void DocumentSourceCursor::setProjection(const BSONObj& projection, const ParsedDeps& deps) {
        verify(!_projection);
        _projection.reset(new Projection);
        _projection->init(projection);

        ClientCursorPin pin (_cursorId);
        verify(pin.c());
        pin.c()->fields = _projection;

        _dependencies = deps;
    }
Example #2
0
std::string runQuery(OperationContext* opCtx,
                     QueryMessage& q,
                     const NamespaceString& nss,
                     Message& result) {
    CurOp& curOp = *CurOp::get(opCtx);
    curOp.ensureStarted();

    uassert(ErrorCodes::InvalidNamespace,
            str::stream() << "Invalid ns [" << nss.ns() << "]",
            nss.isValid());
    invariant(!nss.isCommand());

    // Set CurOp information.
    const auto upconvertedQuery = upconvertQueryEntry(q.query, nss, q.ntoreturn, q.ntoskip);
    beginQueryOp(opCtx, nss, upconvertedQuery, q.ntoreturn, q.ntoskip);

    // Parse the qm into a CanonicalQuery.
    const boost::intrusive_ptr<ExpressionContext> expCtx;
    auto cq = uassertStatusOKWithContext(
        CanonicalQuery::canonicalize(opCtx,
                                     q,
                                     expCtx,
                                     ExtensionsCallbackReal(opCtx, &nss),
                                     MatchExpressionParser::kAllowAllSpecialFeatures),
        "Can't canonicalize query");
    invariant(cq.get());

    LOG(5) << "Running query:\n" << redact(cq->toString());
    LOG(2) << "Running query: " << redact(cq->toStringShort());

    // Parse, canonicalize, plan, transcribe, and get a plan executor.
    AutoGetCollectionForReadCommand ctx(opCtx, nss, AutoGetCollection::ViewMode::kViewsForbidden);
    Collection* const collection = ctx.getCollection();

    {
        const QueryRequest& qr = cq->getQueryRequest();

        // Allow the query to run on secondaries if the read preference permits it. If no read
        // preference was specified, allow the query to run iff slaveOk has been set.
        const bool slaveOK = qr.hasReadPref()
            ? uassertStatusOK(ReadPreferenceSetting::fromContainingBSON(q.query))
                  .canRunOnSecondary()
            : qr.isSlaveOk();
        uassertStatusOK(
            repl::ReplicationCoordinator::get(opCtx)->checkCanServeReadsFor(opCtx, nss, slaveOK));
    }

    // We have a parsed query. Time to get the execution plan for it.
    auto exec = uassertStatusOK(getExecutorLegacyFind(opCtx, collection, nss, std::move(cq)));

    const QueryRequest& qr = exec->getCanonicalQuery()->getQueryRequest();

    // If it's actually an explain, do the explain and return rather than falling through
    // to the normal query execution loop.
    if (qr.isExplain()) {
        BufBuilder bb;
        bb.skip(sizeof(QueryResult::Value));

        BSONObjBuilder explainBob;
        Explain::explainStages(
            exec.get(), collection, ExplainOptions::Verbosity::kExecAllPlans, &explainBob);

        // Add the resulting object to the return buffer.
        BSONObj explainObj = explainBob.obj();
        bb.appendBuf((void*)explainObj.objdata(), explainObj.objsize());

        // Set query result fields.
        QueryResult::View qr = bb.buf();
        qr.setResultFlagsToOk();
        qr.msgdata().setLen(bb.len());
        curOp.debug().responseLength = bb.len();
        qr.msgdata().setOperation(opReply);
        qr.setCursorId(0);
        qr.setStartingFrom(0);
        qr.setNReturned(1);
        result.setData(bb.release());
        return "";
    }

    // Handle query option $maxTimeMS (not used with commands).
    if (qr.getMaxTimeMS() > 0) {
        uassert(40116,
                "Illegal attempt to set operation deadline within DBDirectClient",
                !opCtx->getClient()->isInDirectClient());
        opCtx->setDeadlineAfterNowBy(Milliseconds{qr.getMaxTimeMS()});
    }
    opCtx->checkForInterrupt();  // May trigger maxTimeAlwaysTimeOut fail point.

