#!/usr/bin/env ruby
# We've tried to implement the usage of persistent pipes in Passenger,
# but we found out that it made Apache slower than when we use socket
# connections. That is in contrast to the results of this benchmark.
#
# We couldn't have used persistent pipes (for multiple sessions) in
# Passenger anyway, because it's too fragile. If something goes wrong
# in one session, then the entire pipe becomes unusable for subsequent
# sessions because the protocol will be in an undefined state. Sockets
# don't have this problem because if an error occurs because each socket
# connection belongs to exactly one session.
require 'benchmark'
 
ITERATIONS = 100000
MESSAGE = " " * 512
MESSAGE_SIZE = [MESSAGE.size].pack('n')
 
def start
  if ARGV.empty?
    benchmark_unix_sockets
    benchmark_persistent_pipes
  elsif ARGV.size == 1 && ARGV[0] == 'unix_sockets'
    benchmark_unix_sockets
  elsif ARGV.size == 1 && ARGV[0] == 'pipes'
    benchmark_persistent_pipes
  else
    puts "Benchmarks performance ."
    puts "Usage: socket_connections_vs_persistent_pipes.rb <unix_sockets|pipes>"
    exit(1)
  end
end
 
def benchmark_unix_sockets
  require 'socket'
  begin
    puts "Benchmarking socket connections..."
    File.unlink("benchmark.socket") rescue nil
    pid = fork do
      server = UNIXServer.new("benchmark.socket")
      ITERATIONS.times do
        client = server.accept
        size = client.read(2).unpack('n')[0]
        client.read(size)
        client.write(MESSAGE)
        client.close
      end
      server.close
    end
    result = Benchmark.measure do
      ITERATIONS.times do
        conn = UNIXSocket.new("benchmark.socket")
        conn.write(MESSAGE_SIZE)
        conn.write(MESSAGE)
        conn.read
        conn.close
      end
    end
    Process.waitpid(pid)
    puts "User/system/real time: #{result}"
    printf "%.2f messages per second\n", ITERATIONS / result.real
  ensure
    File.unlink("benchmark.socket") rescue nil
  end
end
 
def benchmark_persistent_pipes
  puts "Benchmarking pipes connections..."
  reader1, writer1 = IO.pipe
  reader2, writer2 = IO.pipe
  pid = fork do
    reader1.close
    writer2.close
    reader = reader2
    writer = writer1
    ITERATIONS.times do
      size = reader.read(2).unpack('n')[0]
      reader.read(size)
      writer.write(MESSAGE_SIZE)
      writer.write(MESSAGE)
    end
  end
  reader2.close
  writer1.close
  reader = reader1
  writer = writer2
  result = Benchmark.measure do
    ITERATIONS.times do
      writer.write(MESSAGE_SIZE)
      writer.write(MESSAGE)
      size = reader.read(2).unpack('n')[0]
      reader.read(size)
    end
  end
  Process.waitpid(pid)
  puts "User/system/real time: #{result}"
  printf "%.2f messages per second\n", ITERATIONS / result.real
end
 
start