Package io.permazen

Class Counter

java.lang.Object
io.permazen.Counter
public class Counter extends Object
Represents a 64-bit counter value that can be adjusted concurrently by multiple transactions, typically without locking (depending on the underlying key/value store).

To define a field of type Counter, annotate the field's getter method as a normal field using @PermazenField. No setter method should be defined. Counter fields do not support indexing or change listeners.

Note: during schema change notifications, counter field values appear as plain Long values.

  • Method Details

    • get

      public long get()
      Read this counter's current value. Invoking this method will typically disable the lock-free behavior of adjust() in the current transaction.
      Returns:
      current value of the counter
      Throws:
      StaleTransactionException - if the transaction from which this instance was read is no longer usable
      DeletedObjectException - if the object from which this instance was read no longer exists

    • set

      public void set(long value)
      Set this counter's value. Invoking this method will typically disable the lock-free behavior of adjust() in the current transaction.
      Parameters:
      value - new value for the counter
      Throws:
      StaleTransactionException - if the transaction from which this instance was read is no longer usable
      DeletedObjectException - if the object from which this instance was read no longer exists

    • adjust

      public void adjust(long offset)
      Adjust this counter's value by the specified amount.
      Parameters:
      offset - amount to add to counter
      Throws:
      StaleTransactionException - if the transaction from which this instance was read is no longer usable
      DeletedObjectException - if the object from which this instance was read no longer exists

    • increment

      public void increment()
      Increment this counter's value by one.
      Throws:
      StaleTransactionException - if the transaction from which this instance was read is no longer usable
      DeletedObjectException - if the object from which this instance was read no longer exists

    • decrement

      public void decrement()
      Decrement this counter's value by one.
      Throws:
      StaleTransactionException - if the transaction from which this instance was read is no longer usable
      DeletedObjectException - if the object from which this instance was read no longer exists