Object2LongCounterMap (Agrona)

java.lang.Object
- org.agrona.collections.Object2LongCounterMap<K>

```
public class Object2LongCounterMap<K>
extends Object
```
An open-addressing with linear probing hash map specialised for object and primitive counter pairs. A counter map views counters which hit initialValue as deleted. This means that changing a counter may impact size().

Constructor Summary

Constructors
Constructor and Description
`Object2LongCounterMap(int initialCapacity, float loadFactor, long initialValue)` Construct a new counter map with the initial value for the counter provided.
`Object2LongCounterMap(long initialValue)` Construct a new counter map with the initial value for the counter provided.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`long`	`addAndGet(K key, long amount)` Add amount to the current value associated with this key.
`int`	`capacity()` Get the total capacity for the map to which the load factor will be a fraction of.
`void`	`clear()` Clear out all entries.
`void`	`compact()` Compact the backing arrays by rehashing with a capacity just larger than current size and giving consideration to the load factor.
`long`	`computeIfAbsent(K key, ToLongFunction<? super K> mappingFunction)` Try `get(Object)` a value for a key and if not present then apply mapping function.
`boolean`	`containsKey(K key)` Does the map contain a value for a given key which is not `initialValue()`.
`boolean`	`containsValue(long value)` Iterate over the values to see if any match the provided value.
`long`	`decrementAndGet(K key)` Convenience version of `addAndGet(Object, long)` (key, -1).
`void`	`forEach(ObjLongConsumer<K> consumer)` Iterate over all value in the map which are not at `initialValue()`.
`long`	`get(K key)` Get the value of a counter associated with a key or `initialValue()` if not found.
`long`	`getAndAdd(K key, long amount)` Add amount to the current value associated with this key.
`long`	`getAndDecrement(K key)` Convenience version of `getAndAdd(Object, long)` (key, -1).
`long`	`getAndIncrement(K key)` Convenience version of `getAndAdd(Object, long)` (key, 1).
`long`	`incrementAndGet(K key)` Convenience version of `addAndGet(Object, long)` (key, 1).
`long`	`initialValue()` The value to be used as a null marker in the map.
`boolean`	`isEmpty()` Is the map empty.
`float`	`loadFactor()` Get the load factor applied for resize operations.
`long`	`maxValue()` Get the maximum value stored in the map.
`long`	`minValue()` Get the minimum value stored in the map.
`long`	`put(K key, long value)` Put the value for a key in the map.
`long`	`remove(K key)` Remove a counter value for a given key.
`int`	`resizeThreshold()` Get the actual threshold which when reached the map will resize.
`int`	`size()` The current size of the map which at not at `initialValue()`.
`String`	`toString()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - Object2LongCounterMap
```
public Object2LongCounterMap(long initialValue)
```
    Construct a new counter map with the initial value for the counter provided.
    
    Parameters:
    
    initialValue - to be used for each counter.
  - Object2LongCounterMap
```
public Object2LongCounterMap(int initialCapacity,
                             float loadFactor,
                             long initialValue)
```
    Construct a new counter map with the initial value for the counter provided.
    
    Parameters:
    
    initialCapacity - of the map.
    
    loadFactor - applied for resize operations.
    
    initialValue - to be used for each counter.
- Method Detail
  - initialValue
```
public long initialValue()
```
    The value to be used as a null marker in the map.
    
    Returns:
    
    value to be used as a null marker in the map.
  - loadFactor
```
public float loadFactor()
```
    Get the load factor applied for resize operations.
    
    Returns:
    
    the load factor applied for resize operations.
  - resizeThreshold
```
public int resizeThreshold()
```
    Get the actual threshold which when reached the map will resize. This is a function of the current capacity and load factor.
    
    Returns:
    
    the threshold when the map will resize.
  - capacity
```
public int capacity()
```
    Get the total capacity for the map to which the load factor will be a fraction of.
    
    Returns:
    
    the total capacity for the map.
  - size
```
public int size()
```
    The current size of the map which at not at initialValue().
    
    Returns:
    
    map size, counters at initialValue() are not counted.
  - isEmpty
```
public boolean isEmpty()
```
    Is the map empty.
    
    Returns:
    
    size == 0
  - get
```
public long get(K key)
```
    Get the value of a counter associated with a key or initialValue() if not found.
    
    Parameters:
    
    key - lookup key.
    
