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// Copyright 2009-present MongoDB, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include <chrono>
#include <cstdlib>
#include <ctime>
#include <iostream>
#include <string>
#include <bsoncxx/builder/stream/document.hpp>
#include <bsoncxx/builder/stream/helpers.hpp>
#include <bsoncxx/json.hpp>
#include <mongocxx/client.hpp>
#include <mongocxx/client_session.hpp>
#include <mongocxx/collection.hpp>
#include <mongocxx/instance.hpp>
#include <mongocxx/options/client_session.hpp>
#include <mongocxx/options/insert.hpp>
#include <mongocxx/read_concern.hpp>
#include <mongocxx/uri.hpp>
#include <mongocxx/write_concern.hpp>
#include <examples/macros.hh>
using bsoncxx::builder::stream::close_document;
using bsoncxx::builder::stream::document;
using bsoncxx::builder::stream::finalize;
using bsoncxx::builder::stream::open_document;
int EXAMPLES_CDECL main() {
if (const char* const topology_env = std::getenv("MONGOCXX_TEST_TOPOLOGY")) {
const auto topology = std::string(topology_env);
if (topology != "replica") {
std::cerr << "Skipping: with_transaction example requires a replica set" << std::endl;
return 0;
}
}
using namespace mongocxx;
instance inst{};
client client{mongocxx::uri{"mongodb://localhost/?replicaSet=repl0"}};
// Start Causal Consistency Example 1
write_concern wc_majority{};
wc_majority.majority(std::chrono::milliseconds(1000));
read_concern rc_majority{};
rc_majority.acknowledge_level(read_concern::level::k_majority);
// Use a causally-consistent session to run some operations.
options::client_session session_opts;
session_opts.causal_consistency(true);
auto session_1 = client.start_session(std::move(session_opts));
auto time_point = std::chrono::system_clock::now();
bsoncxx::types::b_date current_date(time_point);
auto items = client["test"]["items"];
items.write_concern(wc_majority);
items.read_concern(rc_majority);
// Run an update_one with our causally-consistent session.
auto none = bsoncxx::types::b_null{};
auto update_filter = document{} << "sku"
<< "111"
<< "end" << none << finalize;
auto update_op = document{} << "$set" << open_document << "end" << current_date
<< close_document << finalize;
items.update_one(session_1, std::move(update_filter), std::move(update_op), {});
// Run an insert with our causally-consistent session.
auto insert_doc = document{} << "sku"
<< "nuts-111"
<< "name"
<< "Pecans"
<< "start" << current_date << finalize;
items.insert_one(session_1, std::move(insert_doc));
// End Causal Consistency Example 1
// Start Causal Consistency Example 2
// Make a new session, session_2, and make it causally-consistent
// with session_1, so that session_2 will read session_1's writes.
options::client_session session_opts_2;
session_opts_2.causal_consistency(true);
auto session_2 = client.start_session(std::move(session_opts_2));
// Set the cluster time for session_2 to session_1's cluster time,
// and set the operation time for session2 to session2's operation time.
auto cluster_time_1 = session_1.cluster_time();
auto operation_time_1 = session_1.operation_time();
session_2.advance_cluster_time(std::move(cluster_time_1));
session_2.advance_operation_time(std::move(operation_time_1));
read_preference rp_secondary;
rp_secondary.mode(read_preference::read_mode::k_secondary);
items = client["test"]["items"];
items.read_preference(rp_secondary);
items.write_concern(wc_majority);
items.read_concern(rc_majority);
// Run a find on session_2, which should now find all writes done
// inside of session_1.
auto find_query = document{} << "end" << none << finalize;
auto cursor = items.find(session_2, std::move(find_query));
for (auto&& doc : cursor) {
std::cout << bsoncxx::to_json(doc) << std::endl;
}
// End Causal Consistency Example 2
}
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