# Package org.apache.cassandra.utils

- Interface Summary
  Interface | Description
  --- | ---
  BatchRemoveIterator<T> | Iterator that allows us to more efficiently remove many items
  CloseableIterator<T> |
  CoalescingStrategies.Coalescable |
  FastByteOperations.ByteOperations |
  IFilter |
  IFilter.FilterKey |
  IMergeIterator<In,Out> |
  IndexedSearchIterator<K,V> |
  IteratorWithLowerBound<In> |
  LongTimSort.LongComparator |
  OutputHandler |
  SearchIterator<K,V> |
  Throwables.DiscreteAction<E extends java.lang.Exception> |
  TimeSource |

- Class Summary
  Class | Description
  --- | ---
  AbstractIterator<V> |
  AlwaysPresentFilter |
  Architecture |
  AsymmetricOrdering<T1,T2> |
  BiMultiValMap<K,V> | A variant of BiMap which does not enforce uniqueness of values.
  BloomCalculations | The following calculations are taken from: http://www.cs.wisc.edu/~cao/papers/summary-cache/node8.html "Bloom Filters - the math" This class's static methods are meant to facilitate the use of the Bloom Filter class by helping to choose correct values of 'bits per element' and 'number of hash functions, k'.
  BloomCalculations.BloomSpecification | A wrapper class that holds two key parameters for a Bloom Filter: the number of hash functions used, and the number of buckets per element used.
  BloomFilter |
  BooleanSerializer |
  ByteBufferUtil | Utility methods to make ByteBuffers less painful The following should illustrate the different ways byte buffers can be used public void testArrayOffet() { byte[] b = "test_slice_array".getBytes(); ByteBuffer bb = ByteBuffer.allocate(1024); assert bb.position() == 0; assert bb.limit() == 1024; assert bb.capacity() == 1024; bb.put(b); assert bb.position() == b.length; assert bb.remaining() == bb.limit() - bb.position(); ByteBuffer bb2 = bb.slice(); assert bb2.position() == 0; //slice should begin at other buffers current position assert bb2.arrayOffset() == bb.position(); //to match the position in the underlying array one needs to //track arrayOffset assert bb2.limit()+bb2.arrayOffset() == bb.limit(); assert bb2.remaining() == bb.remaining(); } }
  CassandraVersion | Implements versioning used in Cassandra and CQL.
  Clock | Wrapper around time related functions that are either implemented by using the default JVM calls or by using a custom implementation for testing purposes.
  CoalescingStrategies |
  CoalescingStrategies.CoalescingStrategy |
  ConcurrentBiMap<K,V> | A variant of BiMap that permits concurrent access, and expects uniqueness of values in both domain and range.
  CounterId |
  DefaultValue<T> |
  DirectorySizeCalculator | Walks directory recursively, summing up total contents of files within.
  DynamicList<E> |
  DynamicList.Node<E> |
  EstimatedHistogram |
  EstimatedHistogram.EstimatedHistogramSerializer |
  ExpiringMap<K,V> |
  ExpiringMap.CacheableObject<T> |
  FastByteOperations | Utility code to do optimized byte-array comparison.
  FastByteOperations.PureJavaOperations |
  FastByteOperations.UnsafeOperations |
  FBUtilities |
  FilterFactory |
  GuidGenerator |
  HeapUtils | Utility to log heap histogram.
  Hex |
  HistogramBuilder | Simple class for constructing an EsimtatedHistogram from a set of predetermined values
  IntegerInterval | Mutable integer interval class, thread-safe.
  IntegerInterval.Set | A mutable set of closed integer intervals, stored in normalized form (i.e.
  Interval<C,D> |
  IntervalTree<C extends java.lang.Comparable<? super C>,D,I extends Interval<C,D>> |
  IntervalTree.Serializer<C extends java.lang.Comparable<? super C>,D,I extends Interval<C,D>> |
  JavaUtils | Utility method to retrieve information about the JRE.
  JMXServerUtils |
