From fa51b0a96da1c9d7a3c08f19e5a7adce658873ba Mon Sep 17 00:00:00 2001 From: Ketmar Dark Date: Tue, 12 Sep 2017 01:05:50 +0300 Subject: [PATCH] hashtable changes (preparation to exoma scripting) --- src/shared/hashtable.pas | 184 ++++++++++++++++++++++----------------- 1 file changed, 104 insertions(+), 80 deletions(-) diff --git a/src/shared/hashtable.pas b/src/shared/hashtable.pas index fa6ec85..a51fc91 100644 --- a/src/shared/hashtable.pas +++ b/src/shared/hashtable.pas @@ -19,7 +19,7 @@ {.$DEFINE RBHASH_DEBUG_DELETE} {.$DEFINE RBHASH_DEBUG_COMPACT} {$IF DEFINED(D2F_DEBUG)} - {$DEFINE RBHASH_SANITY_CHECKS} + {.$DEFINE RBHASH_SANITY_CHECKS} {$ENDIF} // hash table (robin hood) unit hashtable; @@ -31,13 +31,14 @@ type // WARNING! don't put structures into hash, use ponters or ids! generic THashBase = class(TObject) private - const InitSize = {$IF DEFINED(D2F_DEBUG)}16{$ELSE}512{$ENDIF}; // *MUST* be power of two + const InitSize = {$IF DEFINED(RBHASH_SANITY_CHECKS)}16{$ELSE}256{$ENDIF}; // *MUST* be power of two const LoadFactorPrc = 90; // it is ok for robin hood hashes public type THashFn = function (constref o: KeyT): LongWord; type TEquFn = function (constref a, b: KeyT): Boolean; type TIteratorFn = function (constref k: KeyT; constref v: ValueT): Boolean is nested; // return `true` to stop + type TIteratorExFn = function (constref k: KeyT; constref v: ValueT; keyhash: LongWord): Boolean is nested; // return `true` to stop type PEntry = ^TEntry; @@ -48,6 +49,8 @@ type private hash: LongWord; // key hash or 0 nextFree: PEntry; // next free entry + public + property keyhash: LongWord read hash; end; private @@ -125,13 +128,18 @@ type procedure rehash (); procedure compact (); // call this instead of `rehash()` after alot of deletions - function get (constref akey: KeyT; out rval: ValueT): Boolean; // `true`: found - function put (constref akey: KeyT; constref aval: ValueT): Boolean; // `true`: replaced - function has (constref akey: KeyT): Boolean; // `true`: found - function del (constref akey: KeyT): Boolean; // `true`: deleted + // you may pass `keyhash` to bypass hash calculation + function get (constref akey: KeyT; out rval: ValueT; keyhashin: PLongWord=nil): Boolean; // `true`: found + // the function may return calculated value hash in `keyhash` + function put (constref akey: KeyT; constref aval: ValueT; keyhashout: PLongWord=nil): Boolean; // `true`: replaced + // you may pass `keyhash` to bypass hash calculation + function has (constref akey: KeyT; keyhashin: PLongWord=nil): Boolean; // `true`: found + // you may pass `keyhash` to bypass hash calculation + function del (constref akey: KeyT; keyhashin: PLongWord=nil): Boolean; // `true`: deleted //WARNING! don't modify table in iterator (queries are ok, though) - function forEach (it: TIteratorFn): Boolean; + function forEach (it: TIteratorFn): Boolean; overload; + function forEach (it: TIteratorExFn): Boolean; overload; // default `for ... in` enums values function GetEnumerator (): TValEnumerator; @@ -380,25 +388,7 @@ var begin SetLength(mBuckets, InitSize); for idx := 0 to High(mBuckets) do mBuckets[idx] := nil; - SetLength(mEntries, Length(mBuckets)); - { - for idx := 0 to High(mEntries)-1 do - begin - mEntries[idx].hash := 0; - mEntries[idx].nextFree := @mEntries[idx+1]; //idx+1; - end; - mEntries[High(mEntries)].hash := 0; - mEntries[High(mEntries)].nextFree := nil; - } - { - for idx := 0 to High(mEntries) do - begin - mEntries[idx].hash := 0; - mEntries[idx].nextFree := nil; - end; - } - mBucketsUsed := 0; {$IFDEF RBHASH_SANITY_CHECKS} mEntriesUsed := 0; @@ -416,26 +406,6 @@ begin if (mBucketsUsed > 0) then begin for idx := 0 to High(mBuckets) do mBuckets[idx] := nil; - { - for idx := 0 to High(mEntries)-1 do - begin - mEntries[idx].hash := 0; - mEntries[idx].nextFree := @mEntries[idx+1]; //idx+1; - end; - mEntries[High(mEntries)].hash := 0; - mEntries[High(mEntries)].nextFree := nil; - } - { - if (mFirstEntry >= 0) then - begin - for idx := mFirstEntry to mLastEntry do - begin - mEntries[idx].hash := 0; - mEntries[idx].nextFree := nil; - end; - end; - } - mBucketsUsed := 0; {$IFDEF RBHASH_SANITY_CHECKS} mEntriesUsed := 0; @@ -560,31 +530,43 @@ begin assert(idx < Length(mBuckets)); assert(mBuckets[idx] <> nil); {$ENDIF} - result := mBuckets[idx].hash and High(mBuckets); + result := (mBuckets[idx].hash xor mSeed) and High(mBuckets); if (result <= idx) then result := idx-result else result := idx+(Length(mBuckets)-result); end; *) -function THashBase.has (constref akey: KeyT): Boolean; +function THashBase.has (constref akey: KeyT; keyhashin: PLongWord=nil): Boolean; var khash, idx: LongWord; dist, pdist: LongWord; - bhigh: LongWord; + bhigh, xseed: LongWord; begin result := false; if (mBucketsUsed = 0) then exit; bhigh := High(mBuckets); - khash := hashfn(akey) xor mSeed; if (khash = 0) then khash := $29a; - idx := khash and bhigh; + xseed := mSeed; + + if (keyhashin <> nil) then + begin + khash := keyhashin^; + if (khash = 0) then khash := hashfn(akey); + end + else + begin + khash := hashfn(akey); + end; + if (khash = 0) then khash := $29a; + + idx := (khash xor xseed) and bhigh; if (mBuckets[idx] = nil) then exit; for dist := 0 to bhigh do begin if (mBuckets[idx] = nil) then break; //pdist := distToStIdx(idx); - pdist := mBuckets[idx].hash and bhigh; + pdist := (mBuckets[idx].hash xor xseed) and bhigh; if (pdist <= idx) then pdist := idx-pdist else pdist := idx+((bhigh+1)-pdist); // if (dist > pdist) then break; @@ -595,34 +577,41 @@ begin end; -function THashBase.get (constref akey: KeyT; out rval: ValueT): Boolean; +function THashBase.get (constref akey: KeyT; out rval: ValueT; keyhashin: PLongWord=nil): Boolean; var khash, idx: LongWord; dist, pdist: LongWord; - bhigh: LongWord; + bhigh, xseed: LongWord; begin result := false; if (mBucketsUsed = 0) then begin rval := Default(ValueT); exit; end; bhigh := High(mBuckets); - khash := hashfn(akey) xor mSeed; if (khash = 0) then khash := $29a; - idx := khash and bhigh; - if (mBuckets[idx] = nil) then begin rval := Default(ValueT); exit; end; + xseed := mSeed; + + if (keyhashin <> nil) then + begin + khash := keyhashin^; + if (khash = 0) then khash := hashfn(akey); + end + else + begin + khash := hashfn(akey); + end; + if (khash = 0) then khash := $29a; + + idx := (khash xor xseed) and bhigh; for dist := 0 to bhigh do begin if (mBuckets[idx] = nil) then break; //pdist := distToStIdx(idx); - pdist := mBuckets[idx].hash and bhigh; + pdist := (mBuckets[idx].hash xor xseed) and bhigh; if (pdist <= idx) then pdist := idx-pdist else pdist := idx+((bhigh+1)-pdist); // if (dist > pdist) then break; result := (mBuckets[idx].hash = khash) and equfn(mBuckets[idx].key, akey); - if result then - begin - rval := mBuckets[idx].value; - break; - end; + if result then begin rval := mBuckets[idx].value; break; end; idx := (idx+1) and bhigh; end; @@ -634,10 +623,11 @@ procedure THashBase.putEntryInternal (swpe: PEntry); var idx, dist, pcur, pdist: LongWord; tmpe: PEntry; // current entry to swap (or nothing) - bhigh: LongWord; + bhigh, xseed: LongWord; begin bhigh := High(mBuckets); - idx := swpe.hash and bhigh; + xseed := mSeed; + idx := (swpe.hash xor xseed) and bhigh; {$IFDEF RBHASH_DEBUG_INSERT}writeln('inserting key ', swpe.key, '; value=', swpe.value, '; wantidx=', idx, '; bhigh=', bhigh);{$ENDIF} pcur := 0; for dist := 0 to bhigh do @@ -651,7 +641,7 @@ begin break; end; //pdist := distToStIdx(idx); - pdist := mBuckets[idx].hash and bhigh; + pdist := (mBuckets[idx].hash xor xseed) and bhigh; if (pdist <= idx) then pdist := idx-pdist else pdist := idx+((bhigh+1)-pdist); // if (pcur > pdist) then @@ -668,18 +658,21 @@ begin end; -function THashBase.put (constref akey: KeyT; constref aval: ValueT): Boolean; +function THashBase.put (constref akey: KeyT; constref aval: ValueT; keyhashout: PLongWord=nil): Boolean; var khash, idx, dist, pdist: LongWord; swpe: PEntry = nil; // current