Trait Types

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pub trait Typeswhere
    Self: Debug + Default + PartialEq + Eq + Clone + 'static,{
    type LogId: Debug + Clone + Ord + Eq + Codec + Send + Sync + 'static;
    type LogPayload: Debug + Clone + Codec + Send + Sync + 'static;
    type Vote: Debug + Clone + PartialOrd + Eq + Codec + 'static;
    type Callback: Callback + Send + 'static;
    type UserData: Debug + Clone + Eq + Codec + 'static;

    // Required methods
    fn log_index(log_id: &Self::LogId) -> u64;
    fn payload_size(payload: &Self::LogPayload) -> u64;

    // Provided method
    fn next_log_index(log_id: Option<&Self::LogId>) -> u64 { ... }
}

Expand description

The Types trait defines the core type parameters used throughout the Raft-log implementation.

This trait provides an abstraction layer for the log implementation by defining the core types used throughout the system. Implementations can customize the concrete types for: log id, log payload, vote, callback, and user data.

Required Associated Types§

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type LogId: Debug + Clone + Ord + Eq + Codec + Send + Sync + 'static

Unique identifier for log entries. Usually it contains the term and log index.

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type LogPayload: Debug + Clone + Codec + Send + Sync + 'static

The actual data/command stored in log entries.

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type Vote: Debug + Clone + PartialOrd + Eq + Codec + 'static

Representation of vote in leader election.

A vote typically contains:

The election term number
The candidate node ID
A commitment flag indicating whether a quorum of nodes has granted this vote

The commitment flag is set to true when a majority of nodes in the cluster have voted for this candidate in this term.

In some raft implementation the vote is called hard state

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type Callback: Callback + Send + 'static

Callback handlers for notification of an IO operation.

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type UserData: Debug + Clone + Eq + Codec + 'static

Custom data that can be attached to Raft-log.

This data is not used by the Raft-log implementation, but it can be used by the user. For example, an application could attach a configuration or the node info in this field.