C++ DatagramPtr::add_data方法代码示例

void DBOperationGet::on_complete(DBObjectSnapshot *snapshot)
{
    DatagramPtr resp = Datagram::create();
    resp->add_server_header(m_sender, m_dbserver->m_control_channel,
                            m_resp_msgtype);
    resp->add_uint32(m_context);
    resp->add_uint8(SUCCESS);

    // Calculate the fields that we are sending in our response:
    FieldValues response_fields;
    if(m_resp_msgtype == DBSERVER_OBJECT_GET_ALL_RESP) {
        // Send everything:
        response_fields = snapshot->m_fields;
    } else {
        // Send only what was requested:
        for(auto it = m_get_fields.begin(); it != m_get_fields.end(); ++it) {
            auto it2 = snapshot->m_fields.find(*it);
            if(it2 != snapshot->m_fields.end()) {
                response_fields[it2->first] = it2->second;
            }
        }
    }

    // WHAT we send depends on our m_resp_msgtype, so:
    if(m_resp_msgtype == DBSERVER_OBJECT_GET_FIELD_RESP) {
        if(response_fields.empty()) {
            // We did not find the field we were looking for.
            // Therefore, this is a failure.
            on_failure();
            return;
        }

        resp->add_uint16(response_fields.begin()->first->get_id());
        resp->add_data(response_fields.begin()->second);

        // And that's it. We're done.
        m_dbserver->route_datagram(resp);
        delete snapshot;
        cleanup();
        return;
    }

    if(m_resp_msgtype == DBSERVER_OBJECT_GET_ALL_RESP) {
        resp->add_uint16(snapshot->m_dclass->get_id());
    }

    resp->add_uint16(response_fields.size());
    for(auto it = response_fields.begin(); it != response_fields.end(); ++it) {
        resp->add_uint16(it->first->get_id());
        resp->add_data(it->second);
    }

    m_dbserver->route_datagram(resp);
    delete snapshot;
    cleanup();
}

void DBStateServer::handle_get_fields_resp(DatagramIterator& dgi)
{
    uint32_t db_context = dgi.read_uint32();
    if(!is_expected_context(db_context)) {
        return;
    }

    // Get the datagram from the db_context
    DatagramPtr dg = m_context_datagrams[db_context];
    m_context_datagrams.erase(db_context);

    // Check to make sure the datagram is appropriate
    DatagramIterator check_dgi = DatagramIterator(dg);
    uint16_t resp_type = check_dgi.get_msg_type();
    if(resp_type != STATESERVER_OBJECT_GET_FIELDS_RESP) {
        if(resp_type == STATESERVER_OBJECT_GET_FIELD_RESP) {
            m_log->warning() << "Received GetFieldResp, but expecting GetFieldsResp." << std::endl;
        } else if(resp_type == STATESERVER_OBJECT_GET_ALL_RESP) {
            m_log->warning() << "Received GetAllResp, but expecting GetFieldsResp." << std::endl;
        }
        return;
    }

    m_log->trace() << "Received GetFieldResp from database." << std::endl;

    // Add database field payload to response (don't know dclass, so must copy payload).
    if(dgi.read_bool() == true) {
        dgi.read_uint16(); // Discard field count
        dg->add_data(dgi.read_remainder());
    }
    route_datagram(dg);
}

void DBOperationUpdate::on_criteria_mismatch(DBObjectSnapshot *snapshot)
{
    DatagramPtr resp = Datagram::create();
    resp->add_server_header(m_sender, m_dbserver->m_control_channel,
                            m_resp_msgtype);
    resp->add_uint32(m_context);
    resp->add_uint8(FAILURE);

    // Calculate the fields that we are sending in our response:
    FieldValues mismatched_fields;

    for(auto it = m_criteria_fields.begin(); it != m_criteria_fields.end(); ++it) {
        auto it2 = snapshot->m_fields.find(it->first);
        if(it2 != snapshot->m_fields.end() && !it2->second.empty()) {
            mismatched_fields[it2->first] = it2->second;
        }
    }

    if(m_resp_msgtype == DBSERVER_OBJECT_SET_FIELDS_IF_EQUALS_RESP) {
        resp->add_uint16(mismatched_fields.size());
    }

    for(auto it = mismatched_fields.begin(); it != mismatched_fields.end(); ++it) {
        resp->add_uint16(it->first->get_id());
        resp->add_data(it->second);
    }

    m_dbserver->route_datagram(resp);

