143 lines
4.2 KiB
C++
143 lines
4.2 KiB
C++
//
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// MODULE: APGTSCAC.CPP
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//
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// PURPOSE: Belief network caching support classes
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// Fully implements class CBNCacheItem
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// Fully implements class CBNCache
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//
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// PROJECT: Generic Troubleshooter DLL for Microsoft AnswerPoint
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//
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// COMPANY: Saltmine Creative, Inc. (206)-284-7511 support@saltmine.com
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//
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// AUTHOR: Joe Mabel, modeled on earlier work by Roman Mach
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//
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// ORIGINAL DATE: 10-2-96, completely rewritten 8/98
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//
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// NOTES:
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// 1. The strategy here builds a "Most-recently-used" cache (singly-linked list of
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// CBNCacheItem ordered by how recently used)
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// 2. Although you are first supposed to call FindCacheItem and only call AddCacheItem
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// if that fails, there is no support to do this in a threadsafe manner, so there
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// had better be only one thread with access to a given CCache. Mutex protection
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// must come at a higher level.
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// 3. One cache is associated with each [instance of a] Belief Network
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//
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// Version Date By Comments
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//--------------------------------------------------------------------
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// V0.1 - RM Original
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// V3.0 8/7/98 JM Original
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//
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#include "stdafx.h"
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#include "event.h"
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#include "apgtscac.h"
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#include "baseexception.h"
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#include "CharConv.h"
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#include <algorithm>
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// The CCacheItem comparison operators depend on the assumption that if the cache key
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// is identical, the cache value will be, too.
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bool CCacheItem::operator== (const CCacheItem &item) const
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{
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return (BasisForInference == item.BasisForInference);
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}
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bool CCacheItem::operator!= (const CCacheItem &item) const
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{
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return (BasisForInference != item.BasisForInference);
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}
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// Note that this is not lexicographical order. We're saying any shorter
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// cache key compares as less than any longer.
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bool CCacheItem::operator< (const CCacheItem &item) const
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{
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const CBasisForInference::size_type thisSize = BasisForInference.size();
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const CBasisForInference::size_type otherSize = item.BasisForInference.size();
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if (thisSize < otherSize)
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return true;
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if (thisSize > otherSize)
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return false;
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// same length, use lexicographical order.
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return (BasisForInference < item.BasisForInference);
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}
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// Note that this is not lexicographical order. We're saying any longer
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// cache key compares as greater than any shorter.
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bool CCacheItem::operator> (const CCacheItem &item) const
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{
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const CBasisForInference::size_type thisSize = BasisForInference.size();
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const CBasisForInference::size_type otherSize = item.BasisForInference.size();
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if (thisSize > otherSize)
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return true;
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if (thisSize < otherSize)
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return false;
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// same length, use lexicographical order.
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return (BasisForInference > item.BasisForInference);
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}
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// NOTE: Must call FindCacheItem first and not call this
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// function to prevent duplicate records from going into cache
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bool CCache::AddCacheItem(
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const CBasisForInference &BasisForInference,
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const CRecommendations &Recommendations)
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{
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if (GetCount() >= MAXCACHESIZE)
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listItems.pop_back();
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try
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{
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CCacheItem item(BasisForInference, Recommendations);
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listItems.push_front(item);
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if (listItems.size() >= k_CacheSizeMax)
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listItems.pop_back();
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return true; // always succeeds
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}
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catch (exception& x)
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{
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CString str;
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// Note STL exception in event log.
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CBuildSrcFileLinenoStr SrcLoc( __FILE__, __LINE__ );
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CEvent::ReportWFEvent( SrcLoc.GetSrcFileLineStr(),
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SrcLoc.GetSrcFileLineStr(),
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CCharConversion::ConvertACharToString(x.what(), str),
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_T(""),
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EV_GTS_STL_EXCEPTION );
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return( false );
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}
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}
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bool CCache::FindCacheItem(
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const CBasisForInference &BasisForInference,
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CRecommendations &Recommendations /* output */) const
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{
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Recommendations.clear();
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CCacheItem item(BasisForInference, Recommendations /* effectively, a dummy */ );
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const list<CCacheItem>::const_iterator itBegin = listItems.begin();
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const list<CCacheItem>::const_iterator itEnd = listItems.end();
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const list<CCacheItem>::const_iterator itMatch = find(itBegin, itEnd, item);
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if (itMatch == itEnd)
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return false;
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Recommendations = itMatch->GetRecommendations();
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return true;
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}
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UINT CCache::GetCount() const
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{
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return listItems.size();
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}
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