windows-nt/Source/XPSP1/NT/inetsrv/iis/staxinc/fhash.inl

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2020-09-26 03:20:57 -05:00
//
// FHash.inl
//
// This file contains the template implementation of the class TFHash.
//
//---------------------------------------------
template< class Data, class Key >
TFHash< Data, Key >::TFHash( ) : m_cBuckets( 0 ), m_cActiveBuckets( 0 ),
m_cNumAlloced( 0 ), m_cIncrement( 0 ), m_ppBucket( 0 ), m_pfnHash( 0 ), m_load( 0 ),
m_pFreeStack( 0 ), m_cFreeStack( 0 ) {
//
// Very basic constructor
//
}
//---------------------------------------------
template< class Data, class Key >
BOOL TFHash< Data, Key >::Init(
int cInitial,
int cIncrement,
DWORD (*pfnHash)(const Key&),
int load,
int cMaxBucketCache
) {
//
// The initialization function will allocate the initial array of Bucket pointers
// and set the member variables. The user can specify the following :
//
// cInitial - the initial size of the hash table (this is rounded to the nearest power of 2.)
// cIncrement - the amount the hash table should grow on each growth
// pfnHash() - The function which computes the hash values for the key.
// load - the number of elements we should have on average in each collision chain.
//
//
// Compute nearest power of 2
//
m_cMaxFreeStack = cMaxBucketCache ;
int power = cInitial ;
while( power & (power-1) )
power = power & (power-1) ;
power<<= 1 ;
cInitial = power;
m_load = load ;
m_pfnHash = pfnHash ;
//
// Number of ActiveBuckets is initially half that of the number of buckets.
//
m_cActiveBuckets = power/2 ;
m_cBuckets = power ;
m_cInserts = m_cActiveBuckets * m_load ;
m_cIncrement = m_cActiveBuckets / 4;
m_cNumAlloced = cInitial + 5 * m_cIncrement ;
//
// Allocate bucket pointers and zero initialize
//
m_ppBucket = new CBucket*[m_cNumAlloced] ;
if( m_ppBucket ) {
ZeroMemory( m_ppBucket, m_cNumAlloced * sizeof( CBucket*) ) ;
Assert( IsValid( FALSE ) ) ;
return TRUE ;
}
return FALSE ;
}
//------------------------------------------------
template< class Data, class Key >
BOOL TFHash< Data, Key >::IsValid( BOOL fCheckHash ) {
//
// This function checks that all member variables are consistent and correct.
// Do not call this function until AFTER calling the Init() function.
//
if( m_cBuckets <= 0 ||
m_cActiveBuckets <= 0 ||
m_cNumAlloced <= 0 ||
m_cIncrement <= 0 ||
m_load <= 0 )
return FALSE ;
if( m_cActiveBuckets < (m_cBuckets / 2) || m_cActiveBuckets > m_cBuckets )
return FALSE ;
if( m_cActiveBuckets > m_cNumAlloced )
return FALSE ;
if( m_cInserts > (m_load * m_cActiveBuckets) )
return FALSE ;
if( m_ppBucket == 0 )
return FALSE ;
if( fCheckHash ) {
//
// Examine every bucket chain to ensure that elements are in correct slots.
//
for( int i=0; i<m_cNumAlloced; i++ ) {
if( i>=m_cActiveBuckets ) {
if( m_ppBucket[i] != 0 ) {
return FALSE ;
}
} else {
for( CBucket *p = m_ppBucket[i]; p != 0; p = p->m_pNext ) {
if( ComputeIndex( m_pfnHash( p->m_data.GetKey() ) ) != unsigned(i) ) {
return FALSE ;
}
}
}
}
}
return TRUE ;
}
//-------------------------------------------------
template< class Data, class Key >
TFHash< Data, Key >::~TFHash() {
//
// The destructor discards any memory we have allocated.
//
Clear();
}
//-------------------------------------------------
template< class Data, class Key >
void TFHash< Data, Key >::Clear() {
//
// Discards any memory we have allocated - after this, you must
// call Init() again!
