ChronicleHash (OpenHFT/Chronicle-Map 3.17.1 API)

All Superinterfaces:: AutoCloseable, Closeable

All Known Subinterfaces:: ChronicleMap<K,V>, ChronicleSet<K>

public interface ChronicleHash<K,E extends HashEntry<K>,SC extends HashSegmentContext<K,?>,EQC extends ExternalHashQueryContext<K>>
extends net.openhft.chronicle.core.io.Closeable

Common base interface for ChronicleMap and ChronicleSet.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`void`	`close()` Releases the off-heap memory, used by this hash container and resources, used by replication, if any.
`File`	`file()` Returns the file this hash container mapped to, i.
`void`	`forEachEntry(Consumer<? super E> action)` Performs the given action for each entry in this `ChronicleHash` until all entries have been processed or the action throws an `Exception`.
`boolean`	`forEachEntryWhile(Predicate<? super E> predicate)` Checks the given predicate on each entry in this `ChronicleHash` until all entries have been processed or the predicate returns `false` for some entry, or throws an `Exception`.
`boolean`	`isOpen()` Tells whether or not this `ChronicleHash` (on-heap instance) is open.
`Class<K>`	`keyClass()`
`long`	`longSize()` Returns the number of entries in this store.
`String`	`name()` Returns the name of this `ChronicleHash`, configured by `ChronicleHashBuilder.name(String)`, or `null`, if not configured.
`long`	`offHeapMemoryUsed()` Returns the amount of off-heap memory (in bytes), allocated by this `ChronicleHash` or shared with with other ChronicleHashes, persisting to the same `file()`.
`EQC`	`queryContext(net.openhft.chronicle.bytes.BytesStore keyBytes, long offset, long size)` Returns a context to perform arbitrary operations with the given key, provided in the serialized form.
`EQC`	`queryContext(Data<K> key)` Returns a context to perform arbitrary operations with the given key, provided in `Data` form.
`EQC`	`queryContext(K key)` Returns a context to perform arbitrary operations with the given key in this store.
`SC`	`segmentContext(int segmentIndex)` Returns a context of the segment with the given index.
`int`	`segments()` Returns the number of segments in this `ChronicleHash`.
`String`	`toIdentityString()` Returns a `String`, useful for identifying this `ChronicleHash` in debugging, logging, and error reporting.

Methods inherited from interface net.openhft.chronicle.core.io.Closeable
closeQuietly, closeQuietly, isClosed, notifyClosing

- Method Detail
  - file
```
File file()
```
    Returns the file this hash container mapped to, i. e. when it is created by ChronicleHashBuilder.create() call, or null if it is purely in-memory, i. e. if it is created by ChronicleHashBuilder.create() call.
    
    Returns:
    
    the file this ChronicleMap or ChronicleSet is mapped to, or null if it is not mapped to any file
    
    See Also:
    
    ChronicleHashBuilder.createPersistedTo(File)
  - name
```
String name()
```
    Returns the name of this ChronicleHash, configured by ChronicleHashBuilder.name(String), or null, if not configured.
    
    Returns:
    
    the name of this this ChronicleMap or ChronicleSet
  - toIdentityString
```
String toIdentityString()
```
    Returns a String, useful for identifying this ChronicleHash in debugging, logging, and error reporting. #toString() of concrete ChronicleHash subinterfaces, ChronicleMap and ChronicleSet, has to follow Map#toString() and Set#toString() contracts respectively, making it not always useful (or even impossible to use, if this ChronicleHash contains a lot of entries) for the purposes listed above.
    
    This method return a string of the form:
    
    [ChronicleMap|ChronicleSet]{name=name(), file=file(), identityHashCode=System.identityHashCode(thisChronicleHash)}
    
    This form could be changed in any subsequent Chronicle Map library release (including patch release). The user code shouldn't depend on this form.
    
    Returns:
    
    a String, useful for identifying this ChronicleHash in debugging, logging, and error reporting
  - longSize
```
long longSize()
```
    Returns the number of entries in this store.
    
    Returns:
    
    the number of entries in this store
  - offHeapMemoryUsed
```
long offHeapMemoryUsed()
```
    Returns the amount of off-heap memory (in bytes), allocated by this ChronicleHash or shared with with other ChronicleHashes, persisting to the same file().
    
    After close() this method returns 0.
    
