v3.3.14.RELEASE

Reactor-Core 3.3.14.RELEASE is part of Dysprosium-SR17 release train.

This is a maintenance release.

✨ New features and improvements

• fix #2569 Enrich message of elementAt's IndexOutOfBoundsException
• Add hook to wrap Queues (#2566)

🪲 Bug fixes

• Metrics should prioritize closest tag in case of duplicates (#2560)
• Rework how stepName() is computed (backport #2551 in 3.3.14.RELEASE)
• skipUntil conditional subscriber logic inconsistent (#2578)
• Fix OverflowException in MultiSubscriptionSubscriber, notably affecting concatMap (#2576)

📖 Documentation, Tests and Build

• Fix some metrics tests to avoid implicit use of globalRegistry (#2575)
• [build] Enforce NoHTTP with plugin and relevant exclusions (#2574)
• [build] Document the Java 8/9 stubs in Core's build file (#2573)
• Fix a few return types in Mono javadocs (#2581)
• Amend SerializedSubscriberTest to accept rare double discard (#2592)
• Improve explanations in Retry javadoc (#2609)

👍 Thanks to the following contributors that also participated to this release

@koldat, @mickeelm, @seants, @sjh836

v3.4.2

Reactor-Core 3.4.2 is part of 2020.0.3 Release Train (Europium SR3).

This service release contains a couple bugfixes inherited from 3.3.13.RELEASE as well as additional documentation polishing.

This note focuses on changes specific to this version, see also from 3.3.13.RELEASE release notes

📖 Documentation, Tests and Build

• fix #2494 Clarify Mono.thenReturn javadoc
• fix #2536 Remove references to old retry utils

👍 Thanks to the following contributors that also participated to this release

@bbukaty

v3.3.13.RELEASE

Reactor-Core 3.3.13.RELEASE is part of Dysprosium-SR16 Release Train.

This service release contains a couple bugfixes and documentation polishing.

🪲 Bug fixes

• Fix groupBy initial request off by one (#2450)
• fix #2534 Fix leak in MonoSingle and improve MonoSubscriber setValue

📖 Documentation, Tests and Build

• Mirror the SUPPORT health file in reference guide (#2552)

👍 Thanks to the following contributors that also participated to this release

@OlegDokuka

v3.4.1

Reactor-Core 3.4.1 is part of 2020.0.2 Release Train (Europium SR2).

This service release contains bugfixes and new features.

This note focuses on changes specific to this version, but all changes from 3.2.22.RELEASE and 3.3.12.RELEASE are also included.

⚠️ Update considerations and deprecations

• fix #2459 Add a composite of all source as cause to firstWithValue error
  • this was overlooked when merging the new operator in 3.4.0, so we decided it was fresh enough that the slight behavior change would be acceptable

✨ New features and improvements

• fix #2195 Add timed() operator
  • this new operator exposes various timing information on a Timed wrapper object, allowing richer output of Duration compared to elapsed() and timestamp() (which use Tuple2 and Long)
• [reactor-test] fix #2269 Add test util to capture logs in early-established loggers (see also #2512)
  • LoggerUtils allows the early installation of a Logger factory that will forward to a classic factory AND let the user activate a logging indirection later on during tests
  • this allows a TestLogger to capture internal logs from operators that were classloaded earlier than the unit test
• [reactor-test] fix #1518 Add cold variants of TestPublisher
  • cold variants better behave wrt backpressure and can replay to multiple subscribers at various stages
  • the old behavior (of ignoring requested amount) is still available through a createColdNonCompliant variant
• [reactor-test] When asserting Context in StepVerifier, say from which operator the asserted Context was taken (#2518)

🪲 Bug fixes

• Make RetryWhenMainSubscriber#onError's calls serial (#2499, Fixes #2488)
• fix #2513 ReplayProcessor now correctly pass nanos to buffer, not ms
• from 3.3.12.RELEASE:
  • fix #2519 Cancel propagation on empty collectXxx
• from 3.2..22.RELEASE:
  • fix #2498 Exception thrown in Flux.handle causes hanging in fused case

📖 Documentation, Tests and Build

• Various documentation improvements (#2463, #2457, #2469)
• fix #2468 Review and polish deprecation suppressions
• fix #2502 Generate OSGI Bundle-Version from Europium+ scheme

👍 Thanks to the following contributors that also participated to this release

@dowgiallom, @seants

v3.3.12.RELEASE

Reactor-Core 3.3.12.RELEASE is part of Dysprosium-SR15 Release Train.

This service release contains a couple bugfixes and documentation polishing.

