class McapWriter

Declaration

class McapWriter { /* full declaration omitted */ };

Description

Provides a write interface to an MCAP file.

Declared at: mcap/include/mcap/writer.hpp:326

Method Overview

• public void addChannel(mcap::Channel & channel)
• public void addSchema(mcap::Schema & schema)
• public void close()
• public void closeLastChunk()
• public mcap::IWritable * dataSink()
• public static uint64_t getRecordSize(const mcap::Message & message)
• public mcap::Status open(std::string_view filename, const mcap::McapWriterOptions & options)
• public void open(mcap::IWritable & writer, const mcap::McapWriterOptions & options)
• public void open(std::ostream & stream, const mcap::McapWriterOptions & options)
• public const mcap::Statistics & statistics() const
• public void terminate()
• public static uint64_t write(mcap::IWritable & output, const mcap::Record & record)
• public static uint64_t write(mcap::IWritable & output, const mcap::MessageIndex & index)
• public static uint64_t write(mcap::IWritable & output, const mcap::ChunkIndex & index)
• public static uint64_t write(mcap::IWritable & output, const mcap::AttachmentIndex & index)
• public static uint64_t write(mcap::IWritable & output, const mcap::MetadataIndex & index)
• public static uint64_t write(mcap::IWritable & output, const mcap::Statistics & stats)
• public static uint64_t write(mcap::IWritable & output, const mcap::SummaryOffset & summaryOffset)
• public static uint64_t write(mcap::IWritable & output, const mcap::DataEnd & dataEnd)
• public static void write(mcap::IWritable & output, uint32_t value)
• public static void write(mcap::IWritable & output, const std::string_view str)
• public static void write(mcap::IWritable & output, const mcap::ByteArray bytes)
• public static void write(mcap::IWritable & output, const std::byte * data, uint64_t size)
• public static void write(mcap::IWritable & output, uint64_t value)
• public static void write(mcap::IWritable & output, const mcap::KeyValueMap & map, uint32_t size = 0)
• public static void write(mcap::IWritable & output, mcap::OpCode value)
• public static void write(mcap::IWritable & output, uint16_t value)
• public static uint64_t write(mcap::IWritable & output, const mcap::Metadata & metadata)
• public mcap::Status write(const mcap::Message & message)
• public mcap::Status write(const mcap::MessageHeader & header, const mcap::ByteSpan * payload, std::size_t payloadCount)
• public mcap::Status write(mcap::Attachment & attachment)
• public mcap::Status write(const mcap::AttachmentHeader & header, const mcap::ByteSpan * payload, std::size_t payloadCount)
• public mcap::Status write(const mcap::Metadata & metadata)
• public static uint64_t write(mcap::IWritable & output, const mcap::Header & header)
• public static uint64_t write(mcap::IWritable & output, const mcap::Footer & footer, bool crcEnabled)
• public static uint64_t write(mcap::IWritable & output, const mcap::Schema & schema)
• public static uint64_t write(mcap::IWritable & output, const mcap::Channel & channel)
• public static uint64_t write(mcap::IWritable & output, const mcap::Message & message)
• public static uint64_t write(mcap::IWritable & output, const mcap::MessageHeader & header, const mcap::ByteSpan * payload, std::size_t payloadCount)
• public static uint64_t write(mcap::IWritable & output, const mcap::Attachment & attachment)
• public static uint64_t write(mcap::IWritable & output, const mcap::AttachmentHeader & header, const mcap::ByteSpan * payload, std::size_t payloadCount, uint32_t crc)
• public static uint64_t write(mcap::IWritable & output, const mcap::Chunk & chunk)
• public static void writeMagic(mcap::IWritable & output)
• public ~McapWriter()

Methods

¶void addChannel(mcap::Channel& channel)

Description

Add a new channel to the MCAP file and set `channel.id` to a generated channel id. The channel id is used when adding messages to the file.

Channels are not cleared when the state is reset via `close`() or `terminate`(). If you're re-using a writer for multiple files in a row, the channels only need to be added once, before first use. This method does not de-duplicate channels.