//
if( m_ppBucket ) {
Assert( IsValid( TRUE ) ) ;
for( int i=0; i<m_cNumAlloced; i++ ) {
CBucket *p, *pNext ;
for( p = m_ppBucket[i], pNext = p ? p->m_pNext : 0;
p!=0; p=pNext, pNext= p ? p->m_pNext : 0 ) {
delete p ;
DWORDLONG* pdwl = (DWORDLONG*)((void*)p) ;
delete[] pdwl ;
}
}
delete[] m_ppBucket;
}
for( CFreeElement* p = m_pFreeStack;
p != 0;
p = m_pFreeStack ) {
m_pFreeStack = p->m_pNext ;
DWORDLONG* pdwl = (DWORDLONG*)((void*)p) ;
delete[] pdwl ;
m_cFreeStack -- ;
}
_ASSERT( m_cFreeStack == 0 && m_pFreeStack == 0 ) ;
m_cBuckets = 0;
m_cActiveBuckets = 0;
m_cNumAlloced = 0;
m_cIncrement = 0;
m_ppBucket = 0;
m_pfnHash = 0;
m_load = 0;
m_pFreeStack = 0;
m_cFreeStack = 0;
}
//-------------------------------------------------
template< class Data, class Key >
DWORD TFHash<Data, Key>::ComputeIndex( DWORD dw ) {
//
// This function tells us where we should store elements. To do this we mod with
// m_cBuckets. Since we only have m_cActiveBuckets in reality, we check the result
// of the mod and subtract m_cBuckets over 2 if necessary.
//
DWORD dwTemp = dw % m_cBuckets ;
return (dwTemp >= (unsigned)m_cActiveBuckets) ? dwTemp - (m_cBuckets/2) : dwTemp ;
}
#if 0
//-------------------------------------------------
template< class Data, class Key >
BOOL TFHash< Data, Key >::Insert( Data& d ) {
//
// This function will Insert an element into the Hash table. We will
// actually make a copy of the element using the Copy COnstructor Data::Data( Data& )
// when we do so.
//
Assert( IsValid( FALSE ) ) ;
//
// Do we have some free memory in our cache !?
//
CFreeElement* pTemp = m_pFreeStack ;
if( m_pFreeStack != 0 ) {
m_pFreeStack = m_pFreeStack->m_pNext ;
m_cFreeStack -- ;
}
CBucket* pNew = new( pTemp ) CBucket( d ) ;
if( pNew == 0 ) {
return FALSE ;
}
//
// First check whether it is time to grow the hash table.
//
if( InterlockedDecrement( &m_cInserts ) == 0 ) {
//
// Check whether we need to reallocate the array of Bucket pointers.
//
if( m_cIncrement + m_cActiveBuckets > m_cNumAlloced ) {
CBucket** pTemp = new CBucket*[m_cNumAlloced + 10 * m_cIncrement ] ;
if( pTemp == 0 ) {
if( pNew ) { delete pNew; pNew = NULL; }
return FALSE ;
} else {
ZeroMemory( pTemp, (m_cNumAlloced + 10 *m_cIncrement)* sizeof( CBucket*) ) ;
CopyMemory( pTemp, m_ppBucket, m_cNumAlloced * sizeof( CBucket* ) ) ;
delete[] m_ppBucket;
m_cNumAlloced += 10 * m_cIncrement ;
m_ppBucket = pTemp ;
}
}
//
// Okay grow the array by m_cIncrement.
//
m_cActiveBuckets += m_cIncrement ;
if( m_cActiveBuckets > m_cBuckets ) m_cBuckets *= 2 ;
m_cInserts = m_cIncrement * m_load ;
//
// Now do some rehashing of elements.
//
for( int i = -m_cIncrement; i < 0; i++ ) {
int iCurrent = (m_cActiveBuckets + i) - (m_cBuckets / 2) ;
CBucket** ppNext = &m_ppBucket[ iCurrent ] ;
CBucket* p = *ppNext ;
while( p ) {
int index = ComputeIndex( m_pfnHash( p->m_data.GetKey() ) ) ;
CBucket* pNext = p->m_pNext ;
if( index != iCurrent) {
*ppNext = pNext ;
p->m_pNext = m_ppBucket[index] ;
m_ppBucket[index] = p ;
} else {
ppNext = &p->m_pNext ;
}
p = pNext ;
}
}
}
//
// Finally, insert into the Hash Table.