This note focuses on changes specific to this version, but all changes from 3.2.22.RELEASE are also included.

🪲 Bug fixes

• fix #2519 Cancel propagation on empty collectXxx
• from 3.2.22.RELEASE:
  • fix #2498 Exception thrown in Flux.handle causes hanging in fused case

📖 Documentation, Tests and Build

• The Mono contract was not sufficiently and explicitly stated in the docs, this has been fixed (#2481)
• Effort around test tooling: switch to JUnit5, remove JUnit4, switch to AssertJ (#2442, #2465, #2467, #2491)
• Improvements to the javadoc/marble diagrams (#2413, #2289, #2200, #2483, #2509, #2504
• Improvements to the reference guide:
  • Mention the current latest BOM in the "how to get Reactor" section (#2470)
  • Added a section on how to read marble diagrams (appendix B, #2314)
• Bump to latest generation of plugins for asciidoctor (#2510) + allow forcing rendering of pdf reference guide (97f4e4e)

👍 Thanks to the following contributors that also participated to this release

@BilliAlpha

v3.2.22.RELEASE

Reactor-Core 3.2.22.RELEASE is part of Californium-SR23 Release Train.

This is the last release of Californium 👋

This service release contains a bug fix, as well as some polishing changes.

🪲 Bug fixes

• fix #2498 Exception thrown in Flux.handle causes hanging in fused case

📖 Documentation, Tests and Build

• fix #2482 Fix alignment of 1st onNext in flatMapSequential diagrams
• fix #2506/#2527 Switch to GitHub Actions for CI
• Polish to the build wrt repositories order

👍 Thanks to the following contributors that also participated to this release

@koldat

v3.4.0

Reactor-Core 3.4.0 is part of 2020.0.0 Release Train (codename Europium).

This is the first GA release of Europium 🎉

This note focuses on 3.4.0 proper, curating changes from across all milestones.
Note that the 3.4.0 effort was started right after 3.3.5.RELEASE, so this version also contains changes from 3.3.6 to 3.3.11 (see the end of the notes for links).

⚠️ Known Issues

• the firstWithValue new operator has an undocumented way of checking the cause of failure for individual sources, but it uses a suppressed exception rather than a cause. Please refrain from using that, as we'll switch to initCause in 3.4.1 (and properly document the behavior, setting it in stone) => #2459

⚠️ Update considerations

⚠️ 🗑️ Removals

• Schedulers deprecated back in 3.3 have been removed (WorkQueueProcessor and TopicProcessor, #2208)
• Previously deprecated methods and types have been removed (see #2277)

⚠️ ⌛ Deprecations

• Schedulers.elastic() and variants are deprecated, to be removed in 3.5 (#1893)
• FluxProcessor (as well as all concrete implementations of it) are now deprecated and will be removed in 3.5 (#2188, #2431)
  • see the main focus section below for more details
• [api-change] MonoProcessor is made abstract and deprecated, to be removed in 3.5 (#2188, #1053 / f04bede, #2431)
  • see the main focus section below for more details
• Flux.subscribe(Consumer<Subscription>) variant is deprecated, to be removed in 3.5 (#1825)
• first is deprecated to be renamed to firstWithSignal (see firstWithValue in the new features below). The old deprecated method will be removed in 3.5 (#2173)
• Context changes (#2282):
  • Operators exposing the Context at points where there is no use attempting to use write methods are deprecated and will be removed in 3.5 (#2293, 7d6c862)
    • these all receive a ContextView-based variant (see new features below)
    • deferWithContext => deferContextual with a ContextView
    • Signal.getContext() => Signal.getContextView()
  • Operators modifying the Context are renamed to be clearer. Old names are deprecated and will be removed in 3.5 (see new feature below, #2148, eed93d6)

⚠️ ♻️ Behavior Changes

• Most operators that take a Duration and convert it to milliseconds now use nanosecond precision (#1734)
• Operators.onErrorDropped no longer throws, but only logs the dropped exception (#1431)
• When an onError signal reaches the last (lambda based) subscriber in a chain which doesn't have an error handler, the exception is no longer thrown but only logged (#2176)
• Vanilla implementations of Scheduler now initiate their backing infrastructure and apply Schedulers decorator in start() rather than the constructor (#1778)
  • start() is also now implicitly called when instantiating a Scheduler via the Schedulers.Factory
  • Allows to avoid this leaking from constructor
  • ⚠️ Custom implementations should similarly initialized and optionally decorate in start()
• EmitterProcessor with a full backpressure queue no longer blocks until data is requested, but fails fast (#2049)
• Metrics changes
  • Change in how metric meters/tags are named in accordance with the name operator (#1928, #2302)
    • flow tag has been removed entirely
    • using the name({String}) operator will replace reactor. prefix in meter names with the user-provided {String}.
    • ⚠️ using custom tags via the tags(String...) operator, but not name(String) still creates a sparse set of tags in the application which could be rejected by some metrics backend
  • Change name of some meters that used to include (redundant) unit names (#1807)
    • reactor_requested_requested_amount => {name}_requested
    • reactor_subscribed_subscribers => {name}_subscribed
    • notice these meters also take the user-provided {name} into account from the above change
  • Differentiate empty vs valued sequences in metrics via the status tag, introducing completedEmpty value (#1803)

