net.openhft.chronicle.hash

Interface ChronicleHash

All Superinterfaces:

AutoCloseable, Closeable

All Known Subinterfaces:

ChronicleMap<K,V>, ChronicleSet<E>

public interface ChronicleHash
extends Closeable

This interface defines common ChronicleMap and ChronicleSet, related to off-heap memory management and file-mapping. Not usable by itself.

Method Summary

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.

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(java.io.File)

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 operation 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.

TODO what about commit guarantees, when ChronicleMap is used with memory-mapped files, if ChronicleMap/ChronicleSet closed/not?

After this method call behaviour of all methods of ChronicleMap or ChronicleSet is undefined. Any method call on the map might throw any exception, or even JVM crash. Shortly speaking, don't call use map closing.

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable