org.apache.zookeeper.server.persistence

Class Util

java.lang.Object

org.apache.zookeeper.server.persistence.Util

public class Util
extends java.lang.Object

A collection of utility methods for dealing with file name parsing, low level I/O file operations and marshalling/unmarshalling.

Constructor Summary

Constructors

Constructor and Description
Util()

Method Summary

Modifier and Type	Method and Description
static java.lang.String	getFormatConversionPolicy(java.util.Properties props) Extracts the value of the dbFormatConversion attribute.
static java.io.File	getLogDir(java.util.Properties props) Extracts transaction log directory property value from the container.
static java.io.File	getSnapDir(java.util.Properties props) Extracts snapshot directory property value from the container.
static long	getZxidFromName(java.lang.String name, java.lang.String prefix) Extracts zxid from the file name.
static boolean	isValidSnapshot(java.io.File f) Verifies that the file is a valid snapshot.
static java.net.URI	makeFileLoggerURL(java.io.File dataDir, java.io.File dataLogDir) Given two directory files the method returns a well-formed logfile provider URI.
static java.net.URI	makeFileLoggerURL(java.io.File dataDir, java.io.File dataLogDir, java.lang.String convPolicy)
static java.lang.String	makeLogName(long zxid) Creates a valid transaction log file name.
static java.lang.String	makeSnapshotName(long zxid) Creates a snapshot file name.
static java.lang.String	makeURIString(java.lang.String dataDir, java.lang.String dataLogDir, java.lang.String convPolicy)
static byte[]	marshallTxnEntry(TxnHeader hdr, org.apache.jute.Record txn) Serializes transaction header and transaction data into a byte buffer.
static long	padLogFile(java.io.FileOutputStream f, long currentSize, long preAllocSize) Grows the file to the specified number of bytes.
static byte[]	readTxnBytes(org.apache.jute.InputArchive ia) Reads a transaction entry from the input archive.
static java.util.List<java.io.File>	sortDataDir(java.io.File[] files, java.lang.String prefix, boolean ascending) Sort the list of files.
static void	writeTxnBytes(org.apache.jute.OutputArchive oa, byte[] bytes) Write the serialized transaction record to the output archive.

Methods inherited from class java.lang.Object

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

Constructor Detail

Util

public Util()

Method Detail

makeURIString

public static java.lang.String makeURIString(java.lang.String dataDir,
                                             java.lang.String dataLogDir,
                                             java.lang.String convPolicy)

makeFileLoggerURL

public static java.net.URI makeFileLoggerURL(java.io.File dataDir,
                                             java.io.File dataLogDir)

Given two directory files the method returns a well-formed logfile provider URI. This method is for backward compatibility with the existing code that only supports logfile persistence and expects these two parameters passed either on the command-line or in the configuration file.

Parameters:

dataDir - snapshot directory

dataLogDir - transaction log directory

Returns:

logfile provider URI

makeFileLoggerURL

public static java.net.URI makeFileLoggerURL(java.io.File dataDir,
                                             java.io.File dataLogDir,
                                             java.lang.String convPolicy)

makeLogName

public static java.lang.String makeLogName(long zxid)

Creates a valid transaction log file name.

Parameters:

zxid - used as a file name suffix (extention)

Returns:

file name

makeSnapshotName

public static java.lang.String makeSnapshotName(long zxid)

Creates a snapshot file name.

Parameters:

zxid - used as a suffix

Returns:

file name

getSnapDir

public static java.io.File getSnapDir(java.util.Properties props)

Extracts snapshot directory property value from the container.

Parameters:

props - properties container

Returns:

file representing the snapshot directory

getLogDir

public static java.io.File getLogDir(java.util.Properties props)

Extracts transaction log directory property value from the container.

Parameters:

props - properties container

Returns:

file representing the txn log directory

getFormatConversionPolicy

public static java.lang.String getFormatConversionPolicy(java.util.Properties props)

Extracts the value of the dbFormatConversion attribute.

Parameters:

props - properties container

Returns:

value of the dbFormatConversion attribute

getZxidFromName

public static long getZxidFromName(java.lang.String name,
                                   java.lang.String prefix)

Extracts zxid from the file name. The file name should have been created using one of the makeLogName or makeSnapshotName.

Parameters:

name - the file name to parse

prefix - the file name prefix (snapshot or log)

Returns:

zxid

isValidSnapshot

public static boolean isValidSnapshot(java.io.File f)
                               throws java.io.IOException

Verifies that the file is a valid snapshot. Snapshot may be invalid if it's incomplete as in a situation when the server dies while in the process of storing a snapshot. Any file that is not a snapshot is also an invalid snapshot.

Parameters:

f - file to verify

Returns:

true if the snapshot is valid

Throws:

java.io.IOException

padLogFile

public static long padLogFile(java.io.FileOutputStream f,
                              long currentSize,
                              long preAllocSize)
                       throws java.io.IOException

Grows the file to the specified number of bytes. This only happenes if the current file position is sufficiently close (less than 4K) to end of file.

Parameters:

f - output stream to pad

currentSize - application keeps track of the cuurent file size

preAllocSize - how many bytes to pad

Returns:

the new file size. It can be the same as currentSize if no padding was done.

Throws:

java.io.IOException

readTxnBytes

public static byte[] readTxnBytes(org.apache.jute.InputArchive ia)
                           throws java.io.IOException

Reads a transaction entry from the input archive.

Parameters:

ia - archive to read from

Returns:

null if the entry is corrupted or EOF has been reached; a buffer (possible empty) containing serialized transaction record.

Throws:

java.io.IOException

marshallTxnEntry

public static byte[] marshallTxnEntry(TxnHeader hdr,
                                      org.apache.jute.Record txn)
                               throws java.io.IOException

Serializes transaction header and transaction data into a byte buffer.

Parameters:

hdr - transaction header

txn - transaction data

Returns:

serialized transaction record

Throws:

java.io.IOException

writeTxnBytes

public static void writeTxnBytes(org.apache.jute.OutputArchive oa,
                                 byte[] bytes)
                          throws java.io.IOException

Write the serialized transaction record to the output archive.

Parameters:

oa - output archive

bytes - serialized trasnaction record

Throws:

java.io.IOException

sortDataDir

public static java.util.List<java.io.File> sortDataDir(java.io.File[] files,
                                                       java.lang.String prefix,
                                                       boolean ascending)

Sort the list of files. Recency as determined by the version component of the file name.

Parameters:

files - array of files

prefix - files not matching this prefix are assumed to have a version = -1)

ascending - true sorted in ascending order, false results in descending order

Returns:

sorted input files