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kotlinx.coroutines v1.3.0-M1 Release Notes

  • Flow:

    • Core Flow interfaces and operators are graduated from preview status to experimental.
    • Context preservation invariant rework (#1210).
      • channelFlow and callbackFlow replacements for flowViaChannel for concurrent flows or callback-based APIs.
      • flow prohibits emissions from non-scoped coroutines by default and recommends to use channelFlow instead to avoid most of the concurrency-related bugs.
    • Flow cannot be implemented directly
      • AbstractFlow is introduced for extension (e.g. for managing state) and ensures all context preservation invariants.
    • Buffer size is decoupled from all operators that imply channel usage (#1233)
      • buffer operator can be used to adjust buffer size of any buffer-dependent operator (e.g. channelFlow, flowOn and flatMapMerge).
      • conflate operator is introduced.
    • Flow performance is significantly improved.
    • New operators: scan, scanReduce, first, emitAll.
    • flowWith and flowViaChannel are deprecated.
    • retry ignores cancellation exceptions from upstream when the flow was externally cancelled (#1122).
    • combineLatest overloads for multiple flows (#1193).
    • Fixed numerical overflow in drop operator.

    Channels:

    • consumeEach is promoted to experimental API (#1080).
    • Conflated channels always deliver the latest value after closing (#332, #1235).
    • Non-suspending ChannelIterator.next to improve iteration performance (#1162).
    • Channel exception types are consistent with produce and are no longer swallowed as cancellation exceptions in case of programmatic errors (#957, #1128).
    • All operators on channels (that were prone to coroutine leaks) are deprecated in the favor of Flow.

    General changes:

    • Kotlin updated to 1.3.31
    • Semaphore implementation (#1088)
    • Loading of Dispatchers.Main is tweaked so the latest version of R8 can completely remove I/O when loading it (#1231).
    • Performace of all JS dispatchers is significantly improved (#820).
    • withContext checks cancellation status on exit to make reasoning about sequential concurrent code easier (#1177).
    • Consistent exception handling mechanism for complex hierarchies (#689).
    • Convenient overload for CoroutinesTimeout.seconds (#1184).
    • Fix cancellation bug in onJoin (#1130).
    • Prevent internal names clash that caused errors for ProGuard (#1159).
    • POSIX's nanosleep as delay in runBlocking in K/N (#1225).