Class ConcurrentSuffixTree<O>

  • All Implemented Interfaces:
    PrettyPrintable, SuffixTree<O>, java.io.Serializable

    public class ConcurrentSuffixTree<O>
    extends java.lang.Object
    implements SuffixTree<O>, PrettyPrintable, java.io.Serializable
    An implementation of SuffixTree which supports lock-free concurrent reads, and allows items to be added to and to be removed from the tree atomically by background thread(s), without blocking reads.

    This implementation is based on ConcurrentRadixTree.

    See Also:
    Serialized Form
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      (package private) void addSuffixesToRadixTree​(java.lang.String keyAsString)  
      protected java.util.Set<java.lang.String> createSetForOriginalKeys()
      Creates a new Set in which original keys from which a suffix was generated can be stored.
      java.lang.Iterable<java.lang.CharSequence> getKeysContaining​(java.lang.CharSequence fragment)
      Returns a lazy iterable which returns the set of keys in the tree which contain the given fragment.
      java.lang.Iterable<java.lang.CharSequence> getKeysEndingWith​(java.lang.CharSequence suffix)
      Returns a lazy iterable which returns the set of keys in the tree which end with the given suffix.
      java.lang.Iterable<KeyValuePair<O>> getKeyValuePairsForKeysContaining​(java.lang.CharSequence fragment)
      Returns a lazy iterable which returns the set of KeyValuePairs for keys and their associated values in the tree, where the keys contain the given fragment.
      java.lang.Iterable<KeyValuePair<O>> getKeyValuePairsForKeysEndingWith​(java.lang.CharSequence suffix)
      Returns a lazy iterable which returns the set of KeyValuePairs for keys and their associated values in the tree, where the keys end with the given suffix.
      Node getNode()  
      O getValueForExactKey​(java.lang.CharSequence key)
      Returns the value associated with the given key (exact match), or returns null if no such value is associated with the key.
      java.lang.Iterable<O> getValuesForKeysContaining​(java.lang.CharSequence fragment)
      Returns a lazy iterable which returns the set of values associated with keys in the tree which contain the given fragment.
      java.lang.Iterable<O> getValuesForKeysEndingWith​(java.lang.CharSequence suffix)
      Returns a lazy iterable which returns the set of values associated with keys in the tree which end with the given suffix.
      (package private) static <T> java.util.Iterator<T> nullSafeIterator​(java.lang.Iterable<T> iterable)
      Utility method to return an iterator for the given iterable, or an empty iterator if the iterable is null.
      O put​(java.lang.CharSequence key, O value)
      Associates the given value with the given key; replacing any previous value associated with the key.
      O putIfAbsent​(java.lang.CharSequence key, O value)
      If a value is not already associated with the given key in the tree, associates the given value with the key; otherwise if an existing value is already associated, returns the existing value and does not overwrite it.
      boolean remove​(java.lang.CharSequence key)
      Removes the value associated with the given key (exact match).
      (package private) void removeSuffixesFromRadixTree​(java.lang.String keyAsString)  
      int size()
      Counts the number of keys/values stored in the tree.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Constructor Detail

      • ConcurrentSuffixTree

        public ConcurrentSuffixTree​(NodeFactory nodeFactory)
        Creates a new ConcurrentSuffixTree which will use the given NodeFactory to create nodes.
        Parameters:
        nodeFactory - An object which creates Node objects on-demand, and which might return node implementations optimized for storing the values supplied to it for the creation of each node
    • Method Detail

      • put

        public O put​(java.lang.CharSequence key,
                     O value)
        Associates the given value with the given key; replacing any previous value associated with the key. Returns the previous value associated with the key, if any.

        This operation is performed atomically.

        Specified by:
        put in interface SuffixTree<O>
        Parameters:
        key - The key with which the specified value should be associated
        value - The value to associate with the key, which cannot be null
        Returns:
        The previous value associated with the key, if there was one, otherwise null
      • putIfAbsent

        public O putIfAbsent​(java.lang.CharSequence key,
                             O value)
        If a value is not already associated with the given key in the tree, associates the given value with the key; otherwise if an existing value is already associated, returns the existing value and does not overwrite it.

        This operation is performed atomically.

        Specified by:
        putIfAbsent in interface SuffixTree<O>
        Parameters:
        key - The key with which the specified value should be associated
        value - The value to associate with the key, which cannot be null
        Returns:
        The existing value associated with the key, if there was one; otherwise null in which case the new value was successfully associated
      • remove

        public boolean remove​(java.lang.CharSequence key)
        Removes the value associated with the given key (exact match). If no value is associated with the key, does nothing.
        Specified by:
        remove in interface SuffixTree<O>
        Parameters:
        key - The key for which an associated value should be removed
        Returns:
        True if a value was removed (and therefore was associated with the key), false if no value was associated/removed
      • addSuffixesToRadixTree

        void addSuffixesToRadixTree​(java.lang.String keyAsString)
      • removeSuffixesFromRadixTree

        void removeSuffixesFromRadixTree​(java.lang.String keyAsString)
      • createSetForOriginalKeys

        protected java.util.Set<java.lang.String> createSetForOriginalKeys()
        Creates a new Set in which original keys from which a suffix was generated can be stored.

