windows-nt/Source/XPSP1/NT/inetsrv/iis/staxinc/fdlhash.h

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2020-09-26 03:20:57 -05:00
/*++
FDLHash.h
This file contains a template class for a hash table.
The templates used in here build off the templates in tfdlist.h for
doubly linked lists. The bucket chains implemented in this version
of the hash table are doubly linked lists.
The Data type must support the following :
class Data {
DLSIT_ENTRY m_list;
KEYREF GetKey( ) ;
} ;
int MatchKey( KEYREF otherkey, KEYREF otherkey) ; /* NOTE : MatchKey returns non-zero on equality
DWORD (* m_pfnReHash)(Data* p ) ;
DWORD (* m_pfnHash)( KEYREF k ) ;
--*/
#ifndef _FDLHASH_H_
#define _FDLHASH_H_
#include "tfdlist.h"
class CHashStats {
public :
enum COUNTER {
HASHITEMS = 0, // Number of items in the hash table
INSERTS, // Number of times Insert has been called
SPLITINSERTS, // Number of inserts until the next split !
DELETES, // Number of times Delete has been called
SEARCHES, // Number of times Search has been called
SEARCHHITS, // Number of times we Search and find something !
SPLITS, // Number of times we've split the table on an insert !
REALLOCS, // Number of times we've reallocated memory for a split
DEEPBUCKET, // The deepest bucket we have !
AVERAGEBUCKET, // The average depth of the buckets
EMPTYBUCKET, // The number of Empty buckets !
ALLOCBUCKETS, // Number of buckets we've allocated
ACTIVEBUCKETS, // Number of Active buckets
AVERAGESEARCH, // Average number of buckets we examine each search
DEEPSEARCH, // Longest walk we do on a search
SEARCHCOST, // Sum of the number of items we've visited for all search hits !
SEARCHCOSTMISS, // Sum of the number of items we've visited for search misses !
MAX_HASH_STATS // Number of statistics we report !
} ;
long m_cHashCounters[MAX_HASH_STATS] ;
CHashStats() {
ZeroMemory( m_cHashCounters, sizeof( m_cHashCounters ) ) ;
//m_cHashCounters[SMALLSEARCH] = 0x7FFF ;
}
static inline void
IncrementStat( CHashStats* p, CHashStats::COUNTER c ) {
_ASSERT( c < CHashStats::MAX_HASH_STATS ) ;
if( p != 0 ) {
InterlockedIncrement( &p->m_cHashCounters[c] ) ;
}
}
static inline void
AddStat( CHashStats*p, CHashStats::COUNTER c, long l ) {
_ASSERT( c < CHashStats::MAX_HASH_STATS ) ;
if( p != 0 ) {
InterlockedExchangeAdd( &p->m_cHashCounters[c], l ) ;
}
}
static inline void
DecrementStat( CHashStats* p, CHashStats::COUNTER c ) {
_ASSERT( c < CHashStats::MAX_HASH_STATS ) ;
if( p != 0 ) {
InterlockedDecrement( &p->m_cHashCounters[c] ) ;
}
}
static inline void
SetStat( CHashStats* p, CHashStats::COUNTER c, long l ) {
_ASSERT( c < CHashStats::MAX_HASH_STATS ) ;
if( p != 0 ) {
p->m_cHashCounters[c] = l ;
}
}
} ;
#ifdef METER
#define INCREMENTSTAT( s ) CHashStats::IncrementStat( m_pStat, CHashStats::##s )
#define DECREMENTSTAT( s ) CHashStats::DecrementStat( m_pStat, CHashStats::##s )
#define ADDSTAT( s, a ) CHashStats::AddStat( m_pStat, CHashStats::##s, a )
#define SETSTAT( s, a ) CHashStats::SetStat( m_pStat, CHashStats::##s, a )
//#if 0
#define MAXBUCKET( i ) MaxBucket( i )
#define AVERAGEBUCKET() AverageBucket()
//#else
//#define MAXBUCKET( i )
//#define AVERAGEBUCKET()
//#endif
#else // METER
#define INCREMENTSTAT( s )
#define DECREMENTSTAT( s )
#define ADDSTAT( s, a )
#define SETSTAT( s, a )
#define MAXBUCKET( i )
#define AVERAGEBUCKET()
#endif // METER
template< class HASHTABLE >
class TFDLHashIterator {
private :
//
// The hash table that the item is in !