  JVMStabilityInspector | Responsible for deciding whether to kill the JVM if it gets in an "unstable" state (think OOM).
  JVMStabilityInspector.Killer |
  LockedDynamicList<E> |
  LongTimSort | A stable, adaptive, iterative mergesort that requires far fewer than n lg(n) comparisons when running on partially sorted arrays, while offering performance comparable to a traditional mergesort when run on random arrays.
  MD5Digest | The result of the computation of an MD5 digest.
  MergeIterator<In,Out> | Merges sorted input iterators which individually contain unique items.
  MergeIterator.Candidate<In> |
  MergeIterator.Reducer<In,Out> | Accumulator that collects values of type A, and outputs a value of type B.
  MerkleTree | A MerkleTree implemented as a binary tree.
  MerkleTree.MerkleTreeSerializer |
  MerkleTree.RowHash | Hash value representing a row, to be used to pass hashes to the MerkleTree.
  MerkleTree.TreeDifference |
  MerkleTree.TreeRange | The public interface to a range in the tree.
  MerkleTree.TreeRangeIterator | Returns the leaf (range) of a given tree in increasing order.
  MerkleTrees | Wrapper class for handling of multiple MerkleTrees at once.
  MerkleTrees.MerkleTreesSerializer |
  MurmurHash | This is a very fast, non-cryptographic hash suitable for general hash-based lookup.
  Mx4jTool | If mx4j-tools is in the classpath call maybeLoad to load the HTTP interface of mx4j.
  NanoTimeToCurrentTimeMillis |
  NativeLibrary |
  NativeLibraryDarwin | A `NativeLibraryWrapper` implementation for Darwin/Mac.
  NativeLibraryLinux | A `NativeLibraryWrapper` implementation for Linux.
  NativeLibraryWindows | A `NativeLibraryWrapper` implementation for Windows.
  NativeSSTableLoaderClient |
  NoSpamLogger | Logging that limits each log statement to firing based on time since the statement last fired.
  ObjectSizes | A convenience class for wrapping access to MemoryMeter
  OutputHandler.LogOutput |
  OutputHandler.SystemOutput |
  OverlapIterator<I extends java.lang.Comparable<? super I>,V> | A class for iterating sequentially through an ordered collection and efficiently finding the overlapping set of matching intervals.
  Pair<T1,T2> |
  ResourceWatcher |
  ResourceWatcher.WatchedResource |
  RMIServerSocketFactoryImpl |
  SigarLibrary |
  SlidingTimeRate | Concurrent rate computation over a sliding time window.
  SortedBiMultiValMap<K,V> |
  StatusLogger |
  StreamingHistogram | Histogram that can be constructed from streaming of data.
  StreamingHistogram.StreamingHistogramBuilder |
  StreamingHistogram.StreamingHistogramSerializer |
  SyncUtil |
  SystemTimeSource | Time source backed by JVM clock.
  TestRateLimiter | Helper class to apply rate limiting during fault injection testing; for an example script, see test/resources/byteman/mutation_limiter.btm.
  Throwables |
  TopKSampler<T> |
  TopKSampler.SamplerResult<S> | Represents the cardinality and the topK ranked items collected during a sample period
  UUIDGen | The goods are here: www.ietf.org/rfc/rfc4122.txt.
  UUIDSerializer |
  WindowsTimer |
  Wrapped<T> | Simple wrapper class to be used when a lambda function needs to modify a variable outside it's scope.
  WrappedBoolean | Simple wrapper for native boolean type
  WrappedInt | Simple wrapper for native int type
  WrappedRunnable |

- Enum Summary
  Enum | Description
  --- | ---
  AsymmetricOrdering.Op |
  ChecksumType |
  NativeLibrary.OSType |
  NoSpamLogger.Level | Levels for programmatically specifying the severity of a log statement
  Throwables.FileOpType |

- Exception Summary
  Exception | Description
  --- | ---
  WrappedException | Wrapped runtime exception for lambda functions

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