/** called during recovery (the error message text below assumes that)
*/
unsigned long long journalReadLSN() {
if( !debug ) {
// in nondebug build, for now, be conservative until more tests written, and apply the whole journal.
// however we will still write the lsn file to exercise that code, and use in _DEBUG build.
return 0;
}
if( !MemoryMappedFile::exists(lsnPath()) ) {
log() << "info no lsn file in journal/ directory" << endl;
return 0;
}
try {
// os can flush as it likes. if it flushes slowly, we will just do extra work on recovery.
// however, given we actually close the file when writing, that seems unlikely.
LSNFile L;
File f;
f.open(lsnPath().string().c_str());
assert(f.is_open());
f.read(0,(char*)&L, sizeof(L));
unsigned long long lsn = L.get();
return lsn;
}
catch(std::exception& e) {
uasserted(13611, str::stream() << "can't read lsn file in journal directory : " << e.what());
}
return 0;
}
/** called during recovery (the error message text below assumes that)
*/
unsigned long long journalReadLSN() {
if( !exists(lsnPath()) ) {
log() << "info no lsn file in journal/ directory" << endl;
return 0;
}
try {
// os can flush as it likes. if it flushes slowly, we will just do extra work on recovery.
// however, given we actually close the file when writing, that seems unlikely.
LSNFile L;
File f;
f.open(lsnPath().string().c_str());
assert(f.is_open());
if( f.len() == 0 ) {
// this could be 'normal' if we crashed at the right moment
log() << "info lsn file is zero bytes long" << endl;
return 0;
}
f.read(0,(char*)&L, sizeof(L));
unsigned long long lsn = L.get();
return lsn;
}
catch(std::exception& e) {
uasserted(13611, str::stream() << "can't read lsn file in journal directory : " << e.what());
}
return 0;
}
