class ZStdReader

Declaration

class ZStdReader : public ICompressedReader { /* full declaration omitted */ };

Description

ICompressedReader implementation that decompresses Zstandard (https://facebook.github.io/zstd/) data.

Declared at: mcap/include/mcap/reader.hpp:158

Inherits from: ICompressedReader

Method Overview

  • public static mcap::Status DecompressAll(const std::byte * data, uint64_t compressedSize, uint64_t uncompressedSize, mcap::ByteArray * output)
  • public ZStdReader()
  • public ZStdReader(const mcap::ZStdReader &)
  • public ZStdReader(mcap::ZStdReader &&)
  • public uint64_t read(std::byte ** output, uint64_t offset, uint64_t size)
  • public void reset(const std::byte * data, uint64_t size, uint64_t uncompressedSize)
  • public uint64_t size() const
  • public mcap::Status status() const

Inherited from ICompressedReader:

Inherited from IReadable:

Methods

static mcap::Status DecompressAll(
    const std::byte* data,
    uint64_t compressedSize,
    uint64_t uncompressedSize,
    mcap::ByteArray* output)

Description

Decompresses an entire Zstd-compressed chunk into `output`.

Declared at: mcap/include/mcap/reader.hpp:175

Parameters

const std::byte* data
The Zstd-compressed input chunk.
uint64_t compressedSize
The size of the Zstd-compressed input.
uint64_t uncompressedSize
The size of the data once uncompressed.
mcap::ByteArray* output
The output vector. This will be resized to `uncompressedSize` to fit the data, or 0 if the decompression encountered an error.

Returns

Status

ZStdReader()

Declared at: mcap/include/mcap/reader.hpp:177

ZStdReader(const mcap::ZStdReader&)

Declared at: mcap/include/mcap/reader.hpp:178

Parameters

const mcap::ZStdReader& 

ZStdReader(mcap::ZStdReader&&)

Declared at: mcap/include/mcap/reader.hpp:180

Parameters

mcap::ZStdReader&& 

uint64_t read(std::byte** output,
              uint64_t offset,
              uint64_t size)

Description

This method is called by MCAP reader classes when they need to read a portion of the file.

Declared at: mcap/include/mcap/reader.hpp:161

Parameters

std::byte** output
A pointer to a pointer to the buffer to write to. This method is expected to either maintain an internal buffer, read data into it, and update this pointer to point at the internal buffer, or update this pointer to point directly at the source data if possible. The pointer and data must remain valid and unmodified until the next call to read().
uint64_t offset
The offset in bytes from the beginning of the file to read.
uint64_t size
The number of bytes to read.

Returns

uint64_t Number of bytes actually read. This may be less than the requested size if the end of the file is reached. The output pointer must be readable from `output` to `output + size`. If the read fails, this method should return 0.

void reset(const std::byte* data,
           uint64_t size,
           uint64_t uncompressedSize)

Description

Reset the reader state, clearing any internal buffers and state, and initialize with new compressed data.

Declared at: mcap/include/mcap/reader.hpp:160

Parameters

const std::byte* data
Compressed data to read from.
uint64_t size
Size of the compressed data in bytes.
uint64_t uncompressedSize
Size of the data in bytes after decompression. A buffer of this size will be allocated for the uncompressed data.

uint64_t size() const

Description

Returns the size of the file in bytes.

Declared at: mcap/include/mcap/reader.hpp:162

Returns

uint64_t The total number of bytes in the MCAP file.

mcap::Status status() const

Description

Report the current status of decompression. A StatusCode other than `StatusCode::Success` after `reset()` is called indicates the decompression was not successful and the reader is in an invalid state.

Declared at: mcap/include/mcap/reader.hpp:163