Package com.tangosol.net.cache

Class ReadWriteBackingMap.WriteQueue

  • Enclosing class:
    ReadWriteBackingMap
    public class ReadWriteBackingMap.WriteQueue
extends com.tangosol.license.CoherenceCommunityEdition
    A queue that only releases entries after a configurable period of time.
    Author:
    cp 2002.10.22

    • Constructor Detail

      • WriteQueue

        protected WriteQueue()
        Construct a WriteQueue that holds write-behind entries.

    • Method Detail

      • getDelaySeconds

        public int getDelaySeconds()
        Returns:
        the number of seconds that an entry added to the queue will sit in the queue before being removable ("ripe")

      • setDelaySeconds

        public void setDelaySeconds​(int cSeconds)
        Specify the number of seconds that an entry added to the queue will sit in the queue before being removable ("ripe").
        Parameters:
        cSeconds - the number of seconds to wait before allowing an entry to be removed from the queue

      • getDelayMillis

        public long getDelayMillis()
        Returns:
        the number of milliseconds that an entry added to the queue will sit in the queue before being removable ("ripe")
        Since:
        Coherence 3.4

      • setDelayMillis

        public void setDelayMillis​(long cMillis)
        Specify the number of milliseconds that an entry added to the queue will sit in the queue before being removable ("ripe").
        Parameters:
        cMillis - the number of milliseconds to wait before allowing an entry to be removed from the queue
        Since:
        Coherence 3.4

      • add

        protected ReadWriteBackingMap.Entry add​(ReadWriteBackingMap.Entry entryNew,
                                        long cDelay)
        Add an entry to the queue. By specifying a cDelay that is greater than 0, persisting of this entry will be delayed with the specified number of milliseconds. Note that the delay will always be adjusted to make sure that this entry ripes no earlier than any existing ones.
        Parameters:
        entryNew - the entry to insert
        cDelay - the number of milliseconds until the entry is considered ripe
        Returns:
        an old entry for the same key, if such an entry existed at the time this method was invoked; null otherwise

      • remove

        protected ReadWriteBackingMap.Entry remove​(Object binKey)
        Remove a key from the queue if the key is in the queue. This method is used, for example, if an item has actually been removed from the backing map.
        Parameters:
        binKey - the key object
        Returns:
        the corresponding entry in the queue or null if the specified key was not in the queue

      • removeImmediate

        protected ReadWriteBackingMap.Entry removeImmediate()
        Remove the first key from the queue immediately.
        Returns:
        the first entry in the queue or null if the queue is empty

      • remove

        public ReadWriteBackingMap.Entry remove()
        Wait for item in the queue to ripen (to be ready to be removed), and when there is one and it is ripe, then remove and return it.
        Returns:
        the next item in the queue (it will only return null when the backing map is no longer active)

      • remove

        public ReadWriteBackingMap.Entry remove​(long cMillis)
        Wait for the next item in the queue to ripen (to be ready to be removed), and remove and return it, or return null if the specified wait time has passed.
        Parameters:
        cMillis - the number of ms to wait for an entry to ripen; pass -1 to wait indefinitely or 0 for no wait
        Returns:
        the next item in the queue, or null if the wait time has passed or if the backing map is no longer active

      • removeNoWait

        public ReadWriteBackingMap.Entry removeNoWait()
        Check for a ripe or soft-ripe item in the queue, and if there is one, return it; otherwise, return null.

        Unlike the remove(java.lang.Object) method, this method will also remove soft-ripe items as calculated using the write-batch factor. A soft-ripe item is an item that has been in the write-behind queue for at least the following duration: 

         D' = (1.0 - F)*D
        where: 
         D = write-behind delay
 F = write-batch factor
        Returns:
        the next item in the queue if one is ripe or soft-ripe and if the backing map is active, otherwise null

      • size

        public int size()
        Returns:
        the length of the queue

      • isEmpty

        public boolean isEmpty()
        Returns:
        true if and only if the queue contains no items

      • isFlushed

        public boolean isFlushed()
        Return true iff all contents have been persisted to the underlying store.
        Returns:
        true iff all contents have been persisted to the underlying store

      • flush

        public void flush()
        Asynchronous flush, i.e. effectively mark all currently queue'd entries as ripe.

      • containsKey

        public boolean containsKey​(Object binKey)
        Parameters:
        binKey - the key to look for
        Returns:
        true if and only if the queue contains the specified key

      • checkPending

        public Object checkPending​(Object binKey)
        Check for an item known to the WriteBehind queue.
        Parameters:
        binKey - the key object to look for
        Returns:
        a value from the queue or a pending map

      • clearPending

        public void clearPending()
        Clear the map of pending entries. Notify all threads that may be waiting for pending store operations to complete.

      • accelerateEntryRipe

        public boolean accelerateEntryRipe​(Binary binKey)
        Move the ripe time for the queued entry up to accelerate the store operation.
        Parameters:
        binKey - the binary key
        Returns:
        true if the entry has already been stored

      • getEntryMap

        protected Map getEntryMap()
        Return a map of items queued to be written.
        Returns:
        the map of items queued to be written

      • getRipeArray

        protected LongArray getRipeArray()
        Return a LongArray indexed by ripe time (when entries become eligible to be written), and associated to a list of binary keys.
        Returns:
        a LongArray of items in the queue

      • getPendingMap

        protected Map getPendingMap()
        Obtain a map of entries removed from the queue, but not yet persisted to the underlying datastore. The returned map is not thread safe, so all access to its content must be synchronized by the caller.
        Returns:
        the map of items not yet persisted to the underlying datastore

      • isWaitingOnPending

        protected boolean isWaitingOnPending()
        Check whether any threads are waiting for the store operation to complete.
        Returns:
        true iff there is at least one waiting thread

      • setWaitingOnPending

        protected void setWaitingOnPending​(boolean fPending)
        Set the flag indicating whether any threads are waiting for the pending store operation to complete.
        Parameters:
        fPending - the boolean value to set