state: drop epoch_tx

The stamp is the only lock-free epoch label.

1 files changed, 4 insertions, 5 deletions

diff --git a/src/state/mod.rs b/src/state/mod.rs
index 9ee08b7..5e4a4d3 100644
--- a/src/state/mod.rs
+++ b/src/state/mod.rs
@@ -59,10 +59,9 @@ pub(crate) struct AppState {
     /// The document and its epoch. Derefs to `Document`.
     pub(crate) doc: Arc<DocumentLock>,
 
-    /// Copy of `doc.epoch` for cheap, lock-free reads (handshakes, keepalives, /peers).
-    /// Only ever changed while holding `doc`'s write lock, together with `doc.epoch`.
-    pub(crate) epoch_tx: watch::Sender<Epoch>,
-    /// `doc`'s epoch label and heads, readable without its lock (`Replica::stamps`).
+    /// `doc`'s epoch label and heads, readable without its lock (`Replica::stamps`):
+    /// for cheap reads (handshakes, keepalives, /peers). Only ever changed while holding
+    /// `doc`'s write lock, together with `doc.epoch`.
     pub(crate) stamp: watch::Receiver<Stamp>,
 
     pub(crate) lifecycle: Arc<RwLock<NodeLifecycle>>,
@@ -231,7 +230,7 @@ impl AppState {
     /// The local epoch. Code that labels or applies sync messages must use the epoch
     /// of the locked `Replica` instead, so label and document can't disagree.
     pub(crate) fn local_epoch(&self) -> Epoch {
-        *self.epoch_tx.borrow()
+        self.stamp.borrow().epoch
     }
 
     /// The local epoch and `Replica::epoch_seq`, read together, without waiting for the