    delete snapshot;
    cleanup();
}

bool DistributedObject::handle_one_update(DatagramIterator &dgi, channel_t sender)
{
    vector<uint8_t> data;
    uint16_t field_id = dgi.read_uint16();
    const Field *field = m_dclass->get_field_by_id(field_id);
    if(!field) {
        m_log->error() << "Received set_field for field: " << field_id
                       << ", not valid for class: " << m_dclass->get_name() << ".\n";
        return false;
    }

    m_log->trace() << "Handling update for '" << field->get_name() << "'.\n";

    dgsize_t field_start = dgi.tell();

    try {
        dgi.unpack_field(field, data);
    } catch(const DatagramIteratorEOF&) {
        m_log->error() << "Received truncated update for " << field->get_name() << ".\n";
        return false;
    }

    const MolecularField *molecular = field->as_molecular();
    if(molecular) {
        dgi.seek(field_start);
        int n = molecular->get_num_fields();
        for(int i = 0; i < n; ++i) {
            vector<uint8_t> field_data;
            const Field *atomic = molecular->get_field(i);
            dgi.unpack_field(atomic, field_data);
            save_field(atomic, field_data);
        }
    } else {
        save_field(field, data);
    }

    unordered_set<channel_t> targets;
    if(field->has_keyword("broadcast")) {
        targets.insert(location_as_channel(m_parent_id, m_zone_id));
    }
    if(field->has_keyword("airecv") && m_ai_channel && m_ai_channel != sender) {
        targets.insert(m_ai_channel);
    }
    if(field->has_keyword("ownrecv") && m_owner_channel && m_owner_channel != sender) {
        targets.insert(m_owner_channel);
    }
    if(targets.size()) { // TODO: Review this for efficiency?
        DatagramPtr dg = Datagram::create(targets, sender, STATESERVER_OBJECT_SET_FIELD);
        dg->add_doid(m_do_id);
        dg->add_uint16(field_id);
        dg->add_data(data);
        route_datagram(dg);
    }
    return true;
}

bool DistributedObject::handle_one_get(DatagramPtr out, uint16_t field_id,
                                       bool succeed_if_unset, bool is_subfield)
{
    const Field *field = m_dclass->get_field_by_id(field_id);
    if(!field) {
        m_log->error() << "Received get_field for field: " << field_id
                       << ", not valid for class: " << m_dclass->get_name() << ".\n";
        return false;
    }
    m_log->trace() << "Handling query for '" << field->get_name() << "'.\n";

    const MolecularField *molecular = field->as_molecular();
    if(molecular) {
        int n = molecular->get_num_fields();
        out->add_uint16(field_id);
        for(int i = 0; i < n; ++i) {
            if(!handle_one_get(out, molecular->get_field(i)->get_id(), succeed_if_unset, true)) {
                return false;
            }
        }
        return true;
    }

    if(m_required_fields.count(field)) {
        if(!is_subfield) {
            out->add_uint16(field_id);
        }
        out->add_data(m_required_fields[field]);
    } else if(m_ram_fields.count(field)) {
        if(!is_subfield) {
            out->add_uint16(field_id);
        }
        out->add_data(m_ram_fields[field]);
    } else {
        return succeed_if_unset;
    }

    return true;
}

void DBStateServer::handle_get_field(channel_t sender, DatagramIterator &dgi)
{
    uint32_t r_context = dgi.read_uint32();
    doid_t r_do_id = dgi.read_doid();
    uint16_t field_id = dgi.read_uint16();
    if(is_activated_object(r_do_id)) {
        return;
    }

    m_log->trace() << "Received GetField for field with id " << field_id
                   << " on inactive object with id " << r_do_id << "\n";

    // Check field is "ram db" or "required"
    const Field* field = g_dcf->get_field_by_id(field_id);
    if(!field || !(field->has_keyword("required") || field->has_keyword("ram"))) {
        DatagramPtr dg = Datagram::create(sender, r_do_id, STATESERVER_OBJECT_GET_FIELD_RESP);
        dg->add_uint32(r_context);
        dg->add_bool(false);
        route_datagram(dg);
        return;
    }

    if(field->has_keyword("db")) {
        // Get context for db query
        uint32_t db_context = m_next_context++;

        // Prepare reponse datagram
        DatagramPtr dg_resp = Datagram::create(sender, r_do_id, STATESERVER_OBJECT_GET_FIELD_RESP);
        dg_resp->add_uint32(r_context);
        m_context_datagrams[db_context] = dg_resp;

