Package com.carrotsearch.hppc

Class ShortByteWormMap

java.lang.Object
com.carrotsearch.hppc.ShortByteWormMap
All Implemented Interfaces:
Accountable, Preallocable, ShortByteAssociativeContainer, ShortByteMap, Cloneable, Iterable<ShortByteCursor>
@Generated(date="2021-12-15T10:25:42+0100", value="KTypeVTypeWormMap.java") public class ShortByteWormMap extends Object implements ShortByteMap, Preallocable, Cloneable, Accountable
A hash map of short to byte, implemented using Worm Hashing strategy.

This strategy is appropriate for a medium sized map (less than 2M entries). It takes more time to put entries in the map because it maintains chains of entries having the same hash. Then the lookup speed is fast even if the map is heavy loaded or hashes are clustered. On average it takes slightly less memory than ShortByteHashMap: slightly heavier but the load factor is higher (it varies around 80%) so it enlarges later.

See Also:

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    final class 
    ShortByteWormMap.KeysContainer
    A view of the keys inside this map.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected int
    iterationSeed
    Seed used to ensure the hash iteration order is different from an iteration to another.
    short[]
    keys
    The array holding keys.
    byte[]
    next
    abs(next[i])=offset to next chained entry index.
    protected int
    size
    Map size (number of entries).
    byte[]
    values
    The array holding values.

  • Constructor Summary

    Constructors
    Constructor
    Description
    ShortByteWormMap()
    New instance with sane defaults.
    ShortByteWormMap(int expectedElements)
    New instance with the provided defaults.
    ShortByteWormMap(ShortByteAssociativeContainer container)
    Creates a new instance from all key-value pairs of another container.

  • Method Summary

    Modifier and Type
    Method
    Description
    byte
    addTo(short key, byte additionValue)
    An equivalent of calling
    protected void
    allocateBuffers(int capacity)
     
    void
    clear()
    Clear all keys and values in the container.
    ShortByteWormMap
    clone()
    Clones this map.
    boolean
    containsKey(short key)
    Returns true if this container has an association to a value for the given key.
    void
    ensureCapacity(int expectedElements)
    Ensure this container can hold at least the given number of elements without resizing its buffers.
    boolean
    equals(Object o)
    Compares the specified object with this set for equality.
    <T extends ShortByteProcedure>
    T
    forEach(T procedure)
    Applies a given procedure to all keys-value pairs in this container.
    static ShortByteWormMap
    from(short[] keys, byte[] values)
    Creates a new instance from two index-aligned arrays of key-value pairs.
    byte
    get(short key)
    byte
    getOrDefault(short key, byte defaultValue)
    int
    hashCode()
    protected int
    hashKey(short key)
     
    boolean
    indexExists(int index)
    byte
    indexGet(int index)
    Returns the value associated with an existing key.
    void
    indexInsert(int index, short key, byte value)
    Inserts a key-value pair for a key that is not present in the map.
    int
    indexOf(short key)
    Returns a logical "index" of a given key that can be used to speed up follow-up value setters or getters in certain scenarios (conditional logic).
    byte
    indexRemove(int index)
    Removes a key-value pair at an index previously acquired from ShortByteMap.indexOf(short).
    byte
    indexReplace(int index, byte newValue)
    Replaces the value associated with an existing key and returns any previous value stored for that key.
    boolean
    isEmpty()
    Iterator<ShortByteCursor>
    iterator()
    Returns a cursor over the entries (key-value pairs) in this map.
    ShortByteWormMap.KeysContainer
    keys()
    Returns a collection of keys of this container.
    protected int
    nextIterationSeed()
    Provides the next iteration seed used to build the iteration starting slot and offset increment.
    byte
    noValue()
    The value returned when there is no value associated to a key in this map.
    byte
    put(short key, byte value)
    Place a given key and value in the container.
    int
    putAll(ShortByteAssociativeContainer container)
    Puts all keys from another container to this map, replacing the values of existing keys, if such keys are present.
    int
    putAll(Iterable<? extends ShortByteCursor> iterable)
    Puts all keys from an iterable cursor to this map, replacing the values of existing keys, if such keys are present.
    boolean
    putIfAbsent(short key, byte value)
    If the specified key is not already associated with a value, associates it with the given value.
    byte
    putOrAdd(short key, byte putValue, byte incrementValue)
    If key exists, putValue is inserted into the map, otherwise any existing value is incremented by additionValue.
    long
    ramBytesAllocated()
    Allocated memory estimation
    long
    ramBytesUsed()
    Bytes that is actually been used
    void
    release()
    Removes all elements from the collection and additionally releases any internal buffers.
    byte
    remove(short key)
    Remove all values at the given key.
    int
    removeAll(ShortBytePredicate predicate)
    Removes all keys (and associated values) for which the predicate returns true.
    int
    removeAll(ShortPredicate predicate)
    Removes all keys (and associated values) for which the predicate returns true.
    int
    removeAll(ShortContainer other)
    Removes all keys (and associated values) present in a given container.
    int
    size()
    String
    toString()
    ByteCollection
    values()
    Returns a container view of all values present in this container.
    String
    visualizeKeyDistribution(int characters)
    Visually depict the distribution of keys.

