C++ QueryResult::setResultFlagsToOk方法代码示例

//.........这里部分代码省略.........
        }

        // Append explain information to query results by asking the runner to produce them.
        if (isExplain) {
            TypeExplain* bareExplain;
            Status res = runner->getExplainPlan(&bareExplain);

            if (!res.isOK()) {
                error() << "could not produce explain of query '" << pq.getFilter()
                        << "', error: " << res.reason();
                // If numResults and the data in bb don't correspond, we'll crash later when rooting
                // through the reply msg.
                BSONObj emptyObj;
                bb.appendBuf((void*)emptyObj.objdata(), emptyObj.objsize());
                // The explain output is actually a result.
                numResults = 1;
                // TODO: we can fill out millis etc. here just fine even if the plan screwed up.
            }
            else {
                boost::scoped_ptr<TypeExplain> explain(bareExplain);

                // Fill in the missing run-time fields in explain, starting with propeties of
                // the process running the query.
                std::string server = mongoutils::str::stream()
                    << getHostNameCached() << ":" << serverGlobalParams.port;
                explain->setServer(server);

                // We might have skipped some results due to chunk migration etc. so our count is
                // correct.
                explain->setN(numResults);

                // Clock the whole operation.
                explain->setMillis(curop.elapsedMillis());

                BSONObj explainObj = explain->toBSON();
                bb.appendBuf((void*)explainObj.objdata(), explainObj.objsize());

                // The explain output is actually a result.
                numResults = 1;
            }
        }

        long long ccId = 0;
        if (saveClientCursor) {
            // We won't use the runner until it's getMore'd.
            runner->saveState();

            // Allocate a new ClientCursor.  We don't have to worry about leaking it as it's
            // inserted into a global map by its ctor.
            ClientCursor* cc = new ClientCursor(runner.get(), cq->getParsed().getOptions(),
                                                cq->getParsed().getFilter());
            ccId = cc->cursorid();

            QLOG() << "caching runner with cursorid " << ccId
                   << " after returning " << numResults << " results" << endl;

            // ClientCursor takes ownership of runner.  Release to make sure it's not deleted.
            runner.release();

            // TODO document
            if (pq.hasOption(QueryOption_OplogReplay) && !slaveReadTill.isNull()) {
                cc->slaveReadTill(slaveReadTill);
            }

            // TODO document
            if (pq.hasOption(QueryOption_Exhaust)) {
                curop.debug().exhaust = true;
            }

            // Set attributes for getMore.
            cc->setCollMetadata(collMetadata);
            cc->setPos(numResults);

            // If the query had a time limit, remaining time is "rolled over" to the cursor (for
            // use by future getmore ops).
            cc->setLeftoverMaxTimeMicros(curop.getRemainingMaxTimeMicros());
        }
        else {
            QLOG() << "not caching runner but returning " << numResults << " results\n";
        }

        // Add the results from the query into the output buffer.
        result.appendData(bb.buf(), bb.len());
        bb.decouple();

        // Fill out the output buffer's header.
        QueryResult* qr = static_cast<QueryResult*>(result.header());
        qr->cursorId = ccId;
        curop.debug().cursorid = (0 == ccId ? -1 : ccId);
        qr->setResultFlagsToOk();
        qr->setOperation(opReply);
        qr->startingFrom = 0;
        qr->nReturned = numResults;

        curop.debug().ntoskip = pq.getSkip();
        curop.debug().nreturned = numResults;

        // curop.debug().exhaust is set above.
        return curop.debug().exhaust ? pq.ns() : "";
    }

//.........这里部分代码省略.........
            // of CanonicalQuery. :(
            const bool supportsGetMore = true;
            const bool isExplain = pq.isExplain();
            if (isExplain && enoughForExplain(pq, numResults)) {
                break;
            }
            else if (!supportsGetMore && (enough(pq, numResults)
                                          || bb.len() >= MaxBytesToReturnToClientAtOnce)) {
                break;
            }
            else if (enoughForFirstBatch(pq, numResults, bb.len())) {
                // If only one result requested assume it's a findOne() and don't save the cursor.
                if (pq.wantMore() && 1 != pq.getNumToReturn()) {
                    saveClientCursor = true;
                }
                break;
            }
        }

        // If we cache the runner later, we want to deregister it as it receives notifications
        // anyway by virtue of being cached.
        //
        // If we don't cache the runner later, we are deleting it, so it must be deregistered.
        //
        // So, no matter what, deregister the runner.
        ClientCursor::deregisterRunner(runner.get());