    Returns:
    
    the amount of off-heap memory, used by this ChronicleHash (in bytes)
  - keyClass
```
Class<K> keyClass()
```
    Returns:
    
    the class of <K>
  - queryContext
```
@NotNull
EQC queryContext(K key)
```
    Returns a context to perform arbitrary operations with the given key in this store. Conventionally, should be used in a try-with-resources block:
```
 try (ExternalHashQueryContext<K> q = hash.queryContext(key)) {
     // ... do something
 }
```
    See documentation to HashQueryContext interface and methods in MapMethods interface for examples of using contexts. Also see Working with an entry within a context section in the Chronicle Map tutorial.
    Parameters:
    
    key - the queried key
    
    Returns:
    
    the context to perform operations with the key
    
    See Also:
    
    HashQueryContext, MapQueryContext, ExternalHashQueryContext, MapMethods
  - queryContext
```
@NotNull
EQC queryContext(Data<K> key)
```
    Returns a context to perform arbitrary operations with the given key, provided in Data form. Equivalent to queryContext(Object), but accepts Data instead of object key. This method is useful, when you already have Data, calling this method instead of queryContext(Object) might help to avoid unnecessary deserialization.
    
    See documentation to HashQueryContext interface and methods in MapMethods interface for examples of using contexts. Also see Working with an entry within a context section in the Chronicle Map tutorial.
    
    Parameters:
    
    key - the queried key as Data
    
    Returns:
    
    the context to perform operations with the key
  - queryContext
```
@NotNull
EQC queryContext(net.openhft.chronicle.bytes.BytesStore keyBytes,
                          long offset,
                          long size)
```
    Returns a context to perform arbitrary operations with the given key, provided in the serialized form. See queryContext(Object) and queryContext(Data) for more information on contexts semantics and usage patterns.
    
    Parameters:
    
    keyBytes - the bytes store with the key bytes to query
    
    offset - actual offset of the key bytes within the given BytesStore
    
    size - length of the key bytes sequence within the given BytesStore
    
    Returns:
    
    the context to perform operations with the key
  - segmentContext
```
SC segmentContext(int segmentIndex)
```
    Returns a context of the segment with the given index. Segments are indexed from 0 to segments()- 1.
    
    See Also:
    
    HashSegmentContext
  - segments
```
int segments()
```
    Returns the number of segments in this ChronicleHash.
    
    See Also:
    
    ChronicleHashBuilder.minSegments(int), ChronicleHashBuilder.actualSegments(int)
  - forEachEntryWhile
```
boolean forEachEntryWhile(Predicate<? super E> predicate)
```
    Checks the given predicate on each entry in this ChronicleHash until all entries have been processed or the predicate returns false for some entry, or throws an Exception. Exceptions thrown by the predicate are relayed to the caller.
    
    The order in which the entries will be processed is unspecified. It might differ from the order of iteration via Iterator returned by any method of this ChronicleHash or it's collection view.
    
    If the ChronicleHash is empty, this method returns true immediately.
    
    Parameters:
    
    predicate - the predicate to be checked for each entry
    
    Returns:
    
    true if the predicate returned true for all entries of the ChronicleHash, false if it returned false for the entry
  - forEachEntry
```
void forEachEntry(Consumer<? super E> action)
```
    Performs the given action for each entry in this ChronicleHash until all entries have been processed or the action throws an Exception. Exceptions thrown by the action are relayed to the caller.
    
    The order in which the entries will be processed is unspecified. It might differ from the order of iteration via Iterator returned by any method of this ChronicleHash or it's collection view.
    
    Parameters:
    
    action - the action to be performed for each entry
  - close
```
void close()
```
    Releases the off-heap memory, used by this hash container and resources, used by replication, if any. However, if hash container (hence off-heap memory, used by it) is mapped to the file and there are other instances mapping the same data on the server across JVMs, the memory won't be actually freed on operating system level. I. e. this method call doesn't affect other ChronicleMap or ChronicleSet instances mapping the same data.
    
    If you won't call this method, memory would be held at least until next garbage collection. This could be a problem if, for example, you target rare garbage collections, but load and drop ChronicleHashes regularly.
    
    After this method call, all methods, querying the ChronicleHash's entries, longSize() and size()), throw ChronicleHashClosedException. isOpen() returns false, close() itself returns immediately without effects (i. e. repetitive close(), even from concurrent threads, are safe).
    
    Specified by:
    
    close in interface AutoCloseable
    
    Specified by:
    
    close in interface Closeable
  - isOpen
```
boolean isOpen()
```
    Tells whether or not this ChronicleHash (on-heap instance) is open.
    
    Returns:
    
    true is close() is not yet called

Interface ChronicleHash<K,E extends HashEntry<K>,SC extends HashSegmentContext<K,?>,EQC extends ExternalHashQueryContext<K>>

Method Summary

Methods inherited from interface net.openhft.chronicle.core.io.Closeable

Method Detail

file

name

toIdentityString

longSize

offHeapMemoryUsed

keyClass

queryContext

queryContext

queryContext

segmentContext

segments

forEachEntryWhile

forEachEntry

close

isOpen