com.bigdata.rdf.internal.impl

Class BlobIV<V extends BigdataValue>

java.lang.Object

com.bigdata.rdf.internal.impl.AbstractIV<V,T>

com.bigdata.rdf.internal.impl.AbstractNonInlineIV<V,T>

com.bigdata.rdf.internal.impl.AbstractNonInlineExtensionIV<V,Void>

com.bigdata.rdf.internal.impl.BlobIV<V>

All Implemented Interfaces:

IExtensionIV, IV<V,Void>, IVCache<V,Void>, Serializable, Comparable<IV>, org.openrdf.model.BNode, org.openrdf.model.Literal, org.openrdf.model.Resource, org.openrdf.model.URI, org.openrdf.model.Value

public class BlobIV<V extends BigdataValue>
extends AbstractNonInlineExtensionIV<V,Void>

Implementation for any kind of RDF Value when the value is not being inlined, but primarily used with large RDF Values. Instances of this class can represent URIs, BNodes (if they are not being inlined), or Literals (including datatype literals if they are not being inlined). The representation of the BlobIV is simply the key in the TERMS index for the tuple for a given RDF Value. While flexible, Values models as BlobIVs require indirection through the TERMS index in order to materialize the Value. We are often able to inline Values compactly and efficiently into the statement indices, in which case those values simply do not appear in the TERMS index. The BlobIV remains useful when the RDF Value is large and not otherwise amenable to inlining.

Note: The BlobIV uses a hash code based on the hash code of the RDF Value. This gives us a fixed length key for the TERMS index, even when the RDF Value is very large. This makes the BlobIV suitable for use with very large RDF Values. However, the hash code results in widely dispersed updates which cause a lot of IO scatter. This makes the TERMS index slower on write than the TERM2ID and ID2TERM indices. Therefore shorter RDF Values should be inserted by preference into the TERM2ID / ID2TERM indices while larger values should be inserted as BlobIVs into the TERMS index.

See Also:

Serialized Form

Field Summary

Fields inherited from class com.bigdata.rdf.internal.impl.AbstractIV

flags

Constructor Summary

Constructors

Constructor and Description
BlobIV(byte flags, int hash, short counter)
BlobIV(VTE vte, int hash, short counter)

Method Summary

Methods

Modifier and Type	Method and Description
int	_compareTo(IV o) Compare two IVs having the same intrinsic datatype.
int	byteLength() The byte length of the encoded IV.
IV<V,Void>	clone(boolean clearCache) Return a copy of this IV.
int	counter() The collision counter component of the key in the TERMS index.
IKeyBuilder	encode(IKeyBuilder keyBuilder) Encode the IV as an unsigned byte[].
boolean	equals(Object o) Return true iff the two IVs are the same point in the same value space.
static BlobIV<?>	fromString(String s) Decodes the output of toString(), returning a new BlobIV .
byte	getExtensionByte() Return the extension byte for this type of non-inline IV.
IV	getExtensionIV()
String	getID() Implements BNode.getID().
int	hashCode() Return a hash code based on the value of the point in the value space.
static byte	toFlags(VTE vte) Return the flags byte for a BlobIV.
String	toString() Human readable representation includes the term identifier, whether this is a URI, Literal, Blank node, or Statement identifier and the datatype URI if one is assigned.

Methods inherited from class com.bigdata.rdf.internal.impl.AbstractNonInlineIV

asValue, booleanValue, byteValue, calendarValue, decimalValue, doubleValue, floatValue, getDatatype, getInlineValue, getLabel, getLanguage, getLocalName, getNamespace, integerValue, intValue, isInline, longValue, needsMaterialization, shortValue, stringValue

Methods inherited from class com.bigdata.rdf.internal.impl.AbstractIV

compareTo, flags, getDTE, getDTE, getDTEX, getInternalValueTypeEnum, getValue, getValueCache, getVTE, getVTE, hasValue, isBigNumeric, isBNode, isExtension, isExtension, isFixedNumeric, isFloatingPointNumeric, isInline, isLiteral, isNullIV, isNumeric, isResource, isSignedNumeric, isStatement, isUnsignedNumeric, isURI, isVocabulary, setValue, toFlags

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

BlobIV

public BlobIV(VTE vte,
      int hash,
      short counter)

Parameters:

vte - The VTE.

hash - The hash code.

counter - The counter.

