# encoding: binary
#  Phusion Passenger - https://www.phusionpassenger.com/
#  Copyright (c) 2012-2014 Phusion
#
#  "Phusion Passenger" is a trademark of Hongli Lai & Ninh Bui.
#
#  Permission is hereby granted, free of charge, to any person obtaining a copy
#  of this software and associated documentation files (the "Software"), to deal
#  in the Software without restriction, including without limitation the rights
#  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
#  copies of the Software, and to permit persons to whom the Software is
#  furnished to do so, subject to the following conditions:
#
#  The above copyright notice and this permission notice shall be included in
#  all copies or substantial portions of the Software.
#
#  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
#  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
#  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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#  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
#  THE SOFTWARE.

require 'thread'

module PhusionPassenger
module Rack

class OutOfBandGc
  # Usage:
  #
  #   OutOfBandGc.new(app, frequency, logger = nil)
  #   OutOfBandGc.new(app, options = {})
  def initialize(app, *args)
    @app = app
    if args.size == 0 || (args.size == 1 && args[0].is_a?(Hash))
      # OutOfBandGc.new(app, options = {})
      initialize_with_options(args[0] || {})
    else
      # OutOfBandGc.new(app, frequency, logger = nil)
      initialize_legacy(*args)
    end
  end

  def call(env)
    status, headers, body = @app.call(env)

    case @strategy
    when :counting
      @mutex.synchronize do
        @request_count += 1
        if @request_count == @frequency
          @request_count = 0
          headers['X-Passenger-Request-OOB-Work'] = 'true'
        end
      end

    when :gctools_oobgc
      if GC::OOB.dry_run
        headers['X-Passenger-Request-OOB-Work'] = 'true'
      end

    else
      raise "Unrecognized Out-Of-Band GC strategy #{@strategy.inspect}"
    end

    [status, headers, body]
  end

private
  def initialize_with_options(options)
    @strategy = options[:strategy]
    @logger   = options[:logger]

    case @strategy
    when :counting
      @frequency     = options[:frequency]
      @request_count = 0
      @mutex         = Mutex.new
      if !@frequency || @frequency < 1
        raise ArgumentError, "The :frequency option must be a number that is at least 1."
      end
      ::PhusionPassenger.on_event(:oob_work) do
        t0 = Time.now
        disabled = GC.enable
        GC.start
        GC.disable if disabled
        @logger.info "Out Of Band GC finished in #{Time.now - t0} sec" if @logger
      end

    when :gctools_oobgc
      if !defined?(::GC::OOB)
        raise "To use the :gctools_oobgc strategy, " +
          "first add 'gem \"gctools\"' to your Gemfile, " +
          "then call 'require \"gctools/oobgc\"' and 'GC::OOB.setup' " +
          "before using the #{self.class.name} middleware."
      elsif !::GC::OOB.respond_to?(:dry_run)
        raise "To use the :gctools_oobgc strategy, you must use a sufficiently " +
          "recent version of the gctools gem. Please see this pull request: " +
          "https://github.com/tmm1/gctools/pull/5"
      elsif PhusionPassenger::App.options["spawn_method"] =~ /smart/
        # Using GC::OOB with 'smart' currently results in a segfault.
        raise "The :gctools_oobgc strategy cannot be used with the '" +
          PhusionPassenger::App.options["spawn_method"] + "' spawning method. " +
          "Please use 'direct'."
      end

      ::PhusionPassenger.on_event(:oob_work) do
        t0 = Time.now
        GC::OOB.run
        @logger.info "Out Of Band GC finished in #{Time.now - t0} sec" if @logger
      end

    when nil
      raise ArgumentError, "You must specify an Out-Of-Band GC strategy with the :strategy option."

    else
      raise ArgumentError, "Invalid Out-Of-Band GC strategy #{@strategy.inspect}"
    end
  end

  def initialize_legacy(frequency, logger = nil)
    initialize_with_options(
      :strategy => :counting,
      :frequency => frequency,
      :logger => logger)
  end
end

end # module Rack
end # module PhusionPassenger

