std::string newRunQuery(OperationContext* txn, Message& m, QueryMessage& q, CurOp& curop, Message &result, bool fromDBDirectClient) { // 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::Value)); BSONObjBuilder cmdResBuf; if (!runCommands(txn, 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::View qr = bb.buf(); bb.decouple(); 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(qr.view2ptr(), true); return ""; } const NamespaceString nss(q.ns); // Parse the qm into a CanonicalQuery. CanonicalQuery* cq; Status canonStatus = CanonicalQuery::canonicalize( q, &cq, WhereCallbackReal(txn, StringData(nss.db()))); if (!canonStatus.isOK()) { uasserted(17287, str::stream() << "Can't canonicalize query: " << canonStatus.toString()); } QLOG() << "Running query:\n" << cq->toString(); LOG(2) << "Running query: " << cq->toStringShort(); // Parse, canonicalize, plan, transcribe, and get a plan executor. PlanExecutor* rawExec = NULL; // We use this a lot below. const LiteParsedQuery& pq = cq->getParsed(); AutoGetCollectionForRead ctx(txn, nss); const int dbProfilingLevel = (ctx.getDb() != NULL) ? ctx.getDb()->getProfilingLevel() : serverGlobalParams.defaultProfile; Collection* collection = ctx.getCollection(); // We'll now try to get the query executor that will execute this query for us. There // are a few cases in which we know upfront which executor we should get and, therefore, // we shortcut the selection process here. // // (a) If the query is over a collection that doesn't exist, we use an EOFStage. // // (b) if the query is a replication's initial sync one, we use a specifically designed // stage that skips extents faster (see details in exec/oplogstart.h). // // Otherwise we go through the selection of which executor is most suited to the // query + run-time context at hand. Status status = Status::OK(); if (NULL != collection && pq.getOptions().oplogReplay) { // Takes ownership of 'cq'. status = getOplogStartHack(txn, collection, cq, &rawExec); } else { size_t options = QueryPlannerParams::DEFAULT; if (shardingState.needCollectionMetadata(pq.ns())) { options |= QueryPlannerParams::INCLUDE_SHARD_FILTER; } // Takes ownership of 'cq'. status = getExecutor(txn, collection, cq, PlanExecutor::YIELD_AUTO, &rawExec, options); } if (!status.isOK()) { // NOTE: Do not access cq as getExecutor has deleted it. uasserted(17007, "Unable to execute query: " + status.reason()); } verify(NULL != rawExec); auto_ptr<PlanExecutor> exec(rawExec); // If it's actually an explain, do the explain and return rather than falling through // to the normal query execution loop. if (pq.isExplain()) { BufBuilder bb; bb.skip(sizeof(QueryResult::Value)); BSONObjBuilder explainBob; Explain::explainStages(exec.get(), ExplainCommon::EXEC_ALL_PLANS, &explainBob); // Add the resulting object to the return buffer. BSONObj explainObj = explainBob.obj(); bb.appendBuf((void*)explainObj.objdata(), explainObj.objsize()); curop.debug().iscommand = true; // TODO: Does this get overwritten/do we really need to set this twice? curop.debug().query = q.query; // Set query result fields. QueryResult::View qr = bb.buf(); bb.decouple(); 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(qr.view2ptr(), true); return ""; } // We freak out later if this changes before we're done with the query. const ChunkVersion shardingVersionAtStart = shardingState.getVersion(cq->ns()); // Handle query option $maxTimeMS (not used with commands). curop.setMaxTimeMicros(static_cast<unsigned long long>(pq.getMaxTimeMS()) * 1000); 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 = pq.getOptions().slaveOk || pq.hasReadPref(); status = repl::getGlobalReplicationCoordinator()->checkCanServeReadsFor( txn, NamespaceString(cq->ns()), slaveOK); uassertStatusOK(status); // If this exists, the collection is sharded. // If it doesn't exist, we can assume we're not sharded. // If we're sharded, we might encounter data that is not consistent with our sharding state. // We must ignore this data. CollectionMetadataPtr collMetadata; if (!shardingState.needCollectionMetadata(pq.ns())) { collMetadata = CollectionMetadataPtr(); } else { collMetadata = shardingState.getCollectionMetadata(pq.ns()); } // 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(32768); 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. OpTime slaveReadTill; // Do we save the PlanExecutor in a ClientCursor for getMore calls later? bool saveClientCursor = false; BSONObj obj; PlanExecutor::ExecState state; // uint64_t numMisplacedDocs = 0; // Get summary info about which plan the executor is using. curop.debug().planSummary = Explain::getPlanSummary(exec.get()); while (PlanExecutor::ADVANCED == (state = exec->getNext(&obj, NULL))) { // 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.getOptions().oplogReplay) { BSONElement e = obj["ts"]; if (Date == e.type() || Timestamp == e.type()) { slaveReadTill = e._opTime(); } } // TODO: only one type of 2d search doesn't support this. We need a way to pull it out // of CanonicalQuery. :( const bool supportsGetMore = true; if (!supportsGetMore && (enough(pq, numResults) || bb.len() >= MaxBytesToReturnToClientAtOnce)) { break; } else if (enoughForFirstBatch(pq, numResults, bb.len())) { QLOG() << "Enough for first batch, wantMore=" << pq.wantMore() << " numToReturn=" << pq.getNumToReturn() << " numResults=" << numResults << endl; // If only one result requested assume it's a findOne() and don't save the cursor. if (pq.wantMore() && 1 != pq.getNumToReturn()) { QLOG() << " executor EOF=" << exec->isEOF() << endl; saveClientCursor = !exec->isEOF(); } 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::EXEC_ERROR == state) { scoped_ptr<PlanStageStats> stats(exec->getStats()); error() << "Plan executor error, stats: " << Explain::statsToBSON(*stats); uasserted(17144, "Executor error: " + WorkingSetCommon::toStatusString(obj)); } // Why save a dead executor? if (PlanExecutor::DEAD == state) { saveClientCursor = false; } else if (pq.getOptions().tailable) { // If we're tailing a capped collection, we don't bother saving the cursor if the // collection is empty. Otherwise, the semantics of the tailable cursor is that the // client will keep trying to read from it. So we'll keep it around. if (collection && collection->numRecords(txn) != 0 && pq.getNumToReturn() != 1) { saveClientCursor = true; } } // 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())); } const logger::LogComponent queryLogComponent = logger::LogComponent::kQuery; const logger::LogSeverity logLevelOne = logger::LogSeverity::Debug(1); PlanSummaryStats summaryStats; Explain::getSummaryStats(exec.get(), &summaryStats); curop.debug().ntoskip = pq.getSkip(); curop.debug().nreturned = numResults; curop.debug().scanAndOrder = summaryStats.hasSortStage; curop.debug().nscanned = summaryStats.totalKeysExamined; curop.debug().nscannedObjects = summaryStats.totalDocsExamined; curop.debug().idhack = summaryStats.isIdhack; // Set debug information for consumption by the profiler. if (dbProfilingLevel > 0 || curop.elapsedMillis() > serverGlobalParams.slowMS || logger::globalLogDomain()->shouldLog(queryLogComponent, logLevelOne)) { // Get BSON stats. scoped_ptr<PlanStageStats> execStats(exec->getStats()); BSONObjBuilder statsBob; Explain::statsToBSON(*execStats, &statsBob); curop.debug().execStats.set(statsBob.obj()); // Replace exec stats with plan summary if stats cannot fit into CachedBSONObj. if (curop.debug().execStats.tooBig() && !curop.debug().planSummary.empty()) { BSONObjBuilder bob; bob.append("summary", curop.debug().planSummary.toString()); curop.debug().execStats.set(bob.done()); } } long long ccId = 0; if (saveClientCursor) { // We won't use the executor until it's getMore'd. exec->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(collection, exec.get(), cq->getParsed().getOptions().toInt(), cq->getParsed().getFilter()); ccId = cc->cursorid(); if (fromDBDirectClient) { cc->setUnownedRecoveryUnit(txn->recoveryUnit()); } else if (state == PlanExecutor::IS_EOF && pq.getOptions().tailable) { // Don't stash the RU for tailable cursors at EOF, let them get a new RU on their // next getMore. } else { // We stash away the RecoveryUnit in the ClientCursor. It's used for subsequent // getMore requests. The calling OpCtx gets a fresh RecoveryUnit. cc->setOwnedRecoveryUnit(txn->releaseRecoveryUnit()); StorageEngine* storageEngine = getGlobalEnvironment()->getGlobalStorageEngine(); txn->setRecoveryUnit(storageEngine->newRecoveryUnit(txn)); } QLOG() << "caching executor with cursorid " << ccId << " after returning " << numResults << " results" << endl; // ClientCursor takes ownership of executor. Release to make sure it's not deleted. exec.release(); // TODO document if (pq.getOptions().oplogReplay && !slaveReadTill.isNull()) { cc->slaveReadTill(slaveReadTill); } // TODO document if (pq.getOptions().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 executor 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::View qr = result.header().view2ptr(); qr.setCursorId(ccId); curop.debug().cursorid = (0 == ccId ? -1 : ccId); qr.setResultFlagsToOk(); qr.msgdata().setOperation(opReply); qr.setStartingFrom(0); qr.setNReturned(numResults); // curop.debug().exhaust is set above. return curop.debug().exhaust ? pq.ns() : ""; }
