com.facebook.presto.memory.context

Interface LocalMemoryContext

All Known Implementing Classes:

SimpleLocalMemoryContext

public interface LocalMemoryContext

Method Summary

Modifier and Type	Method and Description
void	close() Closes this LocalMemoryContext.
long	getBytes()
com.google.common.util.concurrent.ListenableFuture<?>	setBytes(long bytes) When this method returns, the bytes tracked by this LocalMemoryContext has been updated.
boolean	trySetBytes(long bytes) This method can return false when there is not enough memory available to satisfy a positive delta allocation (bytes is greater than the bytes tracked by this LocalMemoryContext).

Method Detail

getBytes

long getBytes()

setBytes

com.google.common.util.concurrent.ListenableFuture<?> setBytes(long bytes)

When this method returns, the bytes tracked by this LocalMemoryContext has been updated. The returned future will tell the caller whether it should block before reserving more memory (which happens when the memory pools are low on memory).

Note: Canceling the returned future will complete it immediately even though the memory pools are low on memory, and callers blocked on this future will proceed to allocating more memory from the exhausted pools, which will violate the protocol of Presto MemoryPool implementation.

trySetBytes

boolean trySetBytes(long bytes)

This method can return false when there is not enough memory available to satisfy a positive delta allocation (bytes is greater than the bytes tracked by this LocalMemoryContext).

Returns:

true if the bytes tracked by this LocalMemoryContext can be set to bytes.

close

void close()

Closes this LocalMemoryContext. Once closed the bytes tracked by this LocalMemoryContext will be set to 0, and none of its methods (except getBytes()) can be called.