Class: Xxeo::LockFile

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

Instance Method Summary collapse

Constructor Details

#initialize(pathname, options = {}) ⇒ LockFile

Returns a new instance of LockFile.



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# File 'lib/lockfile.rb', line 31

def initialize(pathname, options = {})
  options[:env]      ||= 'development'
  
  raise "lockfile not writable" if not File.writable? pathname

  @f = File.open(pathname, 'r')

  raise "could not open file" if not @f

  @lock_count = 0
end

Instance Method Details

#lock ⇒ Object

We allow a process that holds a lock to recursively acquire the lock, the allows the higher level programs to not have to keep track of the lock status This is becase the flock mechanism doesn’t do reference counting.



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# File 'lib/lockfile.rb', line 49

def lock
  # already locked, just increase the ref count

  if @lock_count > 0
    @lock_count += 1
    return
  end

  # THIS COULD BLOCK

  @f.flock(File::LOCK_EX)
  @lock_count = 1
end

#lock_count ⇒ Object 



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# File 'lib/lockfile.rb', line 82

def lock_count
  return @lock_count
end

#locked? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/lockfile.rb', line 78

def locked?
  return @lock_count > 0
end

#unlock ⇒ Object 



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# File 'lib/lockfile.rb', line 61

def unlock
  if @lock_count > 1
    @lock_count -= 1
    return
  end

  if @lock_count == 1
    @f.flock(File::LOCK_UN)
    @lock_count -= 1
    return
  end

  if @lock_count < 1
    raise "Attempt to unlock an unlocked LockFile"
  end
end