Package io.permazen.kv

Class AbstractKVStore

java.lang.Object
io.permazen.kv.AbstractKVStore
All Implemented Interfaces:
KVStore
Direct Known Subclasses:
ArrayKVStore, AtomicArrayKVStore, AtomicKVDatabase, BerkeleyKVTransaction, LevelDBKVStore, LMDBKVStore, MemoryKVStore, MutableView, MVMapKVStore, ReadOnlySpannerView, SimpleKVTransaction, XodusKVStore
public abstract class AbstractKVStore extends Object implements KVStore
Support superclass for KVStore implementations.

This class provides a partial implementation via the following methods:

A read-only KVStore implementation is possible by implementing only getRange(), and a read-write implementation by also implementing put(). However, subclasses typically provide more efficient implementations of the methods listed above.

See Also:

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    protected
    AbstractKVStore()
     

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    adjustCounter(byte[] key, long amount)
    Adjust the counter at the given key by the given amount.
    long
    decodeCounter(byte[] value)
    Decode a counter value previously encoded by encodeCounter().
    byte[]
    encodeCounter(long value)
    Encode a counter value into a byte[] value suitable for use with decodeCounter() and/or adjustCounter().
    byte[]
    get(byte[] key)
    Get the value associated with the given key, if any.
    KVPair
    getAtLeast(byte[] minKey, byte[] maxKey)
    Get the key/value pair having the smallest key greater than or equal to the given minimum, if any.
    KVPair
    getAtMost(byte[] maxKey, byte[] minKey)
    Get the key/value pair having the largest key strictly less than the given maximum, if any.
    void
    put(byte[] key, byte[] value)
    Set the value associated with the given key.
    void
    remove(byte[] key)
    Remove the key/value pair with the given key, if it exists.
    void
    removeRange(byte[] minKey, byte[] maxKey)
    Remove all key/value pairs whose keys are in a given range.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    Methods inherited from interface io.permazen.kv.KVStore

    apply, getRange, getRange, getRange, removeRange

  • Constructor Details

    • AbstractKVStore

      protected AbstractKVStore()

  • Method Details

    • get

      public byte[] get(byte[] key)
      Description copied from interface: KVStore
      Get the value associated with the given key, if any.

      Modifications to the returned byte[] array do not affect this instance.

      Specified by:
      get in interface KVStore
      Parameters:
      key - key
      Returns:
      value associated with key, or null if not found

    • getAtLeast

      public KVPair getAtLeast(byte[] minKey, byte[] maxKey)
      Description copied from interface: KVStore
      Get the key/value pair having the smallest key greater than or equal to the given minimum, if any.

      An optional (exclusive) maximum key may also be specified; if maxKey is null, there is no upper bound; if maxKey <= minKey, null is always returned.

      If keys starting with 0xff are not supported by this instance, and minKey starts with 0xff, then this method returns null.

      Modifications to the returned byte[] arrays do not affect this instance.

      Specified by:
      getAtLeast in interface KVStore
      Parameters:
      minKey - minimum key (inclusive), or null for no minimum (get the smallest key)
      maxKey - maximum key (exclusive), or null for no maximum (no upper bound)
      Returns:
      smallest key/value pair with key >= minKey and key < maxKey, or null if none exists

    • getAtMost

      public KVPair getAtMost(byte[] maxKey, byte[] minKey)
      Description copied from interface: KVStore
      Get the key/value pair having the largest key strictly less than the given maximum, if any.

      An optional (inclusive) minimum key may also be specified; if minKey is null, there is no lower bound (equivalent to a lower bound of the empty byte array); if minKey >= maxKey, null is always returned.

      If keys starting with 0xff are not supported by this instance, and maxKey starts with 0xff, then this method behaves as if maxKey were null.

      Modifications to the returned byte[] arrays do not affect this instance.

      Specified by:
      getAtMost in interface KVStore
      Parameters:
      maxKey - maximum key (exclusive), or null for no maximum (get the largest key)
      minKey - minimum key (inclusive), or null for no minimum (no lower bound)
      Returns:
      largest key/value pair with key < maxKey and key >= minKey, or null if none exists

    • put

      public void put(byte[] key, byte[] value)
      Description copied from interface: KVStore
      Set the value associated with the given key.
      Specified by:
      put in interface KVStore
      Parameters:
      key - key
      value - value

    • remove

      public void remove(byte[] key)
      Description copied from interface: KVStore
      Remove the key/value pair with the given key, if it exists.
      Specified by:
      remove in interface KVStore
      Parameters:
      key - key

    • removeRange

      public void removeRange(byte[] minKey, byte[] maxKey)
      Description copied from interface: KVStore
      Remove all key/value pairs whose keys are in a given range.

      The minKey must be less than or equal to maxKey; if they equal (and not null) then nothing happens; if they are both null then all entries are deleted.

      If keys starting with 0xff are not supported by this instance, then:

      • If minKey starts with 0xff, then no change occurs
      • If maxKey starts with 0xff, then this method behaves as if maxKey were null
      Specified by:
      removeRange in interface KVStore
      Parameters:
      minKey - minimum key (inclusive), or null for no minimum
      maxKey - maximum key (exclusive), or null for no maximum

    • encodeCounter

      public byte[] encodeCounter(long value)
      Description copied from interface: KVStore
      Encode a counter value into a byte[] value suitable for use with decodeCounter() and/or adjustCounter().
      Specified by:
      encodeCounter in interface KVStore
      Parameters:
      value - desired counter value
      Returns:
      encoded counter value

    • decodeCounter

      public long decodeCounter(byte[] value)
      Description copied from interface: KVStore
      Decode a counter value previously encoded by encodeCounter().
      Specified by:
      decodeCounter in interface KVStore
      Parameters:
      value - encoded counter value
      Returns:
      decoded counter value

    • adjustCounter

      public void adjustCounter(byte[] key, long amount)
      Description copied from interface: KVStore
      Adjust the counter at the given key by the given amount.

      Ideally this operation should behave in a lock-free manner, so that concurrent transactions can invoke it without conflict. However, when lock-free behavior occurs (if at all) depends on the implementation.

      If there is no value associated with key, or key's value is not a valid counter encoding as would be acceptable to decodeCounter(), then how this operation affects key's value is undefined.

      Specified by:
      adjustCounter in interface KVStore
      Parameters:
      key - key
      amount - amount to adjust counter value by