Class Pool<T>

java.lang.Object
org.eclipse.jetty.util.Pool<T>
Type Parameters:
T -
All Implemented Interfaces:
AutoCloseable, Dumpable
public class Pool<T> extends Object implements AutoCloseable, Dumpable
A fast pool of objects, with optional support for multiplexing, max usage count and several optimized strategies plus an optional ThreadLocal cache of the last release entry.

When the method close() is called, all Closeables in the pool are also closed.

  • Field Details

    • LOGGER

      private static final Logger LOGGER

    • entries

      private final List<Pool<T>.Entry> entries

    • maxEntries

      private final int maxEntries

    • strategyType

      private final Pool.StrategyType strategyType

    • locker

      private final Locker locker

    • cache

      private final ThreadLocal<Pool<T>.Entry> cache

    • nextIndex

      private final AtomicInteger nextIndex

    • closed

      private volatile boolean closed

    • maxMultiplex

      private volatile int maxMultiplex

    • maxUsageCount

      private volatile int maxUsageCount

  • Constructor Details

    • Pool

      public Pool(Pool.StrategyType strategyType, int maxEntries)
      Construct a Pool with a specified lookup strategy and no ThreadLocal cache.
      Parameters:
      strategyType - The strategy to used for looking up entries.
      maxEntries - the maximum amount of entries that the pool will accept.

    • Pool

      public Pool(Pool.StrategyType strategyType, int maxEntries, boolean cache)
      Construct a Pool with the specified thread-local cache size and an optional ThreadLocal cache.
      Parameters:
      strategyType - The strategy to used for looking up entries.
      maxEntries - the maximum amount of entries that the pool will accept.
      cache - True if a ThreadLocal cache should be used to try the most recently released entry.

  • Method Details

    • getReservedCount

      public int getReservedCount()

    • getIdleCount

      public int getIdleCount()

    • getInUseCount

      public int getInUseCount()

    • getClosedCount

      public int getClosedCount()

    • getMaxEntries

      public int getMaxEntries()

    • getMaxMultiplex

      public int getMaxMultiplex()

    • setMaxMultiplex

      public final void setMaxMultiplex(int maxMultiplex)

    • getMaxUsageCount

      public int getMaxUsageCount()
      Get the maximum number of times the entries of the pool can be acquired.
      Returns:
      the max usage count.

    • setMaxUsageCount

      public final void setMaxUsageCount(int maxUsageCount)
      Change the max usage count of the pool's entries. All existing idle entries over this new max usage are removed and closed.
      Parameters:
      maxUsageCount - the max usage count.

    • reserve

      @Deprecated public Pool<T>.Entry reserve(int allotment)
      Deprecated.
      Use reserve() instead
      Create a new disabled slot into the pool. The returned entry must ultimately have the Pool.Entry.enable(Object, boolean) method called or be removed via Pool.Entry.remove() or remove(Pool.Entry).
      Parameters:
      allotment - the desired allotment, where each entry handles an allotment of maxMultiplex, or a negative number to always trigger the reservation of a new entry.
      Returns:
      a disabled entry that is contained in the pool, or null if the pool is closed or if the pool already contains getMaxEntries() entries, or the allotment has already been reserved

    • reserve

      public Pool<T>.Entry reserve()
      Create a new disabled slot into the pool. The returned entry must ultimately have the Pool.Entry.enable(Object, boolean) method called or be removed via Pool.Entry.remove() or remove(Pool.Entry).
      Returns:
      a disabled entry that is contained in the pool, or null if the pool is closed or if the pool already contains getMaxEntries() entries

    • acquireAt

      @Deprecated public Pool<T>.Entry acquireAt(int idx)
      Deprecated.
      No longer supported. Instead use a Pool.StrategyType to configure the pool.
      Acquire the entry from the pool at the specified index. This method bypasses the thread-local mechanism.
      Parameters:
      idx - the index of the entry to acquire.
      Returns:
      the specified entry or null if there is none at the specified index or if it is not available.

    • acquire

      public Pool<T>.Entry acquire()
      Acquire an entry from the pool. Only enabled entries will be returned from this method and their enable method must not be called.
      Returns:
      an entry from the pool or null if none is available.

    • startIndex

      private int startIndex(int size)

    • acquire

      public Pool<T>.Entry acquire(Function<Pool<T>.Entry, T> creator)
      Utility method to acquire an entry from the pool, reserving and creating a new entry if necessary.
      Parameters:
      creator - a function to create the pooled value for a reserved entry.
      Returns:
      an entry from the pool or null if none is available.

    • release

      public boolean release(Pool<T>.Entry entry)
      This method will return an acquired object to the pool. Objects that are acquired from the pool but never released will result in a memory leak.
      Parameters:
      entry - the value to return to the pool
      Returns:
      true if the entry was released and could be acquired again, false if the entry should be removed by calling remove(Pool.Entry) and the object contained by the entry should be disposed.
      Throws:
      NullPointerException - if value is null

    • remove

      public boolean remove(Pool<T>.Entry entry)
      Remove a value from the pool.
      Parameters:
      entry - the value to remove
      Returns:
      true if the entry was removed, false otherwise

    • isClosed

      public boolean isClosed()

    • close

      public void close()
      Specified by:
      close in interface AutoCloseable

    • size

      public int size()

    • values

      public Collection<Pool<T>.Entry> values()

    • dump

      public void dump(Appendable out, String indent) throws IOException
      Description copied from interface: Dumpable
      Dump this object (and children) into an Appendable using the provided indent after any new lines. The indent should not be applied to the first object dumped.
      Specified by:
      dump in interface Dumpable
      Parameters:
      out - The appendable to dump to
      indent - The indent to apply after any new lines.
      Throws:
      IOException - if unable to write to Appendable

    • toString

      public String toString()
      Overrides:
      toString in class Object