        // Send query to database
        DatagramPtr dg = Datagram::create(m_db_channel, r_do_id, DBSERVER_OBJECT_GET_FIELD);
        dg->add_uint32(db_context);
        dg->add_doid(r_do_id);
        dg->add_uint16(field_id);
        route_datagram(dg);
    } else if(field->has_default_value()) { // Field is required and not-db
        DatagramPtr dg = Datagram::create(sender, r_do_id, STATESERVER_OBJECT_GET_FIELD_RESP);
        dg->add_uint32(r_context);
        dg->add_bool(true);
        dg->add_uint16(field_id);
        dg->add_data(field->get_default_value());
        route_datagram(dg);
    } else {
        DatagramPtr dg = Datagram::create(sender, r_do_id, STATESERVER_OBJECT_GET_FIELD_RESP);
        dg->add_uint32(r_context);
        dg->add_bool(false);
        route_datagram(dg);
    }
}

    void handle_create(DBClientBase *client, DBOperation *operation)
    {
        // First, let's convert the requested object into BSON; this way, if
        // a failure happens, it happens before we waste a doid.
        BSONObjBuilder fields;

        try {
            for(auto it = operation->set_fields().begin();
                it != operation->set_fields().end();
                ++it) {
                DatagramPtr dg = Datagram::create();
                dg->add_data(it->second);
                DatagramIterator dgi(dg);
                fields << it->first->get_name()
                       << bamboo2bson(it->first->get_type(), dgi)["_"];
            }
        } catch(mongo::DBException &e) {
            m_log->error() << "While formatting "
                           << operation->dclass()->get_name()
                           << " for insertion: " << e.what() << endl;
            operation->on_failure();
            return;
        }

        doid_t doid = assign_doid(client);
        if(doid == INVALID_DO_ID) {
            // The error will already have been emitted at this point, so
            // all that's left for us to do is fail silently:
            operation->on_failure();
            return;
        }

        BSONObj b = BSON("_id" << doid <<
                         "dclass" << operation->dclass()->get_name() <<
                         "fields" << fields.obj());

        m_log->trace() << "Inserting new " << operation->dclass()->get_name()
                       << "(" << doid << "): " << b << endl;

        try {
            client->insert(m_obj_collection, b);
        } catch(mongo::DBException &e) {
            m_log->error() << "Cannot insert new "
                           << operation->dclass()->get_name()
                           << "(" << doid << "): " << e.what() << endl;
            operation->on_failure();
            return;
        }

        operation->on_complete(doid);
    }

void DistributedObject::append_other_data(DatagramPtr dg, bool client_only, bool also_owner)
{
    if(client_only) {
        vector<const Field*> broadcast_fields;
        for(auto it = m_ram_fields.begin(); it != m_ram_fields.end(); ++it) {
            if(it->first->has_keyword("broadcast") || it->first->has_keyword("clrecv")
               || (also_owner && it->first->has_keyword("ownrecv"))) {
                broadcast_fields.push_back(it->first);
            }
        }

        dg->add_uint16(broadcast_fields.size());
        for(auto it = broadcast_fields.begin(); it != broadcast_fields.end(); ++it) {
            dg->add_uint16((*it)->get_id());
            dg->add_data(m_ram_fields[*it]);
        }
    } else {
        dg->add_uint16(m_ram_fields.size());
        for(auto it = m_ram_fields.begin(); it != m_ram_fields.end(); ++it) {
            dg->add_uint16(it->first->get_id());
            dg->add_data(it->second);
        }
    }
}

void DistributedObject::append_required_data(DatagramPtr dg, bool client_only, bool also_owner)
{
    dg->add_doid(m_do_id);
    dg->add_location(m_parent_id, m_zone_id);
    dg->add_uint16(m_dclass->get_id());
    size_t field_count = m_dclass->get_num_fields();
    for(size_t i = 0; i < field_count; ++i) {
        const Field *field = m_dclass->get_field(i);
        if(field->has_keyword("required") && !field->as_molecular() && (!client_only
                || field->has_keyword("broadcast") || field->has_keyword("clrecv")
                || (also_owner && field->has_keyword("ownrecv")))) {
            dg->add_data(m_required_fields[field]);
        }
    }
}

void DBOperation::announce_fields(const FieldValues& fields)
{
    // Calculate the fields that we are sending in our response:
    FieldValues changed_fields;
    FieldSet deleted_fields;
    for(auto it = fields.begin(); it != fields.end(); ++it) {
        if(it->second.empty())
            deleted_fields.insert(it->first);
        else
            changed_fields[it->first] = it->second;
    }