/** * This is called by db/ops/query.cpp. This is the entry point for answering a query. */ std::string newRunQuery(CanonicalQuery* cq, CurOp& curop, Message &result) { QLOG() << "Running query on new system: " << cq->toString(); // This is a read lock. Client::ReadContext ctx(cq->ns(), storageGlobalParams.dbpath); // Parse, canonicalize, plan, transcribe, and get a runner. Runner* rawRunner = NULL; // We use this a lot below. const LiteParsedQuery& pq = cq->getParsed(); // Need to call cq->toString() now, since upon error getRunner doesn't guarantee // cq is in a consistent state. string cqStr = cq->toString(); // 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 (ctx.ctx().db()->getCollection(cq->ns()) == NULL) { rawRunner = new EOFRunner(cq, cq->ns()); } else if (pq.hasOption(QueryOption_OplogReplay)) { status = getOplogStartHack(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); } if (!status.isOK()) { uasserted(17007, "Couldn't get runner for query because: " + status.reason() + " query is " + cqStr); } verify(NULL != rawRunner); auto_ptr<Runner> runner(rawRunner); // We freak out later if this changes before we're done with the query. const ChunkVersion shardingVersionAtStart = shardingState.getVersion(cq->ns()); // Handle query option $maxTimeMS (not used with commands). curop.setMaxTimeMicros(static_cast<unsigned long long>(pq.getMaxTimeMS()) * 1000); killCurrentOp.checkForInterrupt(); // May trigger maxTimeAlwaysTimeOut fail point. // uassert if we are not on a primary, and not a secondary with SlaveOk query parameter set. replVerifyReadsOk(&pq); // If this exists, the collection is sharded. // If it doesn't exist, we can assume we're not sharded. // If we're sharded, we might encounter data that is not consistent with our sharding state. // We must ignore this data. CollectionMetadataPtr collMetadata; if (!shardingState.needCollectionMetadata(pq.ns())) { collMetadata = CollectionMetadataPtr(); } else { collMetadata = shardingState.getCollectionMetadata(pq.ns()); } // 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(32768); bb.skip(sizeof(QueryResult)); // How many results have we obtained from the runner? int numResults = 0; // If we're replaying the oplog, we save the last time that we read. OpTime slaveReadTill; // Do we save the Runner in a ClientCursor for getMore calls later? bool saveClientCursor = false; // We turn on auto-yielding for the runner here. The runner registers itself with the // active runners list in ClientCursor. ClientCursor::registerRunner(runner.get()); runner->setYieldPolicy(Runner::YIELD_AUTO); auto_ptr<DeregisterEvenIfUnderlyingCodeThrows> safety( new DeregisterEvenIfUnderlyingCodeThrows(runner.get())); BSONObj obj; Runner::RunnerState state; // uint64_t numMisplacedDocs = 0; // set this outside loop. we will need to use this both within loop and when deciding // to fill in explain information const bool isExplain = pq.isExplain(); while (Runner::RUNNER_ADVANCED == (state = runner->getNext(&obj, NULL))) { // Add result to output buffer. This is unnecessary if explain info is requested if (!isExplain) { 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(); } } // TODO: only one type of 2d search doesn't support this. We need a way to pull it out // of CanonicalQuery. :( const bool supportsGetMore = true; if (isExplain) { if (enoughForExplain(pq, numResults)) { break; } } else if (!supportsGetMore && (enough(pq, numResults) || bb.len() >= MaxBytesToReturnToClientAtOnce)) { break; } else if (enoughForFirstBatch(pq, numResults, bb.len())) { QLOG() << "Enough for first batch, wantMore=" << pq.wantMore() << " numToReturn=" << pq.getNumToReturn() << " numResults=" << numResults << endl; // If only one result requested assume it's a findOne() and don't save the cursor. if (pq.wantMore() && 1 != pq.getNumToReturn()) { QLOG() << " runner EOF=" << runner->isEOF() << endl; saveClientCursor = !runner->isEOF(); } 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. safety.reset(); // Caller expects exceptions thrown in certain cases: // * in-memory sort using too much RAM. if (Runner::RUNNER_ERROR == state) { uasserted(17144, "Runner error, memory limit for sort probably exceeded"); } // Why save a dead runner? if (Runner::RUNNER_DEAD == state) { saveClientCursor = false; } else if (pq.hasOption(QueryOption_CursorTailable)) { // If we're tailing a capped collection, we don't bother saving the cursor if the // collection is empty. Otherwise, the semantics of the tailable cursor is that the // client will keep trying to read from it. So we'll keep it around. Collection* collection = ctx.ctx().db()->getCollection(cq->ns()); if (collection && collection->numRecords() != 0 && pq.getNumToReturn() != 1) { saveClientCursor = true; } } // 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())); } // 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() : ""; }