Declared at: mcap/include/mcap/writer.hpp:404

Parameters

mcap::Channel& channel

Description of the channel to register. The `id` value is ignored and will be set to a generated channel id.

¶void addSchema(mcap::Schema& schema)

Description

Add a new schema to the MCAP file and set `schema.id` to a generated schema id. The schema id is used when adding channels to the file.

Schemas are not cleared when the state is reset via `close`() or `terminate`(). If you're re-using a writer for multiple files in a row, the schemas only need to be added once, before first use. This method does not de-duplicate schemas.

Declared at: mcap/include/mcap/writer.hpp:388

Parameters

mcap::Schema& schema

Description of the schema to register. The `id` field is ignored and will be set to a generated schema id.

¶void close()

Description

Write the MCAP footer, flush pending writes to the output stream, and reset internal state. The writer may be re-used with another call to open afterwards.

Declared at: mcap/include/mcap/writer.hpp:366

¶void closeLastChunk()

Description

finishes the current chunk in progress and writes it to the file, if a chunk is in progress.

Declared at: mcap/include/mcap/writer.hpp:479

¶mcap::IWritable* dataSink()

Description

Returns a pointer to the IWritable data destination backing this writer. Will return nullptr if the writer is not open.

Declared at: mcap/include/mcap/writer.hpp:473

¶static uint64_t getRecordSize(
    const mcap::Message& message)

Declared at: mcap/include/mcap/writer.hpp:491

Parameters

const mcap::Message& message

¶mcap::Status open(
    std::string_view filename,
    const mcap::McapWriterOptions& options)

Description

Open a new MCAP file for writing and write the header.

If the writer was already opened, this calls `close`() first to reset the state. A writer may be re-used after being reset via `close`() or `terminate`().

Declared at: mcap/include/mcap/writer.hpp:340

Parameters

std::string_view filename

Filename of the MCAP file to write.

const mcap::McapWriterOptions& options

Options for MCAP writing. `profile` is required.

Returns

A non-success status if the file could not be opened for writing.

¶void open(mcap::IWritable& writer,
          const mcap::McapWriterOptions& options)

Description

Open a new MCAP file for writing and write the header.

If the writer was already opened, this calls `close`() first to reset the state. A writer may be re-used after being reset via `close`() or `terminate`().

Declared at: mcap/include/mcap/writer.hpp:352

Parameters

mcap::IWritable& writer

An implementation of the IWritable interface. Output bytes will be written to this object.

const mcap::McapWriterOptions& options

Options for MCAP writing. `profile` is required.

¶void open(std::ostream& stream,
          const mcap::McapWriterOptions& options)

Description

Open a new MCAP file for writing and write the header.

Declared at: mcap/include/mcap/writer.hpp:360

Parameters

std::ostream& stream

Output stream to write to.

const mcap::McapWriterOptions& options

Options for MCAP writing. `profile` is required.

¶const mcap::Statistics& statistics() const

Description

Current MCAP file-level statistics. This is written as a Statistics record in the Summary section of the MCAP file.

Declared at: mcap/include/mcap/writer.hpp:467

¶void terminate()

Description

Reset internal state without writing the MCAP footer or flushing pending writes. This should only be used in error cases as the output MCAP file will be truncated. The writer may be re-used with another call to open afterwards.

Declared at: mcap/include/mcap/writer.hpp:373

¶static uint64_t write(mcap::IWritable& output,
                      const mcap::Record& record)

Declared at: mcap/include/mcap/writer.hpp:507

Parameters

mcap::IWritable& output

const mcap::Record& record

¶static uint64_t write(
    mcap::IWritable& output,
    const mcap::MessageIndex& index)

Declared at: mcap/include/mcap/writer.hpp:500

Parameters

mcap::IWritable& output

const mcap::MessageIndex& index

¶static uint64_t write(
    mcap::IWritable& output,
    const mcap::ChunkIndex& index)

