static void resetLogBuffer(/*out*/JSectHeader& h, AlignedBuilder& bb) {
bb.reset();
h.setSectionLen(0xffffffff); // total length, will fill in later
h.seqNumber = getLastDataFileFlushTime();
h.fileId = j.curFileId();
}
/** caller handles locking */
static bool PREPLOGBUFFER(AlignedBuilder& bb) {
bb.reset();
unsigned *lenInBlockHeader;
{
// JSectHeader
bb.appendStr("\nHH\n", false);
lenInBlockHeader = (unsigned *) bb.skip(4);
}
string lastFilePath;
{
scoped_lock lk(privateViews._mutex());
for( vector<WriteIntent>::iterator i = wi._writes.begin(); i != wi._writes.end(); i++ ) {
size_t ofs;
MongoMMF *mmf = privateViews._find(i->p, ofs);
if( mmf == 0 ) {
journalingFailure("view pointer cannot be resolved");
}
else {
if( !mmf->dirty() )
mmf->dirty() = true; // usually it will already be dirty so don't bother writing then
{
size_t ofs = ((char *)i->p) - ((char*)mmf->getView().p);
i->w_ptr = ((char*)mmf->view_write()) + ofs;
}
if( mmf->filePath() != lastFilePath ) {
lastFilePath = mmf->filePath();
JDbContext c;
bb.appendStruct(c);
bb.appendStr(lastFilePath);
}
JEntry e;
e.len = i->len;
e.fileNo = mmf->fileSuffixNo();
bb.appendStruct(e);
bb.appendBuf(i->p, i->len);
}
}
}
{
JSectFooter f;
f.hash = 0;
bb.appendStruct(f);
}
{
unsigned L = (bb.len() + 8191) & 0xffffe000; // fill to alignment
dassert( L >= (unsigned) bb.len() );
*lenInBlockHeader = L;
unsigned padding = L - bb.len();
bb.skip(padding);
dassert( bb.len() % 8192 == 0 );
}
return true;
}