/** * Also called by db/ops/query.cpp. This is the new getMore entry point. */ QueryResult* newGetMore(const char* ns, int ntoreturn, long long cursorid, CurOp& curop, int pass, bool& exhaust, bool* isCursorAuthorized) { exhaust = false; int bufSize = 512 + sizeof(QueryResult) + MaxBytesToReturnToClientAtOnce; BufBuilder bb(bufSize); bb.skip(sizeof(QueryResult)); // This is a read lock. TODO: There is a cursor flag for not needing this. Do we care? Client::ReadContext ctx(ns); // TODO: Document. replVerifyReadsOk(); ClientCursorPin ccPin(cursorid); ClientCursor* cc = ccPin.c(); // These are set in the QueryResult msg we return. int resultFlags = ResultFlag_AwaitCapable; int numResults = 0; int startingResult = 0; if (NULL == cc) { cursorid = 0; resultFlags = ResultFlag_CursorNotFound; } else { // Quote: check for spoofing of the ns such that it does not match the one originally // there for the cursor uassert(17011, "auth error", str::equals(ns, cc->ns().c_str())); *isCursorAuthorized = true; // TODO: fail point? // If the operation that spawned this cursor had a time limit set, apply leftover // time to this getmore. curop.setMaxTimeMicros(cc->getLeftoverMaxTimeMicros()); // TODO: // curop.debug().query = BSONForQuery // curop.setQuery(curop.debug().query); // TODO: What is pass? if (0 == pass) { cc->updateSlaveLocation(curop); } CollectionMetadataPtr collMetadata = cc->getCollMetadata(); // If we're replaying the oplog, we save the last time that we read. OpTime slaveReadTill; startingResult = cc->pos(); Runner* runner = cc->getRunner(); const ParsedQuery& pq = runner->getQuery().getParsed(); // Get results out of the runner. // TODO: There may be special handling required for tailable cursors? runner->restoreState(); BSONObj obj; // TODO: Differentiate EOF from error. while (runner->getNext(&obj)) { // If we're sharded make sure that we don't return any data that hasn't been // migrated off of our shard yet. if (collMetadata) { KeyPattern kp(collMetadata->getKeyPattern()); if (!collMetadata->keyBelongsToMe(kp.extractSingleKey(obj))) { continue; } } // Add result to output buffer. bb.appendBuf((void*)obj.objdata(), obj.objsize()); // Count the result. ++numResults; // Possibly note slave's position in the oplog. if (pq.hasOption(QueryOption_OplogReplay)) { BSONElement e = obj["ts"]; if (Date == e.type() || Timestamp == e.type()) { slaveReadTill = e._opTime(); } } if ((numResults && numResults >= ntoreturn) || bb.len() > MaxBytesToReturnToClientAtOnce) { break; } } cc->incPos(numResults); runner->saveState(); // Possibly note slave's position in the oplog. if (pq.hasOption(QueryOption_OplogReplay) && !slaveReadTill.isNull()) { cc->slaveReadTill(slaveReadTill); } exhaust = pq.hasOption(QueryOption_Exhaust); // If the getmore had a time limit, remaining time is "rolled over" back to the // cursor (for use by future getmore ops). cc->setLeftoverMaxTimeMicros( curop.getRemainingMaxTimeMicros() ); } QueryResult* qr = reinterpret_cast<QueryResult*>(bb.buf()); qr->len = bb.len(); qr->setOperation(opReply); qr->_resultFlags() = resultFlags; qr->cursorId = cursorid; qr->startingFrom = startingResult; qr->nReturned = numResults; bb.decouple(); return qr; }