Declared at: mcap/include/mcap/writer.hpp:501

Parameters

mcap::IWritable& output

const mcap::ChunkIndex& index

¶static uint64_t write(
    mcap::IWritable& output,
    const mcap::AttachmentIndex& index)

Declared at: mcap/include/mcap/writer.hpp:502

Parameters

mcap::IWritable& output

const mcap::AttachmentIndex& index

¶static uint64_t write(
    mcap::IWritable& output,
    const mcap::MetadataIndex& index)

Declared at: mcap/include/mcap/writer.hpp:503

Parameters

mcap::IWritable& output

const mcap::MetadataIndex& index

¶static uint64_t write(
    mcap::IWritable& output,
    const mcap::Statistics& stats)

Declared at: mcap/include/mcap/writer.hpp:504

Parameters

mcap::IWritable& output

const mcap::Statistics& stats

¶static uint64_t write(
    mcap::IWritable& output,
    const mcap::SummaryOffset& summaryOffset)

Declared at: mcap/include/mcap/writer.hpp:505

Parameters

mcap::IWritable& output

const mcap::SummaryOffset& summaryOffset

¶static uint64_t write(
    mcap::IWritable& output,
    const mcap::DataEnd& dataEnd)

Declared at: mcap/include/mcap/writer.hpp:506

Parameters

mcap::IWritable& output

const mcap::DataEnd& dataEnd

¶static void write(mcap::IWritable& output,
                  uint32_t value)

Declared at: mcap/include/mcap/writer.hpp:513

Parameters

mcap::IWritable& output

uint32_t value

¶static void write(mcap::IWritable& output,
                  const std::string_view str)

Declared at: mcap/include/mcap/writer.hpp:509

Parameters

mcap::IWritable& output

const std::string_view str

¶static void write(mcap::IWritable& output,
                  const mcap::ByteArray bytes)

Declared at: mcap/include/mcap/writer.hpp:510

Parameters

mcap::IWritable& output

const mcap::ByteArray bytes

¶static void write(mcap::IWritable& output,
                  const std::byte* data,
                  uint64_t size)

Declared at: mcap/include/mcap/writer.hpp:515

Parameters

mcap::IWritable& output

const std::byte* data

uint64_t size

¶static void write(mcap::IWritable& output,
                  uint64_t value)

Declared at: mcap/include/mcap/writer.hpp:514

Parameters

mcap::IWritable& output

uint64_t value

¶static void write(mcap::IWritable& output,
                  const mcap::KeyValueMap& map,
                  uint32_t size = 0)

Declared at: mcap/include/mcap/writer.hpp:516

Parameters

mcap::IWritable& output

const mcap::KeyValueMap& map

uint32_t size = 0

¶static void write(mcap::IWritable& output,
                  mcap::OpCode value)

Declared at: mcap/include/mcap/writer.hpp:511

Parameters

mcap::IWritable& output

mcap::OpCode value

¶static void write(mcap::IWritable& output,
                  uint16_t value)

Declared at: mcap/include/mcap/writer.hpp:512

Parameters

mcap::IWritable& output

uint16_t value

¶static uint64_t write(
    mcap::IWritable& output,
    const mcap::Metadata& metadata)

Declared at: mcap/include/mcap/writer.hpp:498

Parameters

mcap::IWritable& output

const mcap::Metadata& metadata

¶mcap::Status write(const mcap::Message& message)

Description

Write a message to the output stream.

Declared at: mcap/include/mcap/writer.hpp:412

Parameters

const mcap::Message& message

Returns

A non-zero error code on failure.

¶mcap::Status write(
    const mcap::MessageHeader& header,
    const mcap::ByteSpan* payload,
    std::size_t payloadCount)

Description

Write a message to the output stream, gathering its payload from a list of buffers.

The payload written is the concatenation of the spans in `payload`, in the given order.

Declared at: mcap/include/mcap/writer.hpp:427

Parameters

const mcap::MessageHeader& header

Message header fields to add.

const mcap::ByteSpan* payload

Pointer to an array of spans making up the message payload.

std::size_t payloadCount

Number of spans in `payload`.

Returns

A non-zero error code on failure.

