openraft 0.10.0-alpha.35

Advanced Raft consensus
Documentation 
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use openraft_macros::since;

use crate::ChangeMembers;
use crate::RaftTypeConfig;
use crate::batch::Batch;
use crate::raft::Precondition;
use crate::type_config::alias::BatchOf;

/// Parameters for a membership change that may carry an application-defined payload.
#[since(version = "0.10.0", change = "added configurable membership change request")]
pub struct ChangeMembershipRequest<C>
where C: RaftTypeConfig
{
    members: ChangeMembers<C::NodeId, C::Node>,
    retain_removed_as_learners: bool,
    preconditions: BatchOf<C, Precondition<C>>,
    payload: Option<(C::Payload, C::Payload)>,
}

impl<C> ChangeMembershipRequest<C>
where C: RaftTypeConfig
{
    /// Create a request that uses a new blank payload for each membership entry and has no
    /// preconditions.
    #[since(version = "0.10.0", change = "added configurable membership change request")]
    pub fn new(members: impl Into<ChangeMembers<C::NodeId, C::Node>>, retain: bool) -> Self {
        let members = members.into();
        Self {
            members,
            retain_removed_as_learners: retain,
            preconditions: BatchOf::<C, _>::of([]),
            payload: None,
        }
    }

    /// Use separate application-defined payloads for the membership-change steps.
    ///
    /// Each payload is tied to the shape of the membership it carries, not to the order of the
    /// steps. `joint_payload` is used only for a joint membership entry, which the change writes
    /// only when it moves voters. `uniform_payload` is used for the uniform membership entry,
    /// which every completed change writes. A change that needs no joint entry therefore drops
    /// `joint_payload` and writes its single entry with `uniform_payload`.
    #[since(version = "0.10.0", change = "select each payload by the shape of its membership")]
    #[since(version = "0.10.0", change = "accept separate payloads for membership change steps")]
    #[since(version = "0.10.0", change = "added optional membership change payload")]
    pub fn with_payload(mut self, joint_payload: C::Payload, uniform_payload: C::Payload) -> Self {
        self.payload = Some((joint_payload, uniform_payload));
        self
    }

    /// Guard the first membership proposal with the given preconditions.
    #[since(version = "0.10.0", change = "added membership change preconditions")]
    pub fn with_preconditions(mut self, preconditions: impl IntoIterator<Item = Precondition<C>>) -> Self {
        let preconditions = BatchOf::<C, _>::of(preconditions);
        self.preconditions = preconditions;
        self
    }

    pub(crate) fn into_parts(
        self,
    ) -> (
        ChangeMembers<C::NodeId, C::Node>,
        bool,
        BatchOf<C, Precondition<C>>,
        Option<(C::Payload, C::Payload)>,
    ) {
        (
            self.members,
            self.retain_removed_as_learners,
            self.preconditions,
            self.payload,
        )
    }
}