    Methods inherited from class java.lang.Object

    finalize, getClass, notify, notifyAll, wait, wait, wait

    Methods inherited from interface java.lang.Iterable

    forEach, spliterator

  • Field Details

    • keys

      public short[] keys
      The array holding keys.

    • values

      public byte[] values
      The array holding values.

    • next

      public byte[] next
      abs(next[i])=offset to next chained entry index.

      next[i]=0 for free bucket.

      The offset is always forward, and the array is considered circular, meaning that an entry at the end of the array may point to an entry at the beginning with a positive offset.

      The offset is always forward, but the sign of the offset encodes head/tail of chain. next[i] > 0 for the first head-of-chain entry (within [1,WormUtil.maxOffset(int)]), next[i] < 0 for the subsequent tail-of-chain entries (within [-WormUtil.maxOffset(int),-1]. For the last entry in the chain, abs(next[i])=WormUtil.END_OF_CHAIN.

    • size

      protected int size
      Map size (number of entries).

    • iterationSeed

      protected int iterationSeed
      Seed used to ensure the hash iteration order is different from an iteration to another.

  • Constructor Details

    • ShortByteWormMap

      public ShortByteWormMap()
      New instance with sane defaults.

    • ShortByteWormMap

      public ShortByteWormMap(int expectedElements)
      New instance with the provided defaults.

      There is no load factor parameter as this map enlarges automatically. In practice the load factor varies around 80% (between 75% and 90%). The load factor is 100% for tiny maps.

      Parameters:
      expectedElements - The expected number of elements. The capacity of the map is calculated based on it.

    • ShortByteWormMap

      public ShortByteWormMap(ShortByteAssociativeContainer container)
      Creates a new instance from all key-value pairs of another container.

  • Method Details

    • from

      public static ShortByteWormMap from(short[] keys, byte[] values)
      Creates a new instance from two index-aligned arrays of key-value pairs.

    • clone

      public ShortByteWormMap clone()
      Clones this map. The cloning operation is efficient because it copies directly the internal arrays, without having to put entries in the cloned map. The cloned map has the same entries and the same capacity as this map.
      Overrides:
      clone in class Object
      Returns:
      A shallow copy of this map.

    • noValue

      public byte noValue()
      The value returned when there is no value associated to a key in this map. This method can be extended to change it.

    • size

      public int size()
      Specified by:
      size in interface ShortByteAssociativeContainer
      Returns:
      Returns the current size (number of assigned keys) in the container.

    • isEmpty

      public boolean isEmpty()
      Specified by:
      isEmpty in interface ShortByteAssociativeContainer
      Returns:
      Return true if this hash map contains no assigned keys.

    • get

      public byte get(short key)
      Specified by:
      get in interface ShortByteMap
      Returns:
      Returns the value associated with the given key or the default value for the value type, if the key is not associated with any value. For numeric value types, this default value is 0, for object types it is null.

    • getOrDefault

      public byte getOrDefault(short key, byte defaultValue)
      Specified by:
      getOrDefault in interface ShortByteMap
      Returns:
      Returns the value associated with the given key or the provided default value if the key is not associated with any value.

    • put

      public byte put(short key, byte value)
      Place a given key and value in the container.
      Specified by:
      put in interface ShortByteMap
      Returns:
      The value previously stored under the given key in the map is returned.

    • putAll

      public int putAll(ShortByteAssociativeContainer container)
      Puts all keys from another container to this map, replacing the values of existing keys, if such keys are present.
      Specified by:
      putAll in interface ShortByteMap
      Returns:
      Returns the number of keys added to the map as a result of this call (not previously present in the map). Values of existing keys are overwritten.

    • putAll

      public int putAll(Iterable<? extends ShortByteCursor> iterable)
      Puts all keys from an iterable cursor to this map, replacing the values of existing keys, if such keys are present.
      Specified by:
      putAll in interface ShortByteMap
      Returns:
      Returns the number of keys added to the map as a result of this call (not previously present in the map). Values of existing keys are overwritten.

