134 lines
2.5 KiB
C++
134 lines
2.5 KiB
C++
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/*++
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Copyright (c) 1996 Microsoft Corporation
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Module Name :
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cachep.cxx
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Abstract:
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This module contains the internal tsunami caching routines
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Author:
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Murali R. Krishnan ( MuraliK ) 16-Jan-1995
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--*/
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#include "TsunamiP.Hxx"
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#pragma hdrstop
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// specifies how many characters we will use for hashing string names
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# define g_dwFastHashLength (16)
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HASH_TYPE
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CalculateHashAndLengthOfPathName(
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LPCSTR pszPathName,
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PULONG pcbLength
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)
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{
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HASH_TYPE hash = 0;
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CHAR ch;
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DWORD start;
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DWORD index;
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ASSERT( pszPathName != NULL );
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ASSERT( pcbLength != NULL );
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*pcbLength = strlen(pszPathName);
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//
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// hash the last g_dwFastHashLength characters
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//
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if ( *pcbLength < g_dwFastHashLength ) {
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start = 0;
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} else {
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start = *pcbLength - g_dwFastHashLength;
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}
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for ( index = start; pszPathName[index] != '\0'; index++ ) {
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//
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// This is an extremely slimey way of getting upper case.
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// Kids, don't try this at home
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// -johnson
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//
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ch = pszPathName[index] & (CHAR)~0x20;
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hash <<= 1;
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hash ^= ch;
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hash <<= 1;
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hash += ch;
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}
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//
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// Multiply by length. Murali said so.
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//
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return( hash * *pcbLength);
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} // CalculateHashAndLengthOfPathName
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BOOL
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DeCache(
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PCACHE_OBJECT pCacheObject,
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BOOL fLockCacheTable
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)
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/*++
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Description:
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This function removes this cache object from any list it may be on.
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The cache table lock must be taken if fLockCacheTable is FALSE.
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Arguments:
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pCacheObject - Object to decache
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fLockCacheTable - FALSE if the cache table lock has already been taken
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--*/
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{
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ASSERT( pCacheObject->Signature == CACHE_OBJ_SIGNATURE );
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TSUNAMI_TRACE( TRACE_CACHE_DECACHE, pCacheObject );
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//
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// Already decached if not on any cache lists
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//
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if ( !RemoveCacheObjFromLists( pCacheObject, fLockCacheTable ) )
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{
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return TRUE;
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}
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//
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// This undoes the initial reference. The last person to check in this
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// cache object will cause it to be deleted after this point.
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//
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TsDereferenceCacheObj( pCacheObject, fLockCacheTable );
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return( TRUE );
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}
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BOOL
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TsDeCacheCachedBlob(
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PVOID pBlobPayload
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)
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/*++
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Description:
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This function removes a blob payload object from the cache
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Arguments:
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pCacheObject - Object to decache
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--*/
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{
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return DeCache( (((PBLOB_HEADER)pBlobPayload)-1)->pCache, TRUE );
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}
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