¶mcap::Status write(mcap::Attachment& attachment)

Description

Write an attachment to the output stream.

Declared at: mcap/include/mcap/writer.hpp:436

Parameters

mcap::Attachment& attachment

Attachment to add. The `attachment.crc` will be calculated and set if configuration options allow CRC calculation.

Returns

A non-zero error code on failure.

¶mcap::Status write(
    const mcap::AttachmentHeader& header,
    const mcap::ByteSpan* payload,
    std::size_t payloadCount)

Description

Write an attachment to the output stream, gathering its payload from a list of buffers.

The payload written is the concatenation of the spans in `payload`, in the given order. A CRC covering `header` and `payload` is calculated and written to the output if configuration options allow CRC calculation.

Declared at: mcap/include/mcap/writer.hpp:453

Parameters

const mcap::AttachmentHeader& header

Attachment header fields to add.

const mcap::ByteSpan* payload

Pointer to an array of spans making up the attachment payload.

std::size_t payloadCount

Number of spans in `payload`.

Returns

A non-zero error code on failure.

¶mcap::Status write(const mcap::Metadata& metadata)

Description

Write a metadata record to the output stream.

Declared at: mcap/include/mcap/writer.hpp:461

Parameters

const mcap::Metadata& metadata

Named group of key/value string pairs to add.

Returns

A non-zero error code on failure.

¶static uint64_t write(mcap::IWritable& output,
                      const mcap::Header& header)

Declared at: mcap/include/mcap/writer.hpp:487

Parameters

mcap::IWritable& output

const mcap::Header& header

¶static uint64_t write(mcap::IWritable& output,
                      const mcap::Footer& footer,
                      bool crcEnabled)

Declared at: mcap/include/mcap/writer.hpp:488

Parameters

mcap::IWritable& output

const mcap::Footer& footer

bool crcEnabled

¶static uint64_t write(mcap::IWritable& output,
                      const mcap::Schema& schema)

Declared at: mcap/include/mcap/writer.hpp:489

Parameters

mcap::IWritable& output

const mcap::Schema& schema

¶static uint64_t write(
    mcap::IWritable& output,
    const mcap::Channel& channel)

Declared at: mcap/include/mcap/writer.hpp:490

Parameters

mcap::IWritable& output

const mcap::Channel& channel

¶static uint64_t write(
    mcap::IWritable& output,
    const mcap::Message& message)

Declared at: mcap/include/mcap/writer.hpp:492

Parameters

mcap::IWritable& output

const mcap::Message& message

¶static uint64_t write(
    mcap::IWritable& output,
    const mcap::MessageHeader& header,
    const mcap::ByteSpan* payload,
    std::size_t payloadCount)

Declared at: mcap/include/mcap/writer.hpp:493

Parameters

mcap::IWritable& output

const mcap::MessageHeader& header

const mcap::ByteSpan* payload

std::size_t payloadCount

¶static uint64_t write(
    mcap::IWritable& output,
    const mcap::Attachment& attachment)

Declared at: mcap/include/mcap/writer.hpp:495

Parameters

mcap::IWritable& output

const mcap::Attachment& attachment

¶static uint64_t write(
    mcap::IWritable& output,
    const mcap::AttachmentHeader& header,
    const mcap::ByteSpan* payload,
    std::size_t payloadCount,
    uint32_t crc)

Declared at: mcap/include/mcap/writer.hpp:496

Parameters

mcap::IWritable& output

const mcap::AttachmentHeader& header

const mcap::ByteSpan* payload

std::size_t payloadCount

uint32_t crc

¶static uint64_t write(mcap::IWritable& output,
                      const mcap::Chunk& chunk)

Declared at: mcap/include/mcap/writer.hpp:499

Parameters

mcap::IWritable& output

const mcap::Chunk& chunk

¶static void writeMagic(mcap::IWritable& output)

Declared at: mcap/include/mcap/writer.hpp:485

Parameters

mcap::IWritable& output

¶~McapWriter()

Declared at: mcap/include/mcap/writer.hpp:328