/**
* Apply the read concern from the cursor to this operation.
*/
void applyCursorReadConcern(OperationContext* opCtx, repl::ReadConcernArgs rcArgs) {
const auto replicationMode = repl::ReplicationCoordinator::get(opCtx)->getReplicationMode();
// Select the appropriate read source.
if (replicationMode == repl::ReplicationCoordinator::modeReplSet &&
rcArgs.getLevel() == repl::ReadConcernLevel::kMajorityReadConcern) {
switch (rcArgs.getMajorityReadMechanism()) {
case repl::ReadConcernArgs::MajorityReadMechanism::kMajoritySnapshot: {
// Make sure we read from the majority snapshot.
opCtx->recoveryUnit()->setTimestampReadSource(
RecoveryUnit::ReadSource::kMajorityCommitted);
uassertStatusOK(opCtx->recoveryUnit()->obtainMajorityCommittedSnapshot());
break;
}
case repl::ReadConcernArgs::MajorityReadMechanism::kSpeculative: {
// Mark the operation as speculative and select the correct read source.
repl::SpeculativeMajorityReadInfo::get(opCtx).setIsSpeculativeRead();
opCtx->recoveryUnit()->setTimestampReadSource(RecoveryUnit::ReadSource::kNoOverlap);
break;
}
}
}
// For cursor commands that take locks internally, the read concern on the
// OperationContext may affect the timestamp read source selected by the storage engine.
// We place the cursor read concern onto the OperationContext so the lock acquisition
// respects the cursor's read concern.
{
stdx::lock_guard<Client> lk(*opCtx->getClient());
repl::ReadConcernArgs::get(opCtx) = rcArgs;
}
}
StatusWith<Shard::QueryResponse> ShardRemote::_exhaustiveFindOnConfig(
OperationContext* txn,
const ReadPreferenceSetting& readPref,
const repl::ReadConcernLevel& readConcernLevel,
const NamespaceString& nss,
const BSONObj& query,
const BSONObj& sort,
boost::optional<long long> limit) {
invariant(getId() == "config");
ReadPreferenceSetting readPrefWithMinOpTime(readPref);
readPrefWithMinOpTime.minOpTime = grid.configOpTime();
const auto host = _targeter->findHost(txn, readPrefWithMinOpTime);
if (!host.isOK()) {
return host.getStatus();
}
QueryResponse response;
// If for some reason the callback never gets invoked, we will return this status in response.
Status status = Status(ErrorCodes::InternalError, "Internal error running find command");
auto fetcherCallback =
[this, &status, &response](const Fetcher::QueryResponseStatus& dataStatus,
Fetcher::NextAction* nextAction,
BSONObjBuilder* getMoreBob) {
// Throw out any accumulated results on error
if (!dataStatus.isOK()) {
status = dataStatus.getStatus();
response.docs.clear();
return;
}
auto& data = dataStatus.getValue();
if (data.otherFields.metadata.hasField(rpc::kReplSetMetadataFieldName)) {
auto replParseStatus =
rpc::ReplSetMetadata::readFromMetadata(data.otherFields.metadata);
if (!replParseStatus.isOK()) {
status = replParseStatus.getStatus();
response.docs.clear();
return;
}
response.opTime = replParseStatus.getValue().getLastOpCommitted();
// We return the config opTime that was returned for this particular request, but as
// a safeguard we ensure our global configOpTime is at least as large as it.
