raftbare is a minimal but feature-complete, I/O-free implementation of the Raft distributed consensus algorithm.
Node is the main struct that represents a Raft node.
It offers methods for creating a cluster, proposing commands, updating cluster configurations,
handling incoming messages, snapshotting, and more.
Node itself does not execute I/O operations.
Instead, it generates Actions that represent pending I/O operations.
How to execute these actions is up to the crate user.
Except for a few optimizations, raftbare is a very straightforward (yet efficient) implementation of the Raft algorithm.
This crate focuses on the core part of the algorithm.
So, offering various convenience features (which are not described in the Raft paper) is left to the crate user.
The following example outlines a basic usage flow of this crate:
use raftbare::{Action, Node, NodeId};
// Start a node.
let mut node = Node::start(NodeId::new(0));
// Create a three nodes cluster.
let mut promise = node.create_cluster(&[NodeId::new(0), NodeId::new(1), NodeId::new(2)]);
// Execute actions requested by the node until the cluster creation is complete.
while promise.poll(&mut node).is_pending() {
for action in node.actions_mut() {
// How to execute actions is up to the crate user.
match action {
Action::SetElectionTimeout => { /* ... */ },
Action::SaveCurrentTerm => { /* ... */ },
Action::SaveVotedFor => { /* ... */ },
Action::AppendLogEntries(_) => { /* ... */ },
Action::BroadcastMessage(_) => { /* ... */ },
Action::SendMessage(_, _) => { /* ... */ },
Action::InstallSnapshot(_) => { /* ... */ },
}
}
// If the election timeout is expired, handle it.
if is_election_timeout_expired() {
node.handle_election_timeout();
}
// If a message is received, handle it.
while let Some(message) = try_receive_message() {
node.handle_message(message);
}
}
// Propose a user-defined command.
let promise = node.propose_command();
// Execute actions as before.$ rustup component add llvm-tools-preview
$ cargo install cargo-llvm-cov
$ git describe --tags
0.1.1
$ cargo llvm-cov
Filename Regions Missed Regions Cover Functions Missed Functions Executed Lines Missed Lines Cover Branches Missed Branches Cover
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
action.rs 78 3 96.15% 5 0 100.00% 152 0 100.00% 0 0 -
config.rs 36 2 94.44% 14 0 100.00% 76 3 96.05% 0 0 -
lib.rs 3 0 100.00% 3 0 100.00% 9 0 100.00% 0 0 -
log.rs 157 7 95.54% 50 0 100.00% 371 5 98.65% 0 0 -
message.rs 40 4 90.00% 10 0 100.00% 100 6 94.00% 0 0 -
node.rs 306 29 90.52% 49 0 100.00% 637 37 94.19% 0 0 -
promise.rs 56 12 78.57% 11 1 90.91% 52 7 86.54% 0 0 -
quorum.rs 61 5 91.80% 15 1 93.33% 111 4 96.40% 0 0 -
role.rs 16 2 87.50% 4 0 100.00% 14 0 100.00% 0 0 -
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
TOTAL 753 64 91.50% 161 2 98.76% 1522 62 95.93% 0 0 -