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Doc: update architecture: add heartbeat worker
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- Part of: #1225
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@drmingdrmer
drmingdrmer committed Aug 31, 2024
1 parent c279fb8 commit 7d6769a
Showing 1 changed file with 65 additions and 47 deletions.
112 changes: 65 additions & 47 deletions openraft/src/docs/internal/architecture.md
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Expand Up @@ -27,6 +27,17 @@ The major components inside Openraft include:
to replicate logs or snapshots. It communicates with `RaftCore` through
channels.

- **`HeartbeatWorkersHandle`**: This control handle manages all heartbeat
tasks: `HeartbeatWorker`.

- **`HeartbeatWorker`**: This specialized task is solely responsible for
sending heartbeat messages (in the form of an empty
[`AppendEntriesRequest`]) to a specific target node. This task, separate
from the `ReplicationCore`, is responsible for sending heartbeats. This
design prevents intensive log entry replication from blocking heartbeat
acknowledgments, which could otherwise lead to the Leader's lease expiration
and subsequent step down.

- **[`RaftNetwork`]**: This is a user-provided component that implements the
network transport layer, e.g., sending logs to a remote node or sending a
[`VoteRequest`] to a remote node.
Expand All @@ -41,14 +52,15 @@ The major components inside Openraft include:



[`Raft`]: `crate::raft::Raft`
[`client_write`]: `crate::raft::Raft::client_write`
[`RaftLogStorage`]: `crate::storage::RaftLogStorage`
[`RaftStateMachine`]: `crate::storage::RaftStateMachine`
[`Adapter`]: `crate::storage::Adapter`
[`RaftNetwork`]: `crate::network::RaftNetwork`
[`append_entries`]: `crate::network::RaftNetwork::append_entries`
[`VoteRequest`]: `crate::raft::VoteRequest`
[`Raft`]: `crate::raft::Raft`
[`client_write`]: `crate::raft::Raft::client_write`
[`RaftLogStorage`]: `crate::storage::RaftLogStorage`
[`RaftStateMachine`]: `crate::storage::RaftStateMachine`
[`Adapter`]: `crate::storage::Adapter`
[`RaftNetwork`]: `crate::network::RaftNetwork`
[`append_entries`]: `crate::network::RaftNetwork::append_entries`
[`VoteRequest`]: `crate::raft::VoteRequest`
[`AppendEntriesRequest`]: `crate::raft::message::AppendEntriesRequest`

[//]: # (private)
[//]: # ([`RaftMsg`]: `crate::raft::RaftMsg`)
Expand All @@ -65,49 +77,55 @@ The major components inside Openraft include:
! User !
! o !
! | !
! | !
! | "client_write(impl AppData) -> impl AppDataResponse"
! | "is_leader()" !
! | "client_write(impl AppData)"
! | "ensure_linearizable()"
! | "change_membership()"!
! v !
! Raft ! .-----> Raft o---.
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~' | |
| | |
| enum RaftMes | |
| | |
.~~~~~~~|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. | .~~~~~~|~~~~~~~~~~~~.
! v ! | ! v !
.----------------o RaftCore ---------------------------. | ! RaftCore !
| ! o ! | | ! !
| ! | ! | | '~~~~~~~~~~~~~~~~~~~'
| ! .--+--------. ! | |
| ! v v ! | |
| ! ReplicationHandle ReplicationHandle ! | |
| ! | | ! | |
| '~~|~~~~~~~~~~~~~~~~|~~~~~~~~~~~~~~~~~~~' | |
| | | | |
| .~~~~~~~~~~|~~~~~~~~~~. .~~|~~~~~~~~~~~~~~~~~~~. | | RPC:
| ! v ! ! v ! | | "vote()"
| ! ReplicationCore ! ! ReplicationCore ! | | "append_entries()"
| ! o ! ! o o ! | | "install_snapshot()"
| '~|~~~~~~~~~~~~~~~~~~~' ! | | ! | |
| | ! | v ! | |
| | ! | RaftNetwork--------------------'
| | '~~|~~~~~~~~~~~~~~~~~~~' |
| | | | "apply()"
| `------------+------------' | "build_snapshot()"
| | "get_log()" .-----------' "install_snapshot()"
| "append_log()" | |
| "..." | .~~~~~~~~~~|~~~~~~~~~~.
`--------. | ! v !
| | ! RaftStateMachine !
| | ! o !
| | ! | !
| | '~~~~~~~~~~|~~~~~~~~~~'
v v |
RaftLogStorage |
! Raft ! .-----> Raft ----.
'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~' | |
| | |
| enum RaftMes | |
| | |
.~~~~~~~|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. | .~~~~~~|~~~~~~~~~~~~.
"append()" ! v ! | ! v !
.------o RaftCore -------------------------------. | ! RaftCore !
| ! ReplicationHandle ! | | ! !
| ! | ReplicationHandle ! | | '~~~~~~~~~~~~~~~~~~~'
| ! | | HeartbeatWorkersHandle ! | |
| ! | | | ! | |
| '~~~|~~|~~~~~~~|~~~~~~~~~~~~~~~~~~~~~~~~' | |
| | | | | |
| | | | .~~~~~~~~~~~~~~~~~. | |
| | | +------>HeartbeatWorker ! | |
| | | | ! RaftNetwork---------------+
| | | | '~~~~~~~~~~~~~~~~~' | |
| | | | .~~~~~~~~~~~~~~~~~. | | RPC:
| | | `------>HeartbeatWorker ! | | "vote()"
| | | ! RaftNetwork ! | | "append_entries()"
| | | '~~~~~~~~~~~~~~~~~' | | "snapshot()"
| | | | | "transfer_leader()"
| | | .~~~~~~~~~~~~~~~~~. | |
| | `------>ReplicationCore ! | |
| .----|--------!-o RaftNetwork---------------------+
| | | '~~~~~~~~~~~~~~~~~' | |
| | | .~~~~~~~~~~~~~~~~~. | |
| | `--------->ReplicationCore ! | |
| +-------------!-o RaftNetwork---------------------'
| | '~~~~~~~~~~~~~~~~~' |
| | | "apply()"
| | | "build_snapshot()"
| | "try_get_log_entries()" .-----------' "install_snapshot()"
| | |
| | .~~~~~~~~~~|~~~~~~~~~~.
| | ! v !
| | ! RaftStateMachine !
| | ! o !
| | '~~~~~~~~~~|~~~~~~~~~~'
v v |
RaftLogStorage |
o |
| |
| |
v v
local-disk local-disk
----------------------------------------------- -----------------------------------------------
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