Package com.fasterxml.jackson.core.sym

Class ByteQuadsCanonicalizer

java.lang.Object

com.fasterxml.jackson.core.sym.ByteQuadsCanonicalizer

public final class ByteQuadsCanonicalizer
extends Object

Replacement for BytesToNameCanonicalizer which aims at more localized memory access due to flattening of name quad data. Performance improvement modest for simple JSON document data binding (maybe 3%), but should help more for larger symbol tables, or for binary formats like Smile.

Hash area is divided into 4 sections:

1. Primary area (1/2 of total size), direct match from hash (LSB)
2. Secondary area (1/4 of total size), match from hash (LSB) >> 1
3. Tertiary area (1/8 of total size), match from hash (LSB) >> 2
4. Spill-over area (remaining 1/8) with linear scan, insertion order

and within every area, entries are 4 ints, where 1 - 3 ints contain 1 - 12 UTF-8 encoded bytes of name (null-padded), and last int is offset in _names that contains actual name Strings.

Since:

2.6

Method Summary

Modifier and Type	Method	Description
String	addName(String name, int q1)
String	addName(String name, int[] q, int qlen)
String	addName(String name, int q1, int q2)
String	addName(String name, int q1, int q2, int q3)
int	bucketCount()
int	calcHash(int q1)
int	calcHash(int[] q, int qlen)
int	calcHash(int q1, int q2)
int	calcHash(int q1, int q2, int q3)
static ByteQuadsCanonicalizer	createRoot()	Factory method to call to create a symbol table instance with a randomized seed value.
String	findName(int q1)
String	findName(int[] q, int qlen)
String	findName(int q1, int q2)
String	findName(int q1, int q2, int q3)
int	hashSeed()
boolean	isCanonicalizing()
ByteQuadsCanonicalizer	makeChild(int flags)	Factory method used to create actual symbol table instance to use for parsing.
ByteQuadsCanonicalizer	makeChildOrPlaceholder(int flags)	Method similar to makeChild(int) but one that only creates real instance of JsonFactory.Feature.CANONICALIZE_FIELD_NAMES is enabled: otherwise a "bogus" instance is created.
boolean	maybeDirty()	Method called to check to quickly see if a child symbol table may have gotten additional entries.
int	primaryCount()	Method mostly needed by unit tests; calculates number of entries that are in the primary slot set.
void	release()	Method called by the using code to indicate it is done with this instance.
int	secondaryCount()	Method mostly needed by unit tests; calculates number of entries in secondary buckets
int	size()
int	spilloverCount()	Method mostly needed by unit tests; calculates number of entries in shared spill-over area
int	tertiaryCount()	Method mostly needed by unit tests; calculates number of entries in tertiary buckets
String	toString()
int	totalCount()

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Method Details

createRoot

public static ByteQuadsCanonicalizer createRoot()

Factory method to call to create a symbol table instance with a randomized seed value.

Returns:

Root instance to use for constructing new child instances

makeChild

public ByteQuadsCanonicalizer makeChild(int flags)

Factory method used to create actual symbol table instance to use for parsing.

Parameters:

flags - Bit flags of active JsonFactory.Features enabled.

Returns:

Actual canonicalizer instance that can be used by a parser

makeChildOrPlaceholder

public ByteQuadsCanonicalizer makeChildOrPlaceholder(int flags)

Method similar to makeChild(int) but one that only creates real instance of JsonFactory.Feature.CANONICALIZE_FIELD_NAMES is enabled: otherwise a "bogus" instance is created.

Parameters:

flags - Bit flags of active JsonFactory.Features enabled.

Returns:

Actual canonicalizer instance that can be used by a parser if (and only if) canonicalization is enabled; otherwise a non-null "placeholder" instance.

Since:

2.13

release

public void release()

Method called by the using code to indicate it is done with this instance. This lets instance merge accumulated changes into parent (if need be), safely and efficiently, and without calling code having to know about parent information.

size

public int size()

Returns:

Number of symbol entries contained by this canonicalizer instance

bucketCount

public int bucketCount()

Returns:

number of primary slots table has currently

maybeDirty

public boolean maybeDirty()

Method called to check to quickly see if a child symbol table may have gotten additional entries. Used for checking to see if a child table should be merged into shared table.

Returns:

Whether main hash area has been modified

hashSeed

public int hashSeed()

isCanonicalizing

public boolean isCanonicalizing()

Returns:

True for "real", canonicalizing child tables; false for root table as well as placeholder "child" tables.

Since:

2.13

primaryCount

public int primaryCount()

Method mostly needed by unit tests; calculates number of entries that are in the primary slot set. These are "perfect" entries, accessible with a single lookup

Returns:

Number of entries in the primary hash area

secondaryCount

public int secondaryCount()

Method mostly needed by unit tests; calculates number of entries in secondary buckets

Returns:

Number of entries in the secondary hash area

tertiaryCount

public int tertiaryCount()

Method mostly needed by unit tests; calculates number of entries in tertiary buckets

Returns:

Number of entries in the tertiary hash area

spilloverCount

public int spilloverCount()

Method mostly needed by unit tests; calculates number of entries in shared spill-over area

Returns:

Number of entries in the linear spill-over areay

totalCount

public int totalCount()

toString

public String toString()

Overrides:

toString in class Object

findName

public String findName(int q1)

findName

public String findName(int q1,
 int q2)

findName

public String findName(int q1,
 int q2,
 int q3)

findName

public String findName(int[] q,
 int qlen)

addName

public String addName(String name,
 int q1)
               throws StreamConstraintsException

Parameters:

name - Name to add

q1 - Quad representation of the name

Returns:

name (possibly interned)

Throws:

StreamConstraintsException - if the constraint exceptions

addName

public String addName(String name,
 int q1,
 int q2)
               throws StreamConstraintsException

Parameters:

name - Name to add

q1 - First quad of name representation

q2 - Second quad of name representation

Returns:

name (possibly interned)

Throws:

StreamConstraintsException - if the constraint exceptions

addName

public String addName(String name,
 int q1,
 int q2,
 int q3)
               throws StreamConstraintsException

Parameters:

name - Name to add

q1 - First quad of name representation

q2 - Second quad of name representation

q3 - Third quad of name representation

Returns:

name (possibly interned)

Throws:

StreamConstraintsException - if the constraint exceptions

addName

public String addName(String name,
 int[] q,
 int qlen)
               throws StreamConstraintsException

Parameters:

name - Name to add

q - Quads of name representation

qlen - Number of quads in q

Returns:

name (possibly interned)

Throws:

StreamConstraintsException - if the constraint exceptions

calcHash

public int calcHash(int q1)

calcHash

public int calcHash(int q1,
 int q2)

calcHash

public int calcHash(int q1,
 int q2,
 int q3)

calcHash

public int calcHash(int[] q,
 int qlen)

Parameters:

q - int array

qlen - length

Returns:

hash

Throws:

IllegalArgumentException - if qlen is less than 4