2 files changed, 28 insertions, 13 deletions

diff --git a/src/document/file.rs b/src/document/file.rs
index 9efae42..3ea3afd 100644
--- a/src/document/file.rs
+++ b/src/document/file.rs
@@ -197,6 +197,11 @@ impl DocumentFile {
 
     /// What is due for a document of `epoch` at `heads`, written by this node's `actors`
     /// (see the module docs).
+    /// How many of this node's actors the file holds; None before it was written.
+    pub(crate) fn actors(&self) -> Option<usize> {
+        self.lock().as_ref().map(|written| written.actors)
+    }
+
     pub(crate) fn due(&self, epoch: Epoch, actors: usize, heads: &[ChangeHash]) -> Due {
         let written = self.lock().clone();
         let reason = match &written {
diff --git a/src/document/replica.rs b/src/document/replica.rs
index 61f2b3b..df2fafd 100644
--- a/src/document/replica.rs
+++ b/src/document/replica.rs
@@ -182,19 +182,7 @@ impl Replica {
         at: crate::clock::UnixMillis,
         f: impl FnOnce(&mut Transaction<'_>) -> Result<T, E>,
     ) -> Result<T, E> {
-        let mut transaction = self.doc.transaction();
-        let out = f(&mut transaction);
-        match &out {
-            Ok(_) => {
-                transaction.commit_with(
-                    automerge::transaction::CommitOptions::default().with_time(at.as_u64() as i64),
-                );
-            }
-            Err(_) => {
-                transaction.rollback();
-            }
-        }
-        out
+        transact(&mut self.doc, at, f)
     }
 }
 
@@ -272,3 +260,25 @@ mod tests {
         assert_eq!(epoch(2, 0xab).to_string(), "2:abababababab");
     }
 }
+
+/// The writes `f` makes to `doc`, as one change stamped `at` if it succeeds, dropped if
+/// not ([`Replica::transact`], and writes into the document before a rejoin).
+pub(crate) fn transact<T, E>(
+    doc: &mut Document,
+    at: crate::clock::UnixMillis,
+    f: impl FnOnce(&mut Transaction<'_>) -> Result<T, E>,
+) -> Result<T, E> {
+    let mut transaction = doc.transaction();
+    let out = f(&mut transaction);
+    match &out {
+        Ok(_) => {
+            transaction.commit_with(
+                automerge::transaction::CommitOptions::default().with_time(at.as_u64() as i64),
+            );
+        }
+        Err(_) => {
+            transaction.rollback();
+        }
+    }
+    out
+}