windows-xp/Source/XPSP1/NT/inetsrv/iis/lkrhash/new.txt

2000/11
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* Refactored the code
* Public API
* C API
* Kernel-mode support
* Fixed a deadlock bug in the table lock. If you explicitly call
  Table::ReadLock and Table::WriteLock, you >need< this fix, or
  you will deadlock under stress.
* Fixed a bug in table compaction: until now, the table never
  actually compacted after elements were deleted, as the test
  for compaction always evaluated to `false'.
* Changed the signature of AddRefRecord. The second parameter is
  now an LK_ADDREF_REASON, instead of an int whose value is +1
  or -1. The reason code aids in debugging refcount leaks. If
  its value is negative, the refcount should be decremented;
  otherwise the refcount should be incremented.
* Changed behavior of ApplyIf locking: now locks one subtable
  at a time, instead of all subtables. Can use ReadLock or
  WriteLock to retain old behavior.
* Changed names and signatures of void LKRHashTableInit() and
  void LKRHashTableUninit(), to BOOL LKR_Initialize(DWORD) and
  void LKR_Terminate(), respectively.


2000/07/31
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* >REALLY< fixed the bug in Clear that left certain internal state
  variables in an inconsistent state. If you later
  inserted/deleted enough new records, LKRhash would AV. (The
  fix in the 2000/03/22 release did not work in all cases.)



2000/04/24
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* I added support for STL-style iterators
    * New iterators DO NOT LOCK the table or a bucket chain. In
      a multithreaded situation, it is YOUR responsibility to
      call WriteLock (or ReadLock) on the table before
      initializing any iterators, and to call WriteUnlock (or
      ReadUnlock) when you are finished.
    * The table provides begin() and end() methods. As the compiler
      isn't quite smart enough to realize that end() always
      returns a trivial empty iterator, a loop such as
	    MyTable::iterator iter;
	    for (iter = pTbl->begin();  iter != pTbl->end();  ++iter) ...
      is more efficiently expressed as
	    MyTable::iterator iter;
	    MyTable::iterator iterEnd = pTbl->end();
	    for (iter = pTbl->begin();  iter != iterEnd;  ++iter) ...
    * iterators can be pre- and post-incremented; i.e.:
	    ++iter and iter++
      Pre-increment is more efficient.
    * Table provides a constructor that accepts a range of
      iterators into another container.
    * Provides an Insert method that returns an iterator,
      pointing to the newly inserted record, or end() on
      failure.
    * Provides a Find method that returns an iterator pointing
      to the record with the passed-in key, or end() on
      failure.
    * Provides an EqualRange method that returns two iterators
      describing the range that contain all the records whose
      keys match the passed-in key. Until full support for
      multiple, identical keys is added, the range will contain
      either zero or one record(s).
    * Provides an Erase method that deletes the record pointed
      to by the iterator. Updates the iterator to point to the
      next record in the table.
    * Provides an Erase method that takes two iterators, which
      will delete all the records in the range described by the
      two iterators.
    * Unlike the old, deprecated iterators (CIterator), more
      than one iterator can be active at a time. It is best not
      to call the non-iterator insert/delete methods
      (InsertRecord, DeleteRecord, DeleteKey) while iterators
      are open, as the non-iterator methods can rebalance bucket
      chains, leading to invalid iterators, undercounting,
      and/or overcounting. This is true even if the table was
      WriteLocked, before the iterators were initialized. It is
      best to use the iterator Insert or Erase methods in such a
      case.
    * The iterators are reference-counted.

* I have provided an NTSD/CDB debugger extension, lkrdbg.dll,
  with one method, !lkrdbg.lkrhash:
    * !lkrhash -l[0-2] <addr>  will dump the hashtable at <addr>
			       at verbosity level l (default 0)
    * !lkrhash -g[0-2]	       will dump ALL hashtables at
			       at verbosity level l (default 0)
    * I have provided an easy-to-use customization mechanism in
      <lkrcust.h> to provide custom dumps for different
      hashtables. It's keyed off the pszName parameter used in
      the hashtable constructor. You can provide a custom dump
      routine for the table (to dump whatever other fields you
      might have added), as well as a custom dump routine for
      the record class stored by the hashtable. Provided three
      examples of customization, based on the samples.

* Fixed various build issues
    * All debug code is now bracketed with #ifdef IRTLDEBUG
      (instead of #ifdef _DEBUG). Currently equivalent, but you
      can control this in <irtldbg.h>
    * Fix all Unicode build issues. Code is now TCHAR-aware.
    * Added lkrhash.rc to provide a version resource

* Turned on `LKRhash' and `HashFn' namespaces by default. See readme.txt.
* Reorganized the samples into their own subtree.
* Removed more old code that used to be present so that I could
  test some changes (e.g., stuff bracketed by LKR_OLD_SEGMENT,
  LKR_SIGS_NODES, etc).
* Bucket Lock is once again CSmallSpinLock, unless
  LKR_DEPRECATED_ITERATORS is defined (off by default).
* Moved a lot of nested classes out of the table classes, to be
  top-level classes.
* Better compile-time and run-time assertions.



2000/03/22
----------
* Fixed a bug in Clear that left certain internal state variables
  in an inconsistent state. If you later inserted/deleted enough
  new records, LKRhash would AV.
* Changed BucketLock to CReaderWriterLock3 (recursive MRSW lock)
  to support certain scenarios, such as being able to call
  FindKey while enumerating with an old-style iterator. Slightly
  slower, but the speed improvements below more than compensate.
* Removed the 300-line example from the end of lkrhash.h. Now in
  hashtest.cpp, bracketed by SAMPLE_LKRHASH_TESTCLASS.
* Replaced TRACE macro with IRTLTRACE so as not to interfere with
  other TRACE macros (e.g., MFC's)
* Added dirs and sources files so that you can build LKRhash with
  the NT build environment.
* Added STATIC_ASSERT macro for compile-time assertions. The
  IRTLASSERT macro is still used for run-time assertions.
* Removed old code that used to be present so that I could test
  some changes (e.g., stuff bracketed by LKR_NEWCODE, LKR_MASK,
  LKR_SUBTABLE, LKR_COMPACT_DELETE, etc)
* Upped LK_DFLT_MAXLOAD to 6 (NODES_PER_CLUMP) to get better
  memory usage
* Added support for RockAll (not enabled by default)
* Turned CSegment into a concrete base class. Somewhat hacky but faster.
* Made the locks a little faster, esp. CReaderWriterLock3::IsWriteLocked
* Experimented with countdown loops (turned out to be slightly
  slower).
* Experimented with bitwise scrambling for subtable index
  calculation. Faster.
* Experimented with using a bitwise mask for subtable index
  calculation. Faster.
* Removed some inlines from lkrhash.h to improve modularity.
* Removed unimplemented Print methods.
* Bracketed global lists of hashtables with LKR_NO_GLOBAL_LIST.
* Reduced number of subtables to min(1, #CPUs) for LK_SMALL_TABLESIZE
  Was min(2, #CPUs). Max number of subtables is now 64.


1999/11/04
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* New reader-writer locks
* Smarter, faster simple spinlocks
* compact delete
* debugging support
* increased default load factor from 4.0 to 5.0 after reducing
  size of spinlock => reduced memory usage
* deprecated CIterator
* better error checking
* Win64 clean
* expose table locks => composition of operations
* global list
* faster hash scrambling function
* won't fail messily in low-memory situations
* fixed a race condition in some of the assertions
* enhanced test program