add clock module

The Clock module is the system clock that every unix timestamp new goes
through.  It comes with an offset that only tests can set.

3 files changed, 11 insertions, 6 deletions

diff --git a/src/swarm/members.rs b/src/swarm/members.rs
index 895e0cc..9b0de18 100644
--- a/src/swarm/members.rs
+++ b/src/swarm/members.rs
@@ -21,7 +21,7 @@ use serde_json::{Value as JsonValue, json};
 use tracing::{debug, info, warn};
 
 use crate::document::store::{self, StoreError};
-use crate::state::{AppState, unix_millis};
+use crate::state::AppState;
 
 const META_ROOT: &str = "_continuum";
 
@@ -168,7 +168,7 @@ pub(crate) async fn ensure_registered(state: &AppState) {
         )
     };
     let wanted = state.alias.clone();
-    let now = unix_millis();
+    let now = state.clock.now_millis();
 
     if !registered {
         let mut entry = json!({ "since": now, "alive": now });
diff --git a/src/swarm/state_file.rs b/src/swarm/state_file.rs
index 62a6dbe..8b883fc 100644
--- a/src/swarm/state_file.rs
+++ b/src/swarm/state_file.rs
@@ -129,7 +129,12 @@ pub(crate) async fn update(state: &AppState, now: bool) {
 
     let seeds = {
         let replica = state.doc.read().await;
-        seeds(&replica.doc, state.local_id(), state.electorate_window)
+        seeds(
+            &replica.doc,
+            state.local_id(),
+            state.electorate_window,
+            state.clock.now_millis(),
+        )
     };
     let remembered = Remembered { swarm_id, seeds };
 
@@ -172,8 +177,7 @@ pub(crate) async fn update(state: &AppState, now: bool) {
 /// Members to rejoin through: those alive within the electorate window, stable ones
 /// first, at most `MAX_SEEDS`, sorted. Changes only when members join, leave or change
 /// tier, so the file rarely does.
-fn seeds(doc: &automerge::AutoCommit, me: &str, window: Duration) -> Vec<String> {
-    let now = crate::state::unix_millis();
+fn seeds(doc: &automerge::AutoCommit, me: &str, window: Duration, now: u64) -> Vec<String> {
     let (mut stable, transient): (Vec<String>, Vec<String>) = members::electorate(doc, now, window)
         .into_iter()
         .filter(|pk| pk != me)
diff --git a/src/swarm/sync.rs b/src/swarm/sync.rs
index d4503bb..a05e346 100644
--- a/src/swarm/sync.rs
+++ b/src/swarm/sync.rs
@@ -330,6 +330,7 @@ pub(crate) async fn handle_sync(
         let epoch = envelope.epoch;
         let message = envelope.message;
         let peer = peer.to_owned();
+        let clock = Arc::clone(&state.clock);
 
         // Some((caught_up, heads changed)) when applied, None when the message belongs
         // to another epoch.
@@ -366,7 +367,7 @@ pub(crate) async fn handle_sync(
             stats.heads_seen(heads_after.len());
             let changed = heads_after != heads_before;
             if changed && measure_propagation {
-                let now_ms = crate::state::unix_millis() as i64;
+                let now_ms = clock.now_millis() as i64;
                 // Time 0: not stamped (snapshots, older nodes).
                 let delays: Vec<i64> = replica
                     .doc