Struct NippyJarWriter

pub struct NippyJarWriter<H: NippyJarHeader = ()> { /* private fields */ }

Writer of NippyJar. Handles table data and offsets only.

Table data is written directly to disk, while offsets and configuration need to be flushed by calling commit().

Offset file layout

The first byte is the size of a single offset in bytes, m. Then, the file contains n entries, each with a size of m. Each entry represents an offset, except for the last entry, which represents both the total size of the data file, as well as the next offset to write new data to.

Data file layout

The data file is represented just as a sequence of bytes of data without any delimiters

Implementations

impl<H: NippyJarHeader> NippyJarWriter<H>

pub fn new(jar: NippyJar<H>) -> Result<Self, NippyJarError>

Creates a NippyJarWriter from NippyJar.

If will always attempt to heal any inconsistent state when called.

pub const fn user_header(&self) -> &H

Returns a reference to H of NippyJar

pub fn user_header_mut(&mut self) -> &mut H

Returns a mutable reference to H of NippyJar.

Since there’s no way of knowing if H has been actually changed, this sets self.dirty to true.

pub const fn is_dirty(&self) -> bool

Returns whether there are changes that need to be committed.

pub fn set_dirty(&mut self)

Sets writer as dirty.

pub const fn rows(&self) -> usize

Gets total writer rows in jar.

pub fn into_jar(self) -> NippyJar<H>

Consumes the writer and returns the associated NippyJar.

pub fn append_rows( &mut self, column_values_per_row: Vec<impl IntoIterator<Item = ColumnResult<impl AsRef<[u8]>>>>, num_rows: u64, ) -> Result<(), NippyJarError>

Appends rows to data file. fn commit() should be called to flush offsets and config to disk.

column_values_per_row: A vector where each element is a column’s values in sequence, corresponding to each row. The vector’s length equals the number of columns.

pub fn append_column( &mut self, column: Option<ColumnResult<impl AsRef<[u8]>>>, ) -> Result<(), NippyJarError>

Appends a column to data file. fn commit() should be called to flush offsets and config to disk.

pub fn prune_rows(&mut self, num_rows: usize) -> Result<(), NippyJarError>

Prunes rows from data and offsets file and updates its configuration on disk

pub fn commit(&mut self) -> Result<(), NippyJarError>

Commits configuration and offsets to disk. It drains the internal offset list.

pub fn commit_without_sync_all(&mut self) -> Result<(), NippyJarError>

Available on crate feature test-utils only.

Commits changes to the data file and offsets without synchronizing all data to disk.

This function flushes the buffered data to the data file and commits the offsets, but it does not guarantee that all data is synchronized to persistent storage.

pub fn data_file(&mut self) -> &mut BufWriter<File>

Available on crate feature test-utils only.

Returns a mutable reference to the buffered writer for the data file.

pub const fn jar(&self) -> &NippyJar<H>

Available on crate feature test-utils only.

Returns a reference to the associated NippyJar instance.

Trait Implementations

impl<H: Debug + NippyJarHeader> Debug for NippyJarWriter<H>

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

Formats the value using the given formatter.

Layout

Note: Unable to compute type layout, possibly due to this type having generic parameters. Layout can only be computed for concrete, fully-instantiated types.