std::string runQuery(OperationContext* txn, QueryMessage& q, const NamespaceString& nss, CurOp& curop, Message &result) { // Validate the namespace. uassert(16256, str::stream() << "Invalid ns [" << nss.ns() << "]", nss.isValid()); invariant(!nss.isCommand()); // Set curop information. beginQueryOp(nss, q.query, q.ntoreturn, q.ntoskip, &curop); // Parse the qm into a CanonicalQuery. std::auto_ptr<CanonicalQuery> cq; { CanonicalQuery* cqRaw; Status canonStatus = CanonicalQuery::canonicalize(q, &cqRaw, WhereCallbackReal(txn, nss.db())); if (!canonStatus.isOK()) { uasserted(17287, str::stream() << "Can't canonicalize query: " << canonStatus.toString()); } cq.reset(cqRaw); } invariant(cq.get()); LOG(5) << "Running query:\n" << cq->toString(); LOG(2) << "Running query: " << cq->toStringShort(); // Parse, canonicalize, plan, transcribe, and get a plan executor. AutoGetCollectionForRead ctx(txn, nss); Collection* collection = ctx.getCollection(); const int dbProfilingLevel = ctx.getDb() ? ctx.getDb()->getProfilingLevel() : serverGlobalParams.defaultProfile; // We have a parsed query. Time to get the execution plan for it. std::unique_ptr<PlanExecutor> exec; { PlanExecutor* rawExec; Status execStatus = getExecutorFind(txn, collection, nss, cq.release(), PlanExecutor::YIELD_AUTO, &rawExec); uassertStatusOK(execStatus); exec.reset(rawExec); } const LiteParsedQuery& pq = exec->getCanonicalQuery()->getParsed(); // If it's actually an explain, do the explain and return rather than falling through // to the normal query execution loop. if (pq.isExplain()) { BufBuilder bb; bb.skip(sizeof(QueryResult::Value)); BSONObjBuilder explainBob; Explain::explainStages(exec.get(), ExplainCommon::EXEC_ALL_PLANS, &explainBob); // Add the resulting object to the return buffer. BSONObj explainObj = explainBob.obj(); bb.appendBuf((void*)explainObj.objdata(), explainObj.objsize()); // TODO: Does this get overwritten/do we really need to set this twice? curop.debug().query = q.query; // Set query result fields. QueryResult::View qr = bb.buf(); bb.decouple(); 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(qr.view2ptr(), true); return ""; } // We freak out later if this changes before we're done with the query. const ChunkVersion shardingVersionAtStart = shardingState.getVersion(nss.ns()); // Handle query option $maxTimeMS (not used with commands). curop.setMaxTimeMicros(static_cast<unsigned long long>(pq.getMaxTimeMS()) * 1000); 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 = pq.isSlaveOk() || pq.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(32768); 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; // uint64_t numMisplacedDocs = 0; // Get summary info about which plan the executor is using. curop.debug().planSummary = Explain::getPlanSummary(exec.get()); while (PlanExecutor::ADVANCED == (state = exec->getNext(&obj, NULL))) { // 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.isOplogReplay()) { BSONElement e = obj["ts"]; if (Date == e.type() || bsonTimestamp == e.type()) { slaveReadTill = e.timestamp(); } } if (enoughForFirstBatch(pq, numResults, bb.len())) { LOG(5) << "Enough for first batch, wantMore=" << pq.wantMore() << " numToReturn=" << pq.getNumToReturn() << " numResults=" << numResults << endl; 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) { scoped_ptr<PlanStageStats> stats(exec->getStats()); error() << "Plan executor error, stats: " << Explain::statsToBSON(*stats); uasserted(17144, "Executor error: " + WorkingSetCommon::toStatusString(obj)); } // TODO: Currently, chunk ranges are kept around until all ClientCursors created while the // chunk belonged on this node are gone. Separating chunk lifetime management from // ClientCursor should allow this check to go away. if (!shardingState.getVersion(nss.