⚠️ ✨ Main focus: Sinks

Sinks are a new API constructed to replace the FluxProcessor and MonoProcessor APIs, which have been deprecated (#2431, #1053).

We distinguish Sinks.Many<T> (a Flux-like sink), Sinks.One<T> (a Mono-like sink) and Sinks.Empty (a Mono<Void>-like sink).

These sinks are constructed through specs under the Sinks class. They expose a two-faced API:

• methods starting with tryEmit are atomic, never throw (#2319, #2329, #2336, #2426) and immediately return an EmitResult enum (originally named Emission) indicating various variations of success or error (#2319, #2338)
• methods starting with emit attempt to provide an easier facade over the above, take an EmitFailureHandler allowing to fine tune some aspects of the default behavior (#2377)

By default, the instances are "serialized", detecting parallel usage and failing fast in tryEmit (#2342, #2410, #2365, 19fc1ba, #2412).
The vanilla reactor sink implementations of emit API terminate with the equivalent of an emitError when parallel usage is detected (#2365) but by using the EmitFailureHandler to drive the sink to retry, possibly with a small amount of sleeping, it should be possible to optimistically get rid of the contention.

It is also possible to get a low-overhead, low-protection instance of vanilla sinks by using the Sinks.unsafe() spec (#2418).
This doesn't detect parallel usage, so it must be used in a responsible way (in a context where the Reactive Streams contract is already externally enforced).

Sinks also expose a asFlux() view (or asMono(), as relevant) for them to be passed to downstream and subscribed, and also expose a bit of state through currentSubscriberCount() getter (#2372) and by being Scannable (at a minimum for TERMINATED and CANCELLED attributes, #2394).

Compared to existing processors, most flavors have a sink equivalent except DirectProcessor, with two close cousins under Sinks.many().multicast() (#2392, #2451):

• directAllOrNothing will ignore tryEmitNext attempts when at least one subscriber doesn't have enough demand,
• directBestEffort will instead push to the subset of subscribers with demand and drop from the perspective of slow subscribers.

This differs from DirectProcessor in the sense that both these sinks are kept open in such a situation, so slow subscribers that increase their request will start seeing values pushed after that (instead of being immediately terminated in DirectProcessor).

There is also a new flavor: an onBackpressureError() variant of the unicast Sink (#2347)

🐞 Bugfixes

See links to Dysprosium releases (3.3.6 to 3.3.11) at the end.

✨ New features

• concatMap now has a variant with 0 prefetch (#2202)
• All Scannable operators answer the new Attr.RUN_STYLE attribute with a RunStyle enum (#2058, #2123)
  • the enum allows to identify operators that run synchronously. Attribute is accessible both at Publisher and Subscriber level
  • RunStyle.SYNC guarantees the operator doesn't change threads
  • RunStyle.ASYNC indicates the operator MAY change threads
  • RunStyle.UNKNOWN (the default) indicates there's no available information (eg. due to the operator wrapping an arbitrary Publisher)
• A Reactor-wide Micrometer MetricsRegistry other than the global one can now be configured (#2253, 64fd556)
  • Use Metrics.MicrometerConfiguration#useRegistry for that purpose
  • The above will attempt to load Micrometer classes, so Micrometer MUST be on the classpath
• New reactive context features (#2282):
  • Context now extends a simplified ContextView API which only expose the read methods (#2279, #2293)
    • the goal is to avoid exposing a seemingly writable (copy-on-write) Context when the only meaningful operations are read operations
    • exposed in Signal#getContextView(), deferContextual operator (variant to deferWithContext) and new transformDeferredContextual operator
  • Added transformDeferredContextual operator that takes a BiFunction, allowing to access the ContextView in the transformation (#2280 then renamed in #2293)
    • Mono.subscribe(valueConsumer, errorConsumer, ...) error Consumer now gets notified of exceptions thrown by the value Consumer (#1995)
  • Renamed Context operators with clearer names (#2148, eed93d6)
    • Mono.subscriberContext() is not aliased, we now advise to use Mono.deferContextual(Mono::just) to get the exact same behavior
    • subscriberContext(Context) is replaced by contextWrite(ContextView) (notice the use of ContextView)
    • subscriberContext(Function) is replaced by contextWrite(Function)
• Added method to snapshot factory+global schedulers (#2325, #2326, f9c7993)
  • use Schedulers.setFactoryWithSnapshot(Factory) to get a Snapshot object while replacing the Factory
  • reset the old factory by using resetFrom(Snapshot)
  • this is used by the reactor-test VirtualTimeScheduler to reset previously customized factories
• The ParallelFlux.subscribe(array) method is now public to allow delegation in wrappers (#2328)
• The Retry object driving #retryWhen operator can now store user-provided state in the form of a ContextView, which is exposed through RetrySignal (#2312, bd8db8a)
• The GroupedFlux#key() method is now marked as @NonNull (#2397)
• Added firstWithValue factory operator (#2173, 41c937f)
  • like first, it let multiple sources compete
  • except it prioritizes valued sources: empty sources are considered irrelevant
  • if no...

