From b0ac0407ada2d899747f3f6220b7b5f36084ba67 Mon Sep 17 00:00:00 2001
From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Sun, 6 Sep 2020 22:38:44 +0100
Subject: [PATCH] DTRT if /_/updates is too old

---
 src/global.rs  |  8 +++++---
 src/sse.rs     |  2 +-
 src/updates.rs | 26 +++++++++++++++++++++-----
 3 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/src/global.rs b/src/global.rs
index 31bacd45..71e050bb 100644
--- a/src/global.rs
+++ b/src/global.rs
@@ -346,7 +346,8 @@ impl InstanceGuard<'_> {
       e
     })?;
     (||{
-      self.c.g.updates.insert(player, Default::default());
+      let pu_bc = PlayerUpdates::new_begin(&self.c.g.gs);
+      self.c.g.updates.insert(player, pu_bc.new());
     })(); // <- No ?, ensures that IEFE is infallible (barring panics)
     (player, logentry)
   }
@@ -663,7 +664,7 @@ impl InstanceGuard<'_> {
   }
 
   #[throws(StartupError)]
-  pub fn load(name: InstanceName) -> InstanceRef {
+  fn load(name: InstanceName) -> InstanceRef {
     {
       let mut st = GLOBAL.save_area_lock.lock().unwrap();
       let st = &mut *st;
@@ -697,8 +698,9 @@ impl InstanceGuard<'_> {
         Err(e)
       })?;
     let mut updates : SecondarySlotMap<_,_> = Default::default();
+    let pu_bc = PlayerUpdates::new_begin(&gs);
     for player in gs.players.keys() {
-      updates.insert(player, Default::default());
+      updates.insert(player, pu_bc.new());
     }
     let name = Arc::new(name);
     access_load.tokens_players.retain(
diff --git a/src/sse.rs b/src/sse.rs
index 0f20c011..ecf418e2 100644
--- a/src/sse.rs
+++ b/src/sse.rs
@@ -220,7 +220,7 @@ pub fn content(iad : InstanceAccessDetails<ClientId>, gen: Generation)
 
     let to_send = match log.into_iter().rev()
       .find(|(_,update)| update.gen <= gen) {
-        None => log.front_index(),
+        None => UpdateId::min_value(),
         Some((mut i,_)) => { i.try_increment(); i },
       };
     
diff --git a/src/updates.rs b/src/updates.rs
index d8f50fff..1f9c89b6 100644
--- a/src/updates.rs
+++ b/src/updates.rs
@@ -97,14 +97,30 @@ enum TransmitUpdateEntry<'u> {
 
 // ---------- prepared updates, queued in memory ----------
 
-impl Default for PlayerUpdates {
-  fn default() -> PlayerUpdates { PlayerUpdates {
-    log : StableIndexVecDeque::with_capacity(50),
-    cv : Default::default(),
-  } }
+
+pub struct PlayerUpdatesBuildContext {
+  pub(self) u1: Arc<PreparedUpdate>,
+}
+
+impl PlayerUpdatesBuildContext {
+  pub fn new(&self) -> PlayerUpdates {
+    let mut log = StableIndexVecDeque::with_capacity(50);
+    log.push_back(self.u1.clone());
+    let cv = Default::default();
+    PlayerUpdates { log, cv }
+  }
 }
 
 impl PlayerUpdates {
+  pub fn new_begin(gs: &GameState) -> PlayerUpdatesBuildContext {
+    let u1 = Arc::new(PreparedUpdate {
+      gen : gs.gen,
+      when: Instant::now(),
+      us: vec![],
+    });
+    PlayerUpdatesBuildContext { u1 }
+  }
+
   pub fn push<U: Into<Arc<PreparedUpdate>>>(&mut self, update: U) {
     self.log.push_back(update.into());
     self.cv.notify_all();
-- 
2.30.2