On Thu, 2012-05-10 at 21:56 +0100, Caolán McNamara wrote:
> with a scenario of nBgn = 11, nRel = 2, desired result is 13
Ah ! how stupid of me, I missed that - but this case is almost totally
pointless ;-) we are just victims of this optimisation of starting in
the middle - which means we have to go lookup where we are; when we
actually precisely know our offset from the beginning of the chain/array
( which is nNew/nPageSize ).
So - how about the attached diff, hopefully rather easier to review &
back-port :-) should I knock a version up for -3-5 ? the #ifdef bravery
is never triggered if enabled (FWIW) during import / export of the
slow .doc anyhow.
All the best,
Michael.
--
michael.me...@suse.com <><, Pseudo Engineer, itinerant idiot
diff --git a/sot/source/sdstor/stgstrms.cxx b/sot/source/sdstor/stgstrms.cxx
index 88bc416..67da8ee 100644
--- a/sot/source/sdstor/stgstrms.cxx
+++ b/sot/source/sdstor/stgstrms.cxx
@@ -334,27 +334,12 @@ void StgStrm::SetEntry( StgDirEntry& r )
r.SetDirty();
}
-namespace lcl
-{
-#if defined(__GXX_EXPERIMENTAL_CXX0X__) || __cplusplus >= 201103L
- using std::is_sorted;
-#else
- template <typename iter> bool is_sorted(iter aStart, iter aEnd)
- {
- if (aStart == aEnd)
- return true;
-
- for (iter aNext = aStart + 1; aNext != aEnd; aStart = aNext, ++aNext)
- {
- if (*aNext < *aStart)
- return false;
- }
-
- return true;
- }
-#endif
-}
-
+/*
+ * The page chain, is basically a singly linked list of slots each
+ * point to the next page. Instead of traversing the file structure
+ * for this each time build a simple flat in-memory vector list
+ * of pages.
+ */
bool StgStrm::buildPageChainCache()
{
if (nSize > 0)
@@ -370,10 +355,6 @@ bool StgStrm::buildPageChainCache()
return false;
}
- m_bSortedPageChain = lcl::is_sorted(m_aPagesCache.begin(), m_aPagesCache.end());
-
- SAL_WARN_IF(!m_bSortedPageChain, "sot", "unsorted page chain, that's suspicious");
-
return true;
}
@@ -403,6 +384,35 @@ sal_Bool StgStrm::Pos2Page( sal_Int32 nBytePos )
nPos = nBytePos;
if( nOld == nNew )
return sal_True;
+
+ if (m_aPagesCache.empty() && nNew > ARBITRARY_LARGE_AMOUNT_OF_PAGES)
+ {
+ SAL_WARN("sot", "kicking off large seek helper\n");
+ buildPageChainCache();
+ }
+
+ if (!m_aPagesCache.empty())
+ {
+ size_t nIdx = nNew / nPageSize;
+
+#ifdef BRAVE_BUT_UN_NECESSARY
+ // special case: seek to 1st byte of new, unallocated page
+ // (in case the file size is a multiple of the page size)
+ if( nBytePos == nSize && !nOffset )
+ {
+ nIdx--;
+ nOffset = nPageSize;
+ }
+#endif
+
+ if (nIdx < m_aPagesCache.size())
+ {
+ nPage = m_aPagesCache[ nIdx ];
+// fprintf (stderr, "got page ! %d offset %d\n", (int)nPage, (int)nOffset);
+ return sal_Bool( nPage >= 0 );
+ }
+ }
+
if( nNew > nOld )
{
// the new position is after the current, so an incremental
@@ -420,62 +430,19 @@ sal_Bool StgStrm::Pos2Page( sal_Int32 nBytePos )
// now, traverse the FAT chain.
nRel /= nPageSize;
- sal_Int32 nLast = STG_EOF;
- if (m_aPagesCache.empty() && nRel < ARBITRARY_LARGE_AMOUNT_OF_PAGES)
- {
+ sal_Int32 nLast = STG_EOF;
while (nRel && nBgn >= 0)
{
nLast = nBgn;
nBgn = pFat->GetNextPage( nBgn );
nRel--;
}
- }
- else if (nBgn >= 0)
- {
- //Seeking large distances is slow, so if we're starting seeking (some
- //fairly arbitrary) large distances, build a cache and re-use it for
- //subsequent seeks
- if (m_aPagesCache.empty())
- {
- SAL_WARN("sot", "kicking off large seek helper\n");
- buildPageChainCache();
- }
-
- std::vector<sal_Int32>::iterator aI;
-
- if (m_bSortedPageChain)
- aI = std::lower_bound(m_aPagesCache.begin(), m_aPagesCache.end(), nBgn);
- else
- aI = std::find(m_aPagesCache.begin(), m_aPagesCache.end(), nBgn);
-
- if (aI == m_aPagesCache.end())
- {
- SAL_WARN("sot", "Unknown page position");
- nBgn = STG_EOF;
- }
- else
- {
- size_t nBgnDistance = std::distance(m_aPagesCache.begin(), aI);
-
- size_t nIndex = nBgnDistance + nRel;
-
- if (nIndex > m_aPagesCache.size())
- {
- nRel = m_aPagesCache.size() - nBgnDistance;
- nIndex = m_aPagesCache.size() - 1;
- }
- else
- nRel = 0;
-
- nLast = nIndex ? m_aPagesCache[nIndex - 1] : STG_EOF;
- nBgn = m_aPagesCache[nIndex];
- }
- }
// special case: seek to 1st byte of new, unallocated page
// (in case the file size is a multiple of the page size)
if( nBytePos == nSize && nBgn == STG_EOF && !nRel && !nOffset )
nBgn = nLast, nOffset = nPageSize;
+
if( nBgn < 0 && nBgn != STG_EOF )
{
rIo.SetError( SVSTREAM_FILEFORMAT_ERROR );
diff --git a/sot/source/sdstor/stgstrms.hxx b/sot/source/sdstor/stgstrms.hxx
index 3b5c263..125dc67 100644
--- a/sot/source/sdstor/stgstrms.hxx
+++ b/sot/source/sdstor/stgstrms.hxx
@@ -79,7 +79,6 @@ protected:
short nOffset; // offset into current page
short nPageSize; // logical page size
std::vector<sal_Int32> m_aPagesCache;
- bool m_bSortedPageChain;
bool buildPageChainCache();
sal_Bool Copy( sal_Int32 nFrom, sal_Int32 nBytes );
StgStrm( StgIo& );
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