org.apache.hadoop.hbase.wal

Class WALPrettyPrinter

java.lang.Object

org.apache.hadoop.hbase.wal.WALPrettyPrinter

@InterfaceAudience.LimitedPrivate(value="Tools")
 @InterfaceStability.Evolving
public class WALPrettyPrinter
extends Object

WALPrettyPrinter prints the contents of a given WAL with a variety of options affecting formatting and extent of content. It targets two usage cases: pretty printing for ease of debugging directly by humans, and JSON output for consumption by monitoring and/or maintenance scripts. It can filter by row, region, or sequence id. It can also toggle output of values.

Field Summary

Fields

Modifier and Type	Field and Description
private boolean	firstTxn
private static com.fasterxml.jackson.databind.ObjectMapper	MAPPER
private PrintStream	out
private boolean	outputJSON
private boolean	outputValues
private boolean	persistentOutput
private long	position
private String	region
private String	row
private long	sequence

Constructor Summary

Constructors

Constructor and Description
WALPrettyPrinter() Basic constructor that simply initializes values to reasonable defaults.
WALPrettyPrinter(boolean outputValues, boolean outputJSON, long sequence, String region, String row, boolean persistentOutput, PrintStream out) Fully specified constructor.

Method Summary

Modifier and Type	Method and Description
void	beginPersistentOutput() enables output as a single, persistent list.
void	disableJSON() turns JSON output off, and turns on "pretty strings" for human consumption
void	disableValues() turns value output off
void	enableJSON() turns JSON output on
void	enableValues() turns value output on
void	endPersistentOutput() ends output of a single, persistent list.
static void	main(String[] args)
void	processFile(org.apache.hadoop.conf.Configuration conf, org.apache.hadoop.fs.Path p) reads a log file and outputs its contents, one transaction at a time, as specified by the currently configured options
static void	run(String[] args) Pass one or more log file names and formatting options and it will dump out a text version of the contents on stdout.
void	setPosition(long position) sets the position to start seeking the WAL file
void	setRegionFilter(String region) sets the region by which output will be filtered
void	setRowFilter(String row) sets the region by which output will be filtered
void	setSequenceFilter(long sequence) sets the region by which output will be filtered
private static Map<String,Object>	toStringMap(Cell cell)

Methods inherited from class java.lang.Object

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

Field Detail

outputValues

private boolean outputValues

outputJSON

private boolean outputJSON

sequence

private long sequence

region

private String region

row

private String row

persistentOutput

private boolean persistentOutput

firstTxn

private boolean firstTxn

out

private PrintStream out

MAPPER

private static final com.fasterxml.jackson.databind.ObjectMapper MAPPER

position

private long position

Constructor Detail

WALPrettyPrinter

public WALPrettyPrinter()

Basic constructor that simply initializes values to reasonable defaults.

WALPrettyPrinter

public WALPrettyPrinter(boolean outputValues,
                        boolean outputJSON,
                        long sequence,
                        String region,
                        String row,
                        boolean persistentOutput,
                        PrintStream out)

Fully specified constructor.

Parameters:

outputValues - when true, enables output of values along with other log information

outputJSON - when true, enables output in JSON format rather than a "pretty string"

sequence - when nonnegative, serves as a filter; only log entries with this sequence id will be printed

region - when not null, serves as a filter; only log entries from this region will be printed

row - when not null, serves as a filter; only log entries from this row will be printed

persistentOutput - keeps a single list running for multiple files. if enabled, the endPersistentOutput() method must be used!

out - Specifies an alternative to stdout for the destination of this PrettyPrinter's output.

Method Detail

enableValues

public void enableValues()

turns value output on

disableValues

public void disableValues()

turns value output off

enableJSON

public void enableJSON()

turns JSON output on

disableJSON

public void disableJSON()

turns JSON output off, and turns on "pretty strings" for human consumption

setSequenceFilter

public void setSequenceFilter(long sequence)

sets the region by which output will be filtered

Parameters:

sequence - when nonnegative, serves as a filter; only log entries with this sequence id will be printed

setRegionFilter

public void setRegionFilter(String region)

sets the region by which output will be filtered

Parameters:

region - when not null, serves as a filter; only log entries from this region will be printed

setRowFilter

public void setRowFilter(String row)

sets the region by which output will be filtered

Parameters:

row - when not null, serves as a filter; only log entries from this row will be printed

setPosition

public void setPosition(long position)

sets the position to start seeking the WAL file

Parameters:

position - initial position to start seeking the given WAL file

beginPersistentOutput

public void beginPersistentOutput()

enables output as a single, persistent list. at present, only relevant in the case of JSON output.

endPersistentOutput

public void endPersistentOutput()

ends output of a single, persistent list. at present, only relevant in the case of JSON output.

processFile

public void processFile(org.apache.hadoop.conf.Configuration conf,
                        org.apache.hadoop.fs.Path p)
                 throws IOException

reads a log file and outputs its contents, one transaction at a time, as specified by the currently configured options

Parameters:

conf - the HBase configuration relevant to this log file

p - the path of the log file to be read

Throws:

IOException - may be unable to access the configured filesystem or requested file.

toStringMap

private static Map<String,Object> toStringMap(Cell cell)

main

public static void main(String[] args)
                 throws IOException

Throws:

IOException

run

public static void run(String[] args)
                throws IOException

Pass one or more log file names and formatting options and it will dump out a text version of the contents on stdout.

Parameters:

args - Command line arguments

Throws:

IOException - Thrown upon file system errors etc.