Package org.apache.druid.segment.writeout

Class TmpFileSegmentWriteOutMedium

java.lang.Object

org.apache.druid.segment.writeout.TmpFileSegmentWriteOutMedium

All Implemented Interfaces:

Closeable, AutoCloseable, SegmentWriteOutMedium

public final class TmpFileSegmentWriteOutMedium
extends Object
implements SegmentWriteOutMedium

Builds segment write out medium objects that are based on temporary files. Some analysis of usage of these objects shows that they periodically get used for very small things, where the overhead of creating a tmp file is actually very large. It would be best to go back and look at usages and try to make them lazy such that they only actually use a medium when they need it. But, in an attempt to get some benefits, we "shim" in the laziness by returning a heap-based WriteOutBytes that only falls back to making a tmp file when it actually fills up.

Method Summary

Modifier and Type	Method	Description
void	close()
Closer	getCloser()	Returns a closer of this SegmentWriteOutMedium, which is closed in this SegmentWriteOutMedium's close() method.
SegmentWriteOutMedium	makeChildWriteOutMedium()	Creates a 'child' version of the SegmentWriteOutMedium, which can be optionally closed, independent of this SegmentWriteOutMedium but otherwise shares the same configuration.
WriteOutBytes	makeWriteOutBytes()	Creates a new empty WriteOutBytes, attached to this SegmentWriteOutMedium.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

makeWriteOutBytes

public WriteOutBytes makeWriteOutBytes()

Description copied from interface: SegmentWriteOutMedium

Creates a new empty WriteOutBytes, attached to this SegmentWriteOutMedium. When this SegmentWriteOutMedium is closed, the returned WriteOutBytes couldn't be used anymore.

Specified by:

makeWriteOutBytes in interface SegmentWriteOutMedium

makeChildWriteOutMedium

public SegmentWriteOutMedium makeChildWriteOutMedium()
                                              throws IOException

Description copied from interface: SegmentWriteOutMedium

Creates a 'child' version of the SegmentWriteOutMedium, which can be optionally closed, independent of this SegmentWriteOutMedium but otherwise shares the same configuration. This allows callers using a shared SegmentWriteOutMedium but which control the complete lifecycle of the WriteOutBytes which they require to free the backing resources when they are finished, rather than waiting until Closeable.close() is called for this medium.

The 'child' medium will be closed when Closeable.close() is called, if not called explicitly prior to closing this medium.

Specified by:

makeChildWriteOutMedium in interface SegmentWriteOutMedium

Throws:

IOException

getCloser

public Closer getCloser()

Description copied from interface: SegmentWriteOutMedium

Returns a closer of this SegmentWriteOutMedium, which is closed in this SegmentWriteOutMedium's close() method. Could be used to "attach" some random resources to this SegmentWriteOutMedium, to be closed at the same time.

Specified by:

getCloser in interface SegmentWriteOutMedium

close

public void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Throws:

IOException