path: root/comm/mailnews/db/mork/morkProbeMap.cpp

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-  */
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// This code is a port to NS Mork from public domain Mithril C++ sources.
// Note many code comments here come verbatim from cut-and-pasted Mithril.
// In many places, code is identical; Mithril versions stay public domain.
// Changes in porting are mainly class type and scalar type name changes.

#include "nscore.h"

#ifndef _MDB_
#  include "mdb.h"
#endif

#ifndef _MORK_
#  include "mork.h"
#endif

#ifndef _MORKNODE_
#  include "morkNode.h"
#endif

#ifndef _MORKPROBEMAP_
#  include "morkProbeMap.h"
#endif

#ifndef _MORKENV_
#  include "morkEnv.h"
#endif

/*============================================================================*/
/* morkMapScratch */

void morkMapScratch::halt_map_scratch(morkEnv* ev) {
  nsIMdbHeap* heap = sMapScratch_Heap;

  if (heap) {
    if (sMapScratch_Keys) heap->Free(ev->AsMdbEnv(), sMapScratch_Keys);
    if (sMapScratch_Vals) heap->Free(ev->AsMdbEnv(), sMapScratch_Vals);
  }
}

// 456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789

/*============================================================================*/
/* morkProbeMap */

void morkProbeMap::ProbeMapBadTagError(morkEnv* ev) const {
  ev->NewError("bad sProbeMap_Tag");
}

void morkProbeMap::WrapWithNoVoidSlotError(morkEnv* ev) const {
  ev->NewError("wrap without void morkProbeMap slot");
}

void morkProbeMap::GrowFailsMaxFillError(morkEnv* ev) const {
  ev->NewError("grow fails morkEnv > sMap_Fill");
}

void morkProbeMap::MapKeyIsNotIPError(morkEnv* ev) const {
  ev->NewError("not sMap_KeyIsIP");
}

void morkProbeMap::MapValIsNotIPError(morkEnv* ev) const {
  ev->NewError("not sMap_ValIsIP");
}

void morkProbeMap::rehash_old_map(morkEnv* ev, morkMapScratch* ioScratch) {
  mork_size keySize = sMap_KeySize;  // size of every key bucket
  mork_size valSize = sMap_ValSize;  // size of every associated value

  mork_count slots = sMap_Slots;  // number of new buckets
  mork_u1* keys = sMap_Keys;      // destination for rehashed keys
  mork_u1* vals = sMap_Vals;      // destination for any copied values

  mork_bool keyIsIP = (keys && keySize == sizeof(mork_ip) && sMap_KeyIsIP);
  mork_bool valIsIP = (vals && valSize == sizeof(mork_ip) && sMap_ValIsIP);

  mork_count oldSlots = ioScratch->sMapScratch_Slots;  // sMap_Slots
  mork_u1* oldKeys = ioScratch->sMapScratch_Keys;      // sMap_Keys
  mork_u1* oldVals = ioScratch->sMapScratch_Vals;      // sMap_Vals
  mork_u1* end = oldKeys + (keySize * oldSlots);       // one byte past last key

  mork_fill fill = 0;  // let's count the actual fill for a double check

  while (oldKeys < end)  // another old key bucket to rehash if non-nil?
  {
    if (!this->ProbeMapIsKeyNil(ev, oldKeys))  // need to rehash?
    {
      ++fill;  // this had better match sMap_Fill when we are all done
      mork_u4 hash = this->ProbeMapHashMapKey(ev, oldKeys);

      mork_pos i = hash % slots;  // target hash bucket
      mork_pos startPos = i;      // remember start to detect

      mork_u1* k = keys + (i * keySize);
      while (!this->ProbeMapIsKeyNil(ev, k)) {
        if (++i >=
            (mork_pos)slots)  // advanced past end? need to wrap around now?
          i = 0;              // wrap around to first slot in map's hash table

        if (i == startPos)  // no void slots were found anywhere in map?
        {
          this->WrapWithNoVoidSlotError(ev);  // should never happen
          return;  // this is bad, and we can't go on with the rehash
        }
        k = keys + (i * keySize);
      }
      if (keyIsIP)                                    // int special case?
        *((mork_ip*)k) = *((const mork_ip*)oldKeys);  // fast bitwise copy
      else
        MORK_MEMCPY(k, oldKeys, keySize);  // slow bitwise copy

      if (oldVals)  // need to copy values as well?
      {
        mork_size valOffset = (i * valSize);
        mork_u1* v = vals + valOffset;
        mork_u1* ov = oldVals + valOffset;
        if (valIsIP)                               // int special case?
          *((mork_ip*)v) = *((const mork_ip*)ov);  // fast bitwise copy
        else
          MORK_MEMCPY(v, ov, valSize);  // slow bitwise copy
      }
    }
    oldKeys += keySize;  // advance to next key bucket in old map
  }
  if (fill != sMap_Fill)  // is the recorded value of sMap_Fill wrong?
  {
    ev->NewWarning("fill != sMap_Fill");
    sMap_Fill = fill;
  }
}

mork_bool morkProbeMap::grow_probe_map(morkEnv* ev) {
  if (sMap_Heap)  // can we grow the map?
  {
    mork_num newSlots = ((sMap_Slots * 4) / 3) + 1;  // +25%
    morkMapScratch old;  // a place to temporarily hold all the old arrays
    if (this->new_slots(ev, &old, newSlots))  // have more?
    {
      ++sMap_Seed;  // note the map has changed
      this->rehash_old_map(ev, &old);