    // Send delete fields broadcast
    if(!deleted_fields.empty()) {
        bool multi = (deleted_fields.size() > 1);
        DatagramPtr update = Datagram::create();
        update->add_server_header(database_to_object(m_doid), m_sender,
                                  multi ? DBSERVER_OBJECT_DELETE_FIELDS :
                                  DBSERVER_OBJECT_DELETE_FIELD);
        update->add_doid(m_doid);
        if(multi) {
            update->add_uint16(deleted_fields.size());
        }
        for(auto it = deleted_fields.begin(); it != deleted_fields.end(); ++it) {
            update->add_uint16((*it)->get_id());
        }
        m_dbserver->route_datagram(update);
    }

    // Send update fields broadcast
    if(!changed_fields.empty()) {
        bool multi = (changed_fields.size() > 1);
        DatagramPtr update = Datagram::create();
        update->add_server_header(database_to_object(m_doid), m_sender,
                                  multi ? DBSERVER_OBJECT_SET_FIELDS :
                                  DBSERVER_OBJECT_SET_FIELD);
        update->add_doid(m_doid);
        if(multi) {
            update->add_uint16(changed_fields.size());
        }
        for(auto it = changed_fields.begin(); it != changed_fields.end(); ++it) {
            update->add_uint16(it->first->get_id());
            update->add_data(it->second);
        }
        m_dbserver->route_datagram(update);
    }
}

void DBStateServer::handle_set_fields(DatagramIterator &dgi)
{
    doid_t do_id = dgi.read_doid();
    if(m_loading.find(do_id) != m_loading.end()) {
        // Ignore this message for now, it'll be bounced back to us
        // from the loading object if it succeeds or fails at loading.
        return;
    }

    uint16_t field_count = dgi.read_uint16();

    FieldValues db_fields;
    for(uint16_t i = 0; i < field_count; ++i) {
        uint16_t field_id = dgi.read_uint16();
        const Field* field = g_dcf->get_field_by_id(field_id);
        if(!field) {
            m_log->warning() << "Received invalid field with id " << field_id << " in SetFields.\n";
            return;
        }
        if(field->has_keyword("db")) {
            dgi.unpack_field(field, db_fields[field]);
        } else {
            dgi.skip_field(field);
        }
    }

    if(db_fields.size() > 0) {
        m_log->trace() << "Forwarding SetFields on object with id " << do_id << " to database.\n";

        DatagramPtr dg = Datagram::create(m_db_channel, do_id, DBSERVER_OBJECT_SET_FIELDS);
        dg->add_doid(do_id);
        dg->add_uint16(db_fields.size());
        for(const auto& it : db_fields) {
            dg->add_uint16(it.first->get_id());
            dg->add_data(it.second);
        }
        route_datagram(dg);
    }
}

void DBStateServer::handle_set_field(DatagramIterator &dgi)
{
    doid_t do_id = dgi.read_doid();
    if(m_loading.find(do_id) != m_loading.end()) {
        // Ignore this message for now, it'll be bounced back to us
        // from the loading object if it succeeds or fails at loading.
        return;
    }

    uint16_t field_id = dgi.read_uint16();

    const Field* field = g_dcf->get_field_by_id(field_id);
    if(field && field->has_keyword("db")) {
        m_log->trace() << "Forwarding SetField for field \"" << field->get_name()
                       << "\" on object with id " << do_id << " to database.\n";

        DatagramPtr dg = Datagram::create(m_db_channel, do_id, DBSERVER_OBJECT_SET_FIELD);
        dg->add_doid(do_id);
        dg->add_uint16(field_id);
        dg->add_data(dgi.read_remainder());
        route_datagram(dg);
    }
}

// handle_datagram is the handler for datagrams received from the Astron cluster
void Client::handle_datagram(DatagramHandle in_dg, DatagramIterator &dgi)
{
    lock_guard<recursive_mutex> lock(m_client_lock);
    if(is_terminated()) {
        return;
    }

    channel_t sender = dgi.read_channel();
    if(sender == m_channel) {
        return;    // ignore messages from ourselves
    }

    uint16_t msgtype = dgi.read_uint16();
    switch(msgtype) {
    case CLIENTAGENT_EJECT: {
        uint16_t reason = dgi.read_uint16();
        string error_string = dgi.read_string();
        send_disconnect(reason, error_string);
        return;
    }
    break;
    case CLIENTAGENT_DROP: {
        handle_drop();
        return;
    }
    break;
    case CLIENTAGENT_SET_STATE: {
        m_state = (ClientState)dgi.read_uint16();
    }
    break;
    case CLIENTAGENT_ADD_INTEREST: {
        uint32_t context = m_next_context++;

