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-rwxr-xr-xsrc/core/xbblockread.cpp279
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diff --git a/src/core/xbblockread.cpp b/src/core/xbblockread.cpp
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+/* xbblockread.cpp
+
+XBase64 Software Library
+
+Copyright (c) 1997,2003,2014,2022,2023 Gary A Kunkel
+
+The xb64 software library is covered under the terms of the GPL Version 3, 2007 license.
+
+Email Contact:
+
+ XDB-devel@lists.sourceforge.net
+ XDB-users@lists.sourceforge.net
+
+This module handles block read methods. Block reading is used for performance improvement
+during sequential access processing.
+
+*/
+
+#include "xbase.h"
+
+#ifdef XB_BLOCKREAD_SUPPORT
+
+namespace xb{
+
+/************************************************************************/
+xbBlockRead::xbBlockRead( xbDbf * d ) {
+ pBlock = NULL;
+ ulBlkSize = 0;
+ ulFirstBlkRec = 0;
+ ulRecCnt = 0;
+ ulMaxRecs = 0;
+ bEof = xbFalse;
+ this->dbf = d;
+ tFmTime = 0;
+}
+/************************************************************************/
+xbBlockRead::~xbBlockRead(){
+ if( pBlock ){
+ free( pBlock );
+ pBlock = NULL;
+ }
+}
+
+/************************************************************************/
+//! @brief Dump read block internals to stdout.
+/*!
+ Dump the current read block internals to stdout.
+*/
+
+
+#ifdef XB_DEBUG_SUPPORT
+void xbBlockRead::DumpReadBlockInternals(){
+
+ xbUInt32 ulRecCnt;
+ dbf->GetRecordCnt( ulRecCnt );
+
+ std::cout << "------- DumpBlockInternals ---------" << std::endl;
+ std::cout << "Dflt Blk Size = [" << dbf->GetXbasePtr()->GetDefaultBlockReadSize()
+ << "]" << std::endl;
+ std::cout << "Dbf Record Count = [" << ulRecCnt << "]" << std::endl;
+ std::cout << "Dbf Record Len = [" << dbf->GetRecordLen() << "]" << std::endl;
+ std::cout << "ulBlkSize = [" << ulBlkSize << "]" << std::endl;
+ std::cout << "ulMaxRecs = [" << ulMaxRecs << "]" << std::endl;
+ std::cout << "ulFirstBlkRec = [" << ulFirstBlkRec << "]" << std::endl;
+ std::cout << "ulRecCnt = [" << ulRecCnt << "]" << std::endl;
+ std::cout << "bEof = [" << bEof << "]" << std::endl;
+}
+#endif // XB_DEBUG_SUPPORT
+/************************************************************************/
+//! @brief Get the first record number in the current block.
+/*!
+ Retrieve the first record numer in the current block.<br>
+
+ \returns First record number in the current block.
+*/
+
+xbUInt32 xbBlockRead::GetBlockFirstRecNo() const{
+ return ulFirstBlkRec;
+}
+/************************************************************************/
+//! @brief Get record for specified record number.
+/*!
+ Retrieve a record from read block buffer and copy it into the record buffer.
+ If the current record is not in the current block, the routine calls
+ GetBlockForRecNo to load the currect block from disk.<br><br>
+ For performance reasons, this method assumes a valid record number has been
+ passed.<br><br>
+
+ \param ulRecNo - Record number to retrieve.
+ \returns <a href="xbretcod_8h.html">Return Codes</a>
+*/
+
+xbInt16 xbBlockRead::GetRecord( xbUInt32 ulRecNo ){
+ xbInt16 iRc = 0;
+ xbInt16 iErrorStop = 0;
+
+ // std::cout << "xbBlockRead::GetRecord( " << ulRecNo << ")\n";
+
+ try{
+ if( !( ulRecNo >= ulFirstBlkRec && ulRecNo < (ulFirstBlkRec + ulRecCnt))){
+ if(( iRc = GetBlockForRecNo( ulRecNo )) != XB_NO_ERROR ){
+ iErrorStop = 100;
+ throw iRc;
+ }
+ }
+ char *s = pBlock;
+ s += (ulRecNo - ulFirstBlkRec) * dbf->GetRecordLen();
+ char *t = dbf->RecBuf;
+ xbUInt32 ulRecLen = dbf->GetRecordLen();
+ for( xbUInt32 l = 0; l < ulRecLen; l++ ){
+ *t = *s;
+ t++;
+ s++;
+ }
+ dbf->ulCurRec = ulRecNo;
+ }
+ catch (xbInt16 iRc ){
+ xbString sMsg;
+ sMsg.Sprintf( "xbBlockRead::GetBlockForRecNo() Exception Caught. Error Stop = [%d] iRc = [%d]", iErrorStop, iRc );
+ dbf->GetXbasePtr()->WriteLogMessage( sMsg.Str() );
+ dbf->GetXbasePtr()->WriteLogMessage( dbf->GetXbasePtr()->GetErrorMessage( iRc ));
+ }
+ return iRc;
+}
+
+/************************************************************************/
+//! @brief Get record for specified record number.
+/*!
+ Retrieve a block containing specified record. This routine calculates the
+ correct block in the DBF file, updates the internal block fields and retrieves
+ the block of records from disk and loads into the block buffer.<br><br>
+
+ \param ulRecNo - Record number to retrieve.
