Module: Karafka::Embedded

Defined in:
lib/karafka/embedded.rb

Overview

Allows to start and stop Karafka as part of a different process Following limitations and restrictions apply:

  • ‘#start` cannot be called from a trap context - non blocking

  • ‘#quiet` - can be called from a trap context - non blocking

  • ‘#stop` - can be called from a trap context - blocking

Class Method Summary collapse

Class Method Details

.quiet ⇒ Object

Note:

This method is not blocking and will not wait for Karafka to fully quiet.

Note:

This method can be called from a trap context.

Note:

Please keep in mind you need to ‘#stop` to actually stop the server anyhow.

Quiets Karafka upon any event

It will trigger the quiet procedure but won’t wait.



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# File 'lib/karafka/embedded.rb', line 76

def quiet
  Karafka::Server.quiet
end

.start ⇒ Object

Starts Karafka without supervision and without ownership of signals in a background thread so it won’t interrupt other things running



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# File 'lib/karafka/embedded.rb', line 19

def start
  MUTEX.synchronize do
    # Prevent from double-starting
    return if @started

    @started = true
  end

  Thread.new do
    Thread.current.name = 'karafka.embedded'

    Karafka::Process.tags.add(:execution_mode, 'mode:embedded')
    Karafka::Server.execution_mode = :embedded
    Karafka::Server.start
  end
end

.stop ⇒ Object

Note:

This method is blocking because we want to wait until Karafka is stopped with final process shutdown

Note:

This method is safe to run from a trap context.

Stops Karafka upon any event



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# File 'lib/karafka/embedded.rb', line 42

def stop
  # Prevent from double stopping
  unless @stopping
    Thread.new do
      Thread.current.name = 'karafka.embedded.stopping'

      stop = false

      # We spawn a new thread because `#stop` may be called from a trap context
      MUTEX.synchronize do
        break if @stopping

        @stopping = true
        stop = true
      end

      next unless stop

      Karafka::Server.stop
    end
  end

  # Since we want to have this blocking, we wait for the background thread
  sleep(0.1) until Karafka::App.terminated?
end