record node ID and API user for every write

1 files changed, 44 insertions, 10 deletions

diff --git a/src/document/replica.rs b/src/document/replica.rs
index df2fafd..3717865 100644
--- a/src/document/replica.rs
+++ b/src/document/replica.rs
@@ -175,14 +175,16 @@ impl Replica {
     }
 
     /// The writes `f` makes, as one change stamped `at` if it succeeds (receivers tell
-    /// by the stamp how long the change took to reach them, `swarm::stats`), dropped if
-    /// not. Doesn't refresh the heads: the caller does, under the same lock.
+    /// by the stamp how long the change took to reach them, `swarm::stats`), by
+    /// `writer`, dropped if not. Doesn't refresh the heads: the caller does, under the
+    /// same lock.
     pub(crate) fn transact<T, E>(
         &mut self,
         at: crate::clock::UnixMillis,
+        writer: &Writer,
         f: impl FnOnce(&mut Transaction<'_>) -> Result<T, E>,
     ) -> Result<T, E> {
-        transact(&mut self.doc, at, f)
+        transact(&mut self.doc, at, writer, f)
     }
 }
 
@@ -231,7 +233,11 @@ mod tests {
         let path = vec!["a".to_owned()];
         let mut replica = Replica::new(Epoch::GENESIS, Document::new());
 
-        let refused: Result<(), &str> = replica.transact(UnixMillis(1), |doc| {
+        let writer = Writer {
+            node: "node",
+            user: None,
+        };
+        let refused: Result<(), &str> = replica.transact(UnixMillis(1), &writer, |doc| {
             store::write_path(doc, &path, &json!(1)).unwrap();
             Err("refused")
         });
@@ -242,7 +248,7 @@ mod tests {
 
         // The same writer commits afterwards, and that saves too.
         replica
-            .transact(UnixMillis(2), |doc| {
+            .transact(UnixMillis(2), &writer, |doc| {
                 store::write_path(doc, &path, &json!(2))
             })
             .unwrap();
@@ -261,20 +267,33 @@ mod tests {
     }
 }
 
-/// 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).
+/// Who makes a change, as it records: the node, as the change's author (its node ID),
+/// and the user it wrote for through the API, if any, as its message. Every node holds
+/// every change, so who wrote what is known swarm-wide.
+pub(crate) struct Writer<'a> {
+    pub(crate) node: &'a str,
+    pub(crate) user: Option<&'a str>,
+}
+
+/// The writes `f` makes to `doc`, as one change stamped `at` by `writer` 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,
+    writer: &Writer,
     f: impl FnOnce(&mut Transaction<'_>) -> Result<T, E>,
 ) -> Result<T, E> {
+    authored(doc, writer.node);
     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),
-            );
+            let mut options =
+                automerge::transaction::CommitOptions::default().with_time(at.as_u64() as i64);
+            if let Some(user) = writer.user {
+                options.set_message(user);
+            }
+            transaction.commit_with(options);
         }
         Err(_) => {
             transaction.rollback();
@@ -282,3 +301,18 @@ pub(crate) fn transact<T, E>(
     }
     out
 }
+
+/// Makes `node` the author of `doc`'s changes from now on. Setting an author gives the
+/// document a new actor; this node keeps its own (`with_actor`), which it tracks
+/// (`RemakeState::own_actors`, the document file), as only it writes with it.
+fn authored(doc: &mut Document, node: &str) {
+    if doc
+        .get_author()
+        .is_some_and(|author| author.as_bytes() == node.as_bytes())
+    {
+        return;
+    }
+    let actor = doc.get_actor().clone();
+    doc.set_author(Some(automerge::Author::from(node.as_bytes().to_vec())));
+    doc.set_actor(actor);
+}