+ \returns <a href="xbretcod_8h.html">Return Codes</a>
+*/
+
+xbInt16 xbBlockRead::GetBlockForRecNo( xbUInt32 ulRecNo ){
+
+ xbInt16 iRc = 0;
+ xbInt16 iErrorStop = 0;
+
+ try{
+ xbUInt32 ulDbfRecCnt;
+
+ if(( iRc = dbf->GetRecordCnt( ulDbfRecCnt )) != XB_NO_ERROR ){
+ iErrorStop = 100;
+ throw iRc;
+ }
+
+ // calc to determine block number for the requested record, 0 based offset
+ xbUInt32 ulBlockNo = (xbUInt32)(ulRecNo / ulMaxRecs);
+ if( ulRecNo % ulMaxRecs == 0 ) ulBlockNo--;
+
+ // calc the first record
+ ulFirstBlkRec = (ulBlockNo * ulMaxRecs);
+
+ // calc the record count
+ if(( ulFirstBlkRec + ulMaxRecs) > ulDbfRecCnt ){
+ ulRecCnt = ulDbfRecCnt - ulFirstBlkRec;
+ bEof = xbTrue;
+ } else {
+ ulRecCnt = ulMaxRecs;
+ bEof = xbFalse;
+ }
+
+ // position accordingly
+ xbInt64 ulStartPos = dbf->GetHeaderLen() + ((xbInt64) ulFirstBlkRec * dbf->GetRecordLen());
+ if(( dbf->xbFseek( ulStartPos, SEEK_SET )) != XB_NO_ERROR ){
+ iErrorStop = 110;
+ iRc = XB_SEEK_ERROR;
+ throw iRc;
+ }
+
+ if(( dbf->GetFileMtime( tFmTime )) != XB_NO_ERROR ){
+ iErrorStop = 120;
+ throw iRc;
+ }
+ // read it
+ if(( dbf->xbFread( (void *) pBlock, ulRecCnt * dbf->GetRecordLen(), 1 )) != XB_NO_ERROR ){
+ iErrorStop = 130;
+ throw iRc;
+ }
+
+ ulFirstBlkRec++; // zero offset in the routine, regular record number from ths point forward
+ }
+ catch (xbInt16 iRc ){
+ xbString sMsg;
+ sMsg.Sprintf( "xbBlockRead::GetBlockForRecNo() Exception Caught. Error Stop = [%d] iRc = [%d]", iErrorStop, iRc );
+ dbf->GetXbasePtr()->WriteLogMessage( sMsg.Str() );
+ dbf->GetXbasePtr()->WriteLogMessage( dbf->GetXbasePtr()->GetErrorMessage( iRc ));
+ }
+ return iRc;
+}
+
+/************************************************************************/
+//! @brief Get the current block size.
+/*!
+ Retrieve the current block size.<br><br>
+
+ \returns Current Block Size.
+*/
+
+xbUInt32 xbBlockRead::GetBlockSize() const{
+ return ulBlkSize;
+}
+
+/************************************************************************/
+//! @brief Get the current block record count.
+/*!
+ Retrieve the current number of records loaded in the block.<br><br>
+
+ \returns Current Block Size.
+*/
+
+xbUInt32 xbBlockRead::GetBlockRecCnt() const {
+ return ulRecCnt;
+}
+
+/************************************************************************/
+//! @brief Init the block processing for a iven DBF file.
+/*!
+ Initialize the settings for a given DBF file.<br>
+ This routine may adjust the block size as needed to eliminate unused
+ memory or adjust it bigger if too small.
+
+ \param ulRecNo - ulBlockSize - Block size to allocate. If 0 or missing, it uses default block size of 32K.
+ \returns <a href="xbretcod_8h.html">Return Codes</a>
+*/
+
+xbInt16 xbBlockRead::Init(xbUInt32 ulBlockSize ){
+
+ xbInt16 iRc = 0;
+ xbInt16 iErrorStop = 0;
+
+ try{
+
+ // calculate the block size
+ if( ulBlockSize == 0 )
+ ulBlkSize = dbf->GetXbasePtr()->GetDefaultBlockReadSize();
+
+ // if not big enough to handle more than one record, bump it up to something meaningful
+ if( ulBlkSize < (xbUInt32)(dbf->GetRecordLen() * 2 ))
+ ulBlkSize = (xbUInt32) dbf->GetRecordLen() * 10;
+
+ ulMaxRecs = (xbUInt32) ulBlkSize / dbf->GetRecordLen();
+ ulBlkSize = ulMaxRecs * dbf->GetRecordLen();
+
+ // allocate memory for the block
+ if(( pBlock = (char *) calloc( 1, ulBlkSize )) == NULL ){
+ iErrorStop = 100;
+ throw iRc;
+ }
+ }
+ catch (xbInt16 iRc ){
+ xbString sMsg;
+ sMsg.Sprintf( "xbBlockRead::Init() Exception Caught. Error Stop = [%d] iRc = [%d]", iErrorStop, iRc );
+ dbf->GetXbasePtr()->WriteLogMessage( sMsg.Str() );
+ dbf->GetXbasePtr()->WriteLogMessage( dbf->GetXbasePtr()->GetErrorMessage( iRc ));
+ }
+ return iRc;
+}
+
+/************************************************************************/
+//! @brief Set the block size.
+/*!
+ St block size for this DBF file.<br>.
+
+ \param ulBlkSize - Block Size.
+ \returns XB_NO_ERROR
+*/
+
+xbInt16 xbBlockRead::SetBlockSize( xbUInt32 ulBlkSize ){
+ this->ulBlkSize = ulBlkSize;
+ return XB_NO_ERROR;
+}
+
+/************************************************************************/
+} /* namespace */
+#endif /* XB_BLOCKREAD_SUPPORT */ \ No newline at end of file
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