Module: FlockSynchronize

Defined in:
lib/flock_synchronize.rb,
lib/flock_synchronize/version.rb

Constant Summary collapse

VERSION = 
"1.2.0"

Class Method Summary collapse

Class Method Details

.flock_synchronize(key, options = {}) ⇒ Object

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



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# 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