        // Why save a dead runner?
        if (Runner::RUNNER_DEAD == state) { saveClientCursor = false; }

        // TODO: Stage creation can set tailable depending on what's in the parsed query.  We have
        // the full parsed query available during planning...set it there.
        //
        // TODO: If we're tailable we want to save the client cursor.  Make sure we do this later.
        //if (pq.hasOption(QueryOption_CursorTailable) && pq.getNumToReturn() != 1) { ... }

        // TODO(greg): This will go away soon.
        if (!shardingState.getVersion(pq.ns()).isWriteCompatibleWith(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(pq.ns(), "version changed during initial query",
                                           shardingVersionAtStart,
                                           shardingState.getVersion(pq.ns()));
        }

        long long ccId = 0;
        if (saveClientCursor) {
            // We won't use the runner until it's getMore'd.
            runner->saveState();

            // Allocate a new ClientCursor.  We don't have to worry about leaking it as it's
            // inserted into a global map by its ctor.
            ClientCursor* cc = new ClientCursor(runner.get(), cq->getParsed().getOptions(),
                                                cq->getParsed().getFilter());
            ccId = cc->cursorid();

            log() << "caching runner with cursorid " << ccId << endl;

            // ClientCursor takes ownership of runner.  Release to make sure it's not deleted.
            runner.release();

            // TODO document
            if (pq.hasOption(QueryOption_OplogReplay) && !slaveReadTill.isNull()) {
                cc->slaveReadTill(slaveReadTill);
            }

            // TODO document
            if (pq.hasOption(QueryOption_Exhaust)) {
                curop.debug().exhaust = true;
            }

            // Set attributes for getMore.
            cc->setCollMetadata(collMetadata);
            cc->setPos(numResults);

            // If the query had a time limit, remaining time is "rolled over" to the cursor (for
            // use by future getmore ops).
            cc->setLeftoverMaxTimeMicros(curop.getRemainingMaxTimeMicros());
        }

        // Add the results from the query into the output buffer.
        result.appendData(bb.buf(), bb.len());
        bb.decouple();

        // Fill out the output buffer's header.
        QueryResult* qr = static_cast<QueryResult*>(result.header());
        qr->cursorId = ccId;
        curop.debug().cursorid = (0 == ccId ? -1 : ccId);
        qr->setResultFlagsToOk();
        qr->setOperation(opReply);
        qr->startingFrom = 0;
        qr->nReturned = numResults;
        // TODO: nscanned is bogus.
        // curop.debug().nscanned = ( cursor ? cursor->nscanned() : 0LL );
        curop.debug().ntoskip = pq.getSkip();
        curop.debug().nreturned = numResults;

        // curop.debug().exhaust is set above.
        return curop.debug().exhaust ? pq.ns() : "";
    }

    std::string newRunQuery(Message& m, QueryMessage& q, CurOp& curop, Message &result) {
        // Validate the namespace.
        const char *ns = q.ns;
        uassert(16332, "can't have an empty ns", ns[0]);

        const NamespaceString nsString(ns);
        uassert(16256, str::stream() << "Invalid ns [" << ns << "]", nsString.isValid());

        // Set curop information.
        curop.debug().ns = ns;
        curop.debug().ntoreturn = q.ntoreturn;
        curop.debug().query = q.query;
        curop.setQuery(q.query);

        // If the query is really a command, run it.
        if (nsString.isCommand()) {
            int nToReturn = q.ntoreturn;
            uassert(16979, str::stream() << "bad numberToReturn (" << nToReturn
                                         << ") for $cmd type ns - can only be 1 or -1",
                    nToReturn == 1 || nToReturn == -1);

            curop.markCommand();

            BufBuilder bb;
            bb.skip(sizeof(QueryResult));

            BSONObjBuilder cmdResBuf;
            if (!runCommands(ns, q.query, curop, bb, cmdResBuf, false, q.queryOptions)) {
                uasserted(13530, "bad or malformed command request?");
            }

            curop.debug().iscommand = true;
            // TODO: Does this get overwritten/do we really need to set this twice?
            curop.debug().query = q.query;

            QueryResult* qr = reinterpret_cast<QueryResult*>(bb.buf());
            bb.decouple();
            qr->setResultFlagsToOk();
            qr->len = bb.len();
            curop.debug().responseLength = bb.len();
            qr->setOperation(opReply);
            qr->cursorId = 0;
            qr->startingFrom = 0;
            qr->nReturned = 1;
            result.setData(qr, true);
            return "";
        }

