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Contents
#
# Executes a block exclusively.
#
#
# == Example:
#
# Blocker.start do
# # do smething here.
# end
#
#
# == Credit:
#
# Copyright (C) 2008-2013 NEC Corporation
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License, version 2, as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#
class Blocker
class BlockerError < RuntimeError; end
PATH = "/tmp/cruise.lock"
def self.start &code_block
begin
block
code_block.call
rescue BlockerError, Errno::EACCES
$stderr.puts "Another process is already running. Please wait for a while."
sleep 10
retry
ensure
release
end
end
def self.block
lock = File.open( PATH, "a+" )
locked = lock.flock( File::LOCK_EX | File::LOCK_NB )
unless locked
lock.close
raise BlockerError
end
end
def self.release
File.open( PATH, "w" ) do | lock |
lock.flock( File::LOCK_UN | File::LOCK_NB )
lock.close
File.delete lock.path
end
end
end
### Local variables:
### mode: Ruby
### coding: utf-8-unix
### indent-tabs-mode: nil
### End:
Version data entries
19 entries across 19 versions & 1 rubygems