        Interest i;
        build_interest(dgi, false, i);
        handle_add_interest(i, context);
        add_interest(i, context, sender);
    }
    break;
    case CLIENTAGENT_ADD_INTEREST_MULTIPLE: {
        uint32_t context = m_next_context++;

        Interest i;
        build_interest(dgi, true, i);
        handle_add_interest(i, context);
        add_interest(i, context, sender);
    }
    break;
    case CLIENTAGENT_REMOVE_INTEREST: {
        uint32_t context = m_next_context++;

        uint16_t id = dgi.read_uint16();
        Interest &i = m_interests[id];
        handle_remove_interest(id, context);
        remove_interest(i, context, sender);
    }
    break;
    case CLIENTAGENT_SET_CLIENT_ID: {
        if(m_channel != m_allocated_channel) {
            unsubscribe_channel(m_channel);
        }

        m_channel = dgi.read_channel();
        subscribe_channel(m_channel);
    }
    break;
    case CLIENTAGENT_SEND_DATAGRAM: {
        DatagramPtr forward = Datagram::create();
        forward->add_data(dgi.read_string());
        forward_datagram(forward);
    }
    break;
    case CLIENTAGENT_OPEN_CHANNEL: {
        subscribe_channel(dgi.read_channel());
    }
    break;
    case CLIENTAGENT_CLOSE_CHANNEL: {
        unsubscribe_channel(dgi.read_channel());
    }
    break;
    case CLIENTAGENT_ADD_POST_REMOVE: {
        add_post_remove(m_allocated_channel, dgi.read_datagram());
    }
    break;
    case CLIENTAGENT_CLEAR_POST_REMOVES: {
        clear_post_removes(m_allocated_channel);
    }
    break;
    case CLIENTAGENT_DECLARE_OBJECT: {
        doid_t do_id = dgi.read_doid();
        uint16_t dc_id = dgi.read_uint16();

        if(m_declared_objects.find(do_id) != m_declared_objects.end()) {
            m_log->warning() << "Received object declaration for previously declared object "
                             << do_id << ".\n";
            return;
        }

        DeclaredObject obj;
//.........这里部分代码省略.........

void DBStateServer::handle_get_all_resp(DatagramIterator& dgi)
{
    uint32_t db_context = dgi.read_uint32();
    if(!is_expected_context(db_context)) {
        return;
    }

    // Get the datagram from the db_context
    DatagramPtr dg = m_context_datagrams[db_context];
    m_context_datagrams.erase(db_context);

    // Check to make sure the datagram is appropriate
    DatagramIterator check_dgi = DatagramIterator(dg);
    uint16_t resp_type = check_dgi.get_msg_type();
    if(resp_type != STATESERVER_OBJECT_GET_ALL_RESP) {
        if(resp_type == STATESERVER_OBJECT_GET_FIELD_RESP) {
            m_log->warning() << "Received GetFieldResp, but expecting GetAllResp." << std::endl;
        } else if(resp_type == STATESERVER_OBJECT_GET_FIELDS_RESP) {
            m_log->warning() << "Received GetFieldsResp, but expecting GetAllResp." << std::endl;
        }
        return;
    }

    // Get do_id from datagram
    check_dgi.seek_payload();
    check_dgi.skip(sizeof(channel_t) + sizeof(doid_t)); // skip over sender and context to do_id;
    doid_t do_id = check_dgi.read_doid();

    // Remove cached loading operation
    if(m_inactive_loads[do_id].size() > 1) {
        m_inactive_loads[do_id].erase(db_context);
    } else {
        m_inactive_loads.erase(do_id);
    }

    m_log->trace() << "Received GetAllResp from database." << std::endl;

    // If object not found, just cleanup the context map
    if(dgi.read_bool() != true) {
        return; // Object not found
    }

    // Read object class
    uint16_t dc_id = dgi.read_uint16();
    if(!dc_id) {
        m_log->error() << "Received object from database with unknown dclass"
                       << " - id:" << dc_id << std::endl;
        return;
    }
    const Class* r_class = g_dcf->get_class_by_id(dc_id);

