module FlockSynchronize

Constants

VERSION

Public Class Methods

flock_synchronize(key, options={}) { || ... } click to toggle source

flock_synchronize wraps a block with a flock-based mutex.

Any other process calling flock_synchronize with the same key will wait for the previous block to exit before executing.

NOTE: This only works on a per-process basis and is not compatible with Ruby threads. For that, see the built-in Mutex library

FlockSynchronize.flock_synchronize("my operation") do
  some.code_that_needs(synchronizing)
end

Options available:

locking_constant: use a different constant than LOCK_EX. See the
                  File.flock documentation for more info.
timeout:          automatically unlock if the lock was created more
                  this number of seconds ago

# File lib/flock_synchronize.rb, line 24
def self.flock_synchronize(key, options={})
    # Previous versions took locking_constant as second param and now it's
    # a hash
    if !options.kind_of? Hash
        options = {locking_constant: options}
    end
    options[:locking_constant] ||= File::LOCK_EX
    
    filename = File.join(Dir.tmpdir, "#{key}.flock")
    begin
        if options[:timeout]
            if File.exists? filename and (Time.now - File.mtime(filename)) > options[:timeout]
                File.unlink filename
            end
        end
        File.open(filename, 'w') do |f|
            f.flock(options[:locking_constant])
            yield
        end
    ensure
        File.unlink filename if File.exists? filename
    end
end