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(nss.ns(), "version changed during initial query", shardingVersionAtStart, shardingState.getVersion(nss.ns())); } // 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(); // 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(collection->getCursorManager(), exec.release(), nss.ns(), pq.getOptions(), pq.getFilter()); ccId = cc->cursorid(); if (txn->getClient()->isInDirectClient()) { cc->setUnownedRecoveryUnit(txn->recoveryUnit()); } else if (state == PlanExecutor::IS_EOF && pq.isTailable()) { // Don't stash the RU for tailable cursors at EOF, let them get a new RU on their // next getMore. } else { // We stash away the RecoveryUnit in the ClientCursor. It's used for subsequent // getMore requests. The calling OpCtx gets a fresh RecoveryUnit. txn->recoveryUnit()->abandonSnapshot(); cc->setOwnedRecoveryUnit(txn->releaseRecoveryUnit()); StorageEngine* storageEngine = getGlobalServiceContext()->getGlobalStorageEngine(); invariant(txn->setRecoveryUnit(storageEngine->newRecoveryUnit(), OperationContext::kNotInUnitOfWork) == OperationContext::kNotInUnitOfWork); } LOG(5) << "caching executor with cursorid " << ccId << " after returning " << numResults << " results" << endl; // TODO document if (pq.isOplogReplay() && !slaveReadTill.isNull()) { cc->slaveReadTill(slaveReadTill); } // TODO document if (pq.isExhaust()) { curop.debug().exhaust = true; } 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()); endQueryOp(cc->getExecutor(), dbProfilingLevel, numResults, ccId, &curop); } else { LOG(5) << "Not caching executor but returning " << numResults << " results.\n"; endQueryOp(exec.get(), dbProfilingLevel, numResults, ccId, &curop); } // 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::View qr = result.header().view2ptr(); qr.setCursorId(ccId); qr.setResultFlagsToOk(); qr.msgdata().setOperation(opReply); qr.setStartingFrom(0); qr.setNReturned(numResults); // curop.debug().exhaust is set above. return curop.debug().exhaust ? nss.ns() : ""; }
/** * Runs a query using the following steps: * 1) Parsing. * 2) Acquire locks. * 3) Plan query, obtaining an executor that can run it. * 4) Setup a cursor for the query, which may be used on subsequent getMores. * 5) Generate the first batch. * 6) Save state for getMore. * 7) Generate response to send to the client. * * TODO: Rather than using the sharding version available in thread-local storage (i.e. the * call to ShardingState::needCollectionMetadata() below), shard version information * should be passed as part of the command parameter. */ bool run(OperationContext* txn, const std::string& dbname, BSONObj& cmdObj, int options, std::string& errmsg, BSONObjBuilder& result) override { const std::string fullns = parseNs(dbname, cmdObj); const NamespaceString nss(fullns); if (!nss.isValid()) { return appendCommandStatus(result, {ErrorCodes::InvalidNamespace, str::stream() << "Invalid collection name: " << nss.ns()}); } // Although it is a command, a find command gets counted as a query. globalOpCounters.gotQuery(); if (txn->getClient()->isInDirectClient()) { return appendCommandStatus( result, Status(ErrorCodes::IllegalOperation, "Cannot run find command from eval()")); } // 1a) Parse the command BSON to a LiteParsedQuery. const bool isExplain = false; auto lpqStatus = LiteParsedQuery::makeFromFindCommand(nss, cmdObj, isExplain); if (!lpqStatus.isOK()) { return appendCommandStatus(result, lpqStatus.getStatus()); } auto& lpq = lpqStatus.getValue(); // Validate term, if provided. if (auto term = lpq->getReplicationTerm()) { auto replCoord = repl::ReplicationCoordinator::get(txn); Status status = replCoord->updateTerm(*term); // Note: updateTerm returns ok if term stayed the same. if (!status.isOK()) { return appendCommandStatus(result, status); } } // Fill out curop information. long long ntoreturn = lpq->getBatchSize().value_or(0); beginQueryOp(txn, nss, cmdObj, ntoreturn, lpq->getSkip()); // 1b) Finish the parsing step by using the LiteParsedQuery to create a CanonicalQuery. WhereCallbackReal whereCallback(txn, nss.db()); auto statusWithCQ = CanonicalQuery::canonicalize(lpq.release(), whereCallback); if (!statusWithCQ.isOK()) { return appendCommandStatus(result, statusWithCQ.getStatus()); } std::unique_ptr<CanonicalQuery> cq = std::move(statusWithCQ.getValue()); // 2) Acquire locks. AutoGetCollectionForRead ctx(txn, nss); Collection* collection = ctx.getCollection(); const int dbProfilingLevel = ctx.getDb() ? ctx.getDb()->getProfilingLevel() : serverGlobalParams.defaultProfile; ShardingState* const shardingState = ShardingState::get(txn); // It is possible that the sharding version will change during yield while we are // retrieving a plan executor. If this happens we will throw an error and mongos will // retry. const ChunkVersion shardingVersionAtStart = shardingState->getVersion(nss.ns()); // 3) Get the execution plan for the query. auto statusWithPlanExecutor = getExecutorFind(txn, collection, nss, std::move(cq), PlanExecutor::YIELD_AUTO); if (!statusWithPlanExecutor.isOK()) { return appendCommandStatus(result, statusWithPlanExecutor.getStatus()); } std::unique_ptr<PlanExecutor> exec = std::move(statusWithPlanExecutor.getValue()); // TODO: Currently, chunk ranges are kept