Struct Commit

pub struct Commit {
    pub min_tx_offset: u64,
    pub epoch: u64,
    pub n: u16,
    pub records: Vec<u8>,
}

Entry type of a crate::Commitlog.

Fields

min_tx_offset: u64

The offset of the first record in this commit.

The offset starts from zero and is counted from the beginning of the entire log.

epoch: u64

The epoch within which the commit was created.

Indicates the monotonically increasing term number of the leader when the commitlog is being written to in a distributed deployment.

The default epoch is 0 (zero). It should be used when the log is written to by a single process.

Note, however, that an existing log may have a non-zero epoch. It is currently unspecified how a commitlog is transitioned between distributed and single-node deployment, wrt the epoch.

n: u16

The number of records in the commit.

records: Vec<u8>

A buffer of all records in the commit in serialized form.

Readers must bring their own crate::Decoder to interpret this buffer. n indicates how many records the buffer contains.

Implementations

impl Commit

pub const DEFAULT_EPOCH: u64 = 0u64

pub const FRAMING_LEN: usize = 26usize

pub const CHECKSUM_ALGORITHM: u8 = 0u8

pub const CHECKSUM_LEN: usize = 4usize

pub fn tx_range(&self) -> Range<u64>

The range of transaction offsets contained in this commit.

pub fn encoded_len(&self) -> usize

Length in bytes of this commit when written to the log via Self::write.

pub fn write<W: Write>(&self, out: W) -> Result<u32>

Serialize and write self to out.

Returns the crc32 checksum of the commit on success.

pub fn decode<R: Read>(reader: R) -> Result<Option<Self>>

Attempt to read one Commit from the given Reader.

Returns None if the reader is already at EOF.

Verifies the checksum of the commit. If it doesn’t match, an error of kind io::ErrorKind::InvalidData with an inner error downcastable to ChecksumMismatch is returned.

To retain access to the checksum, use StoredCommit::decode.

pub fn into_transactions<D: Decoder>( self, version: u8, from_offset: u64, de: &D, ) -> impl Iterator<Item = Result<Transaction<D::Record>, D::Error>> + '_

Convert self into an iterator yielding Transactions.

The supplied Decoder is responsible for extracting individual transactions from the records buffer.

version is the log format version of the current segment, and gets passed to Decoder::decode_record.

from_offset is the transaction offset within the current commit from which to start decoding. That is:

• if the tx offset within the commit is smaller than from_offset, Decoder::skip_record is called.

  The iterator does not yield a value, unless skip_record returns an error.

• if the tx offset within the commit is greater of equal to from_offset, Decoder::decode_record is called.

  The iterator yields the result of this call.

• if from_offset doesn’t fall into the current commit, the iterator yields nothing.

Trait Implementations

impl Clone for Commit

fn clone(&self) -> Commit

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Commit

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

Formats the value using the given formatter.

impl Default for Commit

fn default() -> Commit

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Commit

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl From<Commit> for Metadata

fn from(commit: Commit) -> Self

Converts to this type from the input type.

impl From<StoredCommit> for Commit

fn from(_: StoredCommit) -> Self

Converts to this type from the input type.

impl PartialEq for Commit

fn eq(&self, other: &Commit) -> bool

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for Commit

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Commit