    • putOrAdd

      public byte putOrAdd(short key, byte putValue, byte incrementValue)
      If key exists, putValue is inserted into the map, otherwise any existing value is incremented by additionValue.
      Specified by:
      putOrAdd in interface ShortByteMap
      Parameters:
      key - The key of the value to adjust.
      putValue - The value to put if key does not exist.
      incrementValue - The value to add to the existing value if key exists.
      Returns:
      Returns the current value associated with key (after changes).

    • addTo

      public byte addTo(short key, byte additionValue)
      An equivalent of calling 
       putOrAdd(key, additionValue, additionValue);
      Specified by:
      addTo in interface ShortByteMap
      Parameters:
      key - The key of the value to adjust.
      additionValue - The value to put or add to the existing value if key exists.
      Returns:
      Returns the current value associated with key (after changes).

    • putIfAbsent

      public boolean putIfAbsent(short key, byte value)
      Description copied from interface: ShortByteMap
      If the specified key is not already associated with a value, associates it with the given value.
      Specified by:
      putIfAbsent in interface ShortByteMap
      Parameters:
      key - The key of the value to check.
      value - The value to put if key does not exist.
      Returns:
      true if key did not exist and value was placed in the map.

    • remove

      public byte remove(short key)
      Remove all values at the given key. The default value for the key type is returned if the value does not exist in the map.
      Specified by:
      remove in interface ShortByteMap

    • removeAll

      public int removeAll(ShortContainer other)
      Removes all keys (and associated values) present in a given container. An alias to: 
       keys().removeAll(container)
      but with no additional overhead.
      Specified by:
      removeAll in interface ShortByteAssociativeContainer
      Returns:
      Returns the number of elements actually removed as a result of this call.

    • removeAll

      public int removeAll(ShortPredicate predicate)
      Removes all keys (and associated values) for which the predicate returns true.
      Specified by:
      removeAll in interface ShortByteAssociativeContainer
      Returns:
      Returns the number of elements actually removed as a result of this call.

    • removeAll

      public int removeAll(ShortBytePredicate predicate)
      Removes all keys (and associated values) for which the predicate returns true.
      Specified by:
      removeAll in interface ShortByteAssociativeContainer
      Returns:
      Returns the number of elements actually removed as a result of this call.

    • forEach

      public <T extends ShortByteProcedure> T forEach(T procedure)
      Applies a given procedure to all keys-value pairs in this container. Returns the argument (any subclass of ShortByteProcedure. This lets the caller to call methods of the argument by chaining the call (even if the argument is an anonymous type) to retrieve computed values, for example.
      Specified by:
      forEach in interface ShortByteAssociativeContainer

    • forEach

      public <T extends ShortBytePredicate> T forEach(T predicate)
      Applies a given predicate to all keys-value pairs in this container. Returns the argument (any subclass of ShortBytePredicate. This lets the caller to call methods of the argument by chaining the call (even if the argument is an anonymous type) to retrieve computed values, for example. The iteration is continued as long as the predicate returns true.
      Specified by:
      forEach in interface ShortByteAssociativeContainer

    • keys

      public ShortByteWormMap.KeysContainer keys()
      Returns a collection of keys of this container. The returned collection is a view over the key set and any modifications (if allowed) introduced to the collection will propagate to the associative container immediately.
      Specified by:
      keys in interface ShortByteAssociativeContainer

    • values

      public ByteCollection values()
      Returns a container view of all values present in this container. The returned collection is a view over the key set and any modifications (if allowed) introduced to the collection will propagate to the associative container immediately.
      Specified by:
      values in interface ShortByteAssociativeContainer

    • iterator

      public Iterator<ShortByteCursor> iterator()
      Returns a cursor over the entries (key-value pairs) in this map. The iterator is implemented as a cursor and it returns the same cursor instance on every call to Iterator.next(). To read the current key and value use the cursor's public fields. An example is shown below. 
       for (IntShortCursor c : intShortMap) {
   System.out.println("index=" + c.index + " key=" + c.key + " value=" + c.value);
 }

      The index field inside the cursor gives the internal index inside the container's implementation. The interpretation of this index depends on to the container.