    Returns:
    
    counter value associated with key or initialValue() if not found.
  - put
```
public long put(K key,
                long value)
```
    Put the value for a key in the map.
    
    Parameters:
    
    key - lookup key.
    
    value - new value, must not be initialValue.
    
    Returns:
    
    current counter value associated with key, or initialValue() if none found.
    
    Throws:
    
    IllegalArgumentException - if value is initialValue().
  - incrementAndGet
```
public long incrementAndGet(K key)
```
    Convenience version of addAndGet(Object, long) (key, 1).
    
    Parameters:
    
    key - for the counter.
    
    Returns:
    
    the new value.
  - decrementAndGet
```
public long decrementAndGet(K key)
```
    Convenience version of addAndGet(Object, long) (key, -1).
    
    Parameters:
    
    key - for the counter.
    
    Returns:
    
    the new value.
  - addAndGet
```
public long addAndGet(K key,
                      long amount)
```
    Add amount to the current value associated with this key. If no such value exists use initialValue() as current value and associate key with initialValue() + amount unless amount is 0, in which case map remains unchanged.
    
    Parameters:
    
    key - new or existing.
    
    amount - to be added.
    
    Returns:
    
    the new value associated with the specified key, or initialValue() + amount if there was no mapping for the key.
  - getAndIncrement
```
public long getAndIncrement(K key)
```
    Convenience version of getAndAdd(Object, long) (key, 1).
    
    Parameters:
    
    key - for the counter.
    
    Returns:
    
    the old value.
  - getAndDecrement
```
public long getAndDecrement(K key)
```
    Convenience version of getAndAdd(Object, long) (key, -1).
    
    Parameters:
    
    key - for the counter.
    
    Returns:
    
    the old value.
  - getAndAdd
```
public long getAndAdd(K key,
                      long amount)
```
    Add amount to the current value associated with this key. If no such value exists use initialValue() as current value and associate key with initialValue() + amount unless amount is 0, in which case map remains unchanged.
    
    Parameters:
    
    key - new or existing.
    
    amount - to be added.
    
    Returns:
    
    the previous value associated with the specified key, or initialValue() if there was no mapping for the key.
  - forEach
```
public void forEach(ObjLongConsumer<K> consumer)
```
    Iterate over all value in the map which are not at initialValue().
    
    Parameters:
    
    consumer - called for each key/value pair in the map.
  - containsKey
```
public boolean containsKey(K key)
```
    Does the map contain a value for a given key which is not initialValue().
    
    Parameters:
    
    key - the key to check.
    
    Returns:
    
    true if the map contains the key with a value other than initialValue(), false otherwise.
  - containsValue
```
public boolean containsValue(long value)
```
    Iterate over the values to see if any match the provided value.
    If value provided is initialValue() then it will always return false.
    
    Parameters:
    
    value - the key to check.
    
    Returns:
    
    true if the map contains value as a mapped value, false otherwise.
  - clear
```
public void clear()
```
    Clear out all entries.
  - compact
```
public void compact()
```
    Compact the backing arrays by rehashing with a capacity just larger than current size and giving consideration to the load factor.
  - computeIfAbsent
```
public long computeIfAbsent(K key,
                            ToLongFunction<? super K> mappingFunction)
```
    Try get(Object) a value for a key and if not present then apply mapping function.
    
    Parameters:
    
    key - to search on.
    
    mappingFunction - to provide a value if the get returns null.
    
    Returns:
    
    the value if found otherwise the missing value.
  - remove
```
public long remove(K key)
```
    Remove a counter value for a given key.
    
    Parameters:
    
    key - to be removed.
    
    Returns:
    
    old value for key.
  - minValue
```
public long minValue()
```
    Get the minimum value stored in the map. If the map is empty then it will return initialValue()
    
    Returns:
    
    the minimum value stored in the map.
  - maxValue
```
public long maxValue()
```
    Get the maximum value stored in the map. If the map is empty then it will return initialValue()
    
    Returns:
    
    the maximum value stored in the map.
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object

Class Object2LongCounterMap<K>

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Object2LongCounterMap

Object2LongCounterMap

Method Detail

initialValue

loadFactor

resizeThreshold

capacity

size

isEmpty

get

put

incrementAndGet

decrementAndGet

addAndGet

getAndIncrement

getAndDecrement

getAndAdd

forEach

containsKey

containsValue

clear

compact

computeIfAbsent

remove

minValue

maxValue

toString