invariant(grid.configOpTime() >= response.opTime);
}
for (const BSONObj& doc : data.documents) {
response.docs.push_back(doc.getOwned());
}
status = Status::OK();
if (!getMoreBob) {
return;
}
getMoreBob->append("getMore", data.cursorId);
getMoreBob->append("collection", data.nss.coll());
};
BSONObj readConcernObj;
{
invariant(readConcernLevel == repl::ReadConcernLevel::kMajorityReadConcern);
const repl::ReadConcernArgs readConcern{grid.configOpTime(), readConcernLevel};
BSONObjBuilder bob;
readConcern.appendInfo(&bob);
readConcernObj =
bob.done().getObjectField(repl::ReadConcernArgs::kReadConcernFieldName).getOwned();
}
const Milliseconds maxTimeMS =
std::min(txn->getRemainingMaxTimeMillis(), kDefaultConfigCommandTimeout);
BSONObjBuilder findCmdBuilder;
{
QueryRequest qr(nss);
qr.setFilter(query);
qr.setSort(sort);
qr.setReadConcern(readConcernObj);
qr.setLimit(limit);
if (maxTimeMS < Milliseconds::max()) {
qr.setMaxTimeMS(durationCount<Milliseconds>(maxTimeMS));
}
qr.asFindCommand(&findCmdBuilder);
}
Fetcher fetcher(Grid::get(txn)->getExecutorPool()->getFixedExecutor(),
host.getValue(),
nss.db().toString(),
findCmdBuilder.done(),
fetcherCallback,
_appendMetadataForCommand(txn, readPrefWithMinOpTime),
maxTimeMS);
Status scheduleStatus = fetcher.schedule();
if (!scheduleStatus.isOK()) {
return scheduleStatus;
}
fetcher.join();
updateReplSetMonitor(host.getValue(), status);
if (!status.isOK()) {
if (status.compareCode(ErrorCodes::ExceededTimeLimit)) {
LOG(0) << "Operation timed out " << causedBy(status);
}
return status;
}
return response;
}
StatusWith<Shard::QueryResponse> ShardRemote::_exhaustiveFindOnConfig(
OperationContext* txn,
const ReadPreferenceSetting& readPref,
const repl::ReadConcernLevel& readConcernLevel,
const NamespaceString& nss,
const BSONObj& query,
const BSONObj& sort,
boost::optional<long long> limit) {
// Do not allow exhaustive finds to be run against regular shards.
invariant(getId() == "config");
const auto host =
_targeter->findHost(readPref, RemoteCommandTargeter::selectFindHostMaxWaitTime(txn));
if (!host.isOK()) {
return host.getStatus();
}
QueryResponse response;
// If for some reason the callback never gets invoked, we will return this status in response.
Status status = Status(ErrorCodes::InternalError, "Internal error running find command");
auto fetcherCallback =
[this, &status, &response](const Fetcher::QueryResponseStatus& dataStatus,
Fetcher::NextAction* nextAction,
BSONObjBuilder* getMoreBob) {
// Throw out any accumulated results on error
if (!dataStatus.isOK()) {
status = dataStatus.getStatus();
response.docs.clear();
return;
}
auto& data = dataStatus.getValue();
if (data.otherFields.metadata.hasField(rpc::kReplSetMetadataFieldName)) {
auto replParseStatus =
rpc::ReplSetMetadata::readFromMetadata(data.otherFields.metadata);
if (!replParseStatus.isOK()) {
status = replParseStatus.getStatus();
response.docs.clear();
return;
}
response.opTime = replParseStatus.getValue().getLastOpCommitted();
// We return the config opTime that was returned for this particular request, but as
// a safeguard we ensure our global configOpTime is at least as large as it.
invariant(grid.configOpTime() >= response.opTime);
}
for (const BSONObj& doc : data.documents) {
response.docs.push_back(doc.getOwned());
}
status = Status::OK();
if (!getMoreBob) {
return;
}
getMoreBob->append("getMore", data.cursorId);
getMoreBob->append("collection", data.nss.coll());
};
BSONObj readConcernObj;
{
invariant(readConcernLevel == repl::ReadConcernLevel::kMajorityReadConcern);
const repl::ReadConcernArgs readConcern{grid.configOpTime(), readConcernLevel};
BSONObjBuilder bob;
readConcern.appendInfo(&bob);
readConcernObj =
bob.done().getObjectField(repl::ReadConcernArgs::kReadConcernFieldName).getOwned();
}
auto qr = stdx::make_unique<QueryRequest>(nss);
qr->setFilter(query);
qr->setSort(sort);
qr->setReadConcern(readConcernObj);
qr->setLimit(limit);
BSONObjBuilder findCmdBuilder;
qr->asFindCommand(&findCmdBuilder);
Microseconds maxTime = std::min(duration_cast<Microseconds>(kConfigCommandTimeout),
txn->getRemainingMaxTimeMicros());
if (maxTime < Milliseconds{1}) {
// If there is less than 1ms remaining before the maxTime timeout expires, set the max time
// to 1ms, since setting maxTimeMs to 1ms in a find command means "no max time".