        By default this method creates a new concurrent set based on ConcurrentHashMap.

        Subclasses could override this method to create an alternative set.

        Specifically it is expected that this would be useful in unit tests, where sets with consistent iteration order would be useful.

        Returns:
        A new Set in which original keys from which a suffix was generated can be stored
      • getValueForExactKey

        public O getValueForExactKey​(java.lang.CharSequence key)
        Returns the value associated with the given key (exact match), or returns null if no such value is associated with the key.
        Specified by:
        getValueForExactKey in interface SuffixTree<O>
        Parameters:
        key - The key with which a sought value might be associated
        Returns:
        The value associated with the given key (exact match), or null if no value was associated with the key
      • getKeysEndingWith

        public java.lang.Iterable<java.lang.CharSequence> getKeysEndingWith​(java.lang.CharSequence suffix)
        Returns a lazy iterable which returns the set of keys in the tree which end with the given suffix.

        This is inclusive - if the given suffix is an exact match for a key in the tree, that key is also returned.

        Specified by:
        getKeysEndingWith in interface SuffixTree<O>
        Parameters:
        suffix - A suffix of sought keys in the tree
        Returns:
        The set of keys in the tree which end with the given suffix, inclusive
      • getValuesForKeysEndingWith

        public java.lang.Iterable<O> getValuesForKeysEndingWith​(java.lang.CharSequence suffix)
        Returns a lazy iterable which returns the set of values associated with keys in the tree which end with the given suffix.

        This is inclusive - if the given suffix is an exact match for a key in the tree, the value associated with that key is also returned.

        Note that although the same value might originally have been associated with multiple keys, or multiple suffixes of the same key, the set returned does not contain duplicates (as determined by the value objects' implementation of Object.equals(Object)).

        Specified by:
        getValuesForKeysEndingWith in interface SuffixTree<O>
        Parameters:
        suffix - A suffix of keys in the tree for which associated values are sought
        Returns:
        The set of values associated with keys in the tree which end with the given suffix, inclusive
      • getKeyValuePairsForKeysEndingWith

        public java.lang.Iterable<KeyValuePair<O>> getKeyValuePairsForKeysEndingWith​(java.lang.CharSequence suffix)
        Returns a lazy iterable which returns the set of KeyValuePairs for keys and their associated values in the tree, where the keys end with the given suffix.

        This is inclusive - if the given suffix is an exact match for a key in the tree, the KeyValuePair for that key is also returned.

        Specified by:
        getKeyValuePairsForKeysEndingWith in interface SuffixTree<O>
        Parameters:
        suffix - A suffix of keys in the tree for which associated KeyValuePairs are sought
        Returns:
        The set of KeyValuePairs for keys in the tree which end with the given suffix, inclusive
      • getKeysContaining

        public java.lang.Iterable<java.lang.CharSequence> getKeysContaining​(java.lang.CharSequence fragment)
        Returns a lazy iterable which returns the set of keys in the tree which contain the given fragment.

        This is inclusive - if the given fragment is an exact match for a key in the tree, that key is also returned.

        Specified by:
        getKeysContaining in interface SuffixTree<O>
        Parameters:
        fragment - A fragment of sought keys in the tree
        Returns:
        The set of keys in the tree which contain the given fragment, inclusive
      • getValuesForKeysContaining

        public java.lang.Iterable<O> getValuesForKeysContaining​(java.lang.CharSequence fragment)
        Returns a lazy iterable which returns the set of values associated with keys in the tree which contain the given fragment.

        This is inclusive - if the given fragment is an exact match for a key in the tree, the value associated with that key is also returned.

        Specified by:
        getValuesForKeysContaining in interface SuffixTree<O>
        Parameters:
        fragment - A fragment of keys in the tree for which associated values are sought
        Returns:
        The set of values associated with keys in the tree which contain the given fragment, inclusive
      • getKeyValuePairsForKeysContaining

        public java.lang.Iterable<KeyValuePair<O>> getKeyValuePairsForKeysContaining​(java.lang.CharSequence fragment)
        Returns a lazy iterable which returns the set of KeyValuePairs for keys and their associated values in the tree, where the keys contain the given fragment.

        This is inclusive - if the given fragment is an exact match for a key in the tree, the KeyValuePair for that key is also returned.

        Specified by:
        getKeyValuePairsForKeysContaining in interface SuffixTree<O>
        Parameters:
        fragment - A fragment of keys in the tree for which associated KeyValuePairs are sought
        Returns:
        The set of KeyValuePairs for keys in the tree which contain the given fragment, inclusive
      • size

        public int size()
        Counts the number of keys/values stored in the tree.

        In the current implementation, this has a time complexity similar to ConcurrentHashMap.size().

        Specified by:
        size in interface SuffixTree<O>
        Returns:
        The number of keys/values stored in the tree
      • nullSafeIterator

        static <T> java.util.Iterator<T> nullSafeIterator​(java.lang.Iterable<T> iterable)
        Utility method to return an iterator for the given iterable, or an empty iterator if the iterable is null.