Class: Ferret::Store::Lock

Inherits:
Object
  • Object
show all
Defined in:
lib/ferret/store/directory.rb

Overview

A Lock is used to lock a data source so that not more than one output stream can access a data source at one time. It is possible that locks could be disabled. For example a read only index stored on a CDROM would have no need for a lock.

You can use a lock in two ways. Firstly:

write_lock = @directory.make_lock(LOCK_NAME)
write_lock.obtain(WRITE_LOCK_TIME_OUT)
  ... # Do your file modifications # ...
write_lock.release()

Alternatively you could use the while locked method. This ensures that the lock will be released once processing has finished.

write_lock = @directory.make_lock(LOCK_NAME)
write_lock.while_locked(WRITE_LOCK_TIME_OUT) do
  ... # Do your file modifications # ...
end

Direct Known Subclasses

FSDirectory::FSLock, RAMDirectory::RAMLock

Constant Summary collapse

MAX_ATTEMPTS =

Attempts made to obtain the lock before the application gives up. If you want the process to wait longer to get the lock then just increase the lock timeout

5

Instance Method Summary collapse

Instance Method Details

#locked? ⇒ Boolean

Returns true if there is a lock on the data source

Returns:

  • (Boolean)

Raises:

  • (NotImplementedError) 


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# File 'lib/ferret/store/directory.rb', line 124

def locked?
  raise NotImplementedError
end

#obtain(lock_timeout = 1) ⇒ Object

Obtain the lock on the data source. If you expect to have to wait for a while on a lock then you should set the lock_timeout to a large number. This may be necessary if you are doing multiple large batch updates on an index but the default 1 second should be fine in most cases.

Raises:

  • (NotImplementedError) 


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# File 'lib/ferret/store/directory.rb', line 114

def obtain(lock_timeout = 1)
  raise NotImplementedError
end

#release ⇒ Object

Release the lock on the data source

Raises:

  • (NotImplementedError) 


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# File 'lib/ferret/store/directory.rb', line 119

def release
  raise NotImplementedError
end

#while_locked(lock_timeout = 1) ⇒ Object

Obtains the lock, processes the block and ensures that the lock is released when the block terminates. The lock timeout is in seconds.



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# File 'lib/ferret/store/directory.rb', line 130

def while_locked(lock_timeout=1)
  obtain(lock_timeout)
  begin
    yield
  ensure
    release()
  end
end