com.tangosol.persistence

Class GUIDHelper

java.lang.Object

com.tangosol.persistence.GUIDHelper

public class GUIDHelper
extends Object

Static helper methods to encode and decode the attributes related to the storage of a persistent form of a partition.

A persistence GUID must at minimum reflect the partition-id and a monotonically increasing partition-version that could be used to determine, given a set of GUIDs representing the same partition, a total ordering of the GUIDs over time.

Author:

rhl/jh 2012.07.06

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	GUIDHelper.GUIDResolver Resolver used during a recovery to discover the newest available GUID for a given partition.

Constructor Summary

Constructors

Constructor and Description
GUIDHelper()

Method Summary

Modifier and Type	Method and Description
static Map<Integer,String[]>	assignStores(Map<Integer,Object[]> mapConstraints, int cDistinctStores) Return a Map containing assignments of member id to stores based on the given constraints.
protected static <K> Map.Entry<K,Object[]>[]	createSortedEntries(Map<K,Object[]> map) Return an array of entries based on the provided map ensuring the value (Object[]) is sorted.
static String	generateGUID(int nPartition, long lVersion, long ldt, Member member) Generate and return a new GUID for the specified partition.
static int	getMemberId(String sGUID) Parse the specified GUID and return the originating member-id.
static int	getPartition(String sGUID) Parse the specified GUID and return the partition-id.
static PartitionSet	getPartitions(Map<Integer,Object[]> mapStores, int cParts) Return a PartitionSet with all partitions present in the provided mapStores.
static long	getServiceJoinTime(String sGUID) Parse the specified GUID and return the service join time.
static long	getVersion(String sGUID) Parse the specified GUID and return the partition-version.
protected static List<String>	intersects(Object[] aoLHS, Object[] aoRHS) Return a List of stores (GUIDs) that allows the caller to derive whether the provided sets are disjoint, intersect or equal.
static void	main(String[] asArg) Utility that outputs information about a given GUID.
protected static String	parseAttribute(String sGUID, int id) Return the specified (0-based) attribute from the GUID.
static String[]	resolveNewest(Collection<String> colGUID, int cPartitions) Return a list of the newest GUID for each partition, indexed by the partition-id.
static boolean	validateGUID(String sGUID) Validate the given GUID.

Methods inherited from class java.lang.Object

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

Constructor Detail

GUIDHelper

public GUIDHelper()

Method Detail

generateGUID

public static String generateGUID(int nPartition,
                                  long lVersion,
                                  long ldt,
                                  Member member)

Generate and return a new GUID for the specified partition.

Parameters:

nPartition - the partition to return a GUID for

lVersion - the creation version of the partition

ldt - the creation timestamp; informational only

member - the member generating the GUID; informational only

Returns:

a new GUID for the specified partition

validateGUID

public static boolean validateGUID(String sGUID)

Validate the given GUID.

Parameters:

sGUID - the GUID to validate

Returns:

true if the specified GUID is valid; false otherwise

getPartition

public static int getPartition(String sGUID)

Parse the specified GUID and return the partition-id.

Parameters:

sGUID - the GUID to return the partition-id for

Returns:

the partition-id

getVersion

public static long getVersion(String sGUID)

Parse the specified GUID and return the partition-version.

Parameters:

sGUID - the GUID to return the partition-version for

Returns:

the partition-version

getServiceJoinTime

public static long getServiceJoinTime(String sGUID)

Parse the specified GUID and return the service join time.

Parameters:

sGUID - the GUID used to return the service join time

Returns:

the service join

getMemberId

public static int getMemberId(String sGUID)

Parse the specified GUID and return the originating member-id.

Parameters:

sGUID - the GUID to return the originating member-id for

Returns:

the originating member-id

resolveNewest

public static String[] resolveNewest(Collection<String> colGUID,
                                     int cPartitions)

Return a list of the newest GUID for each partition, indexed by the partition-id.

Parameters:

colGUID - the collection of GUIDs to resolve

cPartitions - the partition-count

Returns:

a list of the newest GUID for each partition

assignStores

public static Map<Integer,String[]> assignStores(Map<Integer,Object[]> mapConstraints,
                                                 int cDistinctStores)

Return a Map containing assignments of member id to stores based on the given constraints.

The algorithm will attempt to fairly distribute assignment of stores across members while abiding to the given constraints. For example:

Member Id	Constraints	Assignments
1	{a,b,c,d}	{a,c}
2	{a,b,c,d}	{b,d}
3	{e,f,g,h}	{e,g}
4	{e,f,g,h}	{f,h}

Parameters:

mapConstraints - the constraints to perform assignments within

cDistinctStores - the number of expected distinct stores

Returns:

a Map containing assignments of member id to stores based on the given constraints

getPartitions

public static PartitionSet getPartitions(Map<Integer,Object[]> mapStores,
                                         int cParts)

Return a PartitionSet with all partitions present in the provided mapStores.

Parameters:

mapStores - a Map of member id to stores

cParts - the partition count

Returns:

a PartitionSet with all partitions present in the provided mapStores

parseAttribute

protected static String parseAttribute(String sGUID,
                                       int id)

Return the specified (0-based) attribute from the GUID.

Parameters:

sGUID - the GUID

id - the (0-based) attribute index

Returns:

the GUID attribute

intersects

protected static List<String> intersects(Object[] aoLHS,
                                         Object[] aoRHS)

Return a List of stores (GUIDs) that allows the caller to derive whether the provided sets are disjoint, intersect or equal. These three states can be derived as follows:

Result	Reason
null	disjoint sets
listReturn	shared elements across LHS and RHS
listReturn.size() == aoLHS.length == aoRHS.length	LHS and RHS are equal

Parameters:

aoLHS - the first set in the comparison

aoRHS - the second set in the comparison

Returns:

a List of stores that allows the caller to derive whether the provided sets are disjoint, intersect or equal

createSortedEntries

protected static <K> Map.Entry<K,Object[]>[] createSortedEntries(Map<K,Object[]> map)

Return an array of entries based on the provided map ensuring the value (Object[]) is sorted.

Type Parameters:

K - - the key type

Parameters:

map - a map to base the Entry[] on

Returns:

an array of entries ensuring the value (Object[]) is sorted

main

public static void main(String[] asArg)

Utility that outputs information about a given GUID.
Usage: com.tangosol.persistence.GUIDHelper <GUID>

Parameters:

asArg - command line arguments