Field Detail

• _parent

  protected final ByteQuadsCanonicalizer _parent

  Reference to the root symbol table, for child tables, so that they can merge table information back as necessary.

• _tableInfo

  protected final AtomicReference<com.fasterxml.jackson.core.sym.ByteQuadsCanonicalizer.TableInfo> _tableInfo

  Member that is only used by the root table instance: root passes immutable state into child instances, and children may return new state if they add entries to the table. Child tables do NOT use the reference.

• _intern

  protected boolean _intern

  Whether canonical symbol Strings are to be intern()ed before added to the table or not.

  NOTE: non-final to allow disabling intern()ing in case of excessive collisions.

• _failOnDoS

  protected final boolean _failOnDoS

  Flag that indicates whether we should throw an exception if enough hash collisions are detected (true); or just worked around (false).

  Since:

  2.4

• _hashArea

  protected int[] _hashArea

  Primary hash information area: consists of 2 * _hashSize entries of 16 bytes (4 ints), arranged in a cascading lookup structure (details of which may be tweaked depending on expected rates of collisions).

• _hashSize

  protected int _hashSize

  Number of slots for primary entries within _hashArea; which is at most 1/8 of actual size of the underlying array (4-int slots, primary covers only half of the area; plus, additional area for longer symbols after hash area).

• _secondaryStart

  protected int _secondaryStart

  Offset within _hashArea where secondary entries start

• _tertiaryStart

  protected int _tertiaryStart

  Offset within _hashArea where tertiary entries start

• _tertiaryShift

  protected int _tertiaryShift

  Constant that determines size of buckets for tertiary entries: 1 << _tertiaryShift is the size, and shift value is also used for translating from primary offset into tertiary bucket (shift right by 4 + _tertiaryShift).

  Default value is 2, for buckets of 4 slots; grows bigger with bigger table sizes.

• _count

  protected int _count

  Total number of Strings in the symbol table; only used for child tables.

• _names

  protected String[] _names

  Array that contains String instances matching entries in _hashArea. Contains nulls for unused entries. Note that this size is twice that o

• _spilloverEnd

  protected int _spilloverEnd

  Pointer to the offset within spill-over area where there is room for more spilled over entries (if any). Spill over area is within fixed-size portion of _hashArea.

• _longNameOffset

  protected int _longNameOffset

  Offset within _hashArea that follows main slots and contains quads for longer names (13 bytes or longers), and points to the first available int that may be used for appending quads of the next long name. Note that long name area follows immediately after the fixed-size main hash area (_hashArea).

• _overflows

  protected BitSet _overflows

  Lazily constructed structure that is used to keep track of collision buckets that have overflowed once: this is used to detect likely attempts at denial-of-service attacks that uses hash collisions.

  Since:

  2.4

Method Detail

• createRoot

  public static ByteQuadsCanonicalizer createRoot()

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

• createRoot

  protected static ByteQuadsCanonicalizer createRoot(int seed)

  Factory method that should only be called from unit tests, where seed value should remain the same.

• makeChild

  public ByteQuadsCanonicalizer makeChild(int flags)

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

• 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()

• 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.

• hashSeed

  public int hashSeed()

• 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

• secondaryCount

  public int secondaryCount()

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

• tertiaryCount

  public int tertiaryCount()

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

• spilloverCount

  public int spilloverCount()

  Method mostly needed by unit tests; calculates number of entries in shared spillover area

• 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)

• addName

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

• addName

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

• addName

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

• 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)

• _reportTooManyCollisions

  protected void _reportTooManyCollisions()