maxTime = Milliseconds{1};
}
findCmdBuilder.append(QueryRequest::cmdOptionMaxTimeMS, durationCount<Milliseconds>(maxTime));
Fetcher fetcher(Grid::get(txn)->getExecutorPool()->getFixedExecutor(),
host.getValue(),
nss.db().toString(),
findCmdBuilder.done(),
fetcherCallback,
_getMetadataForCommand(readPref),
duration_cast<Milliseconds>(maxTime));
Status scheduleStatus = fetcher.schedule();
if (!scheduleStatus.isOK()) {
return scheduleStatus;
}
fetcher.wait();
updateReplSetMonitor(host.getValue(), status);
if (!status.isOK()) {
if (status.compareCode(ErrorCodes::ExceededTimeLimit)) {
LOG(0) << "Operation timed out with status " << status;
}
return status;
}
return response;
}
Status waitForReadConcern(OperationContext* txn, const repl::ReadConcernArgs& readConcernArgs) {
repl::ReplicationCoordinator* const replCoord = repl::ReplicationCoordinator::get(txn);
if (readConcernArgs.getLevel() == repl::ReadConcernLevel::kLinearizableReadConcern) {
if (replCoord->getReplicationMode() != repl::ReplicationCoordinator::modeReplSet) {
// For master/slave and standalone nodes, Linearizable Read is not supported.
return {ErrorCodes::NotAReplicaSet,
"node needs to be a replica set member to use read concern"};
}
// Replica sets running pv0 do not support linearizable read concern until further testing
// is completed (SERVER-27025).
if (!replCoord->isV1ElectionProtocol()) {
return {
ErrorCodes::IncompatibleElectionProtocol,
"Replica sets running protocol version 0 do not support readConcern: linearizable"};
}
if (!readConcernArgs.getOpTime().isNull()) {
return {ErrorCodes::FailedToParse,
"afterOpTime not compatible with linearizable read concern"};
}
if (!replCoord->getMemberState().primary()) {
return {ErrorCodes::NotMaster,
"cannot satisfy linearizable read concern on non-primary node"};
}
}
// Skip waiting for the OpTime when testing snapshot behavior
if (!testingSnapshotBehaviorInIsolation && !readConcernArgs.isEmpty()) {
Status status = replCoord->waitUntilOpTimeForRead(txn, readConcernArgs);
if (!status.isOK()) {
return status;
}
}
if ((replCoord->getReplicationMode() == repl::ReplicationCoordinator::Mode::modeReplSet ||
testingSnapshotBehaviorInIsolation) &&
readConcernArgs.getLevel() == repl::ReadConcernLevel::kMajorityReadConcern) {
// ReadConcern Majority is not supported in ProtocolVersion 0.
if (!testingSnapshotBehaviorInIsolation && !replCoord->isV1ElectionProtocol()) {
return {ErrorCodes::ReadConcernMajorityNotEnabled,
str::stream() << "Replica sets running protocol version 0 do not support "
"readConcern: majority"};
}
const int debugLevel = serverGlobalParams.clusterRole == ClusterRole::ConfigServer ? 1 : 2;
LOG(debugLevel) << "Waiting for 'committed' snapshot to be available for reading: "
<< readConcernArgs;
Status status = txn->recoveryUnit()->setReadFromMajorityCommittedSnapshot();
// Wait until a snapshot is available.
while (status == ErrorCodes::ReadConcernMajorityNotAvailableYet) {
LOG(debugLevel) << "Snapshot not available yet.";
replCoord->waitUntilSnapshotCommitted(txn, SnapshotName::min());
status = txn->recoveryUnit()->setReadFromMajorityCommittedSnapshot();
}
if (!status.isOK()) {
return status;
}
LOG(debugLevel) << "Using 'committed' snapshot: " << CurOp::get(txn)->query();
}
return Status::OK();
}
