Exemple #1
0
/**
 * 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();
}
Exemple #2
0
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;
}