Работа с топиками

try (GrpcTransport transport = GrpcTransport.forConnectionString(connString)
        .withAuthProvider(CloudAuthHelper.getAuthProviderFromEnviron())
        .build()) {
    // Use YDB transport
}

try (TopicClient topicClient = TopicClient.newClient(transport)
              .setCompressionExecutor(compressionExecutor)
              .build()) {
  // Use topic client
}

err := db.Topic().Create(ctx, "topic-path",
  // optional
  topicoptions.CreateWithSupportedCodecs(topictypes.CodecRaw, topictypes.CodecGzip),

  // optional
  topicoptions.CreateWithMinActivePartitions(3),
)

driver.topic_client.create_topic(topic_path,
    supported_codecs=[ydb.TopicCodec.RAW, ydb.TopicCodec.GZIP], # optional
    min_active_partitions=3,                                    # optional
)

topicClient.createTopic(topicPath, CreateTopicSettings.newBuilder()
                // Optional
                .setSupportedCodecs(SupportedCodecs.newBuilder()
                        .addCodec(Codec.RAW)
                        .addCodec(Codec.GZIP)
                        .build())
                // Optional
                .setPartitioningSettings(PartitioningSettings.newBuilder()
                        .setMinActivePartitions(3)
                        .build())
                .build());

err := db.Topic().Alter(ctx, "topic-path",
  topicoptions.AlterWithAddConsumers(topictypes.Consumer{
    Name:            "new-consumer",
    SupportedCodecs: []topictypes.Codec{topictypes.CodecRaw, topictypes.CodecGzip}, // optional
  }),
)

topicClient.alterTopic(topicPath, AlterTopicSettings.newBuilder()
                .addAddConsumer(Consumer.newBuilder()
                        .setName("new-consumer")
                        .setSupportedCodecs(SupportedCodecs.newBuilder()
                                .addCodec(Codec.RAW)
                                .addCodec(Codec.GZIP)
                                .build())
                        .build())
                .build());

  descResult, err := db.Topic().Describe(ctx, "topic-path")
if err != nil {
  log.Fatalf("failed describe topic: %v", err)
  return
}
fmt.Printf("describe: %#v\n", descResult)

info = driver.topic_client.describe_topic(topic_path)
print(info)

Result<TopicDescription> topicDescriptionResult = topicClient.describeTopic(topicPath)
        .join();
TopicDescription description = topicDescriptionResult.getValue();

  err := db.Topic().Drop(ctx, "topic-path")

driver.topic_client.drop_topic(topic_path)

topicClient.dropTopic(topicPath);

producerAndGroupID := "group-id"
writer, err := db.Topic().StartWriter(producerAndGroupID, "topicName",
  topicoptions.WithMessageGroupID(producerAndGroupID),
)
if err != nil {
    return err
}

writer = driver.topic_client.writer(topic_path)

String producerAndGroupID = "group-id";
WriterSettings settings = WriterSettings.newBuilder()
      .setTopicPath(topicPath)
      .setProducerId(producerAndGroupID)
      .setMessageGroupId(producerAndGroupID)
      .build();

SyncWriter writer = topicClient.createSyncWriter(settings);

String producerAndGroupID = "group-id";
WriterSettings settings = WriterSettings.newBuilder()
      .setTopicPath(topicPath)
      .setProducerId(producerAndGroupID)
      .setMessageGroupId(producerAndGroupID)
      .build();

AsyncWriter writer = topicClient.createAsyncWriter(settings);

// Init in background
writer.init()
        .thenRun(() -> logger.info("Init finished successfully"))
        .exceptionally(ex -> {
            logger.error("Init failed with ex: ", ex);
            return null;
        });

err := writer.Write(ctx,
  topicwriter.Message{Data: strings.NewReader("1")},
  topicwriter.Message{Data: bytes.NewReader([]byte{1,2,3})},
  topicwriter.Message{Data: strings.NewReader("3")},
)
if err == nil {
  return err
}

# Простая отправка сообщений, без явного указания метаданных.
# Удобно начинать, удобно использовать пока важно только содержимое сообщения.
writer = driver.topic_client.writer(topic_path)
writer.write("mess")  # Строки будут переданы в кодировке utf-8, так удобно отправлять
                      # текстовые сообщения.
writer.write(bytes([1, 2, 3]))  # Эти байты будут отправлены "как есть", так удобно отправлять
                                # бинарные данные.
writer.write(["mess-1", "mess-2"])  # Здесь за один вызов отправляется несколько сообщений —
                                    # так снижаются накладные расходы на внутренние процессы SDK,
                                    # имеет смысл при большом потоке сообщений.