      if (ev->Good()) {
        mork_count slots = sMap_Slots;
        mork_num emptyReserve = (slots / 7) + 1;   // keep this many empty
        mork_fill maxFill = slots - emptyReserve;  // new max occupancy
        if (maxFill > sMap_Fill)        // new max is bigger than old occupancy?
          sProbeMap_MaxFill = maxFill;  // we can install new max for fill
        else
          this->GrowFailsMaxFillError(ev);  // we have invariant failure
      }

      if (ev->Bad())  // rehash failed? need to revert map to last state?
        this->revert_map(ev, &old);  // swap the vectors back again

      old.halt_map_scratch(ev);  // remember to free the old arrays
    }
  } else
    ev->OutOfMemoryError();

  return ev->Good();
}

void morkProbeMap::revert_map(morkEnv* ev, morkMapScratch* ioScratch) {
  mork_count tempSlots = ioScratch->sMapScratch_Slots;  // sMap_Slots
  mork_u1* tempKeys = ioScratch->sMapScratch_Keys;      // sMap_Keys
  mork_u1* tempVals = ioScratch->sMapScratch_Vals;      // sMap_Vals

  ioScratch->sMapScratch_Slots = sMap_Slots;
  ioScratch->sMapScratch_Keys = sMap_Keys;
  ioScratch->sMapScratch_Vals = sMap_Vals;

  sMap_Slots = tempSlots;
  sMap_Keys = tempKeys;
  sMap_Vals = tempVals;
}

void morkProbeMap::put_probe_kv(morkEnv* ev, const void* inAppKey,
                                const void* inAppVal, mork_pos inPos) {
  mork_u1* mapVal = 0;
  mork_u1* mapKey = 0;

  mork_num valSize = sMap_ValSize;
  if (valSize && inAppVal)  // map holds values? caller sends value?
  {
    mork_u1* val = sMap_Vals + (valSize * inPos);
    if (valSize == sizeof(mork_ip) && sMap_ValIsIP)  // int special case?
      *((mork_ip*)val) = *((const mork_ip*)inAppVal);
    else
      mapVal = val;  // show possible need to call ProbeMapPushIn()
  }
  if (inAppKey)  // caller sends the key?
  {
    mork_num keySize = sMap_KeySize;
    mork_u1* key = sMap_Keys + (keySize * inPos);
    if (keySize == sizeof(mork_ip) && sMap_KeyIsIP)  // int special case?
      *((mork_ip*)key) = *((const mork_ip*)inAppKey);
    else
      mapKey = key;  // show possible need to call ProbeMapPushIn()
  } else
    ev->NilPointerError();

  if ((inAppVal && mapVal) || (inAppKey && mapKey))
    this->ProbeMapPushIn(ev, inAppKey, inAppVal, mapKey, mapVal);

  if (sMap_Fill > sProbeMap_MaxFill) this->grow_probe_map(ev);
}

void morkProbeMap::get_probe_kv(morkEnv* ev, void* outAppKey, void* outAppVal,
                                mork_pos inPos) const {
  const mork_u1* mapVal = 0;
  const mork_u1* mapKey = 0;

  mork_num valSize = sMap_ValSize;
  if (valSize && outAppVal)  // map holds values? caller wants value?
  {
    const mork_u1* val = sMap_Vals + (valSize * inPos);
    if (valSize == sizeof(mork_ip) && sMap_ValIsIP)  // int special case?
      *((mork_ip*)outAppVal) = *((const mork_ip*)val);
    else
      mapVal = val;  // show possible need to call ProbeMapPullOut()
  }
  if (outAppKey)  // caller wants the key?
  {
    mork_num keySize = sMap_KeySize;
    const mork_u1* key = sMap_Keys + (keySize * inPos);
    if (keySize == sizeof(mork_ip) && sMap_KeyIsIP)  // int special case?
      *((mork_ip*)outAppKey) = *((const mork_ip*)key);
    else
      mapKey = key;  // show possible need to call ProbeMapPullOut()
  }
  if ((outAppVal && mapVal) || (outAppKey && mapKey))
    this->ProbeMapPullOut(ev, mapKey, mapVal, outAppKey, outAppVal);
}

mork_test morkProbeMap::find_key_pos(morkEnv* ev, const void* inAppKey,
                                     mork_u4 inHash, mork_pos* outPos) const {
  mork_u1* k = sMap_Keys;         // array of keys, each of size sMap_KeySize
  mork_num size = sMap_KeySize;   // number of bytes in each key
  mork_count slots = sMap_Slots;  // total number of key buckets
  mork_pos i = inHash % slots;    // target hash bucket
  mork_pos startPos = i;          // remember start to detect

  mork_test outTest = this->MapTest(ev, k + (i * size), inAppKey);
  while (outTest == morkTest_kMiss) {
    if (++i >=
        (mork_pos)slots)  // advancing goes beyond end? need to wrap around now?
      i = 0;              // wrap around to first slot in map's hash table

    if (i == startPos)  // no void slots were found anywhere in map?
    {
      this->WrapWithNoVoidSlotError(ev);  // should never happen
      break;  // end loop on kMiss; note caller expects either kVoid or kHit
    }
    outTest = this->MapTest(ev, k + (i * size), inAppKey);
  }
  *outPos = i;

  return outTest;
}

void morkProbeMap::probe_map_lazy_init(morkEnv* ev) {
  if (this->need_lazy_init() && sMap_Fill == 0)  // pending lazy action?
  {
    // The constructor cannot successfully call virtual ProbeMapClearKey(),
    // so we lazily do so now, when we add the first member to the map.

