Class: Yahns::Worker

Inherits:
Object
  • Object
show all
Defined in:
lib/yahns/worker.rb

Overview

Copyright © 2013, Eric Wong <[email protected]> and all contributors License: GPLv3 or later (www.gnu.org/licenses/gpl-3.0.txt)

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(nr) ⇒ Worker

Returns a new instance of Worker.



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# File 'lib/yahns/worker.rb', line 8

def initialize(nr)
  @nr = nr
  @to_io, @wr = Kgio::Pipe.new
end

Instance Attribute Details

#nr ⇒ Object

:nodoc:



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# File 'lib/yahns/worker.rb', line 5

def nr
  @nr
end

#to_io ⇒ Object (readonly)

Returns the value of attribute to_io.



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# File 'lib/yahns/worker.rb', line 6

def to_io
  @to_io
end

Instance Method Details

#==(other_nr) ⇒ Object

worker objects may be compared to just plain Integers



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# File 'lib/yahns/worker.rb', line 42

def ==(other_nr) # :nodoc:
  @nr == other_nr
end

#atfork_child ⇒ Object 



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# File 'lib/yahns/worker.rb', line 13

def atfork_child
  @wr = @wr.close # nil @wr to save space in worker process
end

#atfork_parent ⇒ Object 



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# File 'lib/yahns/worker.rb', line 17

def atfork_parent
  @to_io = @to_io.close
  self
end

#fake_sig(sig) ⇒ Object

call a signal handler immediately without triggering EINTR We do not use the more obvious Process.kill(sig, $$) here since that signal delivery may be deferred. We want to avoid signal delivery while the Rack app.call is running because some database drivers (e.g. ruby-pg) may cancel pending requests.



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# File 'lib/yahns/worker.rb', line 51

def fake_sig(sig) # :nodoc:
  old_cb = trap(sig, "IGNORE")
  old_cb.call
ensure
  trap(sig, old_cb)
end

#soft_kill(signum) ⇒ Object

master sends fake signals to children



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# File 'lib/yahns/worker.rb', line 59

def soft_kill(signum) # :nodoc:
  # writing and reading 4 bytes on a pipe is atomic on all POSIX platforms
  # Do not care in the odd case the buffer is full, here.
  @wr.kgio_trywrite([signum].pack('l'))
rescue Errno::EPIPE
  # worker will be reaped soon
end

#yahns_step ⇒ Object

used in the worker process. This causes the worker to gracefully exit if the master dies unexpectedly.



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# File 'lib/yahns/worker.rb', line 25

def yahns_step
  case buf = @to_io.kgio_tryread(4)
  when String
    # unpack the buffer and trigger the signal handler
    signum = buf.unpack('l')
    fake_sig(signum[0])
    # keep looping, more signals may be queued
  when nil # EOF: master died, but we are at a safe place to exit
    fake_sig(:QUIT)
    @to_io.close
    return :ignore
  when :wait_readable # keep waiting
    return :ignore
  end while true # loop, as multiple signals may be sent
end