Package org.apache.xerces.util
Class SoftReferenceSymbolTable
java.lang.Object
org.apache.xerces.util.SymbolTable
org.apache.xerces.util.SoftReferenceSymbolTable
This symbol table uses SoftReferences to its String entries, which means that table entries
that have no references to them can be garbage collected when memory is needed. Thus, in
documents with very very large numbers of unique strings, using this SymbolTable will prevent
an out of memory error from occurring.
- Version:
- $Id: SoftReferenceSymbolTable.java 1358350 2012-07-06 19:04:35Z mrglavas $
- Author:
- Peter McCracken, IBM
- See Also:
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionprotected static final class
This class is a symbol table entry.protected static final class
Nested classes/interfaces inherited from class org.apache.xerces.util.SymbolTable
SymbolTable.Entry
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Field Summary
FieldsFields inherited from class org.apache.xerces.util.SymbolTable
fCollisionThreshold, fCount, fHashMultipliers, fLoadFactor, fTableSize, fThreshold, MAX_HASH_COLLISIONS, MULTIPLIERS_MASK, MULTIPLIERS_SIZE, TABLE_SIZE
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Constructor Summary
ConstructorsConstructorDescriptionConstructs a new, empty SymbolTable with a default initial capacity (101) and load factor, which is 0.75.SoftReferenceSymbolTable
(int initialCapacity) Constructs a new, empty SymbolTable with the specified initial capacity and default load factor, which is 0.75.SoftReferenceSymbolTable
(int initialCapacity, float loadFactor) Constructs a new, empty SymbolTable with the specified initial capacity and the specified load factor. -
Method Summary
Modifier and TypeMethodDescriptionaddSymbol
(char[] buffer, int offset, int length) Adds the specified symbol to the symbol table and returns a reference to the unique symbol.Adds the specified symbol to the symbol table and returns a reference to the unique symbol.protected void
compact()
Reduces the capacity of and internally reorganizes this SymbolTable, in order to accommodate and access its entries in a more memory efficient way.boolean
containsSymbol
(char[] buffer, int offset, int length) Returns true if the symbol table already contains the specified symbol.boolean
containsSymbol
(String symbol) Returns true if the symbol table already contains the specified symbol.protected void
Randomly selects a new hash function and reorganizes this SymbolTable in order to more evenly distribute its entries across the table.protected void
rehash()
Increases the capacity of and internally reorganizes this SymbolTable, in order to accommodate and access its entries more efficiently.Methods inherited from class org.apache.xerces.util.SymbolTable
hash, hash
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Field Details
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fBuckets
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Constructor Details
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SoftReferenceSymbolTable
public SoftReferenceSymbolTable(int initialCapacity, float loadFactor) Constructs a new, empty SymbolTable with the specified initial capacity and the specified load factor.- Parameters:
initialCapacity
- the initial capacity of the SymbolTable.loadFactor
- the load factor of the SymbolTable.- Throws:
IllegalArgumentException
- if the initial capacity is less than zero, or if the load factor is nonpositive.
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SoftReferenceSymbolTable
public SoftReferenceSymbolTable(int initialCapacity) Constructs a new, empty SymbolTable with the specified initial capacity and default load factor, which is 0.75.- Parameters:
initialCapacity
- the initial capacity of the hashtable.- Throws:
IllegalArgumentException
- if the initial capacity is less than zero.
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SoftReferenceSymbolTable
public SoftReferenceSymbolTable()Constructs a new, empty SymbolTable with a default initial capacity (101) and load factor, which is 0.75.
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Method Details
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addSymbol
Adds the specified symbol to the symbol table and returns a reference to the unique symbol. If the symbol already exists, the previous symbol reference is returned instead, in order guarantee that symbol references remain unique.- Overrides:
addSymbol
in classSymbolTable
- Parameters:
symbol
- The new symbol.
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addSymbol
Adds the specified symbol to the symbol table and returns a reference to the unique symbol. If the symbol already exists, the previous symbol reference is returned instead, in order guarantee that symbol references remain unique.- Overrides:
addSymbol
in classSymbolTable
- Parameters:
buffer
- The buffer containing the new symbol.offset
- The offset into the buffer of the new symbol.length
- The length of the new symbol in the buffer.
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rehash
protected void rehash()Increases the capacity of and internally reorganizes this SymbolTable, in order to accommodate and access its entries more efficiently. This method is called automatically when the number of keys in the SymbolTable exceeds this hashtable's capacity and load factor.- Overrides:
rehash
in classSymbolTable
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compact
protected void compact()Reduces the capacity of and internally reorganizes this SymbolTable, in order to accommodate and access its entries in a more memory efficient way. This method is called automatically when the number of keys in the SymbolTable drops below 25% of this hashtable's load factor (as a result of SoftReferences which have been cleared). -
rebalance
protected void rebalance()Randomly selects a new hash function and reorganizes this SymbolTable in order to more evenly distribute its entries across the table. This method is called automatically when the number keys in one of the SymbolTable's buckets exceeds the given collision threshold.- Overrides:
rebalance
in classSymbolTable
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containsSymbol
Returns true if the symbol table already contains the specified symbol.- Overrides:
containsSymbol
in classSymbolTable
- Parameters:
symbol
- The symbol to look for.
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containsSymbol
public boolean containsSymbol(char[] buffer, int offset, int length) Returns true if the symbol table already contains the specified symbol.- Overrides:
containsSymbol
in classSymbolTable
- Parameters:
buffer
- The buffer containing the symbol to look for.offset
- The offset into the buffer.length
- The length of the symbol in the buffer.
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