# Полная форма, используется, когда кроме содержимого сообщения нужно вручную задать и его свойства.
writer = driver.topic_client.writer(topic="topic-path", auto_seqno=False, auto_created_at=False)

writer.write(ydb.TopicWriterMessage("asd", seqno=123, created_at=datetime.datetime.now()))
writer.write(ydb.TopicWriterMessage(bytes([1, 2, 3]), seqno=124, created_at=datetime.datetime.now()))

# В полной форме так же можно отправлять несколько сообщений за один вызов функции.
# Это имеет смысл при большом потоке отправляемых сообщений — для снижения
# накладных расходов на внутренние вызовы SDK.
writer.write([
  ydb.TopicWriterMessage("asd", seqno=123, created_at=datetime.datetime.now()),
  ydb.TopicWriterMessage(bytes([1, 2, 3]), seqno=124, created_at=datetime.datetime.now(),
  ])

writer.send(Message.of("11".getBytes()));

long timeoutSeconds = 5; // How long should we wait for a message to be put into sending buffer
try {
    writer.send(
            Message.newBuilder()
                    .setData("22".getBytes())
                    .setCreateTimestamp(Instant.now().minusSeconds(5))
                    .build(),
            timeoutSeconds,
            TimeUnit.SECONDS
    );
} catch (TimeoutException exception) {
    logger.error("Send queue is full. Couldn't put message into sending queue within {} seconds", timeoutSeconds);
} catch (InterruptedException | ExecutionException exception) {
    logger.error("Couldn't put the message into sending queue due to exception: ", exception);
}

try {
    // Non-blocking. Throws QueueOverflowException if send queue is full
    writer.send(Message.of("33".getBytes()));
} catch (QueueOverflowException exception) {
    // Send queue is full. Need to retry with backoff or skip
}

producerAndGroupID := "group-id"
writer, _ := db.Topic().StartWriter(producerAndGroupID, "topicName",
  topicoptions.WithMessageGroupID(producerAndGroupID),
  topicoptions.WithSyncWrite(true),
)

err = writer.Write(ctx,
  topicwriter.Message{Data: strings.NewReader("1")},
  topicwriter.Message{Data: bytes.NewReader([]byte{1,2,3})},
  topicwriter.Message{Data: strings.NewReader("3")},
)
if err == nil {
  return err
}

# Положить несколько сообщений во внутренний буфер, затем дождаться,
# пока все они будут доставлены до сервера.
for mess in messages:
    writer.write(mess)

writer.flush()

# Можно отправить несколько сообщений и дождаться подтверждения на всю группу.
writer.write_with_ack(["mess-1", "mess-2"])

# Ожидание при отправке каждого сообщения — этот метод вернет результат только после получения
# подтверждения от сервера.
# Это самый медленный вариант отправки сообщений, используйте его только если такой режим
# действительно нужен.
writer.write_with_ack("message")

writer.send(Message.of(message))
        .whenComplete((result, ex) -> {
            if (ex != null) {
                logger.error("Exception on writing message message: ", ex);
            } else {
                switch (result.getState()) {
                    case WRITTEN:
                        WriteAck.Details details = result.getDetails();
                        StringBuilder str = new StringBuilder("Message was written successfully");
                        if (details != null) {
                            str.append(", offset: ").append(details.getOffset());
                        }
                        logger.debug(str.toString());
                        break;
                    case ALREADY_WRITTEN:
                        logger.warn("Message has already been written");
                        break;
                    default:
                        break;
                }
            }
        });

producerAndGroupID := "group-id"
writer, _ := db.Topic().StartWriter(producerAndGroupID, "topicName",
  topicoptions.WithMessageGroupID(producerAndGroupID),
  topicoptions.WithCodec(topictypes.CodecGzip),
)

writer = driver.topic_client.writer(topic_path,
    codec=ydb.TopicCodec.GZIP,
)

