Class Lock


  • public class Lock
    extends java.lang.Object
    Lock
    Author:
    Mladen Turk
    • Constructor Summary

      Constructors 
      Constructor Description
      Lock()  
    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static long childInit​(java.lang.String fname, long pool)
      Re-open a mutex in a child process.
      static long create​(java.lang.String fname, int mech, long pool)
      Create and initialize a mutex that can be used to synchronize processes.
      static java.lang.String defname()
      Display the name of the default mutex: APR_LOCK_DEFAULT
      static int destroy​(long mutex)
      Destroy the mutex and free the memory associated with the lock.
      static int lock​(long mutex)
      Acquire the lock for the given mutex.
      static java.lang.String lockfile​(long mutex)
      Return the name of the lockfile for the mutex, or NULL if the mutex doesn't use a lock file
      static java.lang.String name​(long mutex)
      Display the name of the mutex, as it relates to the actual method used.
      static int trylock​(long mutex)
      Attempt to acquire the lock for the given mutex.
      static int unlock​(long mutex)
      Release the lock for the given mutex.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Field Detail

      • APR_LOCK_FCNTL

        public static final int APR_LOCK_FCNTL
        Enumerated potential types for APR process locking methods
        Warning : Check APR_HAS_foo_SERIALIZE defines to see if the platform supports APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable.
        See Also:
        Constant Field Values
      • APR_LOCK_PROC_PTHREAD

        public static final int APR_LOCK_PROC_PTHREAD
        System V Semaphores
        See Also:
        Constant Field Values
      • APR_LOCK_POSIXSEM

        public static final int APR_LOCK_POSIXSEM
        POSIX pthread process-based locking
        See Also:
        Constant Field Values
      • APR_LOCK_DEFAULT

        public static final int APR_LOCK_DEFAULT
        POSIX semaphore process-based locking
        See Also:
        Constant Field Values
    • Constructor Detail

      • Lock

        public Lock()
    • Method Detail

      • create

        public static long create​(java.lang.String fname,
                                  int mech,
                                  long pool)
                           throws Error
        Create and initialize a mutex that can be used to synchronize processes.
        Warning : Check APR_HAS_foo_SERIALIZE defines to see if the platform supports APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable.
        Parameters:
        fname - A file name to use if the lock mechanism requires one. This argument should always be provided. The lock code itself will determine if it should be used.
        mech - The mechanism to use for the interprocess lock, if any; one of
                    APR_LOCK_FCNTL
                    APR_LOCK_FLOCK
                    APR_LOCK_SYSVSEM
                    APR_LOCK_POSIXSEM
                    APR_LOCK_PROC_PTHREAD
                    APR_LOCK_DEFAULT     pick the default mechanism for the platform
         
        pool - the pool from which to allocate the mutex.
        Returns:
        Newly created mutex.
        Throws:
        Error - An error occurred
      • childInit

        public static long childInit​(java.lang.String fname,
                                     long pool)
                              throws Error
        Re-open a mutex in a child process. This function must be called to maintain portability, even if the underlying lock mechanism does not require it.
        Parameters:
        fname - A file name to use if the mutex mechanism requires one. This argument should always be provided. The mutex code itself will determine if it should be used. This filename should be the same one that was passed to apr_proc_mutex_create().
        pool - The pool to operate on.
        Returns:
        Newly opened mutex.
        Throws:
        Error - An error occurred
      • lock

        public static int lock​(long mutex)
        Acquire the lock for the given mutex. If the mutex is already locked, the current thread will be put to sleep until the lock becomes available.
        Parameters:
        mutex - the mutex on which to acquire the lock.
        Returns:
        the operation status
      • trylock

        public static int trylock​(long mutex)
        Attempt to acquire the lock for the given mutex. If the mutex has already been acquired, the call returns immediately with APR_EBUSY. Note: it is important that the APR_STATUS_IS_EBUSY(s) macro be used to determine if the return value was APR_EBUSY, for portability reasons.
        Parameters:
        mutex - the mutex on which to attempt the lock acquiring.
        Returns:
        the operation status
      • unlock

        public static int unlock​(long mutex)
        Release the lock for the given mutex.
        Parameters:
        mutex - the mutex from which to release the lock.
        Returns:
        the operation status
      • destroy

        public static int destroy​(long mutex)
        Destroy the mutex and free the memory associated with the lock.
        Parameters:
        mutex - the mutex to destroy.
        Returns:
        the operation status
      • lockfile

        public static java.lang.String lockfile​(long mutex)
        Return the name of the lockfile for the mutex, or NULL if the mutex doesn't use a lock file
        Parameters:
        mutex - the name of the mutex
        Returns:
        the name of the lock file
      • name

        public static java.lang.String name​(long mutex)
        Display the name of the mutex, as it relates to the actual method used. This matches the valid options for Apache's AcceptMutex directive
        Parameters:
        mutex - the name of the mutex
        Returns:
        the name of the mutex
      • defname

        public static java.lang.String defname()
        Display the name of the default mutex: APR_LOCK_DEFAULT
        Returns:
        the default name