mirror of https://github.com/tongzx/nt5src
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
432 lines
8.3 KiB
432 lines
8.3 KiB
/*++
|
|
|
|
Copyright (c) 1995 Microsoft Corporation
|
|
|
|
Module Name:
|
|
|
|
Table.cxx
|
|
|
|
Abstract:
|
|
|
|
Implementation of the CHashTable and CTableElement.
|
|
|
|
Author:
|
|
|
|
Mario Goertzel [MarioGo]
|
|
|
|
Revision History:
|
|
|
|
MarioGo 02-15-95 Bits 'n pieces
|
|
MarioGo 12-18-95 Changed from UUID to generic object keys
|
|
|
|
--*/
|
|
|
|
#include<or.hxx>
|
|
|
|
CTableElement *
|
|
CTableElement::RemoveMatching(
|
|
IN CTableKey &tk,
|
|
OUT CTableElement **ppRemoved)
|
|
/*++
|
|
|
|
Routine Description:
|
|
|
|
Helper function used to remove an element from a
|
|
bucket in the hash table.
|
|
|
|
Arguments:
|
|
|
|
tk - Key to find the element being removed.
|
|
|
|
ppRemoved - Contains the element removed or NULL upon return.
|
|
|
|
Return Value:
|
|
|
|
Pointer to the remaining elements in the list if any. Use
|
|
to replace the current pointer in the bucket.
|
|
|
|
--*/
|
|
{
|
|
CTableElement *pcurrent = this;
|
|
CTableElement *psaved = 0;
|
|
CTableElement *pfirst = this;
|
|
|
|
while(pcurrent)
|
|
{
|
|
if (pcurrent->Compare(tk))
|
|
{
|
|
*ppRemoved = pcurrent;
|
|
if (0 != psaved)
|
|
{
|
|
psaved->_pnext = pcurrent->_pnext;
|
|
pcurrent->_pnext = 0;
|
|
return(pfirst);
|
|
}
|
|
else
|
|
{
|
|
// removing the first element in the list
|
|
ASSERT(pcurrent == pfirst);
|
|
psaved = pcurrent->_pnext;
|
|
pcurrent->_pnext = 0;
|
|
return(psaved);
|
|
}
|
|
}
|
|
|
|
psaved = pcurrent;
|
|
pcurrent = pcurrent->_pnext;
|
|
}
|
|
|
|
*ppRemoved = 0;
|
|
return(pfirst);
|
|
}
|
|
|
|
|
|
CTableElement *
|
|
CTableElement::RemoveMatching(
|
|
IN CTableElement *pte,
|
|
OUT CTableElement **ppRemoved)
|
|
/*++
|
|
|
|
Routine Description:
|
|
|
|
Helper function used to remove an element from a bucket in the hash table.
|
|
|
|
Arguments:
|
|
|
|
pte - Element to be removed, compared by pointer value.
|
|
|
|
ppRemoved - Contains the element removed or NULL upon return.
|
|
|
|
Return Value:
|
|
|
|
Pointer to the remaining elements in the list if any. Use
|
|
to replace the current pointer in the bucket.