around until all ClientCursors created while // the chunk belonged on this node are gone. Separating chunk lifetime management from // ClientCursor should allow this check to go away. if (!shardingState->getVersion(nss.ns()).isWriteCompatibleWith(shardingVersionAtStart)) { // Version changed while retrieving a PlanExecutor. Terminate the operation, // signaling that mongos should retry. throw SendStaleConfigException(nss.ns(), "version changed during find command", shardingVersionAtStart, shardingState->getVersion(nss.ns())); } if (!collection) { // No collection. Just fill out curop indicating that there were zero results and // there is no ClientCursor id, and then return. const long long numResults = 0; const CursorId cursorId = 0; endQueryOp(txn, *exec, dbProfilingLevel, numResults, cursorId); appendCursorResponseObject(cursorId, nss.ns(), BSONArray(), &result); return true; } const LiteParsedQuery& pq = exec->getCanonicalQuery()->getParsed(); // 4) If possible, register the execution plan inside a ClientCursor, and pin that // cursor. In this case, ownership of the PlanExecutor is transferred to the // ClientCursor, and 'exec' becomes null. // // First unregister the PlanExecutor so it can be re-registered with ClientCursor. exec->deregisterExec(); // Create a ClientCursor containing this plan executor. We don't have to worry // about leaking it as it's inserted into a global map by its ctor. ClientCursor* cursor = new ClientCursor(collection->getCursorManager(), exec.release(), nss.ns(), txn->recoveryUnit()->isReadingFromMajorityCommittedSnapshot(), pq.getOptions(), pq.getFilter()); CursorId cursorId = cursor->cursorid(); ClientCursorPin ccPin(collection->getCursorManager(), cursorId); // On early return, get rid of the the cursor. ScopeGuard cursorFreer = MakeGuard(&ClientCursorPin::deleteUnderlying, ccPin); invariant(!exec); PlanExecutor* cursorExec = cursor->getExecutor(); // 5) Stream query results, adding them to a BSONArray as we go. BSONArrayBuilder firstBatch; BSONObj obj; PlanExecutor::ExecState state; long long numResults = 0; while (!enoughForFirstBatch(pq, numResults, firstBatch.len()) && PlanExecutor::ADVANCED == (state = cursorExec->getNext(&obj, NULL))) { // If adding this object will cause us to exceed the BSON size limit, then we stash // it for later. if (firstBatch.len() + obj.objsize() > BSONObjMaxUserSize && numResults > 0) { cursorExec->enqueue(obj); break; } // Add result to output buffer. firstBatch.append(obj); numResults++; } // Throw an assertion if query execution fails for any reason. if (PlanExecutor::FAILURE == state || PlanExecutor::DEAD == state) { const std::unique_ptr<PlanStageStats> stats(cursorExec->getStats()); error() << "Plan executor error during find command: " << PlanExecutor::statestr(state) << ", stats: " << Explain::statsToBSON(*stats); return appendCommandStatus(result, Status(ErrorCodes::OperationFailed, str::stream() << "Executor error during find command: " << WorkingSetCommon::toStatusString(obj))); } // 6) Set up the cursor for getMore. if (shouldSaveCursor(txn, collection, state, cursorExec)) { // State will be restored on getMore. cursorExec->saveState(); cursorExec->detachFromOperationContext(); cursor->setLeftoverMaxTimeMicros(CurOp::get(txn)->getRemainingMaxTimeMicros()); cursor->setPos(numResults); } else { cursorId = 0; } // Fill out curop based on the results. endQueryOp(txn, *cursorExec, dbProfilingLevel, numResults, cursorId); // 7) Generate the response object to send to the client. appendCursorResponseObject(cursorId, nss.ns(), firstBatch.arr(), &result); if (cursorId) { cursorFreer.Dismiss(); } return true; }
/** * This is called by db/ops/query.cpp. This is the entry point for answering a query. */ string newRunQuery(Message& m, QueryMessage& q, CurOp& curop, Message &result) { log() << "Running query on new system: " << q.query.toString() << endl; // This is a read lock. Client::ReadContext ctx(q.ns, dbpath); // Parse, canonicalize, plan, transcribe, and get a runner. Runner* rawRunner; CanonicalQuery* cq; Status status = getRunner(q, &rawRunner, &cq); if (!status.isOK()) { uasserted(17007, "Couldn't process query " + q.query.toString() + " why: " + status.reason()); } verify(NULL != rawRunner); auto_ptr<Runner> runner(rawRunner); // We freak out later if this changes before we're done with the query. const ChunkVersion shardingVersionAtStart = shardingState.getVersion(q.ns); // We use this a lot below. const LiteParsedQuery& pq = cq->getParsed(); // TODO: Document why we do this. // TODO: do this when we can pass in our own parsed query //replVerifyReadsOk(&pq); // If this exists, the