    // Run the query.
    // bb is used to hold query results
    // this buffer should contain either requested documents per query or
    // explain information, but not both
    BufBuilder bb(FindCommon::kInitReplyBufferSize);
    bb.skip(sizeof(QueryResult::Value));

    // How many results have we obtained from the executor?
    int numResults = 0;

    BSONObj obj;
    PlanExecutor::ExecState state;

    // Get summary info about which plan the executor is using.
    {
        stdx::lock_guard<Client> lk(*opCtx->getClient());
        curOp.setPlanSummary_inlock(Explain::getPlanSummary(exec.get()));
    }

    while (PlanExecutor::ADVANCED == (state = exec->getNext(&obj, NULL))) {
        // If we can't fit this result inside the current batch, then we stash it for later.
        if (!FindCommon::haveSpaceForNext(obj, numResults, bb.len())) {
            exec->enqueue(obj);
            break;
        }

        // Add result to output buffer.
        bb.appendBuf((void*)obj.objdata(), obj.objsize());

        // Count the result.
        ++numResults;

        if (FindCommon::enoughForFirstBatch(qr, numResults)) {
            LOG(5) << "Enough for first batch, wantMore=" << qr.wantMore()
                   << " ntoreturn=" << qr.getNToReturn().value_or(0)
                   << " numResults=" << numResults;
            break;
        }
    }

    // Caller expects exceptions thrown in certain cases.
    if (PlanExecutor::FAILURE == state || PlanExecutor::DEAD == state) {
        error() << "Plan executor error during find: " << PlanExecutor::statestr(state)
                << ", stats: " << redact(Explain::getWinningPlanStats(exec.get()));
        uassertStatusOKWithContext(WorkingSetCommon::getMemberObjectStatus(obj),
                                   "Executor error during OP_QUERY find");
        MONGO_UNREACHABLE;
    }

    // Before saving the cursor, ensure that whatever plan we established happened with the expected
    // collection version
    auto css = CollectionShardingState::get(opCtx, nss);
    css->checkShardVersionOrThrow(opCtx);

    // Fill out CurOp based on query results. If we have a cursorid, we will fill out CurOp with
    // this cursorid later.
    long long ccId = 0;

    if (shouldSaveCursor(opCtx, collection, state, exec.get())) {
        // We won't use the executor until it's getMore'd.
        exec->saveState();
        exec->detachFromOperationContext();

        // Allocate a new ClientCursor and register it with the cursor manager.
        ClientCursorPin pinnedCursor = collection->getCursorManager()->registerCursor(
            opCtx,
            {std::move(exec),
             nss,
             AuthorizationSession::get(opCtx->getClient())->getAuthenticatedUserNames(),
             opCtx->recoveryUnit()->getReadConcernLevel(),
             upconvertedQuery});
        ccId = pinnedCursor.getCursor()->cursorid();

        LOG(5) << "caching executor with cursorid " << ccId << " after returning " << numResults
               << " results";

        // TODO document
        if (qr.isExhaust()) {
            curOp.debug().exhaust = true;
        }

        pinnedCursor.getCursor()->setPos(numResults);

        // We assume that cursors created through a DBDirectClient are always used from their
        // original OperationContext, so we do not need to move time to and from the cursor.
        if (!opCtx->getClient()->isInDirectClient()) {
            // If the query had a time limit, remaining time is "rolled over" to the cursor (for
            // use by future getmore ops).
            pinnedCursor.getCursor()->setLeftoverMaxTimeMicros(opCtx->getRemainingMaxTimeMicros());
        }

        endQueryOp(opCtx, collection, *pinnedCursor.getCursor()->getExecutor(), numResults, ccId);
    } else {
        LOG(5) << "Not caching executor but returning " << numResults << " results.";
        endQueryOp(opCtx, collection, *exec, numResults, ccId);
    }

    // Fill out the output buffer's header.
    QueryResult::View queryResultView = bb.buf();
    queryResultView.setCursorId(ccId);
    queryResultView.setResultFlagsToOk();
    queryResultView.msgdata().setLen(bb.len());
    queryResultView.msgdata().setOperation(opReply);
    queryResultView.setStartingFrom(0);
    queryResultView.setNReturned(numResults);

