std::unique_ptr<Message> LegacyReplyBuilder::done() {
invariant(_state == State::kOutputDocs);
BSONObj reply = uassertStatusOK(rpc::downconvertReplyMetadata(_commandReply, _metadata));
BufBuilder bufBuilder;
bufBuilder.skip(sizeof(QueryResult::Value));
if (_allowAddingOutputDocs) {
BSONObjBuilder topBuilder(bufBuilder);
for (const auto& el : reply) {
if (kCursorTag != el.fieldNameStringData()) {
topBuilder.append(el);
continue;
}
invariant(el.isABSONObj());
BSONObjBuilder curBuilder(topBuilder.subobjStart(kCursorTag));
for (const auto& insideEl : el.Obj()) {
if (kFirstBatchTag != insideEl.fieldNameStringData()) {
curBuilder.append(insideEl);
continue;
}
invariant(insideEl.isABSONObj());
BSONArrayBuilder arrBuilder(curBuilder.subarrayStart(kFirstBatchTag));
for (const auto& doc : _outputDocs) {
arrBuilder.append(doc);
}
arrBuilder.doneFast();
}
curBuilder.doneFast();
}
topBuilder.doneFast();
} else {
reply.appendSelfToBufBuilder(bufBuilder);
}
auto msgHeaderSz = static_cast<std::size_t>(MsgData::MsgDataHeaderSize);
invariant(static_cast<std::size_t>(bufBuilder.len()) + msgHeaderSz <=
mongol::MaxMessageSizeBytes);
QueryResult::View qr = bufBuilder.buf();
qr.setResultFlagsToOk();
qr.msgdata().setLen(bufBuilder.len());
qr.msgdata().setOperation(opReply);
qr.setCursorId(0);
qr.setStartingFrom(0);
qr.setNReturned(1);
_message->setData(qr.view2ptr(), true);
bufBuilder.decouple();
_state = State::kDone;
return std::move(_message);
}
void generateLegacyQueryErrorResponse(const AssertionException* exception,
const QueryMessage& queryMessage,
CurOp* curop,
Message* response) {
curop->debug().exceptionInfo = exception->getInfo();
log(LogComponent::kQuery) << "assertion " << exception->toString() << " ns:" << queryMessage.ns
<< " query:" << (queryMessage.query.valid()
? queryMessage.query.toString()
: "query object is corrupt");
if (queryMessage.ntoskip || queryMessage.ntoreturn) {
log(LogComponent::kQuery) << " ntoskip:" << queryMessage.ntoskip
<< " ntoreturn:" << queryMessage.ntoreturn;
}
const SendStaleConfigException* scex = (exception->getCode() == ErrorCodes::SendStaleConfig)
? static_cast<const SendStaleConfigException*>(exception)
: NULL;
BSONObjBuilder err;
exception->getInfo().append(err);
if (scex) {
err.append("ok", 0.0);
err.append("ns", scex->getns());
scex->getVersionReceived().addToBSON(err, "vReceived");
scex->getVersionWanted().addToBSON(err, "vWanted");
}
BSONObj errObj = err.done();
if (scex) {
log(LogComponent::kQuery) << "stale version detected during query over " << queryMessage.ns
<< " : " << errObj;
}
BufBuilder bb;
bb.skip(sizeof(QueryResult::Value));
bb.appendBuf((void*)errObj.objdata(), errObj.objsize());
// TODO: call replyToQuery() from here instead of this!!! see dbmessage.h
QueryResult::View msgdata = bb.buf();
bb.decouple();
QueryResult::View qr = msgdata;
qr.setResultFlags(ResultFlag_ErrSet);
if (scex)
qr.setResultFlags(qr.getResultFlags() | ResultFlag_ShardConfigStale);
qr.msgdata().setLen(bb.len());
qr.msgdata().setOperation(opReply);
qr.setCursorId(0);
qr.setStartingFrom(0);
qr.setNReturned(1);
response->setData(msgdata.view2ptr(), true);
}
void replyToQuery( int queryResultFlags, Message& response, const BSONObj& resultObj ) {
BufBuilder bufBuilder;
bufBuilder.skip( sizeof( QueryResult::Value ));
bufBuilder.appendBuf( reinterpret_cast< void *>(
const_cast< char* >( resultObj.objdata() )), resultObj.objsize() );
QueryResult::View queryResult = bufBuilder.buf();
bufBuilder.decouple();
queryResult.setResultFlags(queryResultFlags);
queryResult.msgdata().setLen(bufBuilder.len());
queryResult.msgdata().setOperation( opReply );
queryResult.setCursorId(0);
queryResult.setStartingFrom(0);
queryResult.setNReturned(1);
response.setData( queryResult.view2ptr(), true ); // transport will free
}
Message LegacyReplyBuilder::done() {
invariant(_state == State::kOutputDocs);
QueryResult::View qr = _builder.buf();
qr.setResultFlagsToOk();
qr.msgdata().setLen(_builder.len());
qr.msgdata().setOperation(opReply);
qr.setCursorId(0);
qr.setStartingFrom(0);
qr.setNReturned(1);
_message.setData(qr.view2ptr(), true);
_builder.decouple();
_state = State::kDone;
return std::move(_message);
}
void replyToQuery(int queryResultFlags,
AbstractMessagingPort* p, Message& requestMsg,
void *data, int size,
int nReturned, int startingFrom,
long long cursorId
) {
BufBuilder b(32768);
b.skip(sizeof(QueryResult::Value));
b.appendBuf(data, size);
QueryResult::View qr = b.buf();
qr.setResultFlags(queryResultFlags);
qr.msgdata().setLen(b.len());
qr.msgdata().setOperation(opReply);
qr.setCursorId(cursorId);
qr.setStartingFrom(startingFrom);
qr.setNReturned(nReturned);
b.decouple();
Message resp(qr.view2ptr(), true);
p->reply(requestMsg, resp, requestMsg.header().getId());
}
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() : "";
}
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() : "";
}
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(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" << 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 = uassertStatusOK(
getExecutorFind(txn, collection, nss, std::move(cq), PlanExecutor::YIELD_AUTO));
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 "";
}
// 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(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 (pq.isOplogReplay()) {
BSONElement e = obj["ts"];
if (Date == e.type() || bsonTimestamp == e.type()) {
slaveReadTill = e.timestamp();
}
}
if (FindCommon::enoughForFirstBatch(pq, numResults)) {
LOG(5) << "Enough for first batch, wantMore=" << pq.wantMore()
<< " ntoreturn=" << pq.getNToReturn().value_or(0) << " 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 || PlanExecutor::DEAD == state) {
error() << "Plan executor error during find: " << PlanExecutor::statestr(state)
<< ", stats: " << 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. 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(),
txn->recoveryUnit()->isReadingFromMajorityCommittedSnapshot(),
pq.getOptions(),
pq.getFilter());
ccId = cc->cursorid();
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(txn, collection, *cc->getExecutor(), dbProfilingLevel, numResults, ccId);
} else {
LOG(5) << "Not caching executor but returning " << numResults << " results.\n";
endQueryOp(txn, collection, *exec, dbProfilingLevel, numResults, ccId);
}
// 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() : "";
}