Package com.carrotsearch.hppc

Class ObjectObjectWormMap<KType,VType>

java.lang.Object
com.carrotsearch.hppc.ObjectObjectWormMap<KType,VType>
All Implemented Interfaces:
Accountable, ObjectObjectAssociativeContainer<KType,VType>, ObjectObjectMap<KType,VType>, Preallocable, Cloneable, Iterable<ObjectObjectCursor<KType,VType>>
@Generated(date="2021-12-15T10:25:41+0100", value="KTypeVTypeWormMap.java") public class ObjectObjectWormMap<KType,VType> extends Object implements ObjectObjectMap<KType,VType>, Preallocable, Cloneable, Accountable
A hash map of Object to Object, 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 ObjectObjectHashMap: slightly heavier but the load factor is higher (it varies around 80%) so it enlarges later.

See Also:

  • Field Details

    • keys

      public Object[] keys
      The array holding keys.

    • values

      public Object[] 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

    • ObjectObjectWormMap

      public ObjectObjectWormMap()
      New instance with sane defaults.

    • ObjectObjectWormMap

      public ObjectObjectWormMap(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.

    • ObjectObjectWormMap

      public ObjectObjectWormMap(ObjectObjectAssociativeContainer<? extends KType,? extends VType> container)
      Creates a new instance from all key-value pairs of another container.

  • Method Details

    • from

      public static <KType, VType> ObjectObjectWormMap<KType,VType> from(KType[] keys, VType[] values)
      Creates a new instance from two index-aligned arrays of key-value pairs.

    • clone

      public ObjectObjectWormMap<KType,VType> 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 VType 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 ObjectObjectAssociativeContainer<KType,VType>
      Returns:
      Returns the current size (number of assigned keys) in the container.

    • isEmpty

      public boolean isEmpty()
      Specified by:
      isEmpty in interface ObjectObjectAssociativeContainer<KType,VType>
      Returns:
      Return true if this hash map contains no assigned keys.

    • get

      public VType get(KType key)
      Specified by:
      get in interface ObjectObjectMap<KType,VType>
      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 VType getOrDefault(KType key, VType defaultValue)
      Specified by:
      getOrDefault in interface ObjectObjectMap<KType,VType>
      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 VType put(KType key, VType value)
      Place a given key and value in the container.
      Specified by:
      put in interface ObjectObjectMap<KType,VType>
      Returns:
      The value previously stored under the given key in the map is returned.

    • putAll

      public int putAll(ObjectObjectAssociativeContainer<? extends KType,? extends VType> 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 ObjectObjectMap<KType,VType>
      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 ObjectObjectCursor<? extends KType,? extends VType>> 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 ObjectObjectMap<KType,VType>
      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.

    • putIfAbsent

      public boolean putIfAbsent(KType key, VType value)
      Description copied from interface: ObjectObjectMap
      If the specified key is not already associated with a value, associates it with the given value.
      Specified by:
      putIfAbsent in interface ObjectObjectMap<KType,VType>
      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 VType remove(KType 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 ObjectObjectMap<KType,VType>

    • removeAll

      public int removeAll(ObjectContainer<? super KType> 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 ObjectObjectAssociativeContainer<KType,VType>
      Returns:
      Returns the number of elements actually removed as a result of this call.

    • removeAll

      public int removeAll(ObjectPredicate<? super KType> predicate)
      Removes all keys (and associated values) for which the predicate returns true.
      Specified by:
      removeAll in interface ObjectObjectAssociativeContainer<KType,VType>
      Returns:
      Returns the number of elements actually removed as a result of this call.

    • removeAll

      public int removeAll(ObjectObjectPredicate<? super KType,? super VType> predicate)
      Removes all keys (and associated values) for which the predicate returns true.
      Specified by:
      removeAll in interface ObjectObjectAssociativeContainer<KType,VType>
      Returns:
      Returns the number of elements actually removed as a result of this call.

    • forEach

      public <T extends ObjectObjectProcedure<? super KType, ? super VType>> T forEach(T procedure)
      Applies a given procedure to all keys-value pairs in this container. Returns the argument (any subclass of ObjectObjectProcedure. 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 ObjectObjectAssociativeContainer<KType,VType>

    • forEach

      public <T extends ObjectObjectPredicate<? super KType, ? super VType>> T forEach(T predicate)
      Applies a given predicate to all keys-value pairs in this container. Returns the argument (any subclass of ObjectObjectPredicate. 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 ObjectObjectAssociativeContainer<KType,VType>

    • keys

      public ObjectObjectWormMap<KType,VType>.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 ObjectObjectAssociativeContainer<KType,VType>

    • values

      public ObjectCollection<VType> 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 ObjectObjectAssociativeContainer<KType,VType>

    • iterator

      public Iterator<ObjectObjectCursor<KType,VType>> 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<KType>
      Specified by:
      iterator in interface ObjectObjectAssociativeContainer<KType,VType>

    • containsKey

      public boolean containsKey(KType key)
      Returns true if this container has an association to a value for the given key.
      Specified by:
      containsKey in interface ObjectObjectAssociativeContainer<KType,VType>

    • clear

      public void clear()
      Clear all keys and values in the container.
      Specified by:
      clear in interface ObjectObjectMap<KType,VType>
      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 ObjectObjectMap.clear() should be a better alternative since it'll avoid reallocation.
      Specified by:
      release in interface ObjectObjectMap<KType,VType>
      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 ObjectObjectMap and both objects contains exactly the same key-value pairs.
      Specified by:
      equals in interface ObjectObjectMap<KType,VType>
      Overrides:
      equals in class Object

    • equals

      protected boolean equals(Object v1, Object v2)

    • hashCode

      public int hashCode()
      Specified by:
      hashCode in interface ObjectObjectMap<KType,VType>
      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(KType key)

    • indexOf

      public int indexOf(KType 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 ObjectObjectMap<KType,VType>
      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 ObjectObjectMap<KType,VType>
      Parameters:
      index - The index of a given key, as returned from ObjectObjectMap.indexOf(KType).
      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 VType indexGet(int index)
      Returns the value associated with an existing key.
      Specified by:
      indexGet in interface ObjectObjectMap<KType,VType>
      Parameters:
      index - The index of an existing key.
      Returns:
      Returns the value currently associated with the key.
      See Also:

    • indexReplace

      public VType indexReplace(int index, VType newValue)
      Replaces the value associated with an existing key and returns any previous value stored for that key.
      Specified by:
      indexReplace in interface ObjectObjectMap<KType,VType>
      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, KType key, VType 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 ObjectObjectMap<KType,VType>
      Parameters:
      index - The index of a previously non-existing key, as returned from ObjectObjectMap.indexOf(KType).
      See Also:

    • indexRemove

      public VType indexRemove(int index)
      Removes a key-value pair at an index previously acquired from ObjectObjectMap.indexOf(KType).
      Specified by:
      indexRemove in interface ObjectObjectMap<KType,VType>
      Parameters:
      index - The index of the key to remove, as returned from ObjectObjectMap.indexOf(KType).
      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 ObjectObjectMap<KType,VType>
      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.