org.gridgain.grid.ggfs.mapreduce

Interface GridGgfsRecordResolver

All Superinterfaces:

Serializable

All Known Implementing Classes:

GridGgfsByteDelimiterRecordResolver, GridGgfsFixedLengthRecordResolver, GridGgfsNewLineRecordResolver, GridGgfsStringDelimiterRecordResolver

public interface GridGgfsRecordResolver
extends Serializable

GGFS record resolver. When GridGgfsTask is split into GridGgfsJobs each produced job will obtain GridGgfsFileRange based on file data location. Record resolver is invoked in each job before actual execution in order to adjust record boundaries in a way consistent with user data.

E.g., you may want to split your task into jobs so that each job process zero, one or several lines from that file. But file is split into ranges based on block locations, not new line boundaries. Using convenient record resolver you can adjust job range so that it covers the whole line(s).

The following record resolvers are available out of the box:

• GridGgfsFixedLengthRecordResolver
• GridGgfsByteDelimiterRecordResolver
• GridGgfsStringDelimiterRecordResolver
• GridGgfsNewLineRecordResolver

Method Summary

Methods

Modifier and Type	Method and Description
GridGgfsFileRange	resolveRecords(GridGgfs ggfs, GridGgfsInputStream stream, GridGgfsFileRange suggestedRecord) Adjusts record start offset and length.

Method Detail

resolveRecords

@Nullable
GridGgfsFileRange resolveRecords(GridGgfs ggfs,
                                        GridGgfsInputStream stream,
                                        GridGgfsFileRange suggestedRecord)
                                 throws GridException,
                                        IOException

Adjusts record start offset and length.

Parameters:

ggfs - GGFS instance to use.

stream - Input stream for split file.

suggestedRecord - Suggested file system record.

Returns:

New adjusted record. If this method returns null, original record is ignored.

Throws:

GridException - If resolve failed.

IOException - If resolve failed.