|
|
|
|
--*/
|
|
{
|
|
CTableElement *pcurrent = this;
|
|
CTableElement *psaved = 0;
|
|
CTableElement *pfirst = this;
|
|
|
|
while(pcurrent)
|
|
{
|
|
if (pcurrent == pte)
|
|
{
|
|
*ppRemoved = pcurrent;
|
|
if (0 != psaved)
|
|
{
|
|
psaved->_pnext = pcurrent->_pnext;
|
|
pcurrent->_pnext = 0;
|
|
return(pfirst);
|
|
}
|
|
else
|
|
{
|
|
// removing the first element in the list
|
|
ASSERT(pcurrent == pfirst);
|
|
psaved = pcurrent->_pnext;
|
|
pcurrent->_pnext = 0;
|
|
return(psaved);
|
|
}
|
|
}
|
|
|
|
psaved = pcurrent;
|
|
pcurrent = pcurrent->_pnext;
|
|
}
|
|
|
|
*ppRemoved = 0;
|
|
return(pfirst);
|
|
}
|
|
|
|
CHashTable::CHashTable(ORSTATUS &status, UINT start_size)
|
|
{
|
|
_cBuckets = start_size;
|
|
_cElements = 0;
|
|
_last = 0;
|
|
|
|
_buckets = new CTableElement *[start_size];
|
|
|
|
if (0 == _buckets)
|
|
{
|
|
status = OR_NOMEM;
|
|
return;
|
|
}
|
|
|
|
for(UINT i = 0; i < _cBuckets; i++)
|
|
{
|
|
_buckets[i] = NULL;
|
|
}
|
|
|
|
status = OR_OK;
|
|
}
|
|
|
|
|
|
CHashTable::~CHashTable()
|
|
{
|
|
#if 0
|
|
#if DBG
|
|
for(UINT i = 0; i < _cBuckets; i++)
|
|
ASSERT(_buckets[i] == 0);
|
|
#endif
|
|
delete _buckets;
|
|
#endif
|
|
ASSERT(0); // D'tor unused 12/95
|
|
}
|
|
|
|
CTableElement *
|
|
CHashTable::Lookup(
|
|
IN CTableKey &id
|
|
)
|
|
{
|
|
DWORD hash = id.Hash();
|
|
CTableElement *it;
|
|
|
|
it = _buckets[hash % _cBuckets];
|
|
|
|
while(it)
|
|
{
|
|
if (it->Compare(id))
|
|
{
|
|
return(it);
|
|
}
|
|
|
|
it = it->Next();
|
|
}
|
|
|
|
return(0);
|
|
}
|
|
|
|
void
|
|
CHashTable::Add(
|
|
IN CTableElement *pElement
|
|
)
|
|
{
|
|
DWORD hash = pElement->Hash();
|
|
|
|
hash %= _cBuckets;
|
|
|
|
_buckets[hash] = _buckets[hash]->Insert(pElement);
|
|
|
|
_cElements++;
|
|
|
|
if (_cElements > _cBuckets)
|
|
{
|
|
// Try to grow the table. If the allocation fails no need to worry,
|
|
// everything still works but might be a bit slower.
|
|
|
|
CTableElement **ppte = new CTableElement *[_cBuckets * 2];
|
|
|
|
if (ppte)
|
|
{
|
|
UINT i, uiBucketsOld = _cBuckets;
|
|
CTableElement *pteT1, *pteT2;
|
|
CTableElement **ppteOld = _buckets;
|
|
|
|
KdPrintEx((DPFLTR_DCOMSS_ID,
|
|
DPFLTR_INFO_LEVEL,
|
|
"OR: Growing table: %p\n",
|
|
this));
|
|
|
|
// Change to the larger array of buckets.
|
|
_cBuckets *= 2;
|
|
for(i = 0; i < _cBuckets; i++)
|
|
{
|
|
ppte[i] = NULL;
|
|
}
|
|
_buckets = ppte;
|
|
|
|
// Move every element from the old table into the large table.
|
|
for(i = 0; i < uiBucketsOld; i++)
|
|
{
|
|
pteT1 = ppteOld[i];
|
|
|
|
while(pteT1)
|
|
{
|
|
pteT2 = pteT1->Next();
|
|
pteT1->Unlink();
|
|
|
|
// Same as calling Add() but don't update _cElements.
|
|
hash = pteT1->Hash();
|
|
hash %= _cBuckets;
|
|
_buckets[hash] = _buckets[hash]->Insert(pteT1);
|
|
|
|
pteT1 = pteT2;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return;
|
|
}
|
|
|
|
CTableElement *
|
|
CHashTable::Remove(
|
|
IN CTableKey &id
|
|
)
|
|
/*++
|
|
|
|
Routine Description:
|
|
|
|
Looks up and removes an element from the table.
