Class: Arrow::Session::FileLock

Inherits:
Lock show all
Defined in:
lib/arrow/session/filelock.rb

Overview

The Arrow::Session::FileLock class, a derivative of Arrow::Session::Lock. Instances of this class provide file-based locking for Arrow sessions using the flock(2) system call. It (obviously) won’t work on platforms which don’t support flock(2), or on filesystems which don’t provide flock-based locking semantics (e.g., NFS).

Authors

Please see the file LICENSE in the top-level directory for licensing details.

Constant Summary collapse

DefaultLockDir =

The path to the default lockdir

'/tmp'
LockfileFormat =

The format string that will be used for the name of the lock file. The first ‘%s’ will be replaced with a sanitized version of the session id.

"arrow-session-%s.lock"
FileMode =

The mode to open the lockfile in

File::RDWR|File::CREAT

Constants inherited from Lock

Lock::READ, Lock::UNLOCKED, Lock::WRITE

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Lock

create, derivativeDirs, #locked?, #read_lock, #read_locked?, #read_unlock, #release_all_locks, #with_read_lock, #with_write_lock, #write_lock, #write_locked?, #write_unlock

Methods inherited from Object

deprecate_class_method, deprecate_method, inherited

Constructor Details

#initialize(uri, id) ⇒ FileLock

Create a new Arrow::Session::FileLock object.



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# File 'lib/arrow/session/filelock.rb', line 69

def initialize( uri, id )
  @lockDir = uri.path || DefaultLockDir
  super

  # 'foo de barg blag 0x1f2eca'.gsub( /\W/, '_' ) 
  #  => foo_de_barg_blag_0x1f2eca
  lockfilename = LockfileFormat % id.to_s.gsub( /\W/, '_' )
  File.mkpath( @lockDir )
  @filename = File.join( @lockDir, lockfilename ).untaint
  @lockfile = nil
end

Instance Attribute Details

#lockDir ⇒ Object

The path to the directory where session lockfiles are kept.



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# File 'lib/arrow/session/filelock.rb', line 87

def lockDir
  @lockDir
end

Class Method Details

.clean(directory = DefaultLockDir, threshold = 3600) ⇒ Object

Clean the specified directory of lock files older than threshold seconds.



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# File 'lib/arrow/session/filelock.rb', line 39

def self::clean( directory=DefaultLockDir, threshold=3600 )
  pat = File.join( directory, LockfileFormat.gsub(/%s/, '*') )
  threshold = Time.now - threshold
  Dir[ pat ].each do |file|
    if File.mtime( file ) < threshold
      Arrow::Logger[self].info \
        "Removing stale lockfile '%s'" % file
      begin
        fh = File.open( file, FileMode )
        fh.flock( File::LOCK_EX|File::LOCK_NB )
        File.delete( file )
        fh.flock( File::LOCK_UN )
        fh.close
      rescue => err
        Arrow::Logger[self].warning \
          "Could not clean up '%s': %s" %
          [ file, err.message ]
        next
      end
    end
  end
end

Instance Method Details

#finish ⇒ Object

Indicate to the lock that the caller will no longer be using it, and it may free any resources it had been using.



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# File 'lib/arrow/session/filelock.rb', line 92

def finish
  super
  self.close_lock_file
end