    mork_u1* keys = sMap_Keys;
    if (keys)  // okay to call lazy virtual clear method on new map keys?
    {
      if (sProbeMap_ZeroIsClearKey)  // zero is good enough to clear keys?
      {
        mork_num keyVolume = sMap_Slots * sMap_KeySize;
        if (keyVolume) MORK_MEMSET(keys, 0, keyVolume);
      } else
        this->ProbeMapClearKey(ev, keys, sMap_Slots);
    } else
      this->MapNilKeysError(ev);
  }
  sProbeMap_LazyClearOnAdd = 0;  // don't do this ever again
}

mork_bool morkProbeMap::MapAtPut(morkEnv* ev, const void* inAppKey,
                                 const void* inAppVal, void* outAppKey,
                                 void* outAppVal) {
  mork_bool outPut = morkBool_kFalse;

  if (this->GoodProbeMap()) /* looks good? */
  {
    if (this->need_lazy_init() && sMap_Fill == 0)  // pending lazy action?
      this->probe_map_lazy_init(ev);

    if (ev->Good()) {
      mork_pos slotPos = 0;
      mork_u4 hash = this->MapHash(ev, inAppKey);
      mork_test test = this->find_key_pos(ev, inAppKey, hash, &slotPos);
      outPut = (test == morkTest_kHit);

      if (outPut)  // replacing an old assoc? no change in member count?
      {
        if (outAppKey || outAppVal) /* copy old before cobber? */
          this->get_probe_kv(ev, outAppKey, outAppVal, slotPos);
      } else  // adding a new assoc increases membership by one
      {
        ++sMap_Fill; /* one more member in the collection */
      }

      if (test != morkTest_kMiss) /* found slot to hold new assoc? */
      {
        ++sMap_Seed; /* note the map has changed */
        this->put_probe_kv(ev, inAppKey, inAppVal, slotPos);
      }
    }
  } else
    this->ProbeMapBadTagError(ev);

  return outPut;
}

mork_bool morkProbeMap::MapAt(morkEnv* ev, const void* inAppKey,
                              void* outAppKey, void* outAppVal) {
  if (this->GoodProbeMap()) /* looks good? */
  {
    if (this->need_lazy_init() && sMap_Fill == 0)  // pending lazy action?
      this->probe_map_lazy_init(ev);

    mork_pos slotPos = 0;
    mork_u4 hash = this->MapHash(ev, inAppKey);
    mork_test test = this->find_key_pos(ev, inAppKey, hash, &slotPos);
    if (test == morkTest_kHit) /* found an assoc pair for inAppKey? */
    {
      this->get_probe_kv(ev, outAppKey, outAppVal, slotPos);
      return morkBool_kTrue;
    }
  } else
    this->ProbeMapBadTagError(ev);

  return morkBool_kFalse;
}

mork_num morkProbeMap::MapCutAll(morkEnv* ev) {
  mork_num outCutAll = 0;

  if (this->GoodProbeMap()) /* looks good? */
  {
    outCutAll = sMap_Fill; /* number of members cut, which is all of them */

    if (sMap_Keys && !sProbeMap_ZeroIsClearKey)
      this->ProbeMapClearKey(ev, sMap_Keys, sMap_Slots);

    sMap_Fill = 0; /* map now has no members */
  } else
    this->ProbeMapBadTagError(ev);

  return outCutAll;
}

// { ===== node interface =====

/*virtual*/
morkProbeMap::~morkProbeMap()  // assert NodeStop() finished earlier
{
  MORK_ASSERT(sMap_Keys == 0);
  MORK_ASSERT(sProbeMap_Tag == 0);
}

/*public virtual*/ void morkProbeMap::CloseMorkNode(
    morkEnv* ev)  // CloseMap() only if open
{
  if (this->IsOpenNode()) {
    this->MarkClosing();
    this->CloseProbeMap(ev);
    this->MarkShut();
  }
}

void morkProbeMap::CloseProbeMap(morkEnv* ev) {
  if (this->IsNode()) {
    nsIMdbHeap* heap = sMap_Heap;
    if (heap)  // able to free map arrays?
    {
      void* block = sMap_Keys;
      if (block) {
        heap->Free(ev->AsMdbEnv(), block);
        sMap_Keys = 0;
      }

      block = sMap_Vals;
      if (block) {
        heap->Free(ev->AsMdbEnv(), block);
        sMap_Vals = 0;
      }
    }
    sMap_Keys = 0;
    sMap_Vals = 0;

    this->CloseNode(ev);
    sProbeMap_Tag = 0;
    sProbeMap_MaxFill = 0;

    this->MarkShut();
  } else
    this->NonNodeError(ev);
}

void* morkProbeMap::clear_alloc(morkEnv* ev, mork_size inSize) {
  void* p = 0;
  nsIMdbHeap* heap = sMap_Heap;
  if (heap) {
    if (NS_SUCCEEDED(heap->Alloc(ev->AsMdbEnv(), inSize, (void**)&p)) && p) {
      MORK_MEMSET(p, 0, inSize);
      return p;
    }
  } else
    ev->NilPointerError();

  return (void*)0;
}

/*| map_new_keys: allocate an array of inSlots new keys filled with zero.
**| (cf IronDoc's FeHashTable_new_keys())
|*/
mork_u1* morkProbeMap::map_new_keys(morkEnv* ev, mork_num inSlots) {
  mork_num size = inSlots * sMap_KeySize;
  return (mork_u1*)this->clear_alloc(ev, size);
}

