org.apache.nifi.provenance.serialization

Interface RecordReader

All Superinterfaces:

java.lang.AutoCloseable, java.io.Closeable

All Known Implementing Classes:

ByteArraySchemaRecordReader, CompressableRecordReader, EmptyRecordReader, EncryptedSchemaRecordReader, EventIdFirstSchemaRecordReader, StandardRecordReader

public interface RecordReader
extends java.io.Closeable

Method Summary

Modifier and Type	Method and Description
int	getBlockIndex() Returns the block index that the Reader is currently reading from.
long	getBytesConsumed()
long	getMaxEventId() Returns the ID of the last event in this record reader, or -1 if the reader has no records or has already read through all records.
TocReader	getTocReader() Returns the TocReader that is used to keep track of compression blocks, if one exists, null otherwise
boolean	isBlockIndexAvailable() Returns true if the compression block index is available.
boolean	isData() Returns true if there is more data for hte Record Reader to read, false otherwise.
StandardProvenanceEventRecord	nextRecord() Returns the next record in the reader, or null if there is no more data available.
void	skip(long bytesToSkip) Skips the specified number of bytes
void	skipTo(long position) Skips to the specified byte offset in the underlying stream.
void	skipToBlock(int blockIndex) Skips to the specified compression block
java.util.Optional<ProvenanceEventRecord>	skipToEvent(long eventId) Skips to the first event in the stream with an Event ID >= the given ID.

Methods inherited from interface java.io.Closeable

close

Method Detail

nextRecord

StandardProvenanceEventRecord nextRecord()
                                  throws java.io.IOException

Returns the next record in the reader, or null if there is no more data available.

Returns:

the next Provenance event in the stream

Throws:

java.io.IOException - if unable to read the next event from the stream

skip

void skip(long bytesToSkip)
   throws java.io.IOException

Skips the specified number of bytes

Parameters:

bytesToSkip - the number of bytes to skip ahead

Throws:

java.io.IOException - if unable to skip ahead the specified number of bytes (e.g., the stream does not contain this many more bytes)

skipTo

void skipTo(long position)
     throws java.io.IOException

Skips to the specified byte offset in the underlying stream.

Parameters:

position - the byte offset to skip to

Throws:

java.io.IOException - if the underlying stream throws IOException, or if the reader has already passed the specified byte offset

skipToBlock

void skipToBlock(int blockIndex)
          throws java.io.IOException

Skips to the specified compression block

Parameters:

blockIndex - the block index to skip to

Throws:

java.io.IOException - if the underlying stream throws IOException, or if the reader has already read passed the specified compression block index

java.lang.IllegalStateException - if the RecordReader does not have a TableOfContents associated with it

skipToEvent

java.util.Optional<ProvenanceEventRecord> skipToEvent(long eventId)
                                               throws java.io.IOException

Skips to the first event in the stream with an Event ID >= the given ID. If no event is found with an ID >= the given ID an empty Optional is returned. Otherwise, an Optional containing the first event in the stream with an ID >= the given ID is returned. Unlike nextRecord(), this method does not consume the returned event from the stream. I.e., if a record is returned, that same record will be returned again the next time that nextRecord() is called.

Parameters:

eventId - the ID of the event to retrieve

Returns:

the first event in the stream with an Event ID >= the given ID or an empty Optional if no such event can be found

Throws:

java.io.IOException - if the underlying stream throws IOException

getBlockIndex

int getBlockIndex()

Returns the block index that the Reader is currently reading from. Note that the block index is incremented at the beginning of the nextRecord() method. This means that this method will return the block from which the previous record was read, if calling nextRecord() continually, not the block from which the next record will be read.

Returns:

the current block index

Throws:

java.lang.IllegalStateException - if the reader is reading a provenance event file that does not contain a Table of Contents

isBlockIndexAvailable

boolean isBlockIndexAvailable()

Returns true if the compression block index is available. It will be available if and only if the reader is created with a TableOfContents

Returns:

true if the reader is reading from an event file that has a Table of Contents

getTocReader

TocReader getTocReader()

Returns the TocReader that is used to keep track of compression blocks, if one exists, null otherwise

Returns:

the TocReader if the underlying event file has an Table of Contents, null otherwise.

getBytesConsumed

long getBytesConsumed()

Returns:

the number of bytes that have been consumed from the stream (read or skipped).

getMaxEventId

long getMaxEventId()
            throws java.io.IOException

Returns the ID of the last event in this record reader, or -1 if the reader has no records or has already read through all records. Note: This method will consume the stream until the end, so no more records will be available on this reader after calling this method.

Returns:

the ID of the last event in this record reader, or -1 if the reader has no records or has already read through all records

Throws:

java.io.IOException - if unable to get id of the last event

isData

boolean isData()

Returns true if there is more data for hte Record Reader to read, false otherwise.

Returns:

true if there is more data for hte Record Reader to read, false otherwise.