    // Get fields from database
    UnorderedFieldValues required_fields;
    FieldValues ram_fields;
    if(!unpack_db_fields(dgi, r_class, required_fields, ram_fields)) {
        m_log->error() << "Error while unpacking fields from database." << std::endl;
        return;
    }

    // Add class to response
    dg->add_uint16(r_class->get_id());

    // Add required fields to datagram
    int dcc_field_count = r_class->get_num_fields();
    for(int i = 0; i < dcc_field_count; ++i) {
        const Field *field = r_class->get_field(i);
        if(!field->as_molecular() && field->has_keyword("required")) {
            auto req_it = required_fields.find(field);
            if(req_it != required_fields.end()) {
                dg->add_data(req_it->second);
            } else {
                dg->add_data(field->get_default_value());
            }
        }
    }

    // Add ram fields to datagram
    dg->add_uint16(ram_fields.size());
    for(const auto& it : ram_fields) {
        dg->add_uint16(it.first->get_id());
        dg->add_data(it.second);
    }

    // Send response back to caller
    route_datagram(dg);
}

    void handle_modify(DBClientBase *client, DBOperation *operation)
    {
        // First, we have to format our findandmodify.
        BSONObjBuilder sets;
        bool has_sets = false;
        BSONObjBuilder unsets;
        bool has_unsets = false;
        for(auto it  = operation->set_fields().begin();
            it != operation->set_fields().end(); ++it) {
            stringstream fieldname;
            fieldname << "fields." << it->first->get_name();
            if(it->second.empty()) {
                unsets << fieldname.str() << true;
                has_unsets = true;
            } else {
                DatagramPtr dg = Datagram::create();
                dg->add_data(it->second);
                DatagramIterator dgi(dg);
                sets << fieldname.str() << bamboo2bson(it->first->get_type(), dgi)["_"];
                has_sets = true;
            }
        }

        BSONObjBuilder updates_b;
        if(has_sets) {
            updates_b << "$set" << sets.obj();
        }
        if(has_unsets) {
            updates_b << "$unset" << unsets.obj();
        }
        BSONObj updates = updates_b.obj();

        // Also format any criteria for the change:
        BSONObjBuilder query_b;
        query_b << "_id" << operation->doid();
        for(auto it  = operation->criteria_fields().begin();
            it != operation->criteria_fields().end(); ++it) {
            stringstream fieldname;
            fieldname << "fields." << it->first->get_name();
            if(it->second.empty()) {
                query_b << fieldname.str() << BSON("$exists" << false);
            } else {
                DatagramPtr dg = Datagram::create();
                dg->add_data(it->second);
                DatagramIterator dgi(dg);
                query_b << fieldname.str() << bamboo2bson(it->first->get_type(), dgi)["_"];
            }
        }
        BSONObj query = query_b.obj();

        m_log->trace() << "Performing updates to " << operation->doid()
                       << ": " << updates << endl;
        m_log->trace() << "Query is: " << query << endl;

        BSONObj result;
        bool success;
        try {
            success = client->runCommand(
                          m_db,
                          BSON("findandmodify" << "astron.objects"
                               << "query" << query
                               << "update" << updates),
                          result);
        } catch(mongo::DBException &e) {
            m_log->error() << "Unexpected error while modifying "
                           << operation->doid() << ": " << e.what() << endl;
            operation->on_failure();
            return;
        }

        m_log->trace() << "Update result: " << result << endl;

        BSONObj obj;
        if(!success || result["value"].isNull()) {
            // Okay, something didn't work right. If we had criteria, let's
            // try to fetch the object without the criteria to see if it's a
            // criteria mismatch or a missing DOID.
            if(!operation->criteria_fields().empty()) {
                try {
                    obj = client->findOne(m_obj_collection,
                                         BSON("_id" << operation->doid()));
                } catch(mongo::DBException &e) {
                    m_log->error() << "Unexpected error while modifying "
                                   << operation->doid() << ": " << e.what() << endl;
                    operation->on_failure();
                    return;
                }
                if(!obj.isEmpty()) {
                    // There's the problem. Now we can send back a snapshot:
                    DBObjectSnapshot *snap = format_snapshot(operation->doid(), obj);
                    if(snap && operation->verify_class(snap->m_dclass)) {
                        operation->on_criteria_mismatch(snap);
                        return;
                    } else {
                        // Something else weird happened with our snapshot;
                        // either the class wasn't recognized or it was the
                        // wrong class. Either way, an error has been logged,
                        // and we need to fail the operation.
                        operation->on_failure();
                        return;
//.........这里部分代码省略.........