collection is sharded. // If it doesn't exist, we can assume we're not sharded. // If we're sharded, we might encounter data that is not consistent with our sharding state. // We must ignore this data. CollectionMetadataPtr collMetadata; if (!shardingState.needCollectionMetadata(pq.ns())) { collMetadata = CollectionMetadataPtr(); } else { collMetadata = shardingState.getCollectionMetadata(pq.ns()); } // Run the query. BufBuilder bb(32768); bb.skip(sizeof(QueryResult)); // How many results have we obtained from the runner? int numResults = 0; // If we're replaying the oplog, we save the last time that we read. OpTime slaveReadTill; // Do we save the Runner in a ClientCursor for getMore calls later? bool saveClientCursor = false; // We turn on auto-yielding for the runner here, so we must register it with the active // runners list in ClientCursor. ClientCursor::registerRunner(runner.get()); runner->setYieldPolicy(Runner::YIELD_AUTO); BSONObj obj; Runner::RunnerState state; while (Runner::RUNNER_ADVANCED == (state = runner->getNext(&obj, NULL))) { // If we're sharded make sure that we don't return any data that hasn't been migrated // off of our shared yet. if (collMetadata) { // This information can change if we yield and as such we must make sure to re-fetch // it if we yield. KeyPattern kp(collMetadata->getKeyPattern()); // This performs excessive BSONObj creation but that's OK for now. 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(); } } // TODO: only one type of 2d search doesn't support this. We need a way to pull it out // 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); } if (!status.isOK()) { // NOTE: Do not access cq as getRunner has deleted it. uasserted(17007, "Unable to execute query: " + status.reason()); } verify(NULL != rawRunner); auto_ptr<Runner> runner(rawRunner); // We freak out later if this changes before we're done with the query. const ChunkVersion shardingVersionAtStart = shardingState.getVersion(cq->ns()); // Handle query option $maxTimeMS (not used with commands). curop.setMaxTimeMicros(static_cast<unsigned long long>(pq.getMaxTimeMS()) * 1000); killCurrentOp.checkForInterrupt(); // May trigger maxTimeAlwaysTimeOut fail point. // uassert if we are not on a primary, and not a secondary with SlaveOk query parameter set. replVerifyReadsOk(&pq); // If this exists, the collection is sharded. // If it doesn't exist, we can assume we're not sharded. // If we're sharded, we might encounter data that is not consistent with our sharding state. // We must ignore this data. CollectionMetadataPtr collMetadata; if (!shardingState.needCollectionMetadata(pq.ns())) { collMetadata = CollectionMetadataPtr(); } else { collMetadata = shardingState.getCollectionMetadata(pq.ns()); } // 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(32768); bb.skip(sizeof(QueryResult)); // How many results have we obtained from the runner? int numResults = 0; // If we're replaying the oplog, we save the last time that we read. OpTime slaveReadTill; // Do we save the Runner in a ClientCursor for getMore calls later? bool saveClientCursor = false; // We turn on auto-yielding for the runner here. The runner registers itself with the // active runners list in ClientCursor. auto_ptr<ScopedRunnerRegistration> safety(new ScopedRunnerRegistration(runner.get())); runner->setYieldPolicy(Runner::YIELD_AUTO); BSONObj obj; Runner::RunnerState state; // uint64_t numMisplacedDocs = 0; // set this outside loop. we will need to use this both within loop and when deciding // to fill in explain information const bool isExplain = pq.isExplain(); // Have we retrieved info about which plan the runner will // use to execute the query yet? bool gotPlanInfo = false; PlanInfo* rawInfo; boost::scoped_ptr<PlanInfo> planInfo; while (Runner::RUNNER_ADVANCED == (state = runner->getNext(&obj, NULL))) { // Add result to output buffer. This is unnecessary if explain info is requested if (!isExplain) { bb.appendBuf((void*)obj.objdata(), obj.objsize()); } // Count the result. ++numResults; // In the case of the multi plan runner, we may not be able to // successfully retrieve plan info until after the query starts // to run. This is because the multi plan runner doesn't know what // plan it will end up using until it runs candidates and selects // the best. // // TODO: Do we ever want to output what the MPR is comparing? if (!gotPlanInfo) { Status infoStatus = runner->getInfo(NULL, &rawInfo); if (infoStatus.isOK()) { gotPlanInfo = true; planInfo.reset(rawInfo); // planSummary is really a ThreadSafeString which copies the data from // the provided pointer. curop.debug().planSummary = planInfo->planSummary.c_str(); } } // 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(); } } // TODO: only one type of 2d search doesn't support this. We need a way to pull it out // of CanonicalQuery. :( const bool supportsGetMore = true; if (isExplain) { if (enoughForExplain(pq, numResults)) { break; } } else if (!supportsGetMore && (enough(pq, numResults) || bb.len() >= MaxBytesToReturnToClientAtOnce)) { break; } else if (enoughForFirstBatch(pq, numResults, bb.len())) { QLOG() << "Enough for first batch, wantMore=" << pq.wantMore() << " numToReturn=" << pq.getNumToReturn() << " numResults=" << numResults << endl; // If only one result requested assume it's a findOne() and don't save the cursor. if (pq.wantMore() && 1 != pq.getNumToReturn()) { QLOG() << " runner EOF=" << runner->isEOF() << endl; saveClientCursor = !runner->isEOF(); } break; } } // Try to get information about the plan which the runner // will use to execute the query, it we don't have it already. if (!gotPlanInfo) { Status infoStatus = runner->getInfo(NULL, &rawInfo); if (infoStatus.isOK()) { gotPlanInfo = true; planInfo.reset(rawInfo); // planSummary is really a ThreadSafeString which copies the data from // the provided pointer. curop.debug().planSummary = planInfo->planSummary.c_str(); } } // 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. safety.reset(); // Caller expects exceptions thrown in certain cases. if (Runner::RUNNER_ERROR == state) { TypeExplain* bareExplain; Status res = runner->getInfo(&bareExplain, NULL); if (res.isOK()) { boost::scoped_ptr<TypeExplain> errorExplain(bareExplain); error() << "Runner error, stats:\n" << errorExplain->stats.jsonString(Strict, true); } uasserted(17144, "Runner error: " + WorkingSetCommon::toStatusString(obj)); } // Why save a dead runner? if (Runner::RUNNER_DEAD == state) { saveClientCursor = false; } else if (pq.hasOption(QueryOption_CursorTailable)) { // If we're tailing a capped collection, we don't bother saving the cursor if the // collection is empty. Otherwise, the semantics of the tailable cursor is that the // client will keep trying to read from it. So we'll keep it around. Collection* collection = ctx.ctx().db()->getCollection(cq->ns()); if (collection && collection->numRecords() != 0 && pq.getNumToReturn() != 1) { saveClientCursor = true; } } // 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())); } // Used to fill in explain and to determine if the query is slow enough to be logged. int elapsedMillis = curop.elapsedMillis(); // Get explain information if: // 1) it is needed by an explain query; // 2) profiling is enabled; or // 3) profiling is disabled but we still need explain details to log a "slow" query. // Producing explain information is expensive and should be done only if we are certain // the information will be used. boost::scoped_ptr<TypeExplain> explain(NULL); if (isExplain || ctx.ctx().db()->getProfilingLevel() > 0 || elapsedMillis > serverGlobalParams.slowMS) { // Ask the runner to produce explain information. TypeExplain* bareExplain; Status res = runner->getInfo(&bareExplain, NULL); if (res.isOK()) { explain.reset(bareExplain); } else if (isExplain) { 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. } } // Fill in the missing run-time fields in explain, starting with propeties of // the process running the query. if (isExplain && NULL != explain.get()) { 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(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(collection, 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; // Set debug information for consumption by the profiler. curop.debug().ntoskip = pq.getSkip(); curop.debug().nreturned = numResults; if (NULL != explain.get()) { if (explain->isScanAndOrderSet()) { curop.debug().scanAndOrder = explain->getScanAndOrder(); } else { curop.debug().scanAndOrder = false; } if (explain->isNScannedSet()) { curop.debug().nscanned = explain->getNScanned(); } if (explain->isNScannedObjectsSet()) { curop.debug().nscannedObjects = explain->getNScannedObjects(); } if (explain->isIDHackSet()) { curop.debug().idhack = explain->getIDHack(); } if (!explain->stats.isEmpty()) { // execStats is a CachedBSONObj because it lives in the race-prone // curop. curop.debug().execStats.set(explain->stats); // Replace exec stats with plan summary if stats cannot fit into CachedBSONObj. if (curop.debug().execStats.tooBig() && !curop.debug().planSummary.empty()) { BSONObjBuilder bob; bob.append("summary", curop.debug().planSummary.toString()); curop.debug().execStats.set(bob.done()); } } } // curop.debug().exhaust is set above. return curop.debug().exhaust ? pq.ns() : ""; }