/**
* Run a query with a cursor provided by the query optimizer, or FindingStartCursor.
* @yields the db lock.
*/
const char *queryWithQueryOptimizer( Message &m, int queryOptions, const char *ns,
const BSONObj &jsobj, CurOp& curop,
const BSONObj &query, const BSONObj &order,
const shared_ptr<ParsedQuery> &pq_shared,
const BSONObj &oldPlan,
const ConfigVersion &shardingVersionAtStart,
Message &result ) {
const ParsedQuery &pq( *pq_shared );
shared_ptr<Cursor> cursor;
QueryPlan::Summary queryPlan;
if ( pq.hasOption( QueryOption_OplogReplay ) ) {
cursor = FindingStartCursor::getCursor( ns, query, order );
}
else {
cursor =
NamespaceDetailsTransient::getCursor( ns, query, order, QueryPlanSelectionPolicy::any(),
0, &pq, &queryPlan );
}
verify( 16081, cursor );
QueryResponseBuilder queryResponseBuilder( pq, cursor, queryPlan, oldPlan );
bool saveClientCursor = false;
const char *exhaust = 0;
OpTime slaveReadTill;
ClientCursor::CleanupPointer ccPointer;
ccPointer.reset( new ClientCursor( QueryOption_NoCursorTimeout, cursor, ns ) );
for( ; cursor->ok(); cursor->advance() ) {
bool yielded = false;
if ( !ccPointer->yieldSometimes( ClientCursor::MaybeCovered, &yielded ) ||
!cursor->ok() ) {
cursor.reset();
queryResponseBuilder.noteYield();
// !!! TODO The queryResponseBuilder still holds cursor. Currently it will not do
// anything unsafe with the cursor in handoff(), but this is very fragile.
break;
}
if ( yielded ) {
queryResponseBuilder.noteYield();
}
if ( pq.getMaxScan() && cursor->nscanned() > pq.getMaxScan() ) {
break;
}
if ( !queryResponseBuilder.addMatch() ) {
continue;
}
// Note slave's position in the oplog.
if ( pq.hasOption( QueryOption_OplogReplay ) ) {
BSONObj current = cursor->current();
BSONElement e = current["ts"];
if ( e.type() == Date || e.type() == Timestamp ) {
slaveReadTill = e._opTime();
}
}
if ( !cursor->supportGetMore() || pq.isExplain() ) {
if ( queryResponseBuilder.enoughTotalResults() ) {
break;
}
}
else if ( queryResponseBuilder.enoughForFirstBatch() ) {
// if only 1 requested, no cursor saved for efficiency...we assume it is findOne()
if ( pq.wantMore() && pq.getNumToReturn() != 1 ) {
queryResponseBuilder.finishedFirstBatch();
if ( cursor->advance() ) {
saveClientCursor = true;
}
}
break;
}
}
if ( cursor ) {
if ( pq.hasOption( QueryOption_CursorTailable ) && pq.getNumToReturn() != 1 ) {
cursor->setTailable();
}
// If the tailing request succeeded.
if ( cursor->tailable() ) {
saveClientCursor = true;
}
}
if ( shardingState.getVersion( ns ) != shardingVersionAtStart ) {
// if the version changed during the query
// we might be missing some data
// and its safe to send this as mongos can resend
// at this point
throw SendStaleConfigException( ns , "version changed during initial query", shardingVersionAtStart, shardingState.getVersion( ns ) );
}
long long nReturned = queryResponseBuilder.handoff( result );
ccPointer.reset();
long long cursorid = 0;
if ( saveClientCursor ) {
// Create a new ClientCursor, with a default timeout.
ccPointer.reset( new ClientCursor( queryOptions, cursor, ns,
jsobj.getOwned() ) );
cursorid = ccPointer->cursorid();
DEV tlog(2) << "query has more, cursorid: " << cursorid << endl;
if ( cursor->supportYields() ) {
ClientCursor::YieldData data;
ccPointer->prepareToYield( data );
}
else {
ccPointer->updateLocation();
}
// !!! Save the original message buffer, so it can be referenced in getMore.
ccPointer->originalMessage = m;
// Save slave's position in the oplog.
if ( pq.hasOption( QueryOption_OplogReplay ) && !slaveReadTill.isNull() ) {
ccPointer->slaveReadTill( slaveReadTill );
}
if ( !ccPointer->ok() && ccPointer->c()->tailable() ) {
DEV tlog() << "query has no more but tailable, cursorid: " << cursorid << endl;
}
if( queryOptions & QueryOption_Exhaust ) {
exhaust = ns;
curop.debug().exhaust = true;
}
// Set attributes for getMore.
ccPointer->setChunkManager( queryResponseBuilder.chunkManager() );
ccPointer->setPos( nReturned );
ccPointer->pq = pq_shared;
ccPointer->fields = pq.getFieldPtr();
ccPointer.release();
}
QueryResult *qr = (QueryResult *) result.header();
qr->cursorId = cursorid;
curop.debug().cursorid = ( cursorid == 0 ? -1 : qr->cursorId );
qr->setResultFlagsToOk();
// qr->len is updated automatically by appendData()
curop.debug().responseLength = qr->len;
qr->setOperation(opReply);
qr->startingFrom = 0;
qr->nReturned = nReturned;
int duration = curop.elapsedMillis();
bool dbprofile = curop.shouldDBProfile( duration );
if ( dbprofile || duration >= cmdLine.slowMS ) {
curop.debug().nscanned = (int)( cursor ? cursor->nscanned() : 0 );
curop.debug().ntoskip = pq.getSkip();
}
curop.debug().nreturned = nReturned;
return exhaust;
}