/*| map_new_vals: allocate an array of inSlots new values filled with zero.
**| When values are zero sized, we just return a null pointer.
**|
**| (cf IronDoc's FeHashTable_new_values())
|*/
mork_u1* morkProbeMap::map_new_vals(morkEnv* ev, mork_num inSlots) {
  mork_u1* values = 0;
  mork_num size = inSlots * sMap_ValSize;
  if (size) values = (mork_u1*)this->clear_alloc(ev, size);
  return values;
}

void morkProbeMap::MapSeedOutOfSyncError(morkEnv* ev) {
  ev->NewError("sMap_Seed out of sync");
}

void morkProbeMap::MapFillUnderflowWarning(morkEnv* ev) {
  ev->NewWarning("sMap_Fill underflow");
}

void morkProbeMap::MapNilKeysError(morkEnv* ev) {
  ev->NewError("nil sMap_Keys");
}

void morkProbeMap::MapZeroKeySizeError(morkEnv* ev) {
  ev->NewError("zero sMap_KeySize");
}

/*static*/
void morkProbeMap::ProbeMapCutError(morkEnv* ev) {
  ev->NewError("morkProbeMap cannot cut");
}

void morkProbeMap::init_probe_map(morkEnv* ev, mork_size inSlots) {
  // Note we cannot successfully call virtual ProbeMapClearKey() when we
  // call init_probe_map() inside the constructor; so we leave this problem
  // to the caller.  (The constructor will call ProbeMapClearKey() later
  // after setting a suitable lazy flag to show this action is pending.)

  if (ev->Good()) {
    morkMapScratch old;

    if (inSlots < 7)                  // capacity too small?
      inSlots = 7;                    // increase to reasonable minimum
    else if (inSlots > (128 * 1024))  // requested capacity too big?
      inSlots = (128 * 1024);         // decrease to reasonable maximum

    if (this->new_slots(ev, &old, inSlots)) sProbeMap_Tag = morkProbeMap_kTag;

    mork_count slots = sMap_Slots;
    mork_num emptyReserve = (slots / 7) + 1;  // keep this many empty
    sProbeMap_MaxFill = slots - emptyReserve;

    MORK_MEMSET(&old, 0, sizeof(morkMapScratch));  // don't bother halting
  }
}

mork_bool morkProbeMap::new_slots(morkEnv* ev, morkMapScratch* old,
                                  mork_num inSlots) {
  mork_bool outNew = morkBool_kFalse;

  // Note we cannot successfully call virtual ProbeMapClearKey() when we
  // call new_slots() inside the constructor; so we leave this problem
  // to the caller.  (The constructor will call ProbeMapClearKey() later
  // after setting a suitable lazy flag to show this action is pending.)

  // allocate every new array before we continue:
  mork_u1* newKeys = this->map_new_keys(ev, inSlots);
  mork_u1* newVals = this->map_new_vals(ev, inSlots);

  // okay for newVals to be null when values are zero sized?
  mork_bool okayValues = (newVals || !sMap_ValSize);

  if (newKeys && okayValues) {
    outNew = morkBool_kTrue;  // we created every array needed

    // init mapScratch using slots from current map:
    old->sMapScratch_Heap = sMap_Heap;

    old->sMapScratch_Slots = sMap_Slots;
    old->sMapScratch_Keys = sMap_Keys;
    old->sMapScratch_Vals = sMap_Vals;

    // replace all map array slots using the newly allocated members:
    ++sMap_Seed;  // the map has changed
    sMap_Keys = newKeys;
    sMap_Vals = newVals;
    sMap_Slots = inSlots;
  } else  // free any allocations if only partially successful
  {
    nsIMdbHeap* heap = sMap_Heap;
    if (newKeys) heap->Free(ev->AsMdbEnv(), newKeys);
    if (newVals) heap->Free(ev->AsMdbEnv(), newVals);

    MORK_MEMSET(old, 0, sizeof(morkMapScratch));  // zap scratch space
  }

  return outNew;
}

void morkProbeMap::clear_probe_map(morkEnv* ev, nsIMdbHeap* ioMapHeap) {
  sProbeMap_Tag = 0;
  sMap_Seed = 0;
  sMap_Slots = 0;
  sMap_Fill = 0;
  sMap_Keys = 0;
  sMap_Vals = 0;
  sProbeMap_MaxFill = 0;

  sMap_Heap = ioMapHeap;
  if (!ioMapHeap) ev->NilPointerError();
}

morkProbeMap::morkProbeMap(morkEnv* ev, const morkUsage& inUsage,
                           nsIMdbHeap* ioNodeHeap, mork_size inKeySize,
                           mork_size inValSize, nsIMdbHeap* ioMapHeap,
                           mork_size inSlots, mork_bool inZeroIsClearKey)