String producerAndGroupID = "group-id";
WriterSettings settings = WriterSettings.newBuilder()
        .setTopicPath(topicPath)
        .setProducerId(producerAndGroupID)
        .setMessageGroupId(producerAndGroupID)
        .setCodec(Codec.ZSTD)
        .build();

List<MetadataItem> metadataItems = Arrays.asList(
        new MetadataItem("meta-key", "meta-value".getBytes()),
        new MetadataItem("another-key", "value".getBytes())
);
writer.send(
        Message.newBuilder()
                .setMetadataItems(metadataItems)
                .build()
);

writer.send(
        Message.newBuilder()
                .addMetadataItem(new MetadataItem("meta-key", "meta-value".getBytes()))
                .addMetadataItem(new MetadataItem("another-key", "value".getBytes()))
                .build()
);

Message message = reader.receive();
List<MetadataItem> metadata = message.getMetadataItems();

// creating a session in the table service
Result<Session> sessionResult = tableClient.createSession(Duration.ofSeconds(10)).join();
if (!sessionResult.isSuccess()) {
    logger.error("Couldn't get a session from the pool: {}", sessionResult);
    return; // retry or shutdown
}
Session session = sessionResult.getValue();
// creating a transaction in the table service
// this transaction is not yet active and has no id
TableTransaction transaction = session.createNewTransaction(TxMode.SERIALIZABLE_RW);

// get message text within the transaction
Result<DataQueryResult> dataQueryResult = transaction.executeDataQuery("SELECT \"Hello, world!\";")
        .join();
if (!dataQueryResult.isSuccess()) {
    logger.error("Couldn't execute DataQuery: {}", dataQueryResult);
    return; // retry or shutdown
}
// now the transaction is active and has an id

ResultSetReader rsReader = dataQueryResult.getValue().getResultSet(0);
byte[] message;
if (rsReader.next()) {
    message = rsReader.getColumn(0).getBytes();
} else {
    return; // retry or shutdown
}

try {
    writer.send(Message.newBuilder()
                            .setData(message)
                            .build(),
                    SendSettings.newBuilder()
                            .setTransaction(transaction)
                            .build())
            .whenComplete((result, ex) -> {
                if (ex != null) {
                    logger.error("Exception while sending a message: ", ex);
                } else {
                    switch (result.getState()) {
                        case WRITTEN:
                            WriteAck.Details details = result.getDetails();
                            logger.info("Message was written successfully, offset: " + details.getOffset());
                            break;
                        case ALREADY_WRITTEN:
                            logger.info("Message has already been written");
                            break;
                        default:
                            break;
                    }
                }
            })
            // Waiting for the message to reach the server before committing the transaction
            .join();

    Status commitStatus = transaction.commit().join();
    analyzeCommitStatus(commitStatus);
} catch (QueueOverflowException exception) {
    logger.error("Queue overflow exception while sending a message{}: ", index, exception);
    // Send queue is full. Need to retry with backoff or skip
}

reader, err := db.Topic().StartReader("my-consumer", topicoptions.ReadTopic("my-topic"))
if err != nil {
    return err
}

reader = driver.topic_client.reader(topic="topic-path", consumer="consumer_name")

ReaderSettings settings = ReaderSettings.newBuilder()
        .setConsumerName(consumerName)
        .addTopic(TopicReadSettings.newBuilder()
                .setPath(topicPath)
                .setReadFrom(Instant.now().minus(Duration.ofHours(24))) // Optional
                .setMaxLag(Duration.ofMinutes(30)) // Optional
                .build())
        .build();

SyncReader reader = topicClient.createSyncReader(settings);

ReaderSettings settings = ReaderSettings.newBuilder()
        .setConsumerName(consumerName)
        .addTopic(TopicReadSettings.newBuilder()
                .setPath(topicPath)
                .setReadFrom(Instant.now().minus(Duration.ofHours(24))) // Optional
                .setMaxLag(Duration.ofMinutes(30)) // Optional
                .build())
        .build();

