Possibly fully working differential sync
This commit is contained in:
Nicholas Kariniemi
parent
a572b9e1eb
commit
f087309c0f
4 changed files with 88 additions and 57 deletions
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@ -13,9 +13,11 @@
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(def state-history (atom []))
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(defn save-history-state [history new-state]
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(when-not (= (last history) new-state)
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(when-not (= (hasch/uuid (last history)) (hasch/uuid new-state))
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(println "Adding state to history: " (hasch/uuid new-state))
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(println "History size:" (inc (count history)))
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(println "History:")
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(doseq [s (conj history new-state)]
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(println (hasch/uuid s)))
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(conj history new-state)))
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(defn get-history-state [hash]
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@ -34,53 +36,57 @@
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(defn sync-new-client! [to from]
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(let [client-id (java.util.UUID/randomUUID)
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server-shadow (atom cs/empty-state)]
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client-state (atom cs/empty-state)
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log (fn [& args]
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(apply println client-id args))]
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(add-watch state client-id (fn [_ _ _ current-state]
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(when-let [msg (cs/diff-states @server-shadow current-state)]
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(when-let [msg (cs/diff-states @client-state current-state)]
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(a/put! to msg)
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;; send ACK even if nothing changes
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;; TODO: reset only if send succeeds?
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(reset! server-shadow current-state))))
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(reset! client-state current-state))))
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(a/go-loop []
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(if-let [{:keys [type diff hash shadow-hash] :as msg} (<! from)]
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(do (condp = type
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:diff
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(if (= (hasch/uuid @server-shadow) shadow-hash)
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(if (= (hasch/uuid @client-state) shadow-hash)
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;; we have what they thought we had
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;; apply changes normally
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(let [new-shadow (swap! server-shadow sync/patch-state diff)]
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(println "Hash matched state, apply changes")
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(let [new-shadow (swap! client-state sync/patch-state diff)]
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(log "Hash matched state, apply changes")
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(if (= (hasch/uuid new-shadow) hash)
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(let [new-state (swap! state sync/patch-state diff)]
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(>! @to-db diff))
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(do (println "Applying diff failed --> full sync")
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(do (log "Applying diff failed --> full sync")
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(let [sync-state @state]
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(reset! server-shadow sync-state)
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(reset! client-state sync-state)
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(a/put! to (cs/complete-sync-response sync-state))))))
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;; we have something different than they thought
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;; check history
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(if-let [history-state (get-history-state shadow-hash)]
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;; Found what they thought in history,
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;; reset client state to this
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;; and continue as normal
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(do
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(println "Hash check failed --> Reset from history")
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(reset! server-shadow history-state)
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(let [new-shadow (swap! server-shadow sync/patch-state diff)]
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(if (= (hasch/uuid new-shadow) hash)
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(let [new-state (swap! state sync/patch-state diff)]
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(>! @to-db diff))
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(do (println "Applying diff failed --> full sync")
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(let [sync-state @state]
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(reset! server-shadow sync-state)
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(a/put! to (cs/complete-sync-response sync-state)))))))
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;; No history found, do complete sync
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(do (println "Hash check failed, not in history --> full sync")
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(let [sync-state @state]
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(reset! server-shadow sync-state)
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(a/put! to (cs/complete-sync-response sync-state))))))
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:complete (let [new-state (reset! server-shadow @state)]
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;; We have something different than they thought
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;; Check history
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(do
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(log "Hash check failed --> Reset from history")
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(if-let [history-state (get-history-state shadow-hash)]
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;; Found what they thought we had in history,
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;; reset client state to this and continue as normal
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(do
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(reset! client-state history-state)
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(let [new-shadow (swap! client-state sync/patch-state diff)]
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(if (= (hasch/uuid new-shadow) hash)
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(let [new-state (swap! state sync/patch-state diff)]
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(>! @to-db diff))
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(do (log "Applying diff failed --> full sync")
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(let [sync-state @state]
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(reset! client-state sync-state)
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(a/put! to (cs/complete-sync-response sync-state)))))))
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;; Not found in history, do complete sync
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(do (log "Hash check failed, not in history --> full sync")
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(let [sync-state @state]
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(reset! client-state sync-state)
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(a/put! to (cs/complete-sync-response sync-state)))))))
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:complete (let [new-state (reset! client-state @state)]
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(log "full sync")
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(a/put! to (cs/complete-sync-response new-state)))
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(println "Invalid msg:" msg))
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(log "Invalid msg:" msg))
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(recur))
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(remove-watch state client-id)))))
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@ -12,7 +12,7 @@
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(state/sync-state! from-remote to-remote reset?)))
