M src/list/raxos/protocal/src/apaxos/acceptor.rs

src/list/raxos/protocal/src/apaxos/acceptor.rs

@@ -5,6 +5,7 @@ use std::fmt::Debug;
 use validit::Validate;
 
 use crate::apaxos::branch::Branch;
+use crate::apaxos::branch::HEAD_UNDECIDED;
 use crate::apaxos::decided::Decided;
 use crate::apaxos::history::History;
 use crate::Types;
@@ -39,12 +40,12 @@ impl<T: Types> Acceptor<T> {
     pub(crate) fn handle_phase1_request(
         &mut self,
         commit_time: T::Time,
-    ) -> Result<Branch<T>, T::Time> {
+    ) -> Result<Branch<T, { HEAD_UNDECIDED }>, T::Time> {
         self.check_committable(&commit_time)?;
 
         self.forbid_smaller_commit_time(commit_time);
 
-        Ok(self.history.history_view(commit_time))
+        Ok(self.history.branch(commit_time))
     }
 
     pub(crate) fn handle_phase2_request(&mut self, decided: Decided<T>) -> Result<(), T::Time> {

src/list/raxos/protocal/src/apaxos/branch.rs

@@ -1,4 +1,3 @@
-use crate::apaxos::decided::Decided;
 use crate::Types;
 
 // For doc reference
@@ -11,12 +10,15 @@ use crate::apaxos::{
 
 /// Indicate the [`Branch`] includes an event has been set at the head
 /// time.
-pub const HEAD_SET: bool = true;
+pub const HEAD_DECIDED: bool = true;
 
 /// Indicate the [`Branch`] **may** not include an event at the head
 /// time. Note that the head time is already in the internal history.
-pub const HEAD_UNSET: bool = false;
+pub const HEAD_UNDECIDED: bool = false;
 
+/// Whether the head time of a [`Branch`] has been set an event.
+///
+/// Note that before setting, there may already be an event at the head time.
 pub type HeadEventState = bool;
 
 /// Represents a single branch [`History`] that is reachable upto a designated
@@ -40,7 +42,7 @@ where T: Types
     history: T::History,
 }
 
-impl<T> Branch<T, HEAD_UNSET>
+impl<T> Branch<T, HEAD_UNDECIDED>
 where T: Types
 {
     pub fn new(head_time: T::Time, history: T::History) -> Self {
@@ -58,14 +60,14 @@ where T: Types
     pub fn add_event(
         mut self,
         event: T::Event,
-    ) -> Result<Branch<T, HEAD_SET>, Branch<T, HEAD_SET>> {
+    ) -> Result<Branch<T, HEAD_DECIDED>, Branch<T, HEAD_DECIDED>> {
         if let Some(_ev) = self.history.get(&self.head_time) {
             // Nothing to do
         } else {
             self.history.append(self.head_time, event).unwrap();
         }
 
-        Ok(Branch::<T, HEAD_SET> {
+        Ok(Branch::<T, HEAD_DECIDED> {
             head_time: self.head_time,
             history: self.history,
         })

src/list/raxos/protocal/src/apaxos/decided.rs

@@ -1,4 +1,4 @@
 use crate::apaxos::branch::Branch;
-use crate::apaxos::branch::HEAD_SET;
+use crate::apaxos::branch::HEAD_DECIDED;
 
-pub type Decided<T> = Branch<T, { HEAD_SET }>;
+pub type Decided<T> = Branch<T, { HEAD_DECIDED }>;

src/list/raxos/protocal/src/apaxos/history.rs

@@ -1,6 +1,7 @@
 use std::fmt::Debug;
 
 use crate::apaxos::branch::Branch;
+use crate::apaxos::branch::HEAD_UNDECIDED;
 use crate::apaxos::errors::TimeRegression;
 use crate::Types;
 
@@ -34,9 +35,9 @@ where
 
     fn get(&self, time: &T::Time) -> Option<&T::Event>;
 
-    /// Returns a view(subset) of the history that is causally prior to or
-    /// concurrent with the given `time`.
-    fn history_view(&self, time: T::Time) -> Branch<T> {
+    /// Returns a single head [`Branch`] of the history that is causally prior
+    /// to or concurrent with the given `time`.
+    fn branch(&self, time: T::Time) -> Branch<T, { HEAD_UNDECIDED }> {
         let lower = self.lower_bounds(time);
         Branch::new(time, lower)
     }

src/list/raxos/protocal/src/apaxos/proposer/mod.rs

@@ -2,6 +2,7 @@ use phase1::Phase1;
 use phase2::Phase2;
 
 use crate::apaxos::branch::Branch;
+use crate::apaxos::branch::HEAD_UNDECIDED;
 use crate::apaxos::errors::APError;
 use crate::APaxos;
 use crate::Types;
@@ -44,7 +45,7 @@ impl<'a, T: Types> Proposer<'a, T> {
         }
     }
 