BlobIV

public BlobIV(byte flags,
      int hash,
      short counter)

Parameters:

flags - The flags byte.

hash - The hash code.

counter - The counter.

Method Detail

toFlags

public static final byte toFlags(VTE vte)

Return the flags byte for a BlobIV.

clone

public IV<V,Void> clone(boolean clearCache)

Description copied from interface: IVCache

Return a copy of this IV.

Note: This method exists to defeat the hard reference from the IV to the cached BigdataValue in order to avoid a memory leak when the IV is used as the key in a weak value cache whose value is the BigdataValue. Therefore, certain IV implementations MAY return this when they are used for limited collections. The vocabulary IVs are the primary example. For the same reason, we do not need to recursively break the link from the IV to the BigdataValue for IVs which embed other IVs.

Parameters:

clearCache - When true the cached reference (if any) will NOT be set on the copy.

Returns:

The copy.

See Also:

(Thread-local cache combined with unbounded thread pools causes effective memory leak)

toString

public String toString()

Human readable representation includes the term identifier, whether this is a URI, Literal, Blank node, or Statement identifier and the datatype URI if one is assigned. TermId(hashCode:counter:[U|L|B])

Specified by:

toString in interface org.openrdf.model.URI

Overrides:

toString in class Object

See Also:

IVUtility#fromString(String), which parses the string value returned by this method.

fromString

public static BlobIV<?> fromString(String s)

Decodes the output of toString(), returning a new BlobIV .

Parameters:

s - The string representation.

Returns:

The BlobIV.

equals

public boolean equals(Object o)

Description copied from class: AbstractIV

Return true iff the two IVs are the same point in the same value space. Points in different value spaces (as identified by different datatype URIs) are NOT equal even if they have the same value in the corresponding primitive data type.

Note: The IV implementations typically DO NOT compare equals() with BigdataValues. Therefore you MUST NOT mix IVs and BigdataValues in the keys of a map or the values of a set.

Specified by:

equals in interface org.openrdf.model.BNode

Specified by:

equals in interface org.openrdf.model.Literal

Specified by:

equals in interface org.openrdf.model.URI

Specified by:

equals in class AbstractIV<V extends BigdataValue,Void>

hashCode

public final int hashCode()

Return a hash code based on the value of the point in the value space.

Note: The IV implementations typically DO NOT return hash codes that are consistent with BigdataValue#hashCode(). Therefore you MUST NOT mix IVs and BigdataValues in the keys of a map or the values of a set.

Specified by:

hashCode in interface org.openrdf.model.BNode

Specified by:

hashCode in interface org.openrdf.model.Literal

Specified by:

hashCode in interface org.openrdf.model.URI

Specified by:

hashCode in class AbstractIV<V extends BigdataValue,Void>

Returns:

The hash code component of the key in the TERMS index.

counter

public final int counter()

The collision counter component of the key in the TERMS index.

byteLength

public final int byteLength()

Description copied from interface: IV

The byte length of the encoded IV.

_compareTo

public int _compareTo(IV o)

Description copied from class: AbstractIV

Compare two IVs having the same intrinsic datatype.

Specified by:

_compareTo in class AbstractIV<V extends BigdataValue,Void>

encode

public final IKeyBuilder encode(IKeyBuilder keyBuilder)

Encode the IV as an unsigned byte[].

Overridden to entirely take over the encoding of the key from the BlobIV. Note that this simply copies the private unsigned byte[] into the IKeyBuilder since it is already the exact key for the BlobIV.

Specified by:

encode in interface IV<V extends BigdataValue,Void>

Overrides:

encode in class AbstractIV<V extends BigdataValue,Void>

Parameters:

keyBuilder - The object used to encode the IV.

Returns:

the key builder

getID

public String getID()

Implements BNode.getID().

Creates a unique blank node ID based on the BlobIV's internal data.

Specified by:

getID in interface org.openrdf.model.BNode

Overrides:

getID in class AbstractNonInlineIV<V extends BigdataValue,Void>

getExtensionByte

public final byte getExtensionByte()

Description copied from class: AbstractNonInlineExtensionIV

Return the extension byte for this type of non-inline IV.

Specified by:

getExtensionByte in class AbstractNonInlineExtensionIV<V extends BigdataValue,Void>

See Also:

INonInlineExtensionCodes

getExtensionIV

public IV getExtensionIV()