Struct CatalogEntry 

pub struct CatalogEntry<'a> {
    pub model: u8,
    pub value_type: u8,
    pub band: u8,
    pub p_exp: u8,
    pub shape_tag: [u8; 16],
    pub root_addr: u64,
    pub element_count: u64,
    pub bytes: u64,
    pub db: u16,
    pub next: u64,
    pub name: &'a [u8],
    pub schema: &'a [u8],
}

One catalogue entry, decoded, borrowing its name and schema from the file.

Fields

model: u8

Raw model byte. Ask CatalogEntry::model what it means.

value_type: u8

Raw value type byte, zero unless the model is kv.

band: u8

Raw band byte.

p_exp: u8

Partition count as a base two exponent. Never 1: a two way split buys nothing and costs an indirection, so the ladder goes one, four, sixteen.

shape_tag: [u8; 16]

The 128 bit shape hash, or all zeroes for a collection that RESP created and that therefore has no declared shape.

root_addr: u64

Where the collection’s root lives.

element_count: u64

Elements, for SCARD and friends without walking anything.

bytes: u64

Bytes the collection occupies.

db: u16

Which logical database.

next: u64

The next entry in the chain, or 0.

name: &'a [u8]

The collection’s name.

schema: &'a [u8]

The canonical shape description the shape_tag hashes, or empty.

Implementations

impl<'a> CatalogEntry<'a>

pub const fn new(model: Model, name: &'a [u8]) -> CatalogEntry<'a>

An entry for a named collection with no declared shape.

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

Writes the entry and its checksum, returning the length written.

Unlike a log record this one writes its len up front, because a catalogue entry is not appended to a log that a reader is scanning. It is written to a free segment and then reached by a pointer that is published in the next superblock flip, so the entry is either reachable and whole or not reachable at all.

Errors

Code::Invalid for an oversized name or an illegal p_exp, Code::Full if buf is too small.

pub fn decode(bytes: &'a [u8]) -> Result<CatalogEntry<'a>>

Reads the entry at the front of bytes.

Errors

Code::Corrupt if the length is impossible, if the entry runs past the end of bytes, if the name and schema do not fit inside it, or if the checksum fails.

pub fn model(&self) -> Option<Model>

The model, if this version knows it.

pub fn value_type(&self) -> Option<ValueType>

The value type, if the model is kv and this version knows the byte.

pub fn band(&self) -> Option<Band>

The band, if this version knows it.

pub const fn partitions(&self) -> u32

How many partitions the collection is split into.

pub fn is_shape_tagged(&self) -> bool

Whether the collection was declared with a shape.

An all zero tag means it was not, which is the case for anything a RESP client created. Shape checking has nothing to check against there and says so rather than inventing a shape.

Trait Implementations

impl<'a> Clone for CatalogEntry<'a>

fn clone(&self) -> CatalogEntry<'a>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<'a> Copy for CatalogEntry<'a>

impl<'a> Debug for CatalogEntry<'a>

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

Formats the value using the given formatter.

impl<'a> Eq for CatalogEntry<'a>

impl<'a> PartialEq for CatalogEntry<'a>

fn eq(&self, other: &CatalogEntry<'a>) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl<'a> StructuralPartialEq for CatalogEntry<'a>