      Specified by:
      iterator in interface Iterable<ShortByteCursor>
      Specified by:
      iterator in interface ShortByteAssociativeContainer

    • containsKey

      public boolean containsKey(short key)
      Returns true if this container has an association to a value for the given key.
      Specified by:
      containsKey in interface ShortByteAssociativeContainer

    • clear

      public void clear()
      Clear all keys and values in the container.
      Specified by:
      clear in interface ShortByteMap
      See Also:

    • release

      public void release()
      Removes all elements from the collection and additionally releases any internal buffers. Typically, if the object is to be reused, a simple ShortByteMap.clear() should be a better alternative since it'll avoid reallocation.
      Specified by:
      release in interface ShortByteMap
      See Also:

    • equals

      public boolean equals(Object o)
      Compares the specified object with this set for equality. Returns true if and only if the specified object is also a ShortByteMap and both objects contains exactly the same key-value pairs.
      Specified by:
      equals in interface ShortByteMap
      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      Specified by:
      hashCode in interface ShortByteMap
      Overrides:
      hashCode in class Object
      Returns:
      A hash code of elements stored in the map. The hash code is defined as a sum of hash codes of keys and values stored within the set). Because sum is commutative, this ensures that different order of elements in a set does not affect the hash code.

    • hashKey

      protected int hashKey(short key)

    • indexOf

      public int indexOf(short key)
      Returns a logical "index" of a given key that can be used to speed up follow-up value setters or getters in certain scenarios (conditional logic). The semantics of "indexes" are not strictly defined. Indexes may (and typically won't be) contiguous. The index is valid only between map modifications (it will not be affected by read-only operations like iteration or value retrievals).
      Specified by:
      indexOf in interface ShortByteMap
      Parameters:
      key - The key to locate in the map.
      Returns:
      A non-negative value of the logical "index" of the key in the map or a negative value if the key did not exist.
      See Also:

    • indexExists

      public boolean indexExists(int index)
      Specified by:
      indexExists in interface ShortByteMap
      Parameters:
      index - The index of a given key, as returned from ShortByteMap.indexOf(short).
      Returns:
      Returns true if the index corresponds to an existing key or false otherwise. This is equivalent to checking whether the index is a positive value (existing keys) or a negative value (non-existing keys).
      See Also:

    • indexGet

      public byte indexGet(int index)
      Returns the value associated with an existing key.
      Specified by:
      indexGet in interface ShortByteMap
      Parameters:
      index - The index of an existing key.
      Returns:
      Returns the value currently associated with the key.
      See Also:

    • indexReplace

      public byte indexReplace(int index, byte newValue)
      Replaces the value associated with an existing key and returns any previous value stored for that key.
      Specified by:
      indexReplace in interface ShortByteMap
      Parameters:
      index - The index of an existing key.
      Returns:
      Returns the previous value associated with the key.
      See Also:

    • indexInsert

      public void indexInsert(int index, short key, byte value)
      Inserts a key-value pair for a key that is not present in the map. This method may help in avoiding double recalculation of the key's hash.
      Specified by:
      indexInsert in interface ShortByteMap
      Parameters:
      index - The index of a previously non-existing key, as returned from ShortByteMap.indexOf(short).
      See Also:

    • indexRemove

      public byte indexRemove(int index)
      Removes a key-value pair at an index previously acquired from ShortByteMap.indexOf(short).
      Specified by:
      indexRemove in interface ShortByteMap
      Parameters:
      index - The index of the key to remove, as returned from ShortByteMap.indexOf(short).
      Returns:
      Returns the previous value associated with the key.
      See Also:

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • ensureCapacity

      public void ensureCapacity(int expectedElements)
      Ensure this container can hold at least the given number of elements without resizing its buffers.
      Specified by:
      ensureCapacity in interface Preallocable
      Parameters:
      expectedElements - The total number of elements, inclusive.

    • visualizeKeyDistribution

      public String visualizeKeyDistribution(int characters)
      Visually depict the distribution of keys.
      Specified by:
      visualizeKeyDistribution in interface ShortByteMap
      Parameters:
      characters - The number of characters to "squeeze" the entire buffer into.
      Returns:
      Returns a sequence of characters where '.' depicts an empty fragment of the internal buffer and 'X' depicts full or nearly full capacity within the buffer's range and anything between 1 and 9 is between.

    • ramBytesAllocated

      public long ramBytesAllocated()
      Allocated memory estimation
      Specified by:
      ramBytesAllocated in interface Accountable
      Returns:
      Ram allocated in bytes

    • ramBytesUsed

      public long ramBytesUsed()
      Bytes that is actually been used
      Specified by:
      ramBytesUsed in interface Accountable
      Returns:
      Ram used in bytes

    • allocateBuffers

      protected void allocateBuffers(int capacity)

    • nextIterationSeed

      protected int nextIterationSeed()
      Provides the next iteration seed used to build the iteration starting slot and offset increment. This method does not need to be synchronized, what matters is that each thread gets a sequence of varying seeds.