    : morkNode(ev, inUsage, ioNodeHeap),
      sMap_Heap(ioMapHeap)

      ,
      sMap_Keys(0),
      sMap_Vals(0)

      ,
      sMap_Seed(0)  // change count of members or structure

      ,
      sMap_Slots(0)  // count of slots in the hash table
      ,
      sMap_Fill(0)  // number of used slots in the hash table

      ,
      sMap_KeySize(0)  // size of each key (cannot be zero)
      ,
      sMap_ValSize(0)  // size of each val (zero allowed)

      ,
      sMap_KeyIsIP(morkBool_kFalse)  // sMap_KeySize == sizeof(mork_ip)
      ,
      sMap_ValIsIP(morkBool_kFalse)  // sMap_ValSize == sizeof(mork_ip)

      ,
      sProbeMap_MaxFill(0),
      sProbeMap_LazyClearOnAdd(0),
      sProbeMap_ZeroIsClearKey(inZeroIsClearKey),
      sProbeMap_Tag(0) {
  // Note we cannot successfully call virtual ProbeMapClearKey() when we
  // call init_probe_map() inside the constructor; so we leave this problem
  // to the caller.  (The constructor will call ProbeMapClearKey() later
  // after setting a suitable lazy flag to show this action is pending.)

  if (ev->Good()) {
    this->clear_probe_map(ev, ioMapHeap);
    if (ev->Good()) {
      sMap_KeySize = inKeySize;
      sMap_ValSize = inValSize;
      sMap_KeyIsIP = (inKeySize == sizeof(mork_ip));
      sMap_ValIsIP = (inValSize == sizeof(mork_ip));

      this->init_probe_map(ev, inSlots);
      if (ev->Good()) {
        if (!inZeroIsClearKey)  // must lazy clear later with virtual method?
          sProbeMap_LazyClearOnAdd = morkProbeMap_kLazyClearOnAdd;

        mNode_Derived = morkDerived_kProbeMap;
      }
    }
  }
}

/*============================================================================*/

/*virtual*/ mork_test  // hit(a,b) implies hash(a) == hash(b)
morkProbeMap::MapTest(morkEnv* ev, const void* inMapKey,
                      const void* inAppKey) const
// Note inMapKey is always a key already stored in the map, while inAppKey
//   is always a method argument parameter from a client method call.
//   This matters the most in morkProbeMap subclasses, which have the
//   responsibility of putting 'app' keys into slots for 'map' keys, and
//   the bit pattern representation might be different in such cases.
// morkTest_kHit means that inMapKey equals inAppKey (and this had better
//   also imply that hash(inMapKey) == hash(inAppKey)).
// morkTest_kMiss means that inMapKey does NOT equal inAppKey (but this
//   implies nothing at all about hash(inMapKey) and hash(inAppKey)).
// morkTest_kVoid means that inMapKey is not a valid key bit pattern,
//   which means that key slot in the map is not being used.  Note that
//   kVoid is only expected as a return value in morkProbeMap subclasses,
//   because morkProbeMap must ask whether a key slot is used or not.
//   morkChainMap however, always knows when a key slot is used, so only
//   key slots expected to have valid bit patterns will be presented to
//   the MapTest() methods for morkChainMap subclasses.
//
// NOTE: it is very important that subclasses correctly return the value
// morkTest_kVoid whenever the slot for inMapKey contains a bit pattern
// that means the slot is not being used, because this is the only way a
// probe map can terminate an unsuccessful search for a key in the map.
{
  mork_size keySize = sMap_KeySize;
  if (keySize == sizeof(mork_ip) && sMap_KeyIsIP) {
    mork_ip mapKey = *((const mork_ip*)inMapKey);
    if (mapKey == *((const mork_ip*)inAppKey))
      return morkTest_kHit;
    else {
      return (mapKey) ? morkTest_kMiss : morkTest_kVoid;
    }
  } else {
    mork_bool allSame = morkBool_kTrue;
    mork_bool allZero = morkBool_kTrue;
    const mork_u1* ak = (const mork_u1*)inAppKey;
    const mork_u1* mk = (const mork_u1*)inMapKey;
    const mork_u1* end = mk + keySize;
    --mk;  // prepare for preincrement:
    while (++mk < end) {
      mork_u1 byte = *mk;
      if (byte)  // any nonzero byte in map key means slot is not nil?
        allZero = morkBool_kFalse;
      if (byte != *ak++)  // bytes differ in map and app keys?
        allSame = morkBool_kFalse;
    }
    if (allSame)
      return morkTest_kHit;
    else
      return (allZero) ? morkTest_kVoid : morkTest_kMiss;
  }
}

/*virtual*/ mork_u4  // hit(a,b) implies hash(a) == hash(b)
morkProbeMap::MapHash(morkEnv* ev, const void* inAppKey) const {
  mork_size keySize = sMap_KeySize;
  if (keySize == sizeof(mork_ip) && sMap_KeyIsIP) {
    return *((const mork_ip*)inAppKey);
  } else {
    const mork_u1* key = (const mork_u1*)inAppKey;
    const mork_u1* end = key + keySize;
    --key;  // prepare for preincrement:
    while (++key < end) {
      if (*key)  // any nonzero byte in map key means slot is not nil?
        return morkBool_kFalse;
    }
    return morkBool_kTrue;
  }
  return (mork_u4)NS_PTR_TO_INT32(inAppKey);
}

