☀️ May 2021 Release Notes - Version 21.5.0

As we head into the summer months and longer days, we’ve got a new release of the Twitter CSL libraries.

NOTE

We’ve introduced a new case class validation library (util/util-validator) based on the Jakarta Bean Validation specification. This library wraps the Hibernate Validator <https://hibernate.org/validator/>__ reference implementation for validating case classes. Check out the user guide documentation!

Util

New Features

• util-validator: Introduce new library for case class validations (akin to Java bean validation) which follows the Jakarta Bean Validation specification by wrapping the Hibernate Validator library and thus supports jakarta.validation.Constraint annotations and validators for annotating and validating fields of Scala case classes. 5849d91c
• util-app: Introduce a Java-friendly API c.t.app.App#runOnExit(Runnable) and c.t.app.App#runOnExitLast(Runnable) to allow Java 8 users to call c.t.app.App#runOnExit and c.t.app.App#runOnExitLast with lambda expressions. c386ece8

Scrooge

• scrooge-generator: Modify struct field names when they match Java keywords by adding an underscore prefix to the field name. a33de276

Finagle

New Features

• finagle-http2: Added c.t.f.http2.param.EnforceMaxConcurrentStreams which allows users to configure http2 clients to buffer streams once a connection has hit the max concurrent stream limit rather than rejecting them. A buffered_streams gauge has been added to track the current number of buffered streams. c6d5f520
• finagle-mux: Added support for TLS snooping to the mux protocol. This allows a thriftmux server to start a connection as TLS or follow the existing upgrade pathway at the leisure of the client. This also allows the server to support opportunistic TLS and still downgrade to vanilla thrift. 60705fd2
• finagle-netty4: Added a new counter to keep track of the number of TLS connections that were started via snooping. 5569615e
• finagle-thrift: Thrift(Mux) clients and servers now fill in a c.t.f.Thrift.param.ServiceClass stack param with the runtime class corresponding to a IDL-generated service stub. 04a2de2c

Breaking API Changes

• finagle-core: c.t.f.param.Logger has been removed. Use external configuration supported by your logging backend to alter settings of com.twitter.finagle logger. 99982cda

Runtime Behavior Changes

• finagle-http: Make handling of invalid URI consistent across client implementations. There are behavioral inconsistencies amongst the current HTTP client implementations:

  Our HTTP/1.x clients allow for submitting requests that contain non-ASCII characters and invalid character encoded sequences, while our HTTP/2 clients will either mangle the URI and strip out non-ASCII characters within the Netty pipeline or result in an UnknownChannelException when attempting to parse invalid character encoded sequences. With this change, we now consistently propagate an InvalidUriException result, which is marked as NonRetryable for all HTTP client implementations. All HTTP server implementations maintain behavior of returning a 400 Bad Request response status, but now also correctly handle invalid character encoded sequences. fa58caab

Bug Fixes

• finagle-core: Failed writes on Linux due to a remote peer disconnecting should now be properly seen as a c.t.f.ChannelClosedException instead of a c.t.f.UnknownChannelException. 6214e6ac
• finagle-http2: The streams gauge is now correctly added for http2 connections over TLS. c6d5f520
• finagle-core: c.t.f.n.NameTreeFactory will now discard empty elements in c.t.f.NameTree.Unions with zero weight. cf73946d
• finagle-http: All HTTP server implementations consistently return a 400 Bad Request response status when encountering a URI with invalid character encoded sequences. fa58caab

Twitter Server

No Changes

Finatra

Fixed

• finatra-jackson: Do not enforce CaseClassDeserializer deserialization semantics for a field until after any deserializer annotation has been resolved. This fully allows a deserializer to specify how to deserialize a field completely independent of the CaseClassDeserializer requirements for fields. For example, if a user wanted to allow parsing of a JSON null value into a null field instance value, they could define a custom deserializer to do so and annotate the case class field with @JsonDeserialize(using = classOf[CustomNullableDeserializer]).

  Additionally, we fix a bug in how String case class fields are handled when the incoming JSON is not a String-type. The current code incorrectly returns an empty string when the field value is parsed into Jackson ContainerNode or ObjectNode types and an incorrect toString representation for a PojoNode type. We now correctly represent the field value as a string in these cases to deserialize into the case class field. 715890a4

• finatra-jackson: Properly handle Scala enumeration fields wrapped in an Option during deserialization failures in the CaseClassDeserializer#isScalaEnumerationType method. a6cb5a10

Changed

• finatra-kafka: Deprecate c.t.finatra.kafka.consumers.TracingKafkaConsumer as it only produced single-span traces and there is no way to propagate the TraceId back to the caller without changing the entire API. Users should use the c.t.finatra.kafka.consumers.KafkaConsumerTracer.trace method instead to enable tracing for Kafka Consumers. Also added c.t.finatra.kafka.producers.KafkaProducerTraceAnnotator and c.t.finatra.kafka.consumers.KafkaConsumerTraceAnnotator services which will can be used to add custom trace annotations to the producer and consumer spans. bba748e6

• finatra (BREAKING API CHANGE): Update to use the new util/util-validator ScalaValidator for case class field validations. We’ve removed the custom Finatra c.t.finatra.validation.Validator and instead now use the c.t.util.validation.ScalaValidator. Constraint annotations and validator implementations now use the standard jakarta.validation API interface classes instead of any custom Finatra types. We’ve deprecated the custom Finatra constraints as they are duplicative of already existing “standard” or otherwise provided constraints and validators. Additionally, c.t.finatra.validation.ErrorCode is deprecated with no replacement. The same data carried can be obtained via the standard jakarta.validation.ConstraintViolation[T].

  Adapting the Finatra framework to use the util/util-validator also includes the framework Jackson integration. We’re also taking this opportunity to clean up the error reporting interface of the CaseClassFieldMappingException to define a CaseClassFieldMappingException.Reason type to replace the usage of the (removed) ValidationResult.Invalid type. The Reason carries a message String as well as a CaseClassFieldMappingException.Detail which can be one of several possible types including a CaseClassFieldMappingException.ValidationError which carries any failed validation information including the emitted ConstraintViolation[T].

  Lastly, we are deprecating support for JSON serialization/deserialization of JodaTime fields in case classes. This support will be dropped in an upcoming release. Users should prefer to use the JDK 8 java.time classes and we will be adding support for these types in the Finatra Jackson integration in the future. 0731782d

• finatra-jackson: (BREAKING API CHANGE) JsonLogging should use the lazy Scala SLF4J logger and no longer return the passed in argument that’s logged as JSON. 67252f30