Struct q_compress::wrapped::Decompressor

pub struct Decompressor<T: NumberLike>(_);

Converts wrapped Quantile-compressed data into Flags, ChunkMetadata, and vectors of numbers.

All decompressor methods leave its state unchanged if they return an error.

You can use the wrapped decompressor at a data page level.

Implementations

impl<T: NumberLike> Decompressor<T>

pub fn from_config(config: DecompressorConfig) -> Self

Creates a new decompressor, given a DecompressorConfig.

pub fn header(&mut self) -> QCompressResult<Flags>

Reads the header, returning its Flags and updating this decompressor’s state. Will return an error if the decompressor has already parsed a header, is not byte-aligned, runs out of data, finds flags from a newer, incompatible version of q_compress, or finds any corruptions.

pub fn chunk_metadata(&mut self) -> QCompressResult<ChunkMetadata<T>>

Reads the chunk metadata, returning its metadata and updating the decompressor’s state. Will return an error if the decompressor has not parsed the header, runs out of data, or finds any corruptions.

This can be used regardless of whether the decompressor has finished reading all data pages from the preceding chunk.

pub fn begin_data_page( &mut self, n: usize, compressed_page_size: usize ) -> QCompressResult<()>

Initializes the decompressor for the next data page, reading in the data page’s metadata but not the compressed body. Will return an error if the decompressor is not in a chunk, runs out of data, or finds any corruptions.

This can be used regardless of whether the decompressor has finished reading the previous data page.

pub fn next_batch(&mut self, limit: usize) -> QCompressResult<Vec<T>>

Reads up to limit numbers from the current data page. Will return an error if the decompressor is not in a data page, it runs out of data, or any corruptions are found.

pub fn data_page( &mut self, n: usize, compressed_page_size: usize ) -> QCompressResult<Vec<T>>

Reads an entire data page, returning its numbers. Will return an error if the decompressor is not in a chunk, it runs out of data, or any corruptions are found.

This is similar to calling .begin_data_page and then .next_batch(usize::MAX).

pub fn free_compressed_memory(&mut self)

Frees memory used for storing compressed bytes the decompressor has already decoded. Note that calling this too frequently can cause performance issues.

pub fn clear_compressed_bytes(&mut self)

Clears any data written to the decompressor but not yet decompressed. As an example, if you want to want to read the first 5 numbers from each data page, you might write each compressed data page to the decompressor, then repeatedly call .begin_data_page, .next_nums, and this method.

pub fn bit_idx(&self) -> usize

Returns the current bit position into the compressed data the decompressor is pointed at. Note that when memory is freed, this will decrease.

Trait Implementations

impl<T: Clone + NumberLike> Clone for Decompressor<T>

fn clone(&self) -> Decompressor<T>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug + NumberLike> Debug for Decompressor<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T: Default + NumberLike> Default for Decompressor<T>

fn default() -> Decompressor<T>

Returns the “default value” for a type.

impl<T: NumberLike> Write for Decompressor<T>

fn write(&mut self, buf: &[u8]) -> Result<usize>

Write a buffer into this writer, returning how many bytes were written.

fn flush(&mut self) -> Result<()>

Flush this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize, Error>

Like write, except that it writes from a slice of buffers.

fn is_write_vectored(&self) -> bool

🔬This is a nightly-only experimental API. (can_vector)

Determines if this Writer has an efficient write_vectored implementation.

fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>

Attempts to write an entire buffer into this writer.

fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<(), Error>

🔬This is a nightly-only experimental API. (write_all_vectored)

Attempts to write multiple buffers into this writer.

fn write_fmt(&mut self, fmt: Arguments<'_>) -> Result<(), Error>

Writes a formatted string into this writer, returning any error encountered.

fn by_ref(&mut self) -> &mut Selfwhere Self: Sized,

Creates a “by reference” adapter for this instance of Write.