//
HASHTABLE* m_pTable ;
//
// The bucket we are walking on !
//
int m_iBucket ;
//
// Keep track of our position in a list !
//
HASHTABLE::ITER m_Iter ;
//
// Move between hash table buckets as necessary !
//
void
PrevBucket() {
_ASSERT( m_iBucket >= 0 && m_iBucket < m_pTable->m_cActiveBuckets ) ;
_ASSERT( m_Iter.AtEnd() ) ;
if( m_iBucket > 0 ) {
do {
m_Iter.ReBind( &m_pTable->m_pBucket[--m_iBucket] ) ;
} while( m_Iter.AtEnd() && m_iBucket > 0 ) ;
}
_ASSERT( m_iBucket >= 0 && m_iBucket < m_pTable->m_cActiveBuckets ) ;
}
//
// Move between hash table buckets as necessary !
//
void
NextBucket() {
_ASSERT( m_iBucket >= 0 && m_iBucket < m_pTable->m_cActiveBuckets ) ;
_ASSERT( m_Iter.AtEnd() ) ;
if( m_iBucket < m_pTable->m_cActiveBuckets-1 ) {
do {
m_Iter.ReBind( &m_pTable->m_pBucket[++m_iBucket] ) ;
} while( m_Iter.AtEnd() && m_iBucket < m_pTable->m_cActiveBuckets-1 ) ;
}
_ASSERT( m_iBucket >= 0 && m_iBucket < m_pTable->m_cActiveBuckets ) ;
}
public :
typedef HASHTABLE::DATA DATA ;
TFDLHashIterator( HASHTABLE& ref, BOOL fForward = TRUE ) :
m_pTable( &ref ),
m_iBucket( fForward ? 0 : ref.m_cActiveBuckets-1 ),
m_Iter( ref.m_pBucket[m_iBucket] ) {
if( m_Iter.AtEnd() ) {
if( fForward ) {
NextBucket() ;
} else {
PrevBucket() ;
}
}
}
void
Prev() {
/*++
Routine Description :
This function moves the iterator back one slot.
Arguments :
None.
Return Value :
None.
--*/
m_Iter.Prev() ;
if( m_Iter.AtEnd() ) {
PrevBucket() ;
}
}
void
Next() {
/*++
Routine Description :
This function moves the iterator forward one slot.
Arguments :
None.
Return Value :
None.
--*/
m_Iter.Next() ;
if( m_Iter.AtEnd() ) {
NextBucket() ;
}
}
void
Front() {
/*++
Routine Description :
Reset the iterator to reference the first item of the list !
Arguments :
None.
Return Value :
None.
--*/
m_Iter.ReBind( &m_pTable->m_pBucket[0], TRUE ) ;
m_iBucket = 0 ;
if( m_Iter.AtEnd() ) {
NextBucket() ;
}
}
void
Back() {
/*++
Routine Description :
Reset the iterator to reference the last item of the list !
Arguments :
None.
Return Value :
None.
--*/
m_Iter.ReBind( &m_pTable->m_pBucket[m_pTable->m_cActiveBuckets-1], FALSE ) ;
m_iBucket = m_pTable->m_cActiveBuckets-1 ;
if( m_Iter.AtEnd() ) {
PrevBucket() ;
}
}
BOOL
AtEnd() {
/*++
Routine Description :
Return TRUE if we are at the end of the list !
This is a little more complicated to compute -
depends on which way we are going !
Arguments :
None.
Return Value :
None.
--*/
return m_Iter.AtEnd() ;
}
DATA*
CurrentEntry() {
return m_Iter.Current() ;
}
DATA*
RemoveItem() {
/*++
Routine Description :
Remove the item that the iterator currently
references from the list.
If we are going forward then the iterator
will be setting on the previous element,
otherwise the iterator is left on the next element.
We have to take care that we don't leave the iterator
sitting on an invalid element.
Arguments :
None.
Return Value :
Pointer to the removed item.
