ConcurrentIndex (Apache HBase 1.2.12 API)

java.lang.Object
- org.apache.hadoop.hbase.util.ConcurrentIndex<K,V>

Type Parameters:
K - Key type
V - Value type
```
@InterfaceAudience.Private
@InterfaceStability.Evolving
public class ConcurrentIndex<K,V>
extends Object
```
A simple concurrent map of sets. This is similar in concept to Multiset, with the following exceptions:
- The set is thread-safe and concurrent: no external locking or synchronization is required. This is important for the use case where this class is used to index cached blocks by filename for their efficient eviction from cache when the file is closed or compacted.
- The expectation is that all entries may only be removed for a key once no more additions of values are being made under that key.

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

private static class ConcurrentIndex.DefaultValueSetFactory<V>
Default factory class for the sets associated with given keys.

Nested Classes
Modifier and Type	Class and Description
`private static class`	`ConcurrentIndex.DefaultValueSetFactory<V>` Default factory class for the sets associated with given keys.

Field Summary

Fields
Modifier and Type	Field and Description
`private ConcurrentMap<K,Set<V>>`	`container` Container for the sets, indexed by key
`private com.google.common.base.Supplier<Set<V>>`	`valueSetFactory` A factory that constructs new instances of the sets if no set is associated with a given key.

Constructor Summary

Constructors
Constructor and Description
`ConcurrentIndex(Comparator<V> valueComparator)` Creates an instance using the DefaultValueSetFactory for sets, which in turn creates instances of `ConcurrentSkipListSet`
`ConcurrentIndex(com.google.common.base.Supplier<Set<V>> valueSetFactory)` Creates an instance with a specified factory object for sets to be associated with a given key.

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`put(K key, V value)` Associate a new unique value with a specified key.
`boolean`	`remove(K key, V value)` Removes the association between a specified key and value.
`Set<V>`	`values(K key)` Get all values associated with a specified key or null if no values are associated.

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

- Field Detail
  - container
```
private final ConcurrentMap<K,Set<V>> container
```
    Container for the sets, indexed by key
  - valueSetFactory
```
private final com.google.common.base.Supplier<Set<V>> valueSetFactory
```
    A factory that constructs new instances of the sets if no set is associated with a given key.
- Constructor Detail
  - ConcurrentIndex
```
public ConcurrentIndex(com.google.common.base.Supplier<Set<V>> valueSetFactory)
```
    Creates an instance with a specified factory object for sets to be associated with a given key.
    
    Parameters:
    valueSetFactory - The factory instance
  - ConcurrentIndex
```
public ConcurrentIndex(Comparator<V> valueComparator)
```
    Creates an instance using the DefaultValueSetFactory for sets, which in turn creates instances of ConcurrentSkipListSet
    
    Parameters:
    valueComparator - A Comparator for value types
- Method Detail
  - put
```
public void put(K key,
       V value)
```
    Associate a new unique value with a specified key. Under the covers, the method employs optimistic concurrency: if no set is associated with a given key, we create a new set; if another thread comes in, creates, and associates a set with the same key in the mean-time, we simply add the value to the already created set.
    
    Parameters:
    key - The key
    value - An additional unique value we want to associate with a key
  - values
```
public Set<V> values(K key)
```
    Get all values associated with a specified key or null if no values are associated. Note: if the caller wishes to add or removes values to under the specified as they're iterating through the returned value, they should make a defensive copy; otherwise, a ConcurrentModificationException may be thrown.
    
    Parameters:
    key - The key
    
    Returns:
    All values associated with the specified key or null if no values are associated with the key.
  - remove
```
public boolean remove(K key,
             V value)
```
    Removes the association between a specified key and value. If as a result of removing a value a set becomes empty, we remove the given set from the mapping as well.
    
    Parameters:
    key - The specified key
    value - The value to disassociate with the key

Class ConcurrentIndex<K,V>

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

container

valueSetFactory

Constructor Detail

ConcurrentIndex

ConcurrentIndex

Method Detail

put

values

remove