Class: Higgs::FileLock

Inherits:
Object
  • Object
show all
Defined in:
lib/higgs/flock.rb

Constant Summary collapse

CVS_ID =

for ident(1)

'$Id: flock.rb 841 2008-12-24 09:23:20Z toki $'

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(path, read_only = false) ⇒ FileLock

Returns a new instance of FileLock.



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# File 'lib/higgs/flock.rb', line 16

def initialize(path, read_only=false)
  @path = path
  @read_only = read_only
  rdwr_mode = (@read_only) ? File::RDONLY : File::RDWR
  begin
    @f = File.open(path, rdwr_mode | File::CREAT | File::EXCL, 0660)
  rescue Errno::EEXIST
    @f = File.open(path, rdwr_mode, 0660)
  end
end

Instance Attribute Details

#read_only ⇒ Object (readonly)

Returns the value of attribute read_only.



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# File 'lib/higgs/flock.rb', line 27

def read_only
  @read_only
end

Class Method Details

.open(*args) ⇒ Object 



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# File 'lib/higgs/flock.rb', line 72

def self.open(*args)
  flock = new(*args)
  begin
    r = yield(flock)
  ensure
    flock.close
  end
  r
end

Instance Method Details

#close ⇒ Object 



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# File 'lib/higgs/flock.rb', line 47

def close
  unlock
  @f.close
  nil
end

#read_lock ⇒ Object 



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# File 'lib/higgs/flock.rb', line 29

def read_lock
  @f.flock(File::LOCK_SH)
  nil
end

#synchronize(mode = :EX) ⇒ Object 



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# File 'lib/higgs/flock.rb', line 53

def synchronize(mode=:EX)
  case (mode)
  when :SH
    read_lock
  when :EX
    write_lock
  else
    raise ArgumentError, "unknown lock mode: #{mode}"
  end

  begin
    r = yield
  ensure
    unlock
  end

  r
end

#unlock ⇒ Object 



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# File 'lib/higgs/flock.rb', line 42

def unlock
  @f.flock(File::LOCK_UN)
  nil
end

#write_lock ⇒ Object 



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# File 'lib/higgs/flock.rb', line 34

def write_lock
  if (@read_only) then
    raise 'read only'
  end
  @f.flock(File::LOCK_EX)
  nil
end