--*/
DATA* pData = m_Iter.RemoveItem() ;
if( pData ) {
m_pTable->NotifyOfRemoval() ;
}
if( m_Iter.AtEnd() ) {
if( m_Iter.m_fForward ) {
NextBucket() ;
} else {
PrevBucket() ;
}
}
return pData ;
}
inline DATA*
Current( ) {
return m_Iter.Current() ;
}
inline void
InsertBefore( DATA* p ) {
m_Iter.InsertBefore( p ) ;
}
inline void
InsertAfter( DATA* p ) {
m_Iter.InsertAfter( p ) ;
}
} ;
//------------------------------------------------------------
template< class Data, /* This is the item that resides in the hashtable */
class KEYREF, /* This is the type used to point or reference items in the cache*/
Data::PFNDLIST pfnDlist,
BOOL fOrdered = TRUE
>
class TFDLHash {
//
// This class defines a Hash table which can grow dynamically to
// accomodate insertions into the table. The table only grows, and
// does not shrink.
//
public :
//
// This is the iterator object that can walk the hash table !
//
friend class TFDLHashIterator< TFDLHash< Data, KEYREF, pfnDlist > > ;
//
// This is the type of the Data item !
//
//typedef DATAHELPER Data ;
typedef KEYREF (Data::*GETKEY)() ;
//
// This is the type that we use to maintain doubly linked lists of
// hash table items !
//
typedef TDListHead< Data, pfnDlist > DLIST ;
//
// This is the type we use to make iterators over the bucket chains !
//
typedef TDListIterator< DLIST > ITER ;
//
// Define this type for our iterators !
//
typedef Data DATA ;
//
// This is a member function pointer to a function which
// will retrieve the key we are to use !
//
//typedef KEYREF (Data::*GETKEY)( ) ;
//typedef Data::GETKEY GETKEY ;
//
// This is the type of function that computes the hash value !
//
typedef DWORD (*PFNHASH)( KEYREF ) ;
//
// This is the type of function that can recompute the hash value when
// we are splitting up the hash table !
//
typedef DWORD (*PFNREHASH)( Data* ) ;
//
// This is a member function pointer of the type that will
// compare keys for us !
//
typedef int (*MATCHKEY)( KEYREF key1, KEYREF key2 ) ;
private :
//
// An array of buckets !
//
DLIST* m_pBucket ;
//
// Member Pointer - will get the key out of the object for us !
//
GETKEY m_pGetKey ;
//
// Member Pointer - will compare the key in the item for us !
//
MATCHKEY m_pMatchKey ;
//
// A counter that we use to determine when to grow the
// hash table. Each time we grow the table we set this
// to a large positive value, and decrement as we insert
// elements. When this hits 0 its time to grow the table !
//
long m_cInserts ;
//
// The function we use to compute hash values.
// (Provided by the Caller of Init())
//
PFNHASH m_pfnHash ;
//
// The function we call when we are growing the hash table
// and splitting bucket chains and we need to rehash an element !
//
PFNREHASH m_pfnReHash ;
//
// Number of Buckets used in index computation
//
int m_cBuckets ;
//
// Number of Buckets we are actually using
// Assert( m_cBuckets >= m_cActiveBuckets ) always true.
//
int m_cActiveBuckets ;
//
// Number of Buckets we have allocated
// Assert( m_cNumAlloced >= m_cActiveBuckets ) must
// always be true.
//
int m_cNumAlloced ;
//
// The amount we should grow the hash table when we
// decide to grow it.
//
int m_cIncrement ;
//
// The number of CBuckets we should allow in each
// collision chain (on average).
//
int m_load ;
#ifdef METER
//
// The structure for collecting our performance data !
//
CHashStats* m_pStat ;
//
// Compute the depth of a bucket !
//
long
BucketDepth( DWORD index ) ;
//
// set the statistics for the deepest bucket !
//
void
MaxBucket( DWORD index ) ;
//
// Compute the average Search depth !
//
void
AverageSearch( BOOL fHit, long lDepth ) ;
//
// Compute the average Bucket depth !
//
void
AverageBucket( ) ;
#endif
//
// The function we use to compute the
// position of an element in the hash table given its
// Hash Value.
//
DWORD
ComputeIndex( DWORD dw ) ;
DWORD
ReHash( Data* p ) {
if( m_pfnReHash )
return m_pfnReHash( p ) ;
return m_pfnHash( (p->*m_pGetKey)() ) ;
}
public :
TFDLHash( ) ;
~TFDLHash( ) ;
BOOL
Init( int cInitial,
int cIncrement,
int load,
PFNHASH pfnHash,
GETKEY pGetKey,
MATCHKEY pMatchKey,
PFNREHASH pfnReHash = 0,
CHashStats* pStats = 0
) ;
//
// Check that the hash table is in a valid state
// if fCheckHash == TRUE we will walk all the buckets and check that
// the data hashes to the correct value !
