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Refactor: update gRPC example to adapt to
LeaderId changes
- Update the `raft-kv-memstore-grpc` example to use the protobuf-defined `LeaderId`. - Automatically implement `CommittedLeaderId` for all types. - Add `openraft::vote::LeaderIdCompare` to provide comparison functions for both single-leader-per-term and multi-leader-per-term implementations.
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51 changes: 51 additions & 0 deletions
51
examples/raft-kv-memstore-grpc/src/pb_impl/impl_leader_id.rs
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,51 @@ | ||
| //! Implement [`RaftLeaderId`] for protobuf defined LeaderId, so that it can be used in OpenRaft | ||
| use std::cmp::Ordering; | ||
| use std::fmt; | ||
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| use openraft::vote::LeaderIdCompare; | ||
| use openraft::vote::RaftLeaderId; | ||
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| use crate::protobuf as pb; | ||
| use crate::TypeConfig; | ||
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| /// Implements PartialOrd for LeaderId to enforce the standard Raft behavior of at most one leader | ||
| /// per term. | ||
| /// | ||
| /// In standard Raft, each term can have at most one leader. This is enforced by making leader IDs | ||
| /// with the same term incomparable (returning None), unless they refer to the same node. | ||
| /// | ||
| /// This differs from the [`PartialOrd`] default implementation which would allow multiple leaders | ||
| /// in the same term by comparing node IDs. | ||
| impl PartialOrd for pb::LeaderId { | ||
| #[inline] | ||
| fn partial_cmp(&self, other: &Self) -> Option<Ordering> { | ||
| LeaderIdCompare::std(self, other) | ||
| } | ||
| } | ||
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| impl fmt::Display for pb::LeaderId { | ||
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { | ||
| write!(f, "T{}-N{}", self.term, self.node_id) | ||
| } | ||
| } | ||
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| impl RaftLeaderId<TypeConfig> for pb::LeaderId { | ||
| type Committed = u64; | ||
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| fn new(term: u64, node_id: u64) -> Self { | ||
| Self { term, node_id } | ||
| } | ||
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| fn term(&self) -> u64 { | ||
| self.term | ||
| } | ||
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| fn node_id_ref(&self) -> Option<&u64> { | ||
| Some(&self.node_id) | ||
| } | ||
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| fn to_committed(&self) -> Self::Committed { | ||
| self.term | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,3 @@ | ||
| //! Implements traits for protobuf types | ||
| mod impl_leader_id; |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,123 @@ | ||
| use std::cmp::Ordering; | ||
| use std::marker::PhantomData; | ||
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| use crate::vote::RaftLeaderId; | ||
| use crate::RaftTypeConfig; | ||
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| /// Provide comparison functions for [`RaftLeaderId`] implementations. | ||
| pub struct LeaderIdCompare<C>(PhantomData<C>); | ||
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| impl<C> LeaderIdCompare<C> | ||
| where C: RaftTypeConfig | ||
| { | ||
| /// Implements [`PartialOrd`] for LeaderId to enforce the standard Raft behavior of at most one | ||
| /// leader per term. | ||
| /// | ||
| /// In standard Raft, each term can have at most one leader. This is enforced by making leader | ||
| /// IDs with the same term incomparable (returning None), unless they refer to the same | ||
| /// node. | ||
| pub fn std<LID>(a: &LID, b: &LID) -> Option<Ordering> | ||
| where LID: RaftLeaderId<C> { | ||
| match a.term().cmp(&b.term()) { | ||
| Ordering::Equal => match (a.node_id_ref(), b.node_id_ref()) { | ||
| (None, None) => Some(Ordering::Equal), | ||
