Package io.permazen.kv.mvcc

Class MemoryAtomicKVStore

java.lang.Object
io.permazen.kv.AbstractKVStore
io.permazen.kv.util.MemoryKVStore
io.permazen.kv.mvcc.MemoryAtomicKVStore
All Implemented Interfaces:
KVStore, AtomicKVStore, Serializable, Cloneable
@ThreadSafe public class MemoryAtomicKVStore extends MemoryKVStore implements AtomicKVStore
Provides a KVStore view of an underlying ConcurrentNavigableMap<byte[], byte[]> whose keys are sorted lexicographically as unsigned bytes.

Implementaions are serializable if the underlying map is.

See Also:

  • Constructor Details

    • MemoryAtomicKVStore

      public MemoryAtomicKVStore()
      Convenience constructor. Uses an internally constructed ConcurrentSkipListMap.

      Equivalent to: 

       MemoryAtomicKVStore(new ConcurrentSkipListMap<byte[], byte[]>(ByteUtil.COMPARATOR)
      See Also:

    • MemoryAtomicKVStore

      public MemoryAtomicKVStore(ConcurrentNavigableMap<byte[],byte[]> map)
      Primary constructor.

      The underlying map must sort keys lexicographically as unsigned bytes; otherwise, behavior is undefined.

      Parameters:
      map - underlying map
      Throws:
      IllegalArgumentException - if map is null
      IllegalArgumentException - if an invalid comparator is detected (this check is not reliable)
      See Also:

  • 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
      Overrides:
      get in class MemoryKVStore
      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
      Overrides:
      getAtLeast in class MemoryKVStore
      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
      Overrides:
      getAtMost in class MemoryKVStore
      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

    • getRange

      public CloseableIterator<KVPair> getRange(byte[] minKey, byte[] maxKey, boolean reverse)
      Description copied from interface: KVStore
      Iterate the key/value pairs in the specified range. The returned CloseableIterator's remove() method must be supported and should have the same effect as invoking remove() on the corresponding key.

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

      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.

      The returned CloseableIterator is weakly consistent (see java.util.concurrent). In short, the returned CloseableIterator must not throw ConcurrentModificationException; however, whether or not a "live" CloseableIterator reflects any modifications made after its creation is implementation dependent. Implementations that do make post-creation updates visible in the CloseableIterator, even if the update occurs after some delay, must preserve the order in which the modifications actually occurred.

      The returned CloseableIterator itself is not guaranteed to be thread safe; is should only be used in the thread that created it.

      Invokers of this method are encouraged to close() the returned iterators, though this is not required for correct behavior.

      Modifications to the returned KVPair key and value byte[] arrays do not affect this instance.

      Specified by:
      getRange in interface KVStore
      Overrides:
      getRange in class MemoryKVStore
      Parameters:
      minKey - minimum key (inclusive), or null for no minimum (start at the smallest key)
      maxKey - maximum key (exclusive), or null for no maximum (end at the largest key)
      reverse - true to return key/value pairs in reverse order (i.e., keys descending)
      Returns:
      iteration of key/value pairs in the range minKey (inclusive) to maxKey (exclusive)

    • 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
      Overrides:
      put in class MemoryKVStore
      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
      Overrides:
      remove in class MemoryKVStore
      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
      Overrides:
      removeRange in class MemoryKVStore
      Parameters:
      minKey - minimum key (inclusive), or null for no minimum
      maxKey - maximum key (exclusive), or null for no maximum

    • start

      public void start()
      Description copied from interface: AtomicKVStore
      Start this instance. This method must be called prior to creating any transactions.

      This method is idempotent: if this instance is already started, nothing happens.

      Whether an instance that has been started and stopped can be restarted is implementation-dependent.

      Specified by:
      start in interface AtomicKVStore

    • stop

      public void stop()
      Description copied from interface: AtomicKVStore
      Stop this instance.

      Any open AtomicKVStore.readOnlySnapshot()'s should be close()'d before invoking this method; the behavior of those that are not is undefined.

      This method is idempotent: if this instance has not been started, or is already stopped, nothing happens.

      Specified by:
      stop in interface AtomicKVStore

    • readOnlySnapshot

      public CloseableKVStore readOnlySnapshot()
      Description copied from interface: AtomicKVStore
      Create a read-only "snapshot" view of this instance equal to its current state.

      The returned CloseableKVStore should be treated as read-only. It may not actually be read-only, but if it's not, then any changes should have no effect on this instance. The returned CloseableKVStore must be completely independent from this instance (subsequent changes to either one do not affect the other).

      The returned CloseableKVStore should be promply close()'d when no longer needed to release any underlying resources.

      Specified by:
      readOnlySnapshot in interface AtomicKVStore
      Returns:
      read-only, snapshot view of this instance

    • apply

      public void apply(Mutations mutations, boolean sync)
      Description copied from interface: AtomicKVStore
      Apply a set of mutations to this instance atomically.

      If this method returns normally, all of the given mutations will have been applied. If this method returns abnormally, then none of the given mutations will have been applied.

      In any case, other threads observing this instance will never see a partial application of the given mutations.

      This method is required to apply the mutations in this order: removes, puts, adjusts.

      If sync is true, the implementation must durably persist the changes before returning.

      Specified by:
      apply in interface AtomicKVStore
      Parameters:
      mutations - the mutations to apply
      sync - if true, caller requires that the changes be durably persisted