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Reset state from history

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- fails if server changes are made while client is disconnected
This commit is contained in:
Nicholas Kariniemi 2014-08-30 11:47:09 +03:00
parent 763e6f2fc8
commit a572b9e1eb
5 changed files with 85 additions and 34 deletions
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56
src/clj/grub/state.clj
View file

@ -10,6 +10,24 @@
(def to-all (chan))
(def from-all (a/mult to-all))
(def state-history (atom []))
(defn save-history-state [history new-state]
(when-not (= (last history) new-state)
(println "Adding state to history: " (hasch/uuid new-state))
(println "History size:" (inc (count history)))
(conj history new-state)))
(defn get-history-state [hash]
(println "Look for history state:" hash)
(println "History:")
(doseq [s @state-history]
(println (hasch/uuid s)))
(first (filter #(= (hasch/uuid %) hash) @state-history)))
(add-watch state :history (fn [_ _ _ new-state]
(swap! state-history save-history-state new-state)))
(defn initial-state [grubs recipes]
{:grubs (util/map-by-key :id grubs)
:recipes (util/map-by-key :id recipes)})
@ -17,18 +35,46 @@
(defn sync-new-client! [to from]
(let [client-id (java.util.UUID/randomUUID)
server-shadow (atom cs/empty-state)]
(add-watch state client-id (fn [_ _ _ new-state]
(when-let [msg (cs/diff-states new-state @server-shadow)]
(add-watch state client-id (fn [_ _ _ current-state]
(when-let [msg (cs/diff-states @server-shadow current-state)]
(a/put! to msg)
(reset! server-shadow new-state))))
;; TODO: reset only if send succeeds?
(reset! server-shadow current-state))))
(a/go-loop []
(if-let [{:keys [type diff hash shadow-hash] :as msg} (<! from)]
(do (condp = type
:diff (let [new-shadow (swap! server-shadow sync/patch-state diff)]
:diff
(if (= (hasch/uuid @server-shadow) shadow-hash)
;; we have what they thought we had
;; apply changes normally
(let [new-shadow (swap! server-shadow sync/patch-state diff)]
(println "Hash matched state, apply changes")
(if (= (hasch/uuid new-shadow) hash)
(let [new-state (swap! state sync/patch-state diff)]
(>! @to-db diff))
(do (println "Hash check failed --> complete sync")
(do (println "Applying diff failed --> full sync")
(let [sync-state @state]
(reset! server-shadow sync-state)
(a/put! to (cs/complete-sync-response sync-state))))))
;; we have something different than they thought
;; check history
(if-let [history-state (get-history-state shadow-hash)]
;; Found what they thought in history,
;; reset client state to this
;; and continue as normal
(do
(println "Hash check failed --> Reset from history")
(reset! server-shadow history-state)
(let [new-shadow (swap! server-shadow sync/patch-state diff)]
(if (= (hasch/uuid new-shadow) hash)
(let [new-state (swap! state sync/patch-state diff)]
(>! @to-db diff))
(do (println "Applying diff failed --> full sync")
(let [sync-state @state]
(reset! server-shadow sync-state)
(a/put! to (cs/complete-sync-response sync-state)))))))
;; No history found, do complete sync
(do (println "Hash check failed, not in history --> full sync")
(let [sync-state @state]
(reset! server-shadow sync-state)
(a/put! to (cs/complete-sync-response sync-state))))))

9
src/cljs/grub/core.cljs
View file

@ -5,11 +5,14 @@
[cljs.core.async :as a :refer [<! >! chan]])
(:require-macros [grub.macros :refer [log logs]]))
(defn init-app []
(view/render-app state/app-state)
(defn connect-to-server [reset?]
(let [to-remote (chan)
from-remote (chan)]
(ws/connect-client! to-remote from-remote)
(state/sync-state! from-remote to-remote)))
(state/sync-state! from-remote to-remote reset?)))
(defn init-app []
(view/render-app state/app-state)
(connect-to-server true))
(init-app)

12
src/cljs/grub/state.cljs
View file

@ -8,13 +8,13 @@
(def app-state (atom cs/empty-state))
(defn sync-state! [to from]
(defn sync-state! [to from reset?]
(let [client-shadow (atom cs/empty-state)]
(add-watch app-state :app-state (fn [_ _ _ new]
(when-let [msg (cs/diff-states new @client-shadow)]
(add-watch app-state :app-state (fn [_ _ _ current-state]
(when-let [msg (cs/diff-states @client-shadow current-state)]
(a/put! from msg)
;; TODO: reset shadow only if send succeeds
(reset! client-shadow new))))
;; TODO: reset only if send succeeds
(reset! client-shadow current-state))))
(go-loop []
(if-let [{:keys [type diff hash shadow-hash] :as msg} (<! to)]
(do (condp = type
@ -28,4 +28,4 @@
(logs "Invalid msg:" msg))
(recur))
(remove-watch app-state :app-state)))
(a/put! from cs/complete-sync-request)))
(when reset? (a/put! from cs/complete-sync-request))))

3
src/cljs/grub/websocket.cljs
View file

@ -27,10 +27,13 @@
(let [msg (cljs.reader/read-string (.-message event))]
(a/put! from msg)))
(def ws (atom nil))
(defn connect-client! [to from]
(let [handler (goog.events.EventHandler.)
websocket (goog.net.WebSocket.)
listen (fn [type fun] (.listen handler websocket type fun false))]
(reset! ws websocket)
(listen goog.net.WebSocket.EventType.OPENED (partial on-connected websocket))
(listen goog.net.WebSocket.EventType.MESSAGE (partial on-message from))
(listen goog.net.WebSocket.EventType.CLOSED #(log "Closed:" %))

5
src/cljx/grub/common_state.cljx
View file

@ -15,8 +15,7 @@
:hash hash
:shadow-hash shadow-hash})
(defn diff-states [state shadow*]
(let [shadow shadow*]
(defn diff-states [shadow state]
(when (not= state shadow)
(let [diff (sync/diff-states shadow state)
hash (hasch/uuid state)
@ -28,4 +27,4 @@
;(logs "Remote = " shadow)
;(logs "Diff:" diff)
;(logs "Send" shadow-hash "->" hash)
))))
)))