/*============================================================================*/

/*virtual*/ mork_u4 morkProbeMap::ProbeMapHashMapKey(morkEnv* ev,
                                                     const void* inMapKey) const
// ProbeMapHashMapKey() does logically the same thing as MapHash(), and
// the default implementation actually calls virtual MapHash().  However,
// Subclasses must override this method whenever the formats of keys in
// the map differ from app keys outside the map, because MapHash() only
// works on keys in 'app' format, while ProbeMapHashMapKey() only works
// on keys in 'map' format.  This method is called in order to rehash all
// map keys when a map is grown, and this causes all old map members to
// move into new slot locations.
//
// Note it is absolutely imperative that a hash for a key in 'map' format
// be exactly the same the hash of the same key in 'app' format, or else
// maps will seem corrupt later when keys in 'app' format cannot be found.
{
  return this->MapHash(ev, inMapKey);
}

/*virtual*/ mork_bool morkProbeMap::ProbeMapIsKeyNil(morkEnv* ev,
                                                     void* ioMapKey)
// ProbeMapIsKeyNil() must say whether the representation of logical 'nil'
// is currently found inside the key at ioMapKey, for a key found within
// the map.  The the map iterator uses this method to find map keys that
// are actually being used for valid map associations; otherwise the
// iterator cannot determine which map slots actually denote used keys.
// The default method version returns true if all the bits equal zero.
{
  if (sMap_KeySize == sizeof(mork_ip) && sMap_KeyIsIP) {
    return !*((const mork_ip*)ioMapKey);
  } else {
    const mork_u1* key = (const mork_u1*)ioMapKey;
    const mork_u1* end = key + sMap_KeySize;
    --key;  // prepare for preincrement:
    while (++key < end) {
      if (*key)  // any nonzero byte in map key means slot is not nil?
        return morkBool_kFalse;
    }
    return morkBool_kTrue;
  }
}

/*virtual*/ void morkProbeMap::ProbeMapClearKey(
    morkEnv* ev,  // put 'nil' into all keys inside map
    void* ioMapKey, mork_count inKeyCount)  // array of keys inside map
// ProbeMapClearKey() must put some representation of logical 'nil' into
// every key slot in the map, such that MapTest() will later recognize
// that this bit pattern shows each key slot is not actually being used.
//
// This method is typically called whenever the map is either created or
// grown into a larger size, where ioMapKey is a pointer to an array of
// inKeyCount keys, where each key is this->MapKeySize() bytes in size.
// Note that keys are assumed immediately adjacent with no padding, so
// if any alignment requirements must be met, then subclasses should have
// already accounted for this when specifying a key size in the map.
//
// Since this method will be called when a map is being grown in size,
// nothing should be assumed about the state slots of the map, since the
// ioMapKey array might not yet live in sMap_Keys, and the array length
// inKeyCount might not yet live in sMap_Slots.  However, the value kept
// in sMap_KeySize never changes, so this->MapKeySize() is always correct.
{
  if (ioMapKey && inKeyCount) {
    MORK_MEMSET(ioMapKey, 0, (inKeyCount * sMap_KeySize));
  } else
    ev->NilPointerWarning();
}

/*virtual*/ void morkProbeMap::ProbeMapPushIn(
    morkEnv* ev,                                 // move (key,val) into the map
    const void* inAppKey, const void* inAppVal,  // (key,val) outside map
    void* outMapKey, void* outMapVal)            // (key,val) inside map
// This method actually puts keys and vals in the map in suitable format.
//
// ProbeMapPushIn() must copy a caller key and value in 'app' format
// into the map slots provided, which are in 'map' format.  When the
// 'app' and 'map' formats are identical, then this is just a bitwise
// copy of this->MapKeySize() key bytes and this->MapValSize() val bytes,
// and this is exactly what the default implementation performs.  However,
// if 'app' and 'map' formats are different, and MapTest() depends on this
// difference in format, then subclasses must override this method to do
// whatever is necessary to store the input app key in output map format.
//
// Do NOT write more than this->MapKeySize() bytes of a map key, or more
// than this->MapValSize() bytes of a map val, or corruption might ensue.
//
// The inAppKey and inAppVal parameters are the same ones passed into a
// call to MapAtPut(), and the outMapKey and outMapVal parameters are ones
// determined by how the map currently positions key inAppKey in the map.
//
// Note any key or val parameter can be a null pointer, in which case
// this method must do nothing with those parameters.  In particular, do
// no key move at all when either inAppKey or outMapKey is nil, and do
// no val move at all when either inAppVal or outMapVal is nil.  Note that
// outMapVal should always be nil when this->MapValSize() is nil.
{}