//
DWORD index = ComputeIndex( m_pfnHash( d.GetKey() ) ) ;
Assert( index < unsigned(m_cActiveBuckets) ) ;
#if 0
CBucket* pNew = new CBucket( d ) ;
#endif
Assert( pNew );
pNew->m_pNext = m_ppBucket[index] ;
m_ppBucket[index] = pNew ;
Assert( IsValid( FALSE ) ) ;
return TRUE ;
}
#endif
template< class Data, class Key >
BOOL TFHash< Data, Key >::Insert( Data& d ) {
if( InsertData( d ) )
return TRUE ;
return FALSE ;
}
//-------------------------------------------------
template< class Data, class Key >
Data* TFHash< Data, Key >::InsertDataHash(
DWORD dwHash,
Data& d
) {
//
// This function will Insert an element into the Hash table. We will
// actually make a copy of the element using the Copy COnstructor Data::Data( Data& )
// when we do so.
//
Assert( IsValid( FALSE ) ) ;
//
// Do we have some free memory in our cache !?
//
CFreeElement* pTemp = m_pFreeStack ;
if( m_pFreeStack != 0 ) {
m_pFreeStack = m_pFreeStack->m_pNext ;
m_cFreeStack -- ;
}
CBucket* pNew = new( pTemp ) CBucket( d ) ;
if( pNew == 0 ) {
return FALSE ;
}
//
// First check whether it is time to grow the hash table.
//
if( InterlockedDecrement( &m_cInserts ) == 0 ) {
//
// Check whether we need to reallocate the array of Bucket pointers.
//
if( m_cIncrement + m_cActiveBuckets > m_cNumAlloced ) {
CBucket** pTemp = new CBucket*[m_cNumAlloced + 10 * m_cIncrement ] ;
if( pTemp == 0 ) {
//
// bugbug ... need to handles this error better !?
//
if( pNew ) {
delete pNew;
pNew = NULL;
}
return FALSE ;
} else {
ZeroMemory( pTemp, (m_cNumAlloced + 10 *m_cIncrement)* sizeof( CBucket*) ) ;
CopyMemory( pTemp, m_ppBucket, m_cNumAlloced * sizeof( CBucket* ) ) ;
delete[] m_ppBucket;
m_cNumAlloced += 10 * m_cIncrement ;
m_ppBucket = pTemp ;
}
}
//
// Okay grow the array by m_cIncrement.
//
m_cActiveBuckets += m_cIncrement ;
if( m_cActiveBuckets > m_cBuckets ) m_cBuckets *= 2 ;
m_cInserts = m_cIncrement * m_load ;
//
// Now do some rehashing of elements.
//
for( int i = -m_cIncrement; i < 0; i++ ) {
int iCurrent = (m_cActiveBuckets + i) - (m_cBuckets / 2) ;
CBucket** ppNext = &m_ppBucket[ iCurrent ] ;
CBucket* p = *ppNext ;
while( p ) {
int index = ComputeIndex( m_pfnHash( p->m_data.GetKey() ) ) ;
CBucket* pNext = p->m_pNext ;
if( index != iCurrent) {
*ppNext = pNext ;
p->m_pNext = m_ppBucket[index] ;
m_ppBucket[index] = p ;
} else {
ppNext = &p->m_pNext ;
}
p = pNext ;
}
}
}
//
// Finally, insert into the Hash Table.
//
//DWORD index = ComputeIndex( m_pfnHash( d.GetKey() ) ) ;
Assert( dwHash == m_pfnHash( d.GetKey() ) ) ;
DWORD index = ComputeIndex( dwHash ) ;
Assert( index < unsigned(m_cActiveBuckets) ) ;
Assert( pNew );
pNew->m_pNext = m_ppBucket[index] ;
m_ppBucket[index] = pNew ;
Assert( IsValid( FALSE ) ) ;
return &pNew->m_data;
}
//-------------------------------------------------
template< class Data, class Key >
inline Data*
TFHash< Data, Key >::InsertData( Data& d ) {
//
// This function will Insert an element into the Hash table. We will
// actually make a copy of the element using the Copy COnstructor Data::Data( Data& )
// when we do so.