ReadEventHandlersSettings handlerSettings = ReadEventHandlersSettings.newBuilder()
        .setEventHandler(new Handler())
        .build();

private class Handler extends AbstractReadEventHandler {
    @Override
    public void onMessages(DataReceivedEvent event) {
        for (Message message : event.getMessages()) {
            StringBuilder str = new StringBuilder();
            logger.info("Message received. SeqNo={}, offset={}", message.getSeqNo(), message.getOffset());

            process(message);

            message.commit().thenRun(() -> {
                logger.info("Message committed");
            });
        }
    }
}

AsyncReader reader = topicClient.createAsyncReader(readerSettings, handlerSettings);
// Init in background
reader.init()
        .thenRun(() -> logger.info("Init finished successfully"))
        .exceptionally(ex -> {
            logger.error("Init failed with ex: ", ex);
            return null;
        });

reader, err := db.Topic().StartReader("my-consumer", []topicoptions.ReadSelector{
    {
        Path: "my-topic",
    },
    {
        Path:       "my-specific-topic",
        ReadFrom:   time.Date(2022, 7, 1, 10, 15, 0, 0, time.UTC),
    },
    },
)
if err != nil {
    return err
}

ReaderSettings settings = ReaderSettings.newBuilder()
        .setConsumerName(consumerName)
        .addTopic(TopicReadSettings.newBuilder()
                .setPath("my-topic")
                .build())
        .addTopic(TopicReadSettings.newBuilder()
                .setPath("my-specific-topic")
                .setReadFrom(Instant.now().minus(Duration.ofHours(24))) // Optional
                .setMaxLag(Duration.ofMinutes(30)) // Optional
                .build())
        .build();

func SimpleReadMessages(ctx context.Context, r *topicreader.Reader) error {
    for {
        mess, err := r.ReadMessage(ctx)
        if err != nil {
            return err
        }
        processMessage(mess)
    }
}

while True:
    message = reader.receive_message()
    process(message)

while(true) {
    Message message = reader.receive();
    process(message);
}

func SimpleReadBatches(ctx context.Context, r *topicreader.Reader) error {
    for {
        batch, err := r.ReadMessageBatch(ctx)
        if err != nil {
            return err
        }
        processBatch(batch)
    }
}

while True:
  batch = reader.receive_batch()
  process(batch)

private class Handler extends AbstractReadEventHandler {
    @Override
    public void onMessages(DataReceivedEvent event) {
        for (Message message : event.getMessages()) {
            process(message);
        }
    }
}

func SimpleReadMessages(ctx context.Context, r *topicreader.Reader) error {
    for {
      mess, err := r.ReadMessage(ctx)
      if err != nil {
          return err
      }
      processMessage(mess)
      r.Commit(mess.Context(), mess)
    }
}

while True:
    message = reader.receive_message()
    process(message)
    reader.commit(message)

message.commit()
       .whenComplete((result, ex) -> {
           if (ex != null) {
               // Read session was probably closed, there is nothing we can do here.
               // Do not retry this commit on the same event.
               logger.error("exception while committing message: ", ex);
           } else {
               logger.info("message committed successfully");
           }
       });

func SimpleReadMessageBatch(ctx context.Context, r *topicreader.Reader) error {
    for {
      batch, err := r.ReadMessageBatch(ctx)
      if err != nil {
          return err
      }
      processBatch(batch)
      r.Commit(batch.Context(), batch)
    }
}

while True:
  batch = reader.receive_batch()
  process(batch)
  reader.commit(batch)

@Override
public void onMessages(DataReceivedEvent event) {
    for (Message message : event.getMessages()) {
        process(message);
    }
    event.commit()
           .whenComplete((result, ex) -> {
               if (ex != null) {
                   // Read session was probably closed, there is nothing we can do here.
                   // Do not retry this commit on the same message.
                   logger.error("exception while committing message batch: ", ex);
               } else {
                   logger.info("message batch committed successfully");
               }
           });
}

func ReadWithExplicitPartitionStartStopHandlerAndOwnReadProgressStorage(ctx context.Context, db ydb.Connection) error {
    readContext, stopReader := context.WithCancel(context.Background())
    defer stopReader()

    readStartPosition := func(
        ctx context.Context,
        req topicoptions.GetPartitionStartOffsetRequest,
    ) (res topicoptions.GetPartitionStartOffsetResponse, err error) {
        offset, err := readLastOffsetFromDB(ctx, req.Topic, req.PartitionID)
        res.StartFrom(offset)