    // Add the results from the query into the output buffer.
    result.setData(bb.release());

    // curOp.debug().exhaust is set above.
    return curOp.debug().exhaust ? nss.ns() : "";
}
Example #3
0
std::string runQuery(OperationContext* txn,
                     QueryMessage& q,
                     const NamespaceString& nss,
                     Message& result) {
    CurOp& curOp = *CurOp::get(txn);

    uassert(ErrorCodes::InvalidNamespace,
            str::stream() << "Invalid ns [" << nss.ns() << "]",
            nss.isValid());
    invariant(!nss.isCommand());

    // Set CurOp information.
    beginQueryOp(txn, nss, q.query, q.ntoreturn, q.ntoskip);

    // Parse the qm into a CanonicalQuery.

    auto statusWithCQ = CanonicalQuery::canonicalize(txn, q, ExtensionsCallbackReal(txn, &nss));
    if (!statusWithCQ.isOK()) {
        uasserted(17287,
                  str::stream() << "Can't canonicalize query: "
                                << statusWithCQ.getStatus().toString());
    }
    unique_ptr<CanonicalQuery> cq = std::move(statusWithCQ.getValue());
    invariant(cq.get());

    LOG(5) << "Running query:\n" << redact(cq->toString());
    LOG(2) << "Running query: " << redact(cq->toStringShort());

    // Parse, canonicalize, plan, transcribe, and get a plan executor.
    AutoGetCollectionOrViewForRead ctx(txn, nss);
    Collection* collection = ctx.getCollection();

    if (ctx.getView()) {
        uasserted(ErrorCodes::CommandNotSupportedOnView,
                  str::stream()
                      << "Namespace "
                      << nss.ns()
                      << " is a view. Legacy find operations are not supported on views. "
                      << "Only clients which support the find command can be used to query views.");
    }

    // We have a parsed query. Time to get the execution plan for it.
    std::unique_ptr<PlanExecutor> exec = uassertStatusOK(
        getExecutorFind(txn, collection, nss, std::move(cq), PlanExecutor::YIELD_AUTO));

    const QueryRequest& qr = exec->getCanonicalQuery()->getQueryRequest();

    // If it's actually an explain, do the explain and return rather than falling through
    // to the normal query execution loop.
    if (qr.isExplain()) {
        BufBuilder bb;
        bb.skip(sizeof(QueryResult::Value));

        BSONObjBuilder explainBob;
        Explain::explainStages(exec.get(), collection, ExplainCommon::EXEC_ALL_PLANS, &explainBob);

        // Add the resulting object to the return buffer.
        BSONObj explainObj = explainBob.obj();
        bb.appendBuf((void*)explainObj.objdata(), explainObj.objsize());

        // Set query result fields.
        QueryResult::View qr = bb.buf();
        qr.setResultFlagsToOk();
        qr.msgdata().setLen(bb.len());
        curOp.debug().responseLength = bb.len();
        qr.msgdata().setOperation(opReply);
        qr.setCursorId(0);
        qr.setStartingFrom(0);
        qr.setNReturned(1);
        result.setData(bb.release());
        return "";
    }

    // Handle query option $maxTimeMS (not used with commands).
    if (qr.getMaxTimeMS() > 0) {
        uassert(40116,
                "Illegal attempt to set operation deadline within DBDirectClient",
                !txn->getClient()->isInDirectClient());
        txn->setDeadlineAfterNowBy(Milliseconds{qr.getMaxTimeMS()});
    }
    txn->checkForInterrupt();  // May trigger maxTimeAlwaysTimeOut fail point.