v3.3.11.RELEASE

Reactor-Core 3.3.11.RELEASE is part of Dysprosium-SR13 Release Train.

This is a recommended update for all Reactor 3 users.

This release also contains all changes available in 3.2.21.RELEASE

🪲 Bug fixes

• fix #2389 Potential integer overflow on BoundedElasticScheduler constructor

📖 Documentation, Tests and Build

• fix #2416 Don't blanket hide deprecated members in javadoc
• fix #2358 correct marbles for transformDeferred
• [test] Fix flakky boundedElasticScheduler test (#2425)
• [test] #2437 migrate tests to junit5

👍 Thanks to the following contributors that also participated to this release

@yosfik

v3.2.21.RELEASE

Reactor-Core 3.2.21.RELEASE is part of Californium-SR22 Release Train.

This is a minor maintenance release polishing the build and documentation.

📖 Documentation, Tests and Build

• fix #2346 fix windowWithBoundary marble diagram
• fix #2344, #2436 migrate tests to junit 5
• fix #2439 correctly use testNG platform for testNG task
• [doc] Fix List ref name in hybrid push/pull code

👍 Thanks to the following contributors that also participated to this release

@yosfik

v3.4.0-RC2

Reactor-Core 3.4.0-RC2 is part of 2020.0.0-RC2 Release Train (codename Europium).

This second Release Candidate brings further changes to the Sinks API introduced in M2 and polished in RC1.

This release note contains all the changes specific to RC2, as well as some forwarded changes that will be released in 3.3.11.RELEASE.

⚠️ Update considerations and deprecations

• Rework Sinks specs to put unsafe() at root level (#2418)
• Rename Emission to EmitResult (#2426)
• Remove deprecated emit API (#2377)
• Deprecate [Flux|Mono]Processor contracts entirely (#2431)

✨ New features and improvements

• Add emitXxx(EmitFailureHandler) Sinks API (#2377)
• Add firstWithValue operator, alias/deprecate first (#2173)
• VoidProcessor is now a pure empty sink (#2408)
• Add serialized wrappers for Sinks.Empty/Sinks.One (#2410)
• Add currentSubscriberCount() to Sinks.Many|One|Empty (#2372)
• Make sinks scannable for TERMINATED (and CANCELLED) (#2394)
• Add directAllOrNothing/directBestEffort multicast Sinks (#2392)
• Change GroupedFlux#key to @NonNull (#2397)

🪲 Bug fixes

• Fix concurrent terminal signal detection in SerializedManySink (#2412)
• Fix potential integer overflow on BoundedElasticScheduler constructor (#2389)

📖 Documentation, Tests and Build

• correct marbles for transformDeferred (#2358)
• fix windowWithBoundary marble diagram (#2346)
• Don't blanket hide deprecated members in javadoc (#2416)
• Bump jcstress-gradle-plugin to natively fix jar classifier (#2429)
• use a different name for the jcstress jar (#2400)
• [polish] Increase timeout duration to 1ms to avoid hiccups
• [build] Polish granularity of stacks for Nested tests
• [polish] StressSubscriber generified, track onSubscribe, initRequest
• [doc] Polish Sinks doc accounting for RC1 and RC2 latest changes (#2414)
• [test] Polish tests that use nano durations to avoid flakkyness (#2421)

👍 Thanks to the following contributors that also participated to this release

@camsteffen @yosfik