        // Reader will stop if return err != nil
        return res, err
    }

    r, err := db.Topic().StartReader("my-consumer", topicoptions.ReadTopic("my-topic"),
        topicoptions.WithGetPartitionStartOffset(readStartPosition),
    )
    if err != nil {
        return err
    }

    go func() {
        <-readContext.Done()
        _ = r.Close(ctx)
    }()

    for {
        batch, err := r.ReadMessageBatch(readContext)
        if err != nil {
            return err
        }

        processBatch(batch)
        _ = externalSystemCommit(batch.Context(), batch.Topic(), batch.PartitionID(), batch.EndOffset())
    }
}

@Override
public void onStartPartitionSession(StartPartitionSessionEvent event) {
    event.confirm(StartPartitionSessionSettings.newBuilder()
            .setReadOffset(lastReadOffset) // Long
            .setCommitOffset(lastCommitOffset) // Long
            .build());
}

Message message = reader.receive(ReceiveSettings.newBuilder()
        .setTransaction(transaction)
        .build());

@Override
public void onMessages(DataReceivedEvent event) {
    for (Message message : event.getMessages()) {
        // creating a session in the table service
        Result<Session> sessionResult = tableClient.createSession(Duration.ofSeconds(10)).join();
        if (!sessionResult.isSuccess()) {
            logger.error("Couldn't get a session from the pool: {}", sessionResult);
            return; // retry or shutdown
        }
        Session session = sessionResult.getValue();
        // creating a transaction in the table service
        // this transaction is not yet active and has no id
        TableTransaction transaction = session.createNewTransaction(TxMode.SERIALIZABLE_RW);

        // do something else in the transaction
        transaction.executeDataQuery("SELECT 1").join();
        // now the transaction is active and has an id
        // analyzeQueryResultIfNeeded();

        Status updateStatus = reader.updateOffsetsInTransaction(transaction,
                        message.getPartitionOffsets(), new UpdateOffsetsInTransactionSettings.Builder().build())
                // Do not commit a transaction without waiting for updateOffsetsInTransaction result to avoid a race condition
                .join();
        if (!updateStatus.isSuccess()) {
            logger.error("Couldn't update offsets in a transaction: {}", updateStatus);
            return; // retry or shutdown
        }

        Status commitStatus = transaction.commit().join();
        analyzeCommitStatus(commitStatus);
    }
}

r, _ := db.Topic().StartReader("my-consumer", nil,
    topicoptions.WithBatchReadMinCount(1000),
)

for {
    batch, _ := r.ReadMessageBatch(ctx) // <- if partition soft stop batch can be less, then 1000
    processBatch(batch)
    _ = r.Commit(batch.Context(), batch)
}

while True:
  batch = reader.receive_batch()
  process(batch)
  reader.commit(batch)

@Override
public void onStopPartitionSession(StopPartitionSessionEvent event) {
    logger.info("Partition session {} stopped. Committed offset: {}", event.getPartitionSessionId(),
            event.getCommittedOffset());
    // This event means that no more messages will be received by server
    // Received messages still can be read from ReaderBuffer
    // Messages still can be committed, until confirm() method is called

    // Confirm that session can be closed
    event.confirm();
}

ctx := batch.Context() // batch.Context() will cancel if partition revoke by server or connection broke
if len(batch.Messages) == 0 {
    return
}

buf := &bytes.Buffer{}
for _, mess := range batch.Messages {
    buf.Reset()
    _, _ = buf.ReadFrom(mess)
    _, _ = io.Copy(buf, mess)
    writeMessagesToDB(ctx, buf.Bytes())
}

def process_batch(batch):
    for message in batch.messages:
        if not batch.alive:
            return False
        process(message)
    return True

batch = reader.receive_batch()
if process_batch(batch):
    reader.commit(batch)

@Override
public void onPartitionSessionClosed(PartitionSessionClosedEvent event) {
    logger.info("Partition session {} is closed.", event.getPartitionSession().getPartitionId());
}