Package edu.berkeley.cs.jqf.fuzz.util

Class Counter

java.lang.Object
edu.berkeley.cs.jqf.fuzz.util.Counter
Direct Known Subclasses:
FastNonCollidingCounter, NonZeroCachingCounter
public class Counter extends Object
Maps integer keys to integer counts using a fixed-size table.

Hash collisions are completely ignored; therefore, the counts are unreliable.

Throughout the internal documentation, the term "key" is used to refer to the keys that are hashed, while "index" is used to the result of key-hashing, i.e. the location in the internal array storage.

Author:
Rohan Padhye

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected final int[]
    counts
    The counter map as an array of integers.
    protected final int
    size
    The size of the counter map.

  • Constructor Summary

    Constructors
    Constructor
    Description
    Counter(int size)
    Creates a new counter with given size.
    Counter(Counter counter)
     

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    clear()
    Clears the counter by setting all values to zero.
    int
    get(int key)
    Retreives a value for a given key.
    int
    getAtIndex(int idx)
     
    org.eclipse.collections.api.list.primitive.IntList
    getNonZeroIndices()
    Returns a set of indices at which the count is non-zero.
    int
    getNonZeroSize()
    Returns the number of indices with non-zero counts.
    org.eclipse.collections.api.list.primitive.IntList
    getNonZeroValues()
    Returns a set of non-zero count values in this counter.
    boolean
    hasNonZeros()
    Checks if all indices have zero counts and returns a boolean as result.
    int
    increment(int key)
    Increments the count at the given key.
    int
    increment(int key, int delta)
    Increments the count at the given key by a given delta.
    int
    increment1(int k1, int k2)
    Increments the count at the given key pair.
    protected int
    incrementAtIndex(int index, int delta)
     
    void
    setAtIndex(int idx, int value)
     
    int
    size()
    Returns the size of this counter.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

    • size

      protected final int size
      The size of the counter map.

    • counts

      protected final int[] counts
      The counter map as an array of integers.

  • Constructor Details

    • Counter

      public Counter(int size)
      Creates a new counter with given size.
      Parameters:
      size - the fixed-number of elements in the hashtable.

    • Counter

      public Counter(Counter counter)

  • Method Details

    • size

      public int size()
      Returns the size of this counter.
      Returns:
      the size of this counter

    • clear

      public void clear()
      Clears the counter by setting all values to zero.

    • incrementAtIndex

      protected int incrementAtIndex(int index, int delta)

    • increment

      public int increment(int key)
      Increments the count at the given key.

      Note that the key is hashed and therefore the count to increment may be shared with another key that hashes to the same value.

      Parameters:
      key - the key whose count to increment
      Returns:
      the new value after incrementing the count

    • increment1

      public int increment1(int k1, int k2)
      Increments the count at the given key pair.

      Note that the key pair is hashed and therefore the count to increment may be shared with another key pair that hashes to the same value.

      Parameters:
      k1 - the key (part 1) whose count to increment
      k2 - the key (part 2) whose count to increment
      Returns:
      the new value after incrementing the count

    • increment

      public int increment(int key, int delta)
      Increments the count at the given key by a given delta.

      Note that the key is hashed and therefore the count to increment may be shared with another key that hashes to the same value.

      Parameters:
      key - the key whose count to increment
      delta - the amount to increment by
      Returns:
      the new value after incrementing the count

    • getNonZeroSize

      public int getNonZeroSize()
      Returns the number of indices with non-zero counts.
      Returns:
      the number of indices with non-zero counts

    • hasNonZeros

      public boolean hasNonZeros()
      Checks if all indices have zero counts and returns a boolean as result.
      Returns:
      true if some indices have non-zero counts, otherwise false.

    • getNonZeroIndices

      public org.eclipse.collections.api.list.primitive.IntList getNonZeroIndices()
      Returns a set of indices at which the count is non-zero.

      Note that indices are different from keys, in that multiple keys can map to the same index due to hash collisions.

      Returns:
      a set of indices at which the count is non-zero

    • getNonZeroValues

      public org.eclipse.collections.api.list.primitive.IntList getNonZeroValues()
      Returns a set of non-zero count values in this counter.
      Returns:
      a set of non-zero count values in this counter.

    • get

      public int get(int key)
      Retreives a value for a given key.

      The key is first hashed to retreive a value from the counter, and hence the result is modulo collisions.

      Parameters:
      key - the key to query
      Returns:
      the count for the index corresponding to this key

    • getAtIndex

      public int getAtIndex(int idx)

    • setAtIndex

      public void setAtIndex(int idx, int value)