introduce majority voting on remakes

1 files changed, 35 insertions, 3 deletions

diff --git a/src/remake/records.rs b/src/remake/records.rs
index 5c844f1..ed018ca 100644
--- a/src/remake/records.rs
+++ b/src/remake/records.rs
@@ -7,6 +7,7 @@
 //! * `decision`: written once, by the coordinator only (committed or aborted).
 //! * `abortRequested`: written by any node on an operator's request. It is an input to
 //!   the coordinator's decision, not a decision itself.
+//! * `votes/<pk>`: each written by that member only (`vote`).
 //!
 //! A proposal whose coordinator never decides (crash, partition) is reported as
 //! `expired` once its settle period plus a grace margin has passed. Expiry is derived,
@@ -15,6 +16,8 @@
 //! Records edited into an unreadable shape through the store API are skipped with a
 //! warning.
 
+use std::collections::BTreeMap;
+
 use automerge::{AutoCommit, ChangeHash};
 use serde::{Deserialize, Serialize};
 use serde_json::Value as JsonValue;
@@ -127,8 +130,10 @@ pub(crate) struct Proposal {
     /// interval if absent.
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub(crate) switch_delay_ms: Option<u64>,
-    /// Peers that must stay active during the settle period.
-    pub(crate) peers_considered: Vec<String>,
+    /// Members whose votes count (sorted), fixed at proposal time (`vote`).
+    pub(crate) electorate: Vec<String>,
+    /// Votes needed to commit: a majority of the electorate.
+    pub(crate) quorum: usize,
     /// The remake kind (`compact` for records written before kinds existed).
     #[serde(default = "default_kind")]
     pub(crate) kind: String,
@@ -173,6 +178,13 @@ pub(crate) struct AbortRequest {
     pub(crate) at: u64,
 }
 
+/// A member's vote for a remake.
+#[derive(Clone, Debug, Serialize, Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub(crate) struct Vote {
+    pub(crate) at: u64,
+}
+
 #[derive(Clone, Debug, Serialize, Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub(crate) struct Record {
@@ -181,6 +193,9 @@ pub(crate) struct Record {
     pub(crate) decision: Option<Decision>,
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub(crate) abort_requested: Option<AbortRequest>,
+    /// By member public key.
+    #[serde(default)]
+    pub(crate) votes: BTreeMap<String, Vote>,
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize)]
@@ -316,6 +331,18 @@ pub(crate) fn write_abort_request(
     write_part(doc, id, "abortRequested", request)
 }
 
+pub(crate) fn write_vote(
+    doc: &mut AutoCommit,
+    id: &str,
+    voter: &str,
+    vote: &Vote,
+) -> Result<(), StoreError> {
+    let json = serde_json::to_value(vote).map_err(anyhow::Error::from)?;
+    let mut path = record_path(id, "votes");
+    path.push(voter.to_owned());
+    store::write_path(doc, &path, &json)
+}
+
 pub(crate) fn decode_hex32(hex: &str) -> Option<[u8; 32]> {
     if hex.len() != 64 || !hex.is_ascii() {
         return None;
@@ -360,7 +387,8 @@ mod tests {
             proposed_at: settle_until.saturating_sub(1_000),
             settle_until,
             switch_delay_ms: None,
-            peers_considered: vec!["node-b".into()],
+            electorate: vec!["node-a".into(), "node-b".into()],
+            quorum: 2,
             kind: DEFAULT_KIND.to_owned(),
             content: JsonValue::Null,
             translation: JsonValue::Null,
@@ -390,6 +418,7 @@ mod tests {
             decided_at: 11_000,
         };
         write_decision(&mut doc, "c-1", &decision).unwrap();
+        write_vote(&mut doc, "c-1", "node-b", &Vote { at: 7 }).unwrap();
         doc.commit();
 
         let all = load_all(&doc);
@@ -399,6 +428,8 @@ mod tests {
         assert_eq!(record.proposal.policy, p.policy);
         assert_eq!(record.proposal.base_change_hashes().unwrap().len(), 1);
         assert!(record.abort_requested.is_some());
+        assert_eq!(record.votes.keys().collect::<Vec<_>>(), ["node-b"]);
+        assert_eq!(record.proposal.quorum, 2);
         assert_eq!(record.phase(0, 0), Phase::Committed);
     }
 
@@ -408,6 +439,7 @@ mod tests {
             proposal: proposal(10_000),
             decision: None,
             abort_requested: None,
+            votes: BTreeMap::new(),
         };
         assert_eq!(record.phase(10_000, 500), Phase::Proposed);
         assert_eq!(record.phase(10_500, 500), Phase::Proposed);