org.hypergraphdb.util

Class HGUtils

java.lang.Object

org.hypergraphdb.util.HGUtils

public class HGUtils
extends Object

The mandatory bag of static utility method class.

Author:

Borislav Iordanov

Field Summary

Fields

Modifier and Type	Field and Description
static HGPersistentHandle[]	EMPTY_HANDLE_ARRAY

Constructor Summary

Constructors

Constructor and Description
HGUtils()

Method Summary

Methods

Modifier and Type	Method and Description
static <T> T	cloneObject(T p, Mapping<Pair<Object,String>,Boolean> propertyFilter)
static void	closeNoException(HGSearchResult<?> rs)
static void	directoryRecurse(File top, Mapping<File,Boolean> mapping)
static void	dropHyperGraphInstance(String location) Delete a HyperGraph by removing the filesystem directory that holds it.
static boolean	eq(byte[] left, byte[] right)
static boolean	eq(Object[] left, Object[] right) Compare two arrays for equality.
static boolean	eq(Object left, Object right) Compare two objects for equality, checking for null values as well.
static boolean	eq(Ref<?>[] left, Ref<?>[] right)
static boolean	eq(Ref<?> r1, Ref<?> r2)
static ClassLoader	getClassLoader(HGConfiguration config) Returns the configured, the context or the class's classloader.
static ClassLoader	getClassLoader(HyperGraph graph) Returns the configured, the context or the class's classloader.
static <T> Class<T>	getImplementationClass(String interfaceClassName, String defaultImplementation)
static <T> T	getImplementationOf(String interfaceClassName, String defaultImplementation)
static Throwable	getRootCause(Throwable t)
static int	hashIt(Object o) Return an object's hash code or 0 if the object is null.
static int	hashThem(Object one, Object two) Return a composite hash code of two objects.
static boolean	isEmpty(String s)
static <T> Class<T>	loadClass(HGConfiguration config, String classname) Load a class using the class loader configured in the HGConfiguration object, if such a loader was configured.
static <T> Class<T>	loadClass(HyperGraph graph, String classname) Load a class using the class loader configured for the passed in HyperGraph instance, if such a loader was configured.
static void	logCallStack(PrintStream out)
static void	printStackTrace(StackTraceElement[] trace, PrintStream out)
static String	printStackTrace(Throwable t) Print the full stack trace of a Throwable object into a string buffer and return the corresponding string.
static <T> long	queryBatchProcess(HGQuery<T> query, Mapping<T,Boolean> F, int batchSize, T startAfter, long first) Process a potentially large query result in batches where each batch is a encapsulated in a single transaction.
static <T> Set<T>	set(T... members)
static void	throwRuntimeException(Throwable t)
static HGHandle[]	toHandleArray(HGLink link)
static void	visit(Object object, Mapping<Object,Boolean> visitor)
static void	wrapAndRethrow(Throwable t)

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY_HANDLE_ARRAY

public static final HGPersistentHandle[] EMPTY_HANDLE_ARRAY

Constructor Detail

HGUtils

public HGUtils()

Method Detail

isEmpty

public static boolean isEmpty(String s)

throwRuntimeException

public static void throwRuntimeException(Throwable t)

getRootCause

public static Throwable getRootCause(Throwable t)

eq

public static boolean eq(Object left,
         Object right)

Compare two objects for equality, checking for null values as well.

eq

public static boolean eq(Object[] left,
         Object[] right)

Compare two arrays for equality. This will perform a deep comparison, return true if and only if all elements of the passed in arrays are equal.

eq

public static boolean eq(byte[] left,
         byte[] right)

eq

public static boolean eq(Ref<?> r1,
         Ref<?> r2)

eq

public static boolean eq(Ref<?>[] left,
         Ref<?>[] right)

hashIt

public static int hashIt(Object o)

Return an object's hash code or 0 if the object is null.

hashThem

public static int hashThem(Object one,
           Object two)

Return a composite hash code of two objects.

printStackTrace

public static String printStackTrace(Throwable t)

Print the full stack trace of a Throwable object into a string buffer and return the corresponding string.

printStackTrace

public static void printStackTrace(StackTraceElement[] trace,
                   PrintStream out)

logCallStack

public static void logCallStack(PrintStream out)

closeNoException

public static void closeNoException(HGSearchResult<?> rs)

wrapAndRethrow

public static void wrapAndRethrow(Throwable t)

loadClass

public static <T> Class<T> loadClass(HyperGraph graph,
                     String classname)
                          throws ClassNotFoundException

Load a class using the class loader configured for the passed in HyperGraph instance, if such a loader was configured. If no class loader specific to the DB instance was configured, try the thread context class loader. Finally, fall back to HGUtils.class.getClassLoader().

If you have a DB configured class loader that you need to override with a thread context class loader, you'd need to implement the delegating yourself.

Type Parameters:

T -

Parameters:

graph -

classname -

Returns:

Throws:

ClassNotFoundException

loadClass

public static <T> Class<T> loadClass(HGConfiguration config,
                     String classname)
                          throws ClassNotFoundException

Load a class using the class loader configured in the HGConfiguration object, if such a loader was configured. If there is no class loader in the configuration, try the thread context class loader. Finally, fall back to HGUtils.class.getClassLoader().

If you have a DB configured class loader that you need to override with a thread context class loader, you'd need to implement the delegating yourself.

Type Parameters:

T -

Parameters:

graph -

classname -

Returns:

Throws:

ClassNotFoundException

getClassLoader

public static ClassLoader getClassLoader(HyperGraph graph)

Returns the configured, the context or the class's classloader.

Parameters:

graph -

Returns:

never null.

getClassLoader

public static ClassLoader getClassLoader(HGConfiguration config)

Returns the configured, the context or the class's classloader.

Parameters:

config -

Returns:

never null.

toHandleArray

public static HGHandle[] toHandleArray(HGLink link)

queryBatchProcess

public static <T> long queryBatchProcess(HGQuery<T> query,
                         Mapping<T,Boolean> F,
                         int batchSize,
                         T startAfter,
                         long first)

Process a potentially large query result in batches where each batch is a encapsulated in a single transaction. It is assumed that the result of the query is a HGRandomAccessResult so it is possible to quickly position at the beginning of the next batch.

The startAfter and first parameters define a starting point for the process. Use either one of them, but not both.

Type Parameters:

T -

Parameters:

query - The query that produces the result set to be scanned.

F - The function to perform on that query. The function takes a query result item and return a boolean which indicates whether to continue processing (if true) or stop (if false).

batchSize - The number of result items to encapsulate in a single transaction.

startAfter - Start processing at the first element after this parameter.

first - A 1-based index of the first element to process.

Returns:

The total number of elements processed.

directoryRecurse

public static void directoryRecurse(File top,
                    Mapping<File,Boolean> mapping)

dropHyperGraphInstance

public static void dropHyperGraphInstance(String location)

Delete a HyperGraph by removing the filesystem directory that holds it. This method will first make sure to close the HyperGraph if it's currently open.

Parameters:

location - The location of the graph instance.

getImplementationClass

public static <T> Class<T> getImplementationClass(String interfaceClassName,
                                  String defaultImplementation)

getImplementationOf

public static <T> T getImplementationOf(String interfaceClassName,
                        String defaultImplementation)

set

public static <T> Set<T> set(T... members)

cloneObject

public static <T> T cloneObject(T p,
                Mapping<Pair<Object,String>,Boolean> propertyFilter)
                     throws Exception

Throws:

Exception

visit

public static void visit(Object object,
         Mapping<Object,Boolean> visitor)