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4GB clean the offsets in parallel IO for multifile records

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This commit is contained in:
Peter Boyle
2018-03-16 21:54:56 +00:00
parent 01568b0e62
commit 888838473a
3 changed files with 53 additions and 38 deletions
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47
lib/parallelIO/IldgIO.h
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@ -337,6 +337,20 @@ class GridLimeWriter : public BinaryIO {
template<class vobj>
void writeLimeLatticeBinaryObject(Lattice<vobj> &field,std::string record_name)
{
////////////////////////////////////////////////////////////////////
// NB: FILE and iostream are jointly writing disjoint sequences in the
// the same file through different file handles (integer units).
//
// These are both buffered, so why I think this code is right is as follows.
//
// i) write record header to FILE *File, telegraphing the size; flush
// ii) ftello reads the offset from FILE *File .
// iii) iostream / MPI Open independently seek this offset. Write sequence direct to disk.
// Closes iostream and flushes.
// iv) fseek on FILE * to end of this disjoint section.
// v) Continue writing scidac record.
////////////////////////////////////////////////////////////////////
////////////////////////////////////////////
// Create record header
////////////////////////////////////////////
@ -350,25 +364,24 @@ class GridLimeWriter : public BinaryIO {
// std::cout << "W Gsites " <<field._grid->_gsites<<std::endl;
// std::cout << "W Payload expected " <<PayloadSize<<std::endl;
////////////////////////////////////////////////////////////////////
// NB: FILE and iostream are jointly writing disjoint sequences in the
// the same file through different file handles (integer units).
//
// These are both buffered, so why I think this code is right is as follows.
//
// i) write record header to FILE *File, telegraphing the size.
// ii) ftello reads the offset from FILE *File .
// iii) iostream / MPI Open independently seek this offset. Write sequence direct to disk.
// Closes iostream and flushes.
// iv) fseek on FILE * to end of this disjoint section.
// v) Continue writing scidac record.
////////////////////////////////////////////////////////////////////
uint64_t offset = ftello(File);
// std::cout << " Writing to offset "<<offset << std::endl;
fflush(File);
///////////////////////////////////////////
// Write by other means into the binary record
///////////////////////////////////////////
uint64_t offset1 = ftello(File); // std::cout << " Writing to offset "<<offset1 << std::endl;
std::string format = getFormatString<vobj>();
BinarySimpleMunger<sobj,sobj> munge;
BinaryIO::writeLatticeObject<vobj,sobj>(field, filename, munge, offset, format,nersc_csum,scidac_csuma,scidac_csumb);
// fseek(File,0,SEEK_END); offset = ftello(File);std::cout << " offset now "<<offset << std::endl;
BinaryIO::writeLatticeObject<vobj,sobj>(field, filename, munge, offset1, format,nersc_csum,scidac_csuma,scidac_csumb);
///////////////////////////////////////////
// Wind forward and close the record
///////////////////////////////////////////
fseek(File,0,SEEK_END);
unt64_t offset2 = ftello(File); // std::cout << " now at offset "<<offset2 << std::endl;
assert((offset2-offset1) == PayloadSize);
err=limeWriterCloseRecord(LimeW); assert(err>=0);
////////////////////////////////////////