Module: MemprofilerPprof::Atfork

Defined in:
lib/ruby_memprofiler_pprof/atfork.rb

Defined Under Namespace

Classes: Handler

Class Method Summary collapse

Class Method Details

.at_fork(stage = :prepare, &block) ⇒ Object 



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# File 'lib/ruby_memprofiler_pprof/atfork.rb', line 29

def at_fork(stage = :prepare, &block)
  handler = Handler.new.tap do |h|
    h.block = block
    h.stage = stage
  end
  at_fork_handlers << handler
  handler
end

.at_fork_handlers ⇒ Object 



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# File 'lib/ruby_memprofiler_pprof/atfork.rb', line 25

def at_fork_handlers
  @@at_fork_handlers ||= []
end

.fork ⇒ Object 



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# File 'lib/ruby_memprofiler_pprof/atfork.rb', line 38

def fork
  # If a block is provided, it must be wrapped to trigger callbacks.
  child_block = if block_given?
    proc do
      # Trigger :child callback
      at_fork_handlers.select { |h| h.stage == :child }.each(&:call)

      # Invoke original block
      yield
    end
  end

  # Trigger :prepare callback
  at_fork_handlers.select { |h| h.stage == :prepare }.each(&:call)

  # Start fork
  # If a block is provided, use the wrapped version.
  result = child_block.nil? ? super : super(&child_block)

  # Trigger correct callbacks depending on whether we're in the parent or child.
  # If we're in the fork, result = nil: trigger child callbacks.
  # If we're in the parent, result = fork PID: trigger parent callbacks.
  if result.nil?
    # Trigger :child callback
    at_fork_handlers.select { |h| h.stage == :child }.each(&:call)
  else
    # Trigger :parent callback
    at_fork_handlers.select { |h| h.stage == :parent }.each(&:call)
  end
  # rubocop:enable Style/IfInsideElse

  # Return PID from #fork
  result
end