/*virtual*/ void morkProbeMap::ProbeMapPullOut(
    morkEnv* ev,  // move (key,val) out from the map
    const void* inMapKey, const void* inMapVal,  // (key,val) inside map
    void* outAppKey, void* outAppVal) const      // (key,val) outside map
// This method actually gets keys and vals from the map in suitable format.
//
// ProbeMapPullOut() must copy a key and val in 'map' format into the
// caller key and val slots provided, which are in 'app' format.  When the
// 'app' and 'map' formats are identical, then this is just a bitwise
// copy of this->MapKeySize() key bytes and this->MapValSize() val bytes,
// and this is exactly what the default implementation performs.  However,
// if 'app' and 'map' formats are different, and MapTest() depends on this
// difference in format, then subclasses must override this method to do
// whatever is necessary to store the input map key in output app format.
//
// The outAppKey and outAppVal parameters are the same ones passed into a
// call to either MapAtPut() or MapAt(), while inMapKey and inMapVal are
// determined by how the map currently positions the target key in the map.
//
// Note any key or val parameter can be a null pointer, in which case
// this method must do nothing with those parameters.  In particular, do
// no key move at all when either inMapKey or outAppKey is nil, and do
// no val move at all when either inMapVal or outAppVal is nil.  Note that
// inMapVal should always be nil when this->MapValSize() is nil.
{}

/*============================================================================*/
/* morkProbeMapIter */

morkProbeMapIter::morkProbeMapIter(morkEnv* ev, morkProbeMap* ioMap)
    : sProbeMapIter_Map(0),
      sProbeMapIter_Seed(0),
      sProbeMapIter_HereIx(morkProbeMapIter_kBeforeIx) {
  if (ioMap) {
    if (ioMap->GoodProbeMap()) {
      if (ioMap->need_lazy_init())  // pending lazy action?
        ioMap->probe_map_lazy_init(ev);

      sProbeMapIter_Map = ioMap;
      sProbeMapIter_Seed = ioMap->sMap_Seed;
    } else
      ioMap->ProbeMapBadTagError(ev);
  } else
    ev->NilPointerError();
}

void morkProbeMapIter::CloseMapIter(morkEnv* ev) {
  MORK_USED_1(ev);
  sProbeMapIter_Map = 0;
  sProbeMapIter_Seed = 0;

  sProbeMapIter_HereIx = morkProbeMapIter_kAfterIx;
}

morkProbeMapIter::morkProbeMapIter()
// zero most slots; caller must call InitProbeMapIter()
{
  sProbeMapIter_Map = 0;
  sProbeMapIter_Seed = 0;

  sProbeMapIter_HereIx = morkProbeMapIter_kBeforeIx;
}

void morkProbeMapIter::InitProbeMapIter(morkEnv* ev, morkProbeMap* ioMap) {
  sProbeMapIter_Map = 0;
  sProbeMapIter_Seed = 0;

  sProbeMapIter_HereIx = morkProbeMapIter_kBeforeIx;

  if (ioMap) {
    if (ioMap->GoodProbeMap()) {
      if (ioMap->need_lazy_init())  // pending lazy action?
        ioMap->probe_map_lazy_init(ev);

      sProbeMapIter_Map = ioMap;
      sProbeMapIter_Seed = ioMap->sMap_Seed;
    } else
      ioMap->ProbeMapBadTagError(ev);
  } else
    ev->NilPointerError();
}

mork_bool morkProbeMapIter::IterFirst(morkEnv* ev, void* outAppKey,
                                      void* outAppVal) {
  sProbeMapIter_HereIx = morkProbeMapIter_kAfterIx;  // default to done
  morkProbeMap* map = sProbeMapIter_Map;

  if (map && map->GoodProbeMap()) /* looks good? */
  {
    sProbeMapIter_Seed = map->sMap_Seed; /* sync the seeds */

    mork_u1* k = map->sMap_Keys;  // array of keys, each of size sMap_KeySize
    mork_num size = map->sMap_KeySize;   // number of bytes in each key
    mork_count slots = map->sMap_Slots;  // total number of key buckets
    mork_pos here = 0;                   // first hash bucket

    while (here < (mork_pos)slots) {
      if (!map->ProbeMapIsKeyNil(ev, k + (here * size))) {
        map->get_probe_kv(ev, outAppKey, outAppVal, here);

        sProbeMapIter_HereIx = (mork_i4)here;
        return morkBool_kTrue;
      }
      ++here;  // next bucket
    }
  } else
    map->ProbeMapBadTagError(ev);

  return morkBool_kFalse;
}

mork_bool morkProbeMapIter::IterNext(morkEnv* ev, void* outAppKey,
                                     void* outAppVal) {
  morkProbeMap* map = sProbeMapIter_Map;

  if (map && map->GoodProbeMap()) /* looks good? */
  {
    if (sProbeMapIter_Seed == map->sMap_Seed) /* in sync? */
    {
      if (sProbeMapIter_HereIx != morkProbeMapIter_kAfterIx) {
        mork_pos here = (mork_pos)sProbeMapIter_HereIx;
        if (sProbeMapIter_HereIx < 0)
          here = 0;
        else
          ++here;

        sProbeMapIter_HereIx = morkProbeMapIter_kAfterIx;  // default to done

        mork_u1* k = map->sMap_Keys;  // key array, each of size sMap_KeySize
        mork_num size = map->sMap_KeySize;   // number of bytes in each key
        mork_count slots = map->sMap_Slots;  // total number of key buckets

        while (here < (mork_pos)slots) {
          if (!map->ProbeMapIsKeyNil(ev, k + (here * size))) {
            map->get_probe_kv(ev, outAppKey, outAppVal, here);

            sProbeMapIter_HereIx = (mork_i4)here;
            return morkBool_kTrue;
          }
          ++here;  // next bucket
        }
      }
    } else
      map->MapSeedOutOfSyncError(ev);
  } else
    map->ProbeMapBadTagError(ev);