-    fn new_phase2(&mut self, maybe_committed: Branch<T>) -> Phase2<T> {
+    fn new_phase2(&mut self, maybe_committed: Branch<T, HEAD_UNDECIDED>) -> Phase2<T> {
         // If the current time already has an event, no new event is added.
 
         let decided = match maybe_committed.add_event(self.event.clone()) {
@@ -60,7 +61,6 @@ impl<'a, T: Types> Proposer<'a, T> {
 
         Phase2 {
             apaxos: &mut self.apaxos,
-            time: self.time,
             decided,
             accepted: Default::default(),
         }

src/list/raxos/protocal/src/apaxos/proposer/phase1.rs

@@ -1,6 +1,7 @@
 use std::collections::BTreeMap;
 
 use crate::apaxos::branch::Branch;
+use crate::apaxos::branch::HEAD_UNDECIDED;
 use crate::apaxos::errors::APError;
 use crate::apaxos::history::History;
 use crate::APaxos;
@@ -29,7 +30,7 @@ pub struct Phase1<'a, T: Types> {
 }
 
 impl<'a, T: Types> Phase1<'a, T> {
-    pub fn run(mut self) -> Result<Branch<T>, APError<T>> {
+    pub fn run(mut self) -> Result<Branch<T, { HEAD_UNDECIDED }>, APError<T>> {
         let apaxos = &mut self.apaxos;
 
         let mut sent = 0;

src/list/raxos/protocal/src/apaxos/proposer/phase2.rs

@@ -10,9 +10,6 @@ use crate::Types;
 pub struct Phase2<'a, T: Types> {
     pub apaxos: &'a mut APaxos<T>,
 
-    /// The time of the Proposer that running phase1.
-    pub time: T::Time,
-
     pub decided: Decided<T>,
 
     pub accepted: BTreeMap<T::AcceptorId, ()>,

src/list/raxos/protocal/src/commonly_used/transport.rs

@@ -3,6 +3,7 @@ use std::collections::VecDeque;
 
 use crate::apaxos::acceptor::Acceptor;
 use crate::apaxos::branch::Branch;
+use crate::apaxos::branch::HEAD_UNDECIDED;
 use crate::apaxos::decided::Decided;
 use crate::Transport;
 use crate::Types;
@@ -11,7 +12,10 @@ use crate::Types;
 pub struct DirectCall<T: Types> {
     acceptors: BTreeMap<T::AcceptorId, Acceptor<T>>,
 
-    p1_replies: VecDeque<(T::AcceptorId, Result<Branch<T>, T::Time>)>,
+    p1_replies: VecDeque<(
+        T::AcceptorId,
+        Result<Branch<T, { HEAD_UNDECIDED }>, T::Time>,
+    )>,
     p2_replies: VecDeque<(T::AcceptorId, Result<(), T::Time>)>,
 }
 
@@ -33,7 +37,12 @@ impl<T: Types> Transport<T> for DirectCall<T> {
         self.p1_replies.push_back((target, reply));
     }
 
-    fn recv_phase1_reply(&mut self) -> (T::AcceptorId, Result<Branch<T>, T::Time>) {
+    fn recv_phase1_reply(
+        &mut self,
+    ) -> (
+        T::AcceptorId,
+        Result<Branch<T, { HEAD_UNDECIDED }>, T::Time>,
+    ) {
         self.p1_replies.pop_front().unwrap()
     }
 

src/list/raxos/protocal/src/lib.rs

@@ -11,6 +11,7 @@ use std::fmt::Debug;
 use apaxos::ptime::Time;
 
 use crate::apaxos::branch::Branch;
+use crate::apaxos::branch::HEAD_UNDECIDED;
 use crate::apaxos::decided::Decided;
 use crate::apaxos::history::History;
 
@@ -54,7 +55,12 @@ where Self: Default + Debug + Clone + Sized + 'static
 
 pub trait Transport<T: Types> {
     fn send_phase1_request(&mut self, target: T::AcceptorId, t: T::Time);
-    fn recv_phase1_reply(&mut self) -> (T::AcceptorId, Result<Branch<T>, T::Time>);
+    fn recv_phase1_reply(
+        &mut self,
+    ) -> (
+        T::AcceptorId,
+        Result<Branch<T, { HEAD_UNDECIDED }>, T::Time>,
+    );
 
     fn send_phase2_request(&mut self, target: T::AcceptorId, decided: Decided<T>);
     fn recv_phase2_reply(&mut self) -> (T::AcceptorId, Result<(), T::Time>);