    // uassert if we are not on a primary, and not a secondary with SlaveOk query parameter set.
    bool slaveOK = qr.isSlaveOk() || qr.hasReadPref();
    Status serveReadsStatus =
        repl::getGlobalReplicationCoordinator()->checkCanServeReadsFor(txn, nss, slaveOK);
    uassertStatusOK(serveReadsStatus);

    // Run the query.
    // bb is used to hold query results
    // this buffer should contain either requested documents per query or
    // explain information, but not both
    BufBuilder bb(FindCommon::kInitReplyBufferSize);
    bb.skip(sizeof(QueryResult::Value));

    // How many results have we obtained from the executor?
    int numResults = 0;

    // If we're replaying the oplog, we save the last time that we read.
    Timestamp slaveReadTill;

    BSONObj obj;
    PlanExecutor::ExecState state;

    // Get summary info about which plan the executor is using.
    {
        stdx::lock_guard<Client> lk(*txn->getClient());
        curOp.setPlanSummary_inlock(Explain::getPlanSummary(exec.get()));
    }

    while (PlanExecutor::ADVANCED == (state = exec->getNext(&obj, NULL))) {
        // If we can't fit this result inside the current batch, then we stash it for later.
        if (!FindCommon::haveSpaceForNext(obj, numResults, bb.len())) {
            exec->enqueue(obj);
            break;
        }

        // 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 (qr.isOplogReplay()) {
            BSONElement e = obj["ts"];
            if (Date == e.type() || bsonTimestamp == e.type()) {
                slaveReadTill = e.timestamp();
            }
        }

        if (FindCommon::enoughForFirstBatch(qr, numResults)) {
            LOG(5) << "Enough for first batch, wantMore=" << qr.wantMore()
                   << " ntoreturn=" << qr.getNToReturn().value_or(0)
                   << " numResults=" << numResults;
            break;
        }
    }

    // If we cache the executor later, we want to deregister it as it receives notifications
    // anyway by virtue of being cached.
    //
    // If we don't cache the executor later, we are deleting it, so it must be deregistered.
    //
    // So, no matter what, deregister the executor.
    exec->deregisterExec();

    // Caller expects exceptions thrown in certain cases.
    if (PlanExecutor::FAILURE == state || PlanExecutor::DEAD == state) {
        error() << "Plan executor error during find: " << PlanExecutor::statestr(state)
                << ", stats: " << redact(Explain::getWinningPlanStats(exec.get()));
        uasserted(17144, "Executor error: " + WorkingSetCommon::toStatusString(obj));
    }

    // Before saving the cursor, ensure that whatever plan we established happened with the expected
    // collection version
    auto css = CollectionShardingState::get(txn, nss);
    css->checkShardVersionOrThrow(txn);

    // Fill out CurOp based on query results. If we have a cursorid, we will fill out CurOp with
    // this cursorid later.
    long long ccId = 0;

    if (shouldSaveCursor(txn, collection, state, exec.get())) {
        // We won't use the executor until it's getMore'd.
        exec->saveState();
        exec->detachFromOperationContext();

        // Allocate a new ClientCursor and register it with the cursor manager.
        ClientCursorPin pinnedCursor = collection->getCursorManager()->registerCursor(
            {exec.release(),
             nss.ns(),
             txn->recoveryUnit()->isReadingFromMajorityCommittedSnapshot(),
             qr.getOptions(),
             qr.getFilter()});
        ccId = pinnedCursor.getCursor()->cursorid();

        LOG(5) << "caching executor with cursorid " << ccId << " after returning " << numResults
               << " results";

        // TODO document
        if (qr.isOplogReplay() && !slaveReadTill.isNull()) {
            pinnedCursor.getCursor()->slaveReadTill(slaveReadTill);
        }

        // TODO document
        if (qr.isExhaust()) {
            curOp.debug().exhaust = true;
        }

        pinnedCursor.getCursor()->setPos(numResults);

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

        endQueryOp(txn, collection, *pinnedCursor.getCursor()->getExecutor(), numResults, ccId);
    } else {
        LOG(5) << "Not caching executor but returning " << numResults << " results.";
        endQueryOp(txn, collection, *exec, numResults, ccId);
    }

    // Fill out the output buffer's header.
    QueryResult::View queryResultView = bb.buf();
    queryResultView.setCursorId(ccId);
    queryResultView.setResultFlagsToOk();
    queryResultView.msgdata().setLen(bb.len());
    queryResultView.msgdata().setOperation(opReply);
    queryResultView.setStartingFrom(0);
    queryResultView.setNReturned(numResults);

    // Add the results from the query into the output buffer.
    result.setData(bb.release());

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