  return morkBool_kFalse;
}

mork_bool morkProbeMapIter::IterHere(morkEnv* ev, void* outAppKey,
                                     void* outAppVal) {
  morkProbeMap* map = sProbeMapIter_Map;

  if (map && map->GoodProbeMap()) /* looks good? */
  {
    if (sProbeMapIter_Seed == map->sMap_Seed) /* in sync? */
    {
      mork_pos here = (mork_pos)sProbeMapIter_HereIx;
      mork_count slots = map->sMap_Slots;  // total number of key buckets
      if (sProbeMapIter_HereIx >= 0 && (here < (mork_pos)slots)) {
        mork_u1* k = map->sMap_Keys;  // key array, each of size sMap_KeySize
        mork_num size = map->sMap_KeySize;  // number of bytes in each key

        if (!map->ProbeMapIsKeyNil(ev, k + (here * size))) {
          map->get_probe_kv(ev, outAppKey, outAppVal, here);
          return morkBool_kTrue;
        }
      }
    } else
      map->MapSeedOutOfSyncError(ev);
  } else
    map->ProbeMapBadTagError(ev);

  return morkBool_kFalse;
}

mork_change* morkProbeMapIter::First(morkEnv* ev, void* outKey, void* outVal) {
  if (this->IterFirst(ev, outKey, outVal)) return &sProbeMapIter_Change;

  return (mork_change*)0;
}

mork_change* morkProbeMapIter::Next(morkEnv* ev, void* outKey, void* outVal) {
  if (this->IterNext(ev, outKey, outVal)) return &sProbeMapIter_Change;

  return (mork_change*)0;
}

mork_change* morkProbeMapIter::Here(morkEnv* ev, void* outKey, void* outVal) {
  if (this->IterHere(ev, outKey, outVal)) return &sProbeMapIter_Change;

  return (mork_change*)0;
}

mork_change* morkProbeMapIter::CutHere(morkEnv* ev, void* outKey,
                                       void* outVal) {
  morkProbeMap::ProbeMapCutError(ev);

  return (mork_change*)0;
}

// 456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789

// NOTE: the following methods ONLY work for sMap_ValIsIP pointer values.
// (Note the implied assumption that zero is never a good value pattern.)

void* morkProbeMapIter::IterFirstVal(morkEnv* ev, void* outKey)
// equivalent to { void* v=0; this->IterFirst(ev, outKey, &v); return v; }
{
  morkProbeMap* map = sProbeMapIter_Map;
  if (map) {
    if (map->sMap_ValIsIP) {
      void* v = 0;
      this->IterFirst(ev, outKey, &v);
      return v;
    } else
      map->MapValIsNotIPError(ev);
  }
  return (void*)0;
}

void* morkProbeMapIter::IterNextVal(morkEnv* ev, void* outKey)
// equivalent to { void* v=0; this->IterNext(ev, outKey, &v); return v; }
{
  morkProbeMap* map = sProbeMapIter_Map;
  if (map) {
    if (map->sMap_ValIsIP) {
      void* v = 0;
      this->IterNext(ev, outKey, &v);
      return v;
    } else
      map->MapValIsNotIPError(ev);
  }
  return (void*)0;
}

void* morkProbeMapIter::IterHereVal(morkEnv* ev, void* outKey)
// equivalent to { void* v=0; this->IterHere(ev, outKey, &v); return v; }
{
  morkProbeMap* map = sProbeMapIter_Map;
  if (map) {
    if (map->sMap_ValIsIP) {
      void* v = 0;
      this->IterHere(ev, outKey, &v);
      return v;
    } else
      map->MapValIsNotIPError(ev);
  }
  return (void*)0;
}

// NOTE: the following methods ONLY work for sMap_KeyIsIP pointer values.
// (Note the implied assumption that zero is never a good key pattern.)

void* morkProbeMapIter::IterFirstKey(morkEnv* ev)
// equivalent to { void* k=0; this->IterFirst(ev, &k, 0); return k; }
{
  morkProbeMap* map = sProbeMapIter_Map;
  if (map) {
    if (map->sMap_KeyIsIP) {
      void* k = 0;
      this->IterFirst(ev, &k, (void*)0);
      return k;
    } else
      map->MapKeyIsNotIPError(ev);
  }
  return (void*)0;
}

void* morkProbeMapIter::IterNextKey(morkEnv* ev)
// equivalent to { void* k=0; this->IterNext(ev, &k, 0); return k; }
{
  morkProbeMap* map = sProbeMapIter_Map;
  if (map) {
    if (map->sMap_KeyIsIP) {
      void* k = 0;
      this->IterNext(ev, &k, (void*)0);
      return k;
    } else
      map->MapKeyIsNotIPError(ev);
  }
  return (void*)0;
}

void* morkProbeMapIter::IterHereKey(morkEnv* ev)
// equivalent to { void* k=0; this->IterHere(ev, &k, 0); return k; }
{
  morkProbeMap* map = sProbeMapIter_Map;
  if (map) {
    if (map->sMap_KeyIsIP) {
      void* k = 0;
      this->IterHere(ev, &k, (void*)0);
      return k;
    } else
      map->MapKeyIsNotIPError(ev);
  }
  return (void*)0;
}

// 456789_123456789_123456789_123456789_123456789_123456789_123456789_123456789