openraft 0.9.23

Advanced Raft consensus
Documentation 
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use std::fmt::Debug;
use std::fmt::Display;
use std::fmt::Formatter;
use std::hash::Hash;

use crate::OptionalSend;
use crate::OptionalSync;

/// Essential trait bound for node-id, except serde.
#[doc(hidden)]
pub trait NodeIdEssential:
    Sized
    + OptionalSend
    + OptionalSync
    + Eq
    + PartialEq
    + Ord
    + PartialOrd
    + Debug
    + Display
    + Hash
    + Clone
    + Default
    + 'static
{
}

impl<T> NodeIdEssential for T where T: Sized
        + OptionalSend
        + OptionalSync
        + Eq
        + PartialEq
        + Ord
        + PartialOrd
        + Debug
        + Display
        + Hash
        + Copy
        + Clone
        + Default
        + 'static
{
}

/// A Raft node's ID.
///
/// A `NodeId` uniquely identifies a node in the Raft cluster.
#[cfg(feature = "serde")]
pub trait NodeId: NodeIdEssential + serde::Serialize + for<'a> serde::Deserialize<'a> {}

#[cfg(feature = "serde")]
impl<T> NodeId for T where T: NodeIdEssential + serde::Serialize + for<'a> serde::Deserialize<'a> {}

#[cfg(not(feature = "serde"))]
pub trait NodeId: NodeIdEssential {}

#[cfg(not(feature = "serde"))]
impl<T> NodeId for T where T: NodeIdEssential {}

/// Essential trait bound for application level node-data, except serde.
pub trait NodeEssential:
    Sized + OptionalSend + OptionalSync + Eq + PartialEq + Debug + Clone + Default + 'static
{
}
impl<T> NodeEssential for T where T: Sized + OptionalSend + OptionalSync + Eq + PartialEq + Debug + Clone + Default + 'static
{}

/// A Raft `Node`, this trait holds all relevant node information.
///
/// For the most generic case `BasicNode` provides an example implementation including the node's
/// network address, but the used `Node` implementation can be customized to include additional
/// information.
#[cfg(feature = "serde")]
pub trait Node: NodeEssential + serde::Serialize + for<'a> serde::Deserialize<'a> {}

#[cfg(feature = "serde")]
impl<T> Node for T where T: NodeEssential + serde::Serialize + for<'a> serde::Deserialize<'a> {}

#[cfg(not(feature = "serde"))]
pub trait Node: NodeEssential {}

#[cfg(not(feature = "serde"))]
impl<T> Node for T where T: NodeEssential {}

/// EmptyNode is an implementation of trait [`Node`] that contains nothing.
///
/// Such a node store nothing but is just a place holder.
#[derive(Debug, Clone, Default, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
pub struct EmptyNode {}

impl EmptyNode {
    /// Creates an [`EmptyNode`].
    pub fn new() -> Self {
        Self {}
    }
}

impl Display for EmptyNode {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        write!(f, "{{}}")
    }
}

/// An implementation of trait [`Node`] that contains minimal node information.
///
/// The most common usage is to store the connecting address of a node.
/// So that an application does not need an additional store to support its
/// [`RaftNetwork`](crate::RaftNetwork) implementation.
///
/// An application is also free not to use this storage and implements its own node-id to address
/// mapping.
#[derive(Debug, Clone, Default, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
pub struct BasicNode {
    /// User defined string that represent the endpoint of the target node.
    ///
    /// It is used by [`RaftNetwork`](crate::RaftNetwork) for connecting to target node.
    pub addr: String,
}

impl BasicNode {
    /// Creates as [`BasicNode`].
    pub fn new(addr: impl ToString) -> Self {
        Self { addr: addr.to_string() }
    }
}

impl Display for BasicNode {
    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
        write!(f, "{}", self.addr)
    }
}