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(defn init-app []
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(view/render-app state/app-state)
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(view/render-app state/state)
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(connect-to-server true))
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(init-app)
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@ -6,26 +6,48 @@
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(:require-macros [grub.macros :refer [log logs]]
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[cljs.core.async.macros :refer [go go-loop]]))
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(def app-state (atom cs/empty-state))
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(def state (atom cs/empty-state))
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(def unacked-history (atom {}))
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(defn get-unacked-state [hash]
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(logs "Look for history state:" hash)
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(get @unacked-history hash))
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(defn sync-state! [to from reset?]
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(let [client-shadow (atom cs/empty-state)]
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(add-watch app-state :app-state (fn [_ _ _ current-state]
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(when-let [msg (cs/diff-states @client-shadow current-state)]
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(a/put! from msg)
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;; TODO: reset only if send succeeds
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(reset! client-shadow current-state))))
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(let [server-state (atom cs/empty-state)]
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(add-watch state :state (fn [_ _ _ current-state]
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(when-not (= @server-state current-state)
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(let [msg (cs/diff-states @server-state current-state)]
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(when-not (get @unacked-history (hasch/uuid current-state))
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(logs "state change! msg: " msg)
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(swap! unacked-history assoc (hasch/uuid current-state) current-state)
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(logs "History:" (keys @unacked-history))
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(a/put! from msg))
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))))
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(go-loop []
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(if-let [{:keys [type diff hash shadow-hash] :as msg} (<! to)]
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(do (condp = type
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:diff (let [new-shadow (swap! client-shadow #(sync/patch-state % diff))]
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(if (= (hasch/uuid new-shadow) hash)
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(swap! app-state #(sync/patch-state % diff))
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(do (log "Hash check failed --> complete sync")
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(a/put! from cs/complete-sync-request))))
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:complete (do (reset! client-shadow (:state msg))
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(reset! app-state (:state msg)))
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:diff (do
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(logs "Received diff:" msg)
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(when (not (= (hasch/uuid @server-state) shadow-hash))
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(reset! server-state (get-unacked-state shadow-hash)))
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(reset! unacked-history {})
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(let [ ;; what they now think we have (after updating)
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new-shadow (swap! server-state #(sync/patch-state % diff))]
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;; should match hash
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(if (= (hasch/uuid new-shadow) hash)
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;; apply same changes locally
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;; if there are differences, they will be sent back
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(swap! state sync/patch-state diff)
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(do (log "Hash check failed --> complete sync")
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(a/put! from cs/complete-sync-request)))))
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:complete (do
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(logs "Complete sync:" (hasch/uuid (:state msg)))
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(reset! unacked-history {})
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(reset! server-state (:state msg))
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(reset! state (:state msg)))
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(logs "Invalid msg:" msg))
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(recur))
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(remove-watch app-state :app-state)))
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(remove-watch state :state)))
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(when reset? (a/put! from cs/complete-sync-request))))
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@ -16,15 +16,18 @@
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:shadow-hash shadow-hash})
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(defn diff-states [shadow state]
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(when (not= state shadow)
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(let [diff (sync/diff-states shadow state)
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hash (hasch/uuid state)
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shadow-hash (hasch/uuid shadow)
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msg (diff-msg diff hash shadow-hash)]
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msg
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(let [diff (sync/diff-states shadow state)
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;; what we now have
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hash (hasch/uuid state)
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;; what we had/what you used to have
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;; should match what they think we have
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shadow-hash (hasch/uuid shadow)
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msg (diff-msg diff hash shadow-hash)]
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msg
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;(logs "Sync because:")
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;(logs "Local = " state)
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;(logs "Remote = " shadow)
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;(logs "Diff:" diff)
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;(logs "Send" shadow-hash "->" hash)
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)))
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))
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