| (Some(_), None) => Some(Ordering::Greater), | ||
| (None, Some(_)) => Some(Ordering::Less), | ||
| (Some(a), Some(b)) => { | ||
| if a == b { | ||
| Some(Ordering::Equal) | ||
| } else { | ||
| None | ||
| } | ||
| } | ||
| }, | ||
| cmp => Some(cmp), | ||
| } | ||
| } | ||
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| /// Implements [`PartialOrd`] for LeaderId to allow multiple leaders per term. | ||
| pub fn adv<LID>(a: &LID, b: &LID) -> Option<Ordering> | ||
| where LID: RaftLeaderId<C> { | ||
| let res = (a.term(), a.node_id_ref()).cmp(&(b.term(), b.node_id_ref())); | ||
| Some(res) | ||
| } | ||
| } | ||
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| #[cfg(test)] | ||
| mod tests { | ||
| use std::cmp::Ordering; | ||
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| use crate::engine::testing::UTConfig; | ||
| use crate::vote::RaftLeaderId; | ||
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| #[derive(Debug, PartialEq, Eq, Default, Clone, PartialOrd, derive_more::Display)] | ||
| #[display("T{}-N{:?}", _0, _1)] | ||
| #[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))] | ||
| struct LeaderId(u64, Option<u64>); | ||
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| impl RaftLeaderId<UTConfig> for LeaderId { | ||
| type Committed = u64; | ||
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| fn new(term: u64, node_id: u64) -> Self { | ||
| Self(term, Some(node_id)) | ||
| } | ||
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| fn term(&self) -> u64 { | ||
| self.0 | ||
| } | ||
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| fn node_id_ref(&self) -> Option<&u64> { | ||
| self.1.as_ref() | ||
| } | ||
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| fn to_committed(&self) -> Self::Committed { | ||
| self.0 | ||
| } | ||
| } | ||
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| #[test] | ||
| fn test_std_cmp() { | ||
| use Ordering::*; | ||
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| use super::LeaderIdCompare as Cmp; | ||
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| let lid = |term, node_id| LeaderId(term, Some(node_id)); | ||
| let lid_none = |term| LeaderId(term, None); | ||
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| // Compare term first | ||
| assert_eq!(Cmp::std(&lid(2, 2), &lid(1, 2)), Some(Greater)); | ||
| assert_eq!(Cmp::std(&lid(1, 2), &lid(2, 2)), Some(Less)); | ||
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| // Equal term, Some > None | ||
| assert_eq!(Cmp::std(&lid(2, 2), &lid_none(2)), Some(Greater)); | ||
| assert_eq!(Cmp::std(&lid_none(2), &lid(2, 2)), Some(Less)); | ||
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| // Equal | ||
| assert_eq!(Cmp::std(&lid(2, 2), &lid(2, 2)), Some(Equal)); | ||
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| // Incomparable | ||
| assert_eq!(Cmp::std(&lid(2, 2), &lid(2, 1)), None); | ||
| assert_eq!(Cmp::std(&lid(2, 1), &lid(2, 2)), None); | ||
| assert_eq!(Cmp::std(&lid(2, 2), &lid(2, 3)), None); | ||
| } | ||
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| #[test] | ||
| fn test_adv_cmp() { | ||
| use Ordering::*; | ||
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| use super::LeaderIdCompare as Cmp; | ||
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| let lid = |term, node_id| LeaderId(term, Some(node_id)); | ||
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| // Compare term first | ||
| assert_eq!(Cmp::adv(&lid(2, 2), &lid(1, 2)), Some(Greater)); | ||
| assert_eq!(Cmp::adv(&lid(1, 2), &lid(2, 2)), Some(Less)); | ||
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| // Equal term | ||
| assert_eq!(Cmp::adv(&lid(2, 2), &lid(2, 1)), Some(Greater)); | ||
| assert_eq!(Cmp::adv(&lid(2, 1), &lid(2, 2)), Some(Less)); | ||
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| // Equal term, node_id | ||
| assert_eq!(Cmp::adv(&lid(2, 2), &lid(2, 2)), Some(Equal)); | ||
| } | ||
| } |
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