/** apply the writes back to the non-private MMF after they are for certain in redo log
(1) todo we don't need to write back everything every group commit. we MUST write back
that which is going to be a remapped on its private view - but that might not be all
views.
(2) todo should we do this using N threads? would be quite easy
see Hackenberg paper table 5 and 6. 2 threads might be a good balance.
locking: in read lock when called
*/
static void WRITETODATAFILES() {
/* we go backwards as what is at the end is most likely in the cpu cache. it won't be much, but we'll take it. */
for( int i = commitJob.writes().size() - 1; i >= 0; i-- ) {
const WriteIntent& intent = commitJob.writes()[i];
char *dst = (char *) (intent.w_ptr);
memcpy(dst, intent.p, intent.len);
}
debugValidateMapsMatch();
}
/** (SLOW) diagnostic to check that the private view and the non-private view are in sync.
*/
static void debugValidateMapsMatch() {
if( !DebugValidateMapsMatch )
return;
Timer t;
set<MongoFile*>& files = MongoFile::getAllFiles();
for( set<MongoFile*>::iterator i = files.begin(); i != files.end(); i++ ) {
MongoFile *mf = *i;
if( mf->isMongoMMF() ) {
MongoMMF *mmf = (MongoMMF*) mf;
const char *p = (const char *) mmf->getView();
const char *w = (const char *) mmf->view_write();
unsigned low = 0xffffffff;
unsigned high = 0;
for( unsigned i = 0; i < mmf->length(); i++ ) {
if( p[i] != w[i] ) {
log() << i << '\t' << (int) p[i] << '\t' << (int) w[i] << endl;
if( i < low ) low = i;
if( i > high ) high = i;
}
}
if( low != 0xffffffff ) {
std::stringstream ss;
ss << "dur error warning views mismatch " << mmf->filename() << ' ' << (hex) << low << ".." << high << " len:" << high-low+1;
log() << ss.str() << endl;
log() << "priv loc: " << (void*)(p+low) << endl;
vector<WriteIntent>& w = commitJob.writes();
(void)w; // mark as unused. Useful for inspection in debugger
breakpoint();
}
}
}
log() << "debugValidateMapsMatch " << t.millis() << "ms " << endl;
}
void DurableImpl::debugCheckLastDeclaredWrite() {
if( !DebugCheckLastDeclaredWrite )
return;
if( testIntent )
return;
static int n;
++n;
assert(debug && cmdLine.dur);
vector<WriteIntent>& w = commitJob.writes();
if( w.size() == 0 )
return;
const WriteIntent &i = w[w.size()-1];
size_t ofs;
MongoMMF *mmf = privateViews.find(i.p, ofs);
if( mmf == 0 )
return;
size_t past = ofs + i.len;
if( mmf->length() < past + 8 )
return; // too close to end of view
char *priv = (char *) mmf->getView();
char *writ = (char *) mmf->view_write();
unsigned long long *a = (unsigned long long *) (priv+past);
unsigned long long *b = (unsigned long long *) (writ+past);
if( *a != *b ) {
for( unsigned z = 0; z < w.size() - 1; z++ ) {
const WriteIntent& wi = w[z];
char *r1 = (char*) wi.p;
char *r2 = r1 + wi.len;
if( r1 <= (((char*)a)+8) && r2 > (char*)a ) {
//log() << "it's ok " << wi.p << ' ' << wi.len << endl;
return;
}
}
log() << "dur data after write area " << i.p << " does not agree" << endl;
log() << " was: " << ((void*)b) << " " << hexdump((char*)b, 8) << endl;
log() << " now: " << ((void*)a) << " " << hexdump((char*)a, 8) << endl;
log() << " n: " << n << endl;
log() << endl;
}
}
/** we will build an output buffer ourself and then use O_DIRECT
we could be in read lock for this
caller handles locking
*/
static void PREPLOGBUFFER() {
assert( cmdLine.dur );
AlignedBuilder& bb = commitJob._ab;
bb.reset();
unsigned lenOfs;
// JSectHeader
{
bb.appendStr("\nHH\n", false);
lenOfs = bb.skip(4);
}
// ops other than basic writes
{
for( vector< shared_ptr<DurOp> >::iterator i = commitJob.ops().begin(); i != commitJob.ops().end(); ++i ) {
(*i)->serialize(bb);
}
}
// write intents
{
scoped_lock lk(privateViews._mutex());
string lastFilePath;
for( vector<WriteIntent>::iterator i = commitJob.writes().begin(); i != commitJob.writes().end(); i++ ) {
size_t ofs;
MongoMMF *mmf = privateViews._find(i->p, ofs);
if( mmf == 0 ) {
string s = str::stream() << "view pointer cannot be resolved " << (size_t) i->p;
journalingFailure(s.c_str()); // asserts
return;
}
if( !mmf->willNeedRemap() ) {
mmf->willNeedRemap() = 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;
assert( ofs <= 0x80000000 );
e.ofs = (unsigned) ofs;
e.fileNo = mmf->fileSuffixNo();
bb.appendStruct(e);
bb.appendBuf(i->p, i->len);
}
}
{
JSectFooter f(bb.buf(), bb.len());
bb.appendStruct(f);
}
{
assert( 0xffffe000 == (~(Alignment-1)) );
unsigned L = (bb.len() + Alignment-1) & (~(Alignment-1)); // fill to alignment
dassert( L >= (unsigned) bb.len() );
*((unsigned*)bb.atOfs(lenOfs)) = L;
unsigned padding = L - bb.len();
bb.skip(padding);
dassert( bb.len() % Alignment == 0 );
}
return;
}