        // This is a read lock.  We require this because if we're parsing a $where, the
        // where-specific parsing code assumes we have a lock and creates execution machinery that
        // requires it.
        Client::ReadContext ctx(q.ns);
        Collection* collection = ctx.ctx().db()->getCollection( ns );

        // Parse the qm into a CanonicalQuery.
        CanonicalQuery* cq;
        Status canonStatus = CanonicalQuery::canonicalize(q, &cq);
        if (!canonStatus.isOK()) {
            uasserted(17287, str::stream() << "Can't canonicalize query: " << canonStatus.toString());
        }
        verify(cq);

        QLOG() << "Running query:\n" << cq->toString();
        LOG(2) << "Running query: " << cq->toStringShort();

        // Parse, canonicalize, plan, transcribe, and get a runner.
        Runner* rawRunner = NULL;

        // We use this a lot below.
        const LiteParsedQuery& pq = cq->getParsed();

        // We'll now try to get the query runner that will execute this query for us. There
        // are a few cases in which we know upfront which runner we should get and, therefore,
        // we shortcut the selection process here.
        //
        // (a) If the query is over a collection that doesn't exist, we get a special runner
        // that's is so (a runner) which doesn't return results, the EOFRunner.
        //
        // (b) if the query is a replication's initial sync one, we get a SingleSolutinRunner
        // that uses a specifically designed stage that skips extents faster (see details in
        // exec/oplogstart.h)
        //
        // Otherwise we go through the selection of which runner is most suited to the
        // query + run-time context at hand.
        Status status = Status::OK();
        if (collection == NULL) {
            rawRunner = new EOFRunner(cq, cq->ns());
        }
        else if (pq.hasOption(QueryOption_OplogReplay)) {
            status = getOplogStartHack(collection, cq, &rawRunner);
        }
        else {
            // Takes ownership of cq.
            size_t options = QueryPlannerParams::DEFAULT;
            if (shardingState.needCollectionMetadata(pq.ns())) {
                options |= QueryPlannerParams::INCLUDE_SHARD_FILTER;
            }
            status = getRunner(cq, &rawRunner, options);
        }

//.........这里部分代码省略.........

//.........这里部分代码省略.........
                lastBSONObjSet = true;
                
                // the first row returned is equal to the last element that
                // the slave has synced up to, so we might as well update
                // the slave location
                if (!slaveLocationUpdated) {
                    ccPointer->updateSlaveLocation(curop);
                    slaveLocationUpdated = true;
                }
                // check if data we are about to return may be too stale
                if (!opChecked) {
                    ccPointer->storeOpForSlave(current);
                    uassert(16785, "oplog cursor reading data that is too old", !ccPointer->lastOpForSlaveTooOld());
                    opChecked = true;
                }
            }
            
            if ( 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 the tailing request succeeded
        if ( cursor->tailable() ) {
            saveClientCursor = true;
        }
        
        if ( ! shardingState.getVersion( ns ).isWriteCompatibleWith( 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 ) );
        }
        
        int 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(), inMultiStatementTxn ) );
            cursorid = ccPointer->cursorid();
            DEV tlog(2) << "query has more, cursorid: " << cursorid << endl;
            
            if ( !ccPointer->ok() && ccPointer->c()->tailable() ) {
                DEV tlog() << "query has no more but tailable, cursorid: " << cursorid << endl;
            }
            
            if( queryOptions & QueryOption_Exhaust ) {
                curop.debug().exhaust = true;
            }
            
            // Set attributes for getMore.
            ccPointer->setChunkManager( queryResponseBuilder->chunkManager() );
            ccPointer->setPos( nReturned );
            ccPointer->pq = pq_shared;
            ccPointer->fields = pq.getFieldPtr();
            if (pq.hasOption( QueryOption_OplogReplay ) && lastBSONObjSet) {
                ccPointer->storeOpForSlave(last);
            }
            if (!inMultiStatementTxn) {
                // This cursor is not part of a multi-statement transaction, so
                // we pass off the current client's transaction stack to the
                // cursor so that it may be live as long as the cursor.
                cc().swapTransactionStack(ccPointer->transactions);
                verify(!cc().hasTxn());
            }
            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;

        curop.debug().nscanned = ( cursor ? cursor->nscanned() : 0LL );
        curop.debug().ntoskip = pq.getSkip();
        curop.debug().nreturned = nReturned;

        return saveClientCursor;
    }

//.........这里部分代码省略.........
            
            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 ) );
        }

        int 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->c()->noteLocation();
            }
            
            // !!! 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;
    }