/**
* Checks the first batch of results from query.
* 'documents' are the first batch of results returned from tailing the remote oplog.
* 'lastFetched' optime and hash should be consistent with the predicate in the query.
* Returns RemoteOplogStale if the oplog query has no results.
* Returns OplogStartMissing if we cannot find the optime of the last fetched operation in
* the remote oplog.
*/
Status checkRemoteOplogStart(const Fetcher::Documents& documents, OpTimeWithHash lastFetched) {
if (documents.empty()) {
// The GTE query from upstream returns nothing, so we're ahead of the upstream.
return Status(ErrorCodes::RemoteOplogStale,
str::stream() << "We are ahead of the sync source. Our last op time fetched: "
<< lastFetched.opTime.toString());
}
const auto& o = documents.front();
auto opTimeResult = OpTime::parseFromOplogEntry(o);
if (!opTimeResult.isOK()) {
return Status(ErrorCodes::OplogStartMissing,
str::stream() << "our last op time fetched: " << lastFetched.opTime.toString()
<< " (hash: "
<< lastFetched.value
<< ")"
<< ". failed to parse optime from first oplog on source: "
<< o.toString()
<< ": "
<< opTimeResult.getStatus().toString());
}
auto opTime = opTimeResult.getValue();
long long hash = o["h"].numberLong();
if (opTime != lastFetched.opTime || hash != lastFetched.value) {
return Status(ErrorCodes::OplogStartMissing,
str::stream() << "our last op time fetched: " << lastFetched.opTime.toString()
<< ". source's GTE: "
<< opTime.toString()
<< " hashes: ("
<< lastFetched.value
<< "/"
<< hash
<< ")");
}
return Status::OK();
}
StatusWith<OplogFetcher::DocumentsInfo> OplogFetcher::validateDocuments(
const Fetcher::Documents& documents, bool first, Timestamp lastTS) {
if (first && documents.empty()) {
return Status(ErrorCodes::OplogStartMissing,
str::stream() << "The first batch of oplog entries is empty, but expected at "
"least 1 document matching ts: "
<< lastTS.toString());
}
DocumentsInfo info;
// The count of the bytes of the documents read off the network.
info.networkDocumentBytes = 0;
info.networkDocumentCount = 0;
for (auto&& doc : documents) {
info.networkDocumentBytes += doc.objsize();
++info.networkDocumentCount;
// If this is the first response (to the $gte query) then we already applied the first doc.
if (first && info.networkDocumentCount == 1U) {
continue;
}
// Check to see if the oplog entry goes back in time for this document.
const auto docOpTime = OpTime::parseFromOplogEntry(doc);
// entries must have a "ts" field.
if (!docOpTime.isOK()) {
return docOpTime.getStatus();
}
info.lastDocument = {doc["h"].numberLong(), docOpTime.getValue()};
const auto docTS = info.lastDocument.opTime.getTimestamp();
if (lastTS >= docTS) {
return Status(ErrorCodes::OplogOutOfOrder,
str::stream() << "Out of order entries in oplog. lastTS: "
<< lastTS.toString()
<< " outOfOrderTS:"
<< docTS.toString()
<< " in batch with "
<< info.networkDocumentCount
<< "docs; first-batch:"
<< first
<< ", doc:"
<< doc);
}
lastTS = docTS;
}
// These numbers are for the documents we will apply.
info.toApplyDocumentCount = documents.size();
info.toApplyDocumentBytes = info.networkDocumentBytes;
if (first) {
// The count is one less since the first document found was already applied ($gte $ts query)
// and we will not apply it again.
--info.toApplyDocumentCount;
auto alreadyAppliedDocument = documents.cbegin();
info.toApplyDocumentBytes -= alreadyAppliedDocument->objsize();
}
return info;
}