mruby-posix_ipc

The POSIX message queue wrapper

install by mrbgems

• add conf.gem line to build_config.rb

MRuby::Build.new do |conf|

  # ... (snip) ...

  conf.gem :github => 'udzura/mruby-posix_ipc'
end

examples

POSIX MQ

## One process

mq = PMQ.create('/sample1', mode: "w")
mq.send("The test message!!1")
# => "The test message!!1"

## Another process

mq = PMQ.create('/tmp/sample1', mode: "r")
mq.receive
# => "The test message!!1"
# will block if no message

## Use channel

r, w = PMQ.channel2 "/hello_2"
Process.fork do
  sleep 0.5
  w.send "foobar"
end

res = r.receive
#=> "foobar"

options for .create and .channel

• :mode specify MQ descriptor read/write mode by letters
• :queue_size specify MQ's max size
• :message_size specify MQ's max message size, default to /proc/sys/fs/mqueue/msgsize_max
• NOTE: .new is a raw and low-level API.

POSIX Semaphore

## Running jobs by 3

begin
  sem = PSem.open('/job_by_3', value: 3)
 
  pids = (0..10).map do |i|
    Process.fork do
      puts "Waiting job: #{i}"
      sem.wait
      puts "Enter job: #{i}"
      sleep rand(10)
      puts "(Now sem.value = #{sem.value})"
      sem.post
    end
  end
 
  pids.each do |pid|
    Process.waitpid pid
  end
 
  puts "Exit all"
ensure
  sem.unlink
end

# log:

    Waiting job: 4
    Waiting job: 0
    Enter job: 0
    Waiting job: 10
    Enter job: 4
    Waiting job: 2
    Waiting job: 3
    Enter job: 3
    Waiting job: 5
    Waiting job: 7
    Waiting job: 9
    Waiting job: 1
    Waiting job: 6
    Waiting job: 8
    (Now sem.value = 0)
    Enter job: 10
    (Now sem.value = 0)
    Enter job: 5
    (Now sem.value = 0)
    Enter job: 7
    (Now sem.value = 0)
    (Now sem.value = 1)
    (Now sem.value = 2)
    Enter job: 1
    Enter job: 2
    Enter job: 6
    (Now sem.value = 0)
    (Now sem.value = 1)
    (Now sem.value = 2)
    Enter job: 9
    Enter job: 8
    (Now sem.value = 1)
    (Now sem.value = 2)
    Exit all


## trywait

sem = PSem.open "/sample4, value: 1
sem.trywait #=> 0
sem.trywait #=> nonblock, but -1

sem.post
sem.trywait #=> 0

• Please examine the test directory for example.

License

under the MIT License:

• see LICENSE file

See also

• posix-mqueue MRI gem