BetaExamples.java

/*
 * Copyright 2018 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.
 *
 */

import com.mongodb.MongoClient;
import com.mongodb.MongoClientURI;
import com.mongodb.MongoServerException;
import com.mongodb.MongoSocketException;
import com.mongodb.TransactionOptions;
import com.mongodb.WriteConcern;
import com.mongodb.client.ClientSession;
import com.mongodb.client.MongoCollection;
import com.mongodb.client.MongoDatabase;
import org.bson.Document;

import java.util.Arrays;

import static com.mongodb.client.model.Filters.eq;
import static com.mongodb.client.model.Updates.inc;

public class BetaExamples {

    static MongoClientURI uri;

    static MongoClient client;
    static MongoDatabase database;

    static MongoCollection<Document> inventory;
    static MongoCollection<Document> shipment;

    public static void main(String[] args) throws InterruptedException {

        // setup code
        uri = new MongoClientURI("mongodb://localhost,localhost:27018");

        client = new MongoClient(uri);
        database = client.getDatabase("test");

        // drop the database so that we can run this repeatedly
        database.drop();

        // create the collections in advance so there is no attempt to implicitly create them within the transaction
        database.createCollection("inventory");
        database.createCollection("shipment");

        inventory = database.getCollection("inventory");
        shipment = database.getCollection("shipment");

        inventory.insertOne(new Document("sku", "abc123").append("qty", 500));

        // Start Beta Transaction Example 1

        try (ClientSession clientSession = client.startSession()) {
            
            clientSession.startTransaction(TransactionOptions.builder().writeConcern(WriteConcern.MAJORITY).build());

            inventory.updateOne(clientSession, eq("sku", "abc123"), inc("qty", -100));
            shipment.insertOne(clientSession, new Document("sku", "abc123").append("qty", 100));

            clientSession.commitTransaction();
        }

        // End Beta Transaction Example 1


        // Start Beta Transaction Example 2

        // In the following block, the following write concerns are used:
        // the updateOne and insertOne operations uses w = 1, the transaction commit/abort uses w = "majority".
        try (ClientSession clientSession = client.startSession()) {

            clientSession.startTransaction(TransactionOptions.builder().writeConcern(WriteConcern.MAJORITY).build());

            inventory.updateOne(clientSession, eq("sku", "abc123"), inc("qty", -100));

            // The write concern specified here will be ignored
            shipment.withWriteConcern(WriteConcern.MAJORITY)
                    .insertOne(clientSession, new Document("sku", "abc123").append("qty", 100));

            clientSession.commitTransaction();
        }

        // End Beta Transaction Example 2


        // Start Beta Transaction Example 3

        try {
            runShipmentTransaction();
        } catch (MongoSocketException e) {
            runShipmentTransaction();
        } catch (MongoServerException e) {
            if (Arrays.asList(112, 244, 251).contains(e.getCode())) {
                runShipmentTransaction();
            } else {
                throw e;
            }
        }

        // End Beta Transaction Example 3

        client.close();
    }

    static void runShipmentTransaction() {
        try (ClientSession clientSession = client.startSession()) {

            clientSession.startTransaction();

            inventory.updateOne(clientSession, eq("sku", "abc123"), inc("qty", -100));
            shipment.insertOne(clientSession, new Document("sku", "abc123").append("qty", 100));

            clientSession.commitTransaction();
        }
    }
}

Add a comment explaining the error codes?
// Retry the transaction after WriteConflict, TransactionAborted, orNoSuchTransaction.