entry to swap (or nothing) - bhigh: LongWord; + bhigh, xseed: LongWord; newsz, eidx: Integer; begin result := false; bhigh := High(mBuckets); - khash := hashfn(akey) xor mSeed; if (khash = 0) then khash := $29a; - idx := khash and bhigh; + xseed := mSeed; + khash := hashfn(akey); + if (khash = 0) then khash := $29a; + if (keyhashout <> nil) then keyhashout^ := khash; + idx := (khash xor xseed) and bhigh; // check if we already have this key if (mBucketsUsed <> 0) and (mBuckets[idx] <> nil) then @@ -688,7 +681,7 @@ begin begin if (mBuckets[idx] = nil) then break; //pdist := distToStIdx(idx); - pdist := mBuckets[idx].hash and bhigh; + pdist := (mBuckets[idx].hash xor xseed) and bhigh; if (pdist <= idx) then pdist := idx-pdist else pdist := idx+((bhigh+1)-pdist); // if (dist > pdist) then break; @@ -721,8 +714,6 @@ begin // mFreeEntryHead will be fixed in `rehash()` // reinsert entries rehash(); - // as seed was changed, recalc hash - khash := hashfn(akey) xor mSeed; if (khash = 0) then khash := $29a; end; // create new entry @@ -736,17 +727,29 @@ end; // see http://codecapsule.com/2013/11/17/robin-hood-hashing-backward-shift-deletion/ -function THashBase.del (constref akey: KeyT): Boolean; +function THashBase.del (constref akey: KeyT; keyhashin: PLongWord=nil): Boolean; var khash, idx, idxnext, pdist, dist: LongWord; - bhigh: LongWord; + bhigh, xseed: LongWord; begin result := false; if (mBucketsUsed = 0) then exit; bhigh := High(mBuckets); - khash := hashfn(akey) xor mSeed; if (khash = 0) then khash := $29a; - idx := khash and bhigh; + xseed := mSeed; + + if (keyhashin <> nil) then + begin + khash := keyhashin^; + if (khash = 0) then khash := hashfn(akey); + end + else + begin + khash := hashfn(akey); + end; + if (khash = 0) then khash := $29a; + + idx := (khash xor xseed) and bhigh; // find key if (mBuckets[idx] = nil) then exit; // no key @@ -754,7 +757,7 @@ begin begin if (mBuckets[idx] = nil) then break; //pdist := distToStIdx(idxcur); - pdist := mBuckets[idx].hash and bhigh; + pdist := (mBuckets[idx].hash xor xseed) and bhigh; if (pdist <= idx) then pdist := idx-pdist else pdist := idx+((bhigh+1)-pdist); // if (dist > pdist) then break; @@ -785,7 +788,7 @@ begin {$ENDIF} if (mBuckets[idxnext] = nil) then begin {$IFDEF RBHASH_DEBUG_DELETE}writeln(' idxnext nil');{$ENDIF} mBuckets[idx] := nil; break; end; //pdist := distToStIdx(idxnext); - pdist := mBuckets[idxnext].hash and bhigh; + pdist := (mBuckets[idxnext].hash xor xseed) and bhigh; if (pdist <= idxnext) then pdist := idxnext-pdist else pdist := idxnext+((bhigh+1)-pdist); // if (pdist = 0) then begin {$IFDEF RBHASH_DEBUG_DELETE}writeln(' pdist is zero');{$ENDIF} mBuckets[idx] := nil; break; end; @@ -809,6 +812,7 @@ var {$ENDIF} begin // change seed, to minimize pathological cases + //TODO: use prng to generate new hash if (mSeed = 0) then mSeed := $29a; mSeed := u32Hash(mSeed); // clear buckets @@ -828,7 +832,8 @@ begin Inc(cnt); if (cnt = mBucketsUsed) and (idx <> mLastEntry) then raise Exception.Create('internal error in rehash: inconsistent (2)'); {$ENDIF} - e.hash := hashfn(e.key) xor mSeed; if (e.hash = 0) then e.hash := $29a; + // no need to recalculate hash + //e.hash := hashfn(e.key) xor mSeed; if (e.hash = 0) then e.hash := $29a; putEntryInternal(e); end else @@ -918,7 +923,7 @@ begin end; -function THashBase.forEach (it: TIteratorFn): Boolean; +function THashBase.forEach (it: TIteratorFn): Boolean; overload; var i: Integer; begin @@ -937,6 +942,25 @@ begin end; end; +function THashBase.forEach (it: TIteratorExFn): Boolean; overload; +var + i: Integer; +begin + result := false; + if not assigned(it) then exit; + i := mFirstEntry; + if (i < 0) then exit; + while (i <= mLastEntry) do + begin + if (mEntries[i].hash <> 0) then + begin + result := it(mEntries[i].key, mEntries[i].value, mEntries[i].hash); + if result then exit; + end; + Inc(i); + end; +end; + // enumerators function THashBase.GetEnumerator (): TValEnumerator; -- 2.29.2