[PATCH] Related: fdo#47644 for huge files build a page chain cache for seeks
Caolán McNamara
caolanm at redhat.com
Thu May 10 07:43:47 PDT 2012
For huge ole2 structured storage files build a page chain cache on
demand to speed up long distance seeks
i.e. reduces .doc parse time for fdo#47644 from 1 minute 7 seconds to 18
seconds for me
---
sot/source/sdstor/stgstrms.cxx | 133 +++++++++++++++++++++++++++++++++++-----
sot/source/sdstor/stgstrms.hxx | 4 +
2 files changed, 121 insertions(+), 16 deletions(-)
diff --git a/sot/source/sdstor/stgstrms.cxx b/sot/source/sdstor/stgstrms.cxx
index 5e6c1ea..e982837 100644
--- a/sot/source/sdstor/stgstrms.cxx
+++ b/sot/source/sdstor/stgstrms.cxx
@@ -26,9 +26,10 @@
*
************************************************************************/
+#include <algorithm>
#include <string.h> // memcpy()
-
+#include <sal/log.hxx>
#include <osl/file.hxx>
#include <tools/tempfile.hxx>
#include <tools/debug.hxx>
@@ -334,6 +335,56 @@ 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
+}
+
+bool StgStrm::buildPageChainCache()
+{
+ if (nSize > 0)
+ m_aPagesCache.reserve(nSize/nPageSize);
+
+ sal_Int32 nBgn = nStart;
+ while (nBgn >= 0)
+ {
+ m_aPagesCache.push_back(nBgn);
+ sal_Int32 nOldBgn = nBgn;
+ nBgn = pFat->GetNextPage(nBgn);
+ if (nBgn == nOldBgn)
+ 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;
+}
+
+//See fdo#47644 for a .doc with a vast amount of pages where seeking around the
+//document takes a colossal amount of time
+//
+//There's a cost to building a page cache, so only build one if the number of
+//pages to seek through hits some sufficiently high value where it's worth it.
+#define ARBITRARY_LARGE_AMOUNT_OF_PAGES 256
+
// Compute page number and offset for the given byte position.
// If the position is behind the size, set the stream right
// behind the EOF.
@@ -355,7 +406,7 @@ sal_Bool StgStrm::Pos2Page( sal_Int32 nBytePos )
return sal_True;
if( nNew > nOld )
{
- // the new position is behind the current, so an incremental
+ // the new position is after the current, so an incremental
// positioning is OK. Set the page relative position
nRel = nNew - nOld;
nBgn = nPage;
@@ -369,13 +420,59 @@ sal_Bool StgStrm::Pos2Page( sal_Int32 nBytePos )
}
// now, traverse the FAT chain.
nRel /= nPageSize;
+
sal_Int32 nLast = STG_EOF;
- while( nRel && nBgn >= 0 )
+ if (m_aPagesCache.empty() && nRel < ARBITRARY_LARGE_AMOUNT_OF_PAGES)
+ {
+ while (nRel && nBgn >= 0)
+ {
+ nLast = nBgn;
+ nBgn = pFat->GetNextPage( nBgn );
+ nRel--;
+ }
+ }
+ else if (nBgn >= 0)
{
- nLast = nBgn;
- nBgn = pFat->GetNextPage( nBgn );
- nRel--;
+ //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_INFO("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 )
@@ -404,6 +501,8 @@ StgPage* StgStrm::GetPhysPage( sal_Int32 nBytePos, sal_Bool bForce )
sal_Bool StgStrm::Copy( sal_Int32 nFrom, sal_Int32 nBytes )
{
+ m_aPagesCache.clear();
+
sal_Int32 nTo = nStart;
sal_Int32 nPgs = ( nBytes + nPageSize - 1 ) / nPageSize;
while( nPgs-- )
@@ -430,6 +529,8 @@ sal_Bool StgStrm::Copy( sal_Int32 nFrom, sal_Int32 nBytes )
sal_Bool StgStrm::SetSize( sal_Int32 nBytes )
{
+ m_aPagesCache.clear();
+
// round up to page size
sal_Int32 nOld = ( ( nSize + nPageSize - 1 ) / nPageSize ) * nPageSize;
sal_Int32 nNew = ( ( nBytes + nPageSize - 1 ) / nPageSize ) * nPageSize;
@@ -528,6 +629,8 @@ sal_Int32 StgFATStrm::GetPage( short nOff, sal_Bool bMake, sal_uInt16 *pnMasterA
{
if( bMake )
{
+ m_aPagesCache.clear();
+
// create a new master page
nFAT = nMaxPage++;
pMaster = rIo.Copy( nFAT, STG_FREE );
@@ -582,6 +685,8 @@ sal_Int32 StgFATStrm::GetPage( short nOff, sal_Bool bMake, sal_uInt16 *pnMasterA
sal_Bool StgFATStrm::SetPage( short nOff, sal_Int32 nNewPage )
{
+ m_aPagesCache.clear();
+
sal_Bool bRes = sal_True;
if( nOff < rIo.aHdr.GetFAT1Size() )
rIo.aHdr.SetFATPage( nOff, nNewPage );
@@ -631,6 +736,8 @@ sal_Bool StgFATStrm::SetPage( short nOff, sal_Int32 nNewPage )
sal_Bool StgFATStrm::SetSize( sal_Int32 nBytes )
{
+ m_aPagesCache.clear();
+
// Set the number of entries to a multiple of the page size
short nOld = (short) ( ( nSize + ( nPageSize - 1 ) ) / nPageSize );
short nNew = (short) (
@@ -747,16 +854,10 @@ void StgDataStrm::Init( sal_Int32 nBgn, sal_Int32 nLen )
{
// determine the actual size of the stream by scanning
// the FAT chain and counting the # of pages allocated
- nSize = 0;
- sal_Int32 nOldBgn = -1;
- while( nBgn >= 0 && nBgn != nOldBgn )
- {
- nOldBgn = nBgn;
- nBgn = pFat->GetNextPage( nBgn );
- if( nBgn == nOldBgn )
- rIo.SetError( ERRCODE_IO_WRONGFORMAT );
- nSize += nPageSize;
- }
+ bool bOk = buildPageChainCache();
+ if (!bOk)
+ rIo.SetError( ERRCODE_IO_WRONGFORMAT );
+ nSize = m_aPagesCache.size() * nPageSize;
}
}
diff --git a/sot/source/sdstor/stgstrms.hxx b/sot/source/sdstor/stgstrms.hxx
index a6a0ad1..cfae9e2 100644
--- a/sot/source/sdstor/stgstrms.hxx
+++ b/sot/source/sdstor/stgstrms.hxx
@@ -30,6 +30,7 @@
#define _STGSTRMS_HXX
#include <tools/stream.hxx>
+#include <vector>
class StgIo;
class StgStrm;
@@ -77,6 +78,9 @@ protected:
sal_Int32 nPage; // current logical page
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& );
public:
--
1.7.7.6
--=-r6tz3jYvke2/iB3cGwd0--
More information about the LibreOffice
mailing list