Package org.agrona.concurrent.status

Class AtomicCounter

java.lang.Object
org.agrona.concurrent.status.AtomicCounter
All Implemented Interfaces:
AutoCloseable
public class AtomicCounter extends Object implements AutoCloseable
Atomic counter that is backed by an AtomicBuffer that can be read across threads and processes.

  • Constructor Details

    • AtomicCounter

      public AtomicCounter(AtomicBuffer buffer, int counterId)
      Map a counter over a buffer. This version will NOT free the counter on close.
      Parameters:
      buffer - containing the counter.
      counterId - identifier of the counter.

    • AtomicCounter

      public AtomicCounter(AtomicBuffer buffer, int counterId, CountersManager countersManager)
      Map a counter over a buffer. This version will free the counter on close.
      Parameters:
      buffer - containing the counter.
      counterId - identifier for the counter.
      countersManager - to be called to free the counter on close.

  • Method Details

    • id

      public int id()
      Identity for the counter within the CountersManager.
      Returns:
      identity for the counter within the CountersManager.

    • disconnectCountersManager

      public void disconnectCountersManager()
      Disconnect from CountersManager if allocated, so it can be closed without freeing the slot.

    • close

      public void close()
      Close counter and free the counter slot for reuse of connected to CountersManager.
      Specified by:
      close in interface AutoCloseable

    • isClosed

      public boolean isClosed()
      Has this counter been closed?
      Returns:
      true if this counter has already been closed.

    • label

      public String label()
      Return the label for the counter within the CountersManager.
      Returns:
      the label for the counter within the CountersManager.

    • updateLabel

      public void updateLabel(String newLabel)
      Update the label for the counter constructed with a CountersManager.
      Parameters:
      newLabel - for the counter with a CountersManager.
      Throws:
      IllegalStateException - is not constructed CountersManager.

    • appendToLabel

      public AtomicCounter appendToLabel(String suffix)
      Append to the label for a counter constructed with a CountersManager.
      Parameters:
      suffix - for the counter within a CountersManager.
      Returns:
      this for a fluent API.
      Throws:
      IllegalStateException - is not constructed CountersManager.

    • updateKey

      public void updateKey(Consumer<MutableDirectBuffer> keyFunc)
      Update the key for a counter constructed with a CountersManager.
      Parameters:
      keyFunc - callback to use to update the counter's key
      Throws:
      IllegalStateException - is not constructed CountersManager.

    • updateKey

      public void updateKey(DirectBuffer keyBuffer, int offset, int length)
      Update the key for a counter constructed with a CountersManager.
      Parameters:
      keyBuffer - contains key data to be copied into the counter.
      offset - start of the key data within the keyBuffer
      length - length of the data within the keyBuffer (must be <= CountersReader.MAX_KEY_LENGTH)
      Throws:
      IllegalStateException - is not constructed CountersManager.

    • increment

      public long increment()
      Perform an atomic increment that will not lose updates across threads.
      Returns:
      the previous value of the counter

    • incrementOrdered

      public long incrementOrdered()
      Perform an atomic increment that is not safe across threads.
      Returns:
      the previous value of the counter

    • decrement

      public long decrement()
      Perform an atomic decrement that will not lose updates across threads.
      Returns:
      the previous value of the counter

    • decrementOrdered

      public long decrementOrdered()
      Perform an atomic decrement that is not safe across threads.
      Returns:
      the previous value of the counter

    • set

      public void set(long value)
      Set the counter with volatile semantics.
      Parameters:
      value - to be set with volatile semantics.

    • setOrdered

      public void setOrdered(long value)
      Set the counter with ordered semantics.
      Parameters:
      value - to be set with ordered semantics.

    • setWeak

      public void setWeak(long value)
      Set the counter with normal semantics.
      Parameters:
      value - to be set with normal semantics.

    • getAndAdd

      public long getAndAdd(long increment)
      Add an increment to the counter that will not lose updates across threads.
      Parameters:
      increment - to be added.
      Returns:
      the previous value of the counter

    • getAndAddOrdered

      public long getAndAddOrdered(long increment)
      Add an increment to the counter with ordered store semantics.
      Parameters:
      increment - to be added with ordered store semantics.
      Returns:
      the previous value of the counter

    • getAndSet

      public long getAndSet(long value)
      Get the current value of a counter and atomically set it to a new value.
      Parameters:
      value - to be set.
      Returns:
      the previous value of the counter

    • compareAndSet

      public boolean compareAndSet(long expectedValue, long updateValue)
      Compare the current value to expected and if true then set to the update value atomically.
      Parameters:
      expectedValue - for the counter.
      updateValue - for the counter.
      Returns:
      true if successful otherwise false.

    • get

      public long get()
      Get the latest value for the counter with volatile semantics.
      Returns:
      the latest value for the counter.

    • getWeak

      public long getWeak()
      Get the value of the counter using weak ordering semantics. This is the same a standard read of a field.
      Returns:
      the value for the counter.

    • proposeMax

      public boolean proposeMax(long proposedValue)
      Set the value to a new proposedValue if greater than the current value with memory ordering semantics.
      Parameters:
      proposedValue - for the new max.
      Returns:
      true if a new max as been set otherwise false.

    • proposeMaxOrdered

      public boolean proposeMaxOrdered(long proposedValue)
      Set the value to a new proposedValue if greater than the current value with memory ordering semantics.
      Parameters:
      proposedValue - for the new max.
      Returns:
      true if a new max as been set otherwise false.

    • toString

      public String toString()
      Overrides:
      toString in class Object