Package com.arjuna.ats.txoj

Class Lock

  • public class Lock
extends StateManager
    Instances of this class (or derived user classes) are used when trying to set a lock. The default implementation provides a single-write/multiple-reader policy. However, by overridding the appropriate methods, other, type-specific concurrency control locks can be implemented.
    Since:
    JTS 1.0.
    Version:
    $Id: Lock.java 2342 2006-03-30 13:06:17Z $
    Author:
    Mark Little (mark@arjuna.com)

    • Constructor Detail

      • Lock

        public Lock()
        Create a new lock.

      • Lock

        public Lock​(int lm)
        Create a new Lock object and initialise it. Mode is based upon argument. The value of BasicAction.Current determines the values of the remainder of the fields. If there is no action running the owner field is set to be the application uid created when the application starts.

      • Lock

        public Lock​(Uid storeUid)
        This is used when re-initialising a Lock after retrieval from the object store.

    • Method Detail

      • getLockMode

        public final int getLockMode()
        Returns:
        the mode this lock is currently in, e.g., LockMode.READ.

      • getCurrentOwner

        public final Uid getCurrentOwner()
        Returns:
        the identity of the lock's current owner (the transaction id).

      • getAllOwners

        public final ActionHierarchy getAllOwners()
        Returns:
        the transaction hierarchy associated with this lock.

      • getCurrentStatus

        public final int getCurrentStatus()
        Returns:
        the lock's current status.

      • changeHierarchy

        public final void changeHierarchy​(ActionHierarchy newOwner)
        Change the transaction hierarchy associated with the lock to that provided.

      • propagate

        public final void propagate()
        Propagate the lock.

      • modifiesObject

        public boolean modifiesObject()
        Does this lock imply a modification of the object it is applied to? For example, a READ lock would return false, but a WRITE lock would return true.
        Returns:
        true if this lock implies the object's state will be modified, false otherwise.

      • conflictsWith

        public boolean conflictsWith​(Lock otherLock)
        Implementation of Lock conflict check. Returns TRUE if there is conflict FALSE otherwise. Does not take account of relationship in the atomic action hierarchy since this is a function of LockManager.
        Returns:
        true if this lock conflicts with the parameter, false otherwise.

      • equals

        public boolean equals​(Object otherLock)
        Overrides Object.equals()
        Overrides:
        equals in class Object

      • equals

        public boolean equals​(Lock otherLock)
        Are the two locks equal?
        Returns:
        true if the locks are equal, false otherwise.

      • toString

        public String toString()
        Overrides Object.toString()
        Overrides:
        toString in class Object

      • restore_state

        public boolean restore_state​(InputObjectState os,
                             int ot)
        Carefully restore the state of a Lock.
        Overrides:
        restore_state in class StateManager
        Returns:
        true if successful, false otherwise.

      • save_state

        public boolean save_state​(OutputObjectState os,
                          int ot)
        Save the state of a lock object.
        Overrides:
        save_state in class StateManager
        Returns:
        true if successful, false otherwise.

      • getLink

        protected Lock getLink()
        Get the next lock in the chain.

      • setLink

        protected void setLink​(Lock pointTo)
        Set the next lock in the chain.