config`: a `ConfigProvider` and a `ConfigTransformer`. The `ConfigProvider` is an interface that allows key-value pairs to be provided by an external source for a given "path". An a TTL can be associated with the key-value pairs returned from the path. The `ConfigTransformer` will use instances of `ConfigProvider` to replace variable references in a set of configuration values.
In the Connect framework, `ConfigProvider` classes can be specified in the worker config, and then variable references can be used in the connector config. In addition, the herder can be configured to restart connectors (or not) based on the TTL returned from a `ConfigProvider`. The main class that performs restarts and transformations is `WorkerConfigTransformer`.
Finally, a `configs()` method has been added to both `SourceTaskContext` and `SinkTaskContext`. This allows connectors to get configs with variables replaced by the latest values from instances of `ConfigProvider`.
Most of the other changes in the Connect framework are threading various objects through classes to enable the above functionality.
Author: Robert Yokota <rayokota@gmail.com>
Author: Ewen Cheslack-Postava <me@ewencp.org>
Reviewers: Randall Hauch <rhauch@gmail.com>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#5068 from rayokota/KAFKA-6886-connect-secrets
This PR provides the implementation for KIP-285 and also a reference implementation for authenticating BasicAuth credentials using JAAS LoginModule
Author: Magesh Nandakumar <magesh.n.kumar@gmail.com>
Reviewers: Randall Hauch <rhauch@gmail.com>, Arjun Satish <wicknicks@users.noreply.github.com>, Konstantine Karantasis <konstantine@confluent.io>, Ewen Cheslack-Postava <ewen@confluent.io>
Closes#4931 from mageshn/KIP-285
This KIP adds the following functionality related to SASL/OAUTHBEARER:
1) Allow clients (both brokers when SASL/OAUTHBEARER is the inter-broker protocol as well as non-broker clients) to flexibly retrieve an access token from an OAuth 2 authorization server based on the declaration of a custom login CallbackHandler implementation and have that access token transparently and automatically transmitted to a broker for authentication.
2) Allow brokers to flexibly validate provided access tokens when a client establishes a connection based on the declaration of a custom SASL Server CallbackHandler implementation.
3) Provide implementations of the above retrieval and validation features based on an unsecured JSON Web Token that function out-of-the-box with minimal configuration required (i.e. implementations of the two types of callback handlers mentioned above will be used by default with no need to explicitly declare them).
4) Allow clients (both brokers when SASL/OAUTHBEARER is the inter-broker protocol as well as non-broker clients) to transparently retrieve a new access token in the background before the existing access token expires in case the client has to open new connections.
* Set --source, --target and --release to 1.8.
* Build Scala 2.12 by default.
* Remove some conditionals in the build file now that Java 8
is the minimum version.
* Bump the version of Jetty, Jersey and Checkstyle (the newer
versions require Java 8).
* Fixed issues uncovered by the new version if Checkstyle.
* A couple of minor updates to handle an incompatible source
change in the new version of Jetty.
* Add dependency to jersey-hk2 to fix failing tests caused
by Jersey upgrade.
* Update release script to use Java 8 and to take into account
that Scala 2.12 is now built by default.
* While we're at it, bump the version of Gradle, Gradle plugins,
ScalaLogging, JMH and apache directory api.
* Minor documentation updates including the readme and upgrade
notes. A number of Streams Java 7 examples can be removed
subsequently.
* unify skipped records metering
* log warnings when things get skipped
* tighten up metrics usage a bit
### Testing strategy:
Unit testing of the metrics and the logs should be sufficient.
Author: John Roesler <john@confluent.io>
Reviewers: Bill Bejeck <bill@confluent.io>, Matthias J. Sax <matthias@confluent.io>, Guozhang Wang <wangguoz@gmail.com>
Closes#4812 from vvcephei/kip-274-streams-skip-metrics
Guozhang Wang
Adam Bellemare
Lucas Bradstreet
Scott Hendricks
Boyang Chen
Rajini Sivaram
cpettitt-confluent
Stanislav Kozlovski
Justine Olshan
Andy Coates
Ismael Juma
A. Sophie Blee-Goldman
Magesh Nandakumar
Chris Egerton
Manikumar Reddy
Viktor Somogyi
Konstantine Karantasis
Mickael Maison
Alex Diachenko
Chia-Ping Tsai
Matthias J. Sax
Tom Bentley
Colin Patrick McCabe
Arjun Satish
Arjun Satish
Ron Dagostino
Randall Hauch
Anna Povzner
John Roesler
Joan Goyeau
Robert Yokota
John Roesler