//
BOOL
IsValid( BOOL fCheckHash = FALSE ) ;
//
// Check that the Bucket is valid - everything contains
// proper hash value and is in order !
//
BOOL
IsValidBucket( int i ) ;
//
// This function grows the number of hash buckets as the
// total number of items in the table grows !
//
BOOL
Split() ;
//
// Insert a piece of Data into the Hash Table
// We take a pointer to the Data object.
//
BOOL
InsertDataHash( DWORD dw,
KEYREF k,
Data* pd
) ;
//
// Insert a piece of Data into the Hash Table
//
// We take an iterator that is already position in the
// correct location for inserting the item !
//
BOOL
InsertDataHashIter( ITER& iter,
DWORD dw,
KEYREF k,
Data* pd
) ;
//
// Insert a piece of Data into the Hash Table
//
BOOL
InsertData( Data* pd ) {
KEYREF keyref = (pd->*m_pGetKey)() ;
return InsertDataHash( m_pfnHash(keyref), keyref, pd ) ;
}
//
// Insert a piece of Data into the Hash table
// given an iterator that should be at the right location !
//
BOOL
InsertDataIter( ITER& iter,
Data* pd ) {
KEYREF keyref = (pd->*m_pGetKey)() ;
return InsertDataHashIter( iter, m_pfnHash(keyref), keyref, pd ) ;
}
//
// Search for an item in the cache - if we don't find
// it we return an ITERATOR that the user can use to insert
// the item by calling ITER.InsertBefore() ;
//
// If the item is found, we'll return the item, as well
// as returning an iterator who's current element
// points at the data item !
//
ITER
SearchKeyHashIter(
DWORD dw,
KEYREF k,
Data* &pd
) ;
//
// Search for a given Key in the Hash Table - return a pointer
// to the Data within our Bucket object
//
void
SearchKeyHash( DWORD dw,
KEYREF k,
Data* &pd
) ;
//
// Search for a given Key in the Hash Table - return a pointer
// to the Data within our Bucket object
//
Data*
SearchKey( KEYREF k ) {
Data* p ;
SearchKeyHash( m_pfnHash( k ), k, p ) ;
return p ;
}
//
// Search for the given item and return a good iterator !
//
ITER
SearchKeyIter( KEYREF k,
Data* &pd ) {
pd = 0 ;
return SearchKeyHashIter( m_pfnHash( k ), k, pd ) ;
}
Data*
SearchKey( DWORD dw,
KEYREF k
) {
Data* p = 0 ;
_ASSERT( dw == m_pfnHash( k ) ) ;
SearchKeyHash( dw, k, p ) ;
return p ;
}
//
// Given an item in the hash table - remove it !
//
void
Delete( Data* pd ) ;
//
// Find an element in the hash table - and remove it !
// (Confirm that the found item matches the Key!)
//
void
DeleteData( KEYREF k,
Data* pd
) ;
//
// Remove an item from the hash table - and return it !
//
Data*
DeleteData( KEYREF k ) {
Data* p ;
//
// Find the item
//
SearchKeyHash( m_pfnHash( k ), k, p ) ;
//
// Remove from Hash Table
//
if( p )
Delete( p ) ;
return p ;
}
//
// Delete the key and associated data from the table.
//
BOOL
Destroy( KEYREF k ) {
Data* p = DeleteData( k ) ;
if( p ) {
delete p ;
return TRUE ;
}
return FALSE ;
}
//
// Discards any memory we have allocated - after this, you must
// call Init() again!
//
void Clear( ) ;
//
// Removes all of the items in the hash table. Does not call "delete"
// on them.
//
void Empty( ) ;
//
// Called by Iterators that want to let us know that items have been
// removed from the cache so we can do our splits correctly etc... !
//
void NotifyOfRemoval() ;
//
// Function to compute hash value of a key for callers
// who don't keep track of the hash function
//
DWORD
ComputeHash( KEYREF k ) ;
} ;
#include "fdlhash.inl"
#endif // _FDLHASH_H_