|
|
|
|
Arguments:
|
|
|
|
id - The key to match the element to be removed
|
|
|
|
Return Value:
|
|
|
|
NULL - The element was not in the table
|
|
|
|
non-NULL - A pointer to the element which was removed.
|
|
|
|
--*/
|
|
|
|
{
|
|
DWORD hash = id.Hash();
|
|
CTableElement *pte;
|
|
|
|
hash %= _cBuckets;
|
|
|
|
_buckets[hash] = (_buckets[hash])->RemoveMatching(id, &pte);
|
|
|
|
if (pte)
|
|
{
|
|
_cElements--;
|
|
|
|
if (_last == pte)
|
|
{
|
|
_last = _buckets[hash];
|
|
}
|
|
}
|
|
|
|
return pte;
|
|
}
|
|
|
|
void
|
|
CHashTable::Remove(
|
|
IN CTableElement *pElement
|
|
)
|
|
/*++
|
|
|
|
Routine Description:
|
|
|
|
Used to remove an element from the table given a pointer to it.
|
|
|
|
Arguments:
|
|
|
|
pElement - the element to be removed. This pointer value,
|
|
keys are not compared.
|
|
|
|
Return Value:
|
|
|
|
None
|
|
|
|
--*/
|
|
|
|
{
|
|
DWORD hash = pElement->Hash();
|
|
CTableElement *pte;
|
|
|
|
hash %= _cBuckets;
|
|
|
|
_buckets[hash] = (_buckets[hash])->RemoveMatching(pElement, &pte);
|
|
|
|
if (pte)
|
|
{
|
|
ASSERT(pte == pElement);
|
|
|
|
_cElements--;
|
|
|
|
if (_last == pElement)
|
|
{
|
|
_last = _buckets[hash];
|
|
}
|
|
}
|
|
|
|
return;
|
|
}
|
|
|
|
CTableElement *
|
|
CHashTable::Another(
|
|
)
|
|
/*++
|
|
|
|
Routine Description:
|
|
|
|
Returns an element from the table. Usually this will be
|
|
element found after the element last returned from this
|
|
function. It may, due to races not solved here, repeat
|
|
an element or skip an element.
|
|
|
|
Races occur when accessing the "_last" memeber; this
|
|
function is called while holding a shared lock. (More
|
|
then one thread may call it at a time.)
|
|
|
|
This isn't as bad as it sounds. _last can only
|
|
be set to null in Remove() which requires exclusive
|
|
access.
|
|
|
|
Arguments:
|
|
|
|
None
|
|
|
|
Return Value:
|
|
|
|
NULL or a pointer to an element in the table.
|
|
|
|
--*/
|
|
|
|
{
|
|
CTableElement *panother;
|
|
int i, end;
|
|
|
|
if (_cElements == 0)
|
|
{
|
|
return(0);
|
|
}
|
|
|
|
if (_last)
|
|
{
|
|
if (panother = _last->Next())
|
|
{
|
|
if (panother)
|
|
{
|
|
_last = panother;
|
|
return(panother);
|
|
}
|
|
}
|
|
|
|
ASSERT(panother == 0);
|
|
|
|
// no next, start looking from just after last's hash.
|
|
|
|
i = _last->Hash();
|
|
|
|
// Exersise for the reader (x + y) mod n == ( x mod n + y mod n ) mod n
|
|
|
|
end = i = (i + 1) % _cBuckets;
|
|
}
|
|
else
|
|
{
|
|
// no last, start from the start.
|
|
i = 0;
|
|
end = _cBuckets - 1;
|
|
}
|
|
|
|
do
|
|
{
|
|
if (_buckets[i])
|
|
{
|
|
panother = _buckets[i];
|
|
ASSERT(panother);
|
|
_last = panother;
|
|
return(panother);
|
|
}
|
|
i = (i + 1) % _cBuckets;
|
|
}
|
|
while (i != end);
|
|
|
|
// Doesn't mean the table is empty, just that we didn't find
|
|
// another element. These are not the same thing.
|
|
return(0);
|
|
}
|
|
|