gered/views
1
0
Fork 0
Code Issues Pull requests Packages Projects Releases Wiki Activity

Fix concurrency error where an unsubscription can come in before the subscription is finished causing views to get stuck in the system.

Browse source
This commit is contained in:
Alexander Hudek 2015-08-10 16:54:37 -04:00
parent ced5a7abd0
commit bff7c9eb5f
2 changed files with 21 additions and 12 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
project.clj
View file

@ -1,4 +1,4 @@
(defproject views "1.4.2"
(defproject views "1.4.3"
:description "A view to the past helps navigate the future."
:url "https://github.com/kirasystems/views"

31
src/views/core.clj
View file

@ -40,23 +40,32 @@
(def refresh-queue (ArrayBlockingQueue. refresh-queue-size))
(defn subscribe-view!
[view-system view-sig subscriber-key data-hash]
[view-system view-sig subscriber-key]
(-> view-system
(update-in [:subscribed subscriber-key] (fnil conj #{}) view-sig)
(update-in [:subscribers view-sig] (fnil conj #{}) subscriber-key)
(update-in [:hashes view-sig] #(or % data-hash)))) ;; see note #1
(update-in [:subscribers view-sig] (fnil conj #{}) subscriber-key)))
(defn update-hash!
[view-system view-sig data-hash]
(update-in view-system [:hashes view-sig] #(or % data-hash))) ;; see note #1 in NOTES.md
(defn subscribe!
[view-system namespace view-id parameters subscriber-key]
(when-let [view (get-in @view-system [:views view-id])]
(future
(try
(let [vdata (data view namespace parameters)]
(swap! view-system subscribe-view! [namespace view-id parameters] subscriber-key (hash vdata))
((get @view-system :send-fn) subscriber-key [[view-id parameters] vdata]))
(catch Exception e
(error "error subscribing:" namespace view-id parameters
"e:" e "msg:" (.getMessage e)))))))
(let [view-sig [namespace view-id parameters]]
(swap! view-system subscribe-view! view-sig subscriber-key)
(future
(try
(let [vdata (data view namespace parameters)
data-hash (hash vdata)]
;; Check to make sure that we are still subscribed. It's possible that
;; an unsubscription event came in while computing the view.
(when (get-in @view-system [:subscribed subscriber-key view-sig])
(update-hash! view-system view-sig data-hash)
((get @view-system :send-fn) subscriber-key [[view-id parameters] vdata])))
(catch Exception e
(error "error subscