From 12ac165f241089cc25f97f49befe7a4467e64ac5 Mon Sep 17 00:00:00 2001
From: Nicholas Kariniemi <nicholas.kariniemi@gmail.com>
Date: Mon, 6 Oct 2014 22:13:50 +0300
Subject: [PATCH] Store max 20 history states, reset on client when server ACKs

---
 src/cljx/grub/state.cljx          | 6 ++++--
 src/cljx/grub/sync.cljx           | 7 ++++++-
 src/test/grub/test/unit/state.clj | 2 --
 3 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/src/cljx/grub/state.cljx b/src/cljx/grub/state.cljx
index 265abe3..5edd4ac 100644
--- a/src/cljx/grub/state.cljx
+++ b/src/cljx/grub/state.cljx
@@ -20,8 +20,10 @@
                    (let [new-states (sync/apply-diff states* (:diff msg))
                          new-shadow (diff/patch-state shadow (:diff msg))
                          {:keys [diff hash]} (sync/diff-states (sync/get-current-state new-states) new-shadow)]
-                     (when-not (= states* new-states)
-                       (reset! states new-states))
+                     (if client?
+                       (reset! states (sync/new-state (sync/get-current-state new-states)))
+                       (when-not (= states* new-states)
+                         (reset! states new-states)))
                      (when-not (or client? (sync/empty-diff? (:diff msg)))
                        (>! out (message/diff-msg diff hash)))
                      (if client?
diff --git a/src/cljx/grub/sync.cljx b/src/cljx/grub/sync.cljx
index 033449b..3da74e1 100644
--- a/src/cljx/grub/sync.cljx
+++ b/src/cljx/grub/sync.cljx
@@ -3,6 +3,8 @@
             [grub.util :as util]
             [hasch.core :as hasch]))
 
+(def num-history-states 20)
+
 (def empty-state {:grubs {} :recipes {}})
 
 (defn initial-state [grubs recipes]
@@ -25,7 +27,10 @@
         new-hash (hasch/uuid new-state)]
     (if (= last-hash new-hash)
       states
-      (conj states {:hash new-hash :state new-state}))))
+      (let [new-states (conj states {:hash new-hash :state new-state})]
+        (if (>= (count states) num-history-states)
+          (into [] (rest new-states))
+          new-states)))))
 
 (defn diff-states [states shadow]
   (let [state states;(get-current-state states)
diff --git a/src/test/grub/test/unit/state.clj b/src/test/grub/test/unit/state.clj
index e241c1b..ce91379 100644
--- a/src/test/grub/test/unit/state.clj
+++ b/src/test/grub/test/unit/state.clj
@@ -197,8 +197,6 @@
     (>!! client-in msg)
     (<!!? client-state-changes)
     @client-states => (hashed-states
-                       {:grubs {"1" {:completed false, :text "2 apples"}}, :recipes {}}
-                       {:grubs {"1" {:completed true, :text "2 apples"}}, :recipes {}}
                        {:grubs {"1" {:completed true, :text "4 apples"}}, :recipes {}})
     @server-states => (hashed-states
                        {:grubs {"1" {:completed false, :text "2 apples"}}, :recipes {}}