• [Maintenance] Rename the positional topic name parameters of Producer#partition_count, Clients::Buffered#messages_for and the Datadog metrics listener to topic_name.
• [Maintenance] Rename the positional topic name parameter of Clients::Dummy::Handle#initialize to topic_name.
• [Maintenance] Declare rake in the Gemfile. It came only through karafka-rdkafka, which will stop depending on it for precompiled platform gems.
• [Fix] Copy the buffer in Producer#messages (and so the buffer.flushed_async/buffer.flushed_sync payloads) under a dedicated lock, so reading it while other threads buffer no longer raises ConcurrencyError on JRuby.
• [Fix] Re-buffer the undispatched rest of a #flush batch when a concurrent #close stops it, and expose the handles dispatched before the close as ProducerClosedError#dispatched.
• [Fix] Copy the buffer in Producer#messages (and so the buffer.flushed_async/buffer.flushed_sync payloads) under a dedicated lock, so reading it while other threads buffer no longer raises ConcurrencyError on JRuby.