//
Assert( IsValid( FALSE ) ) ;
return InsertDataHash( m_pfnHash( d.GetKey() ), d ) ;
}
//-----------------------------------------------
template< class Data, class Key >
BOOL
TFHash< Data, Key >::Search( Key& k, Data &dOut ) {
//
// Search for an element in the hash table.
// We will return TRUE if found, FALSE otherwise.
// If we return false the dOut return parameter is untouched.
//
const Data* pData = SearchKey( k ) ;
if( pData ) {
dOut = *pData ;
return TRUE ;
}
return FALSE ;
}
//-----------------------------------------------
template< class Data, class Key >
Data*
TFHash< Data, Key >::SearchKeyHash(
DWORD dwHash,
Key& k
) {
//
// Search for an element in the hash table.
// We will return TRUE if found, FALSE otherwise.
// If we return false the dOut return parameter is untouched.
//
Assert( IsValid( FALSE ) ) ;
Assert( dwHash == (m_pfnHash)(k) ) ;
DWORD index = ComputeIndex( dwHash ) ;
CBucket* p = m_ppBucket[index] ;
while( p ) {
if( p->m_data.MatchKey( k ) )
break ;
p = p->m_pNext ;
}
if( p ) {
return &p->m_data ;
}
return 0 ;
}
//-----------------------------------------------
template< class Data, class Key >
inline Data*
TFHash< Data, Key >::SearchKey( Key& k ) {
//
// Search for an element in the hash table.
// We will return TRUE if found, FALSE otherwise.
// If we return false the dOut return parameter is untouched.
//
Assert( IsValid( FALSE ) ) ;
return SearchKeyHash( m_pfnHash( k ), k ) ;
}
//-----------------------------------------------
template< class Data, class Key >
BOOL TFHash< Data, Key >::Delete( Key k ) {
//
// Remove an element from the Hash Table. We only need the
// Key to find the element we wish to remove.
//
return DeleteData( k, 0 ) ;
}
//-----------------------------------------------
template< class Data, class Key >
BOOL TFHash< Data, Key >::DeleteData( Key& k,
Data* pd
) {
//
// Remove an element from the Hash Table. We only need the
// Key to find the element we wish to remove.
//
Assert( IsValid( FALSE ) ) ;
DWORD dwHash = (m_pfnHash)( k ) ;
DWORD index = ComputeIndex( dwHash ) ;
CBucket** ppNext = &m_ppBucket[index] ;
CBucket* p = *ppNext ;
while( p ) {
if( p->m_data.MatchKey( k ) )
break ;
ppNext = &p->m_pNext ;
p = *ppNext ;
}
if( p ) {
//
// If we were given a pointer to a data block, than the client
// wants us to check to make sure that we are deleting the correct
// instance !!
//
if( !pd || pd == &p->m_data ) {
*ppNext = p->m_pNext ;
//
// Call our do-nothing delete operator - we need to do more
// work to manage the free'd memory !
//
delete p ;
//
// Now in debug versions zap that memory to make sure nobody tries
// to use it !!
//
#ifdef DEBUG
FillMemory( p, sizeof( *p ), 0xCC ) ;
#endif
//
// Okay, put that piece of free memory on a little queue we
// maintain if we haven't saved up too much already !
//
if( m_cFreeStack < m_cMaxFreeStack ) {
CFreeElement* pFree = (CFreeElement*)((void*)p) ;
pFree->m_pNext = m_pFreeStack ;
m_pFreeStack = pFree ;
m_cFreeStack ++ ;
} else {
//
// otherwise - release this memory to the system !
//
DWORDLONG* pdwl = (DWORDLONG*)((void*)p) ;
::delete[] pdwl ;
}
//
// Finally - since we removed something from the hash table
// increment the number of inserts so that we don't keep splitting
// the table unnecessarily !
//
InterlockedIncrement( &m_cInserts ) ;
Assert( IsValid( FALSE ) ) ;
return TRUE ;
}
}
Assert( IsValid( FALSE ) ) ;
return FALSE ;
}