Class: ProcessLock

Inherits:
Object
  • Object
show all
Defined in:
lib/process_lock.rb,
lib/process_lock/version.rb

Defined Under Namespace

Classes: AlreadyLocked, NotLocked

Constant Summary collapse

VERSION = 
"0.1.1"

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(filename) ⇒ ProcessLock

Returns a new instance of ProcessLock.



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# File 'lib/process_lock.rb', line 14

def initialize(filename)
  @filename = filename
  if defined?(Rails) and Rails.root and (File.basename(filename) == @filename)
    @filename = File.join(Rails.root, 'tmp', 'pids', filename)
    unless filename =~ /\./
      @filename << '.pid'
    end
  end
  FileUtils.touch(@filename)
end

Instance Attribute Details

#filename ⇒ Object (readonly)

Returns the value of attribute filename.



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# File 'lib/process_lock.rb', line 6

def filename
  @filename
end

Instance Method Details

#acquire ⇒ Object 



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# File 'lib/process_lock.rb', line 38

def acquire
  result = acquire_without_block
  if result and block_given?
    begin
      result = yield
    ensure
      release
    end
  end
  result
end

#acquire! ⇒ Object

Raises:



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# File 'lib/process_lock.rb', line 25

def acquire!
  result = acquired = acquire_without_block
  if acquired and block_given?
    begin
      result = yield
    ensure
      release
    end
  end
  raise(AlreadyLocked.new('Unable to acquire lock')) unless acquired
  result
end

#alive? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/process_lock.rb', line 68

def alive?
  pid = read
  return pid > 0 ? Process.kill(0, pid) > 0 : false
rescue
  return false
end

#owner? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/process_lock.rb', line 75

def owner?
  pid = read
  pid and pid > 0 and pid == Process.pid
end

#read ⇒ Object 



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# File 'lib/process_lock.rb', line 80

def read
  open_and_lock{|f| f.read.to_i}
end

#release ⇒ Object 



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# File 'lib/process_lock.rb', line 57

def release
  acquired = false
  open_and_lock do |f|
    acquired = owner?
    if acquired
      f.truncate(f.write(''))
    end
  end
  acquired
end

#release! ⇒ Object 



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# File 'lib/process_lock.rb', line 50

def release!
  unless release
    raise NotLocked.new('Unable to release lock (probably did not own it)')
  end
  true
end