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| | # -*- encoding: binary -*-
class POSIX_MQ
# version of POSIX_MQ, currently 0.4.0
VERSION = '0.4.0'
# An analogous Struct to "struct mq_attr" in C.
# This may be used in arguments for POSIX_MQ.new and
# POSIX_MQ#attr=. POSIX_MQ#attr returns an instance
# of this class.
#
# See the mq_getattr(3) manpage for more information on the values.
Attr = Struct.new(:flags, :maxmsg, :msgsize, :curmsgs)
class << self
# Opens a POSIX message queue and performs operations on the
# given block, closing the message queue at exit.
# All all arguments are passed to POSIX_MQ.new.
def open(*args)
mq = new(*args)
block_given? or return mq
begin
yield mq
ensure
mq.close unless mq.closed?
end
end
end
# Executes the given block upon reception of the next message in an
# empty queue. If the message queue is not empty, then this block
# will only be fired after the queue is emptied and repopulated with
# one message.
#
# This block will only be executed upon the arrival of the
# first message and must be reset/reenabled for subsequent
# notifications. This block will execute in a separate Ruby
# Thread (and thus will safely have the GVL by default).
#
# This method is only supported on platforms that implement
# SIGEV_THREAD functionality in mq_notify(3). So far we only
# know of glibc + Linux supporting this. Please let us
# know if your platform can support this functionality and
# are willing to test for us <ruby.posix.mq@librelist.com>
def notify(&block)
block.arity == 1 or
raise ArgumentError, "arity of notify block must be 1"
r, w = IO.pipe
self.notify_thread = Thread.new(r, w, self) do |r, w, mq|
begin
begin
r.read(1) or raise Errno::EINTR
rescue Errno::EINTR, Errno::EAGAIN
retry
end
block.call(mq)
ensure
mq.notify_thread = nil
r.close rescue nil
w.close rescue nil
end
end
self.notify = w
nil
end if RUBY_PLATFORM =~ /linux/
# There's no point in ever duping a POSIX_MQ object.
# All send/receive operations are atomic and only one
# native thread may be notified at a time
def dup
self
end
# There's no point in ever cloning a POSIX_MQ object.
# All send/receive operations are atomic and only one
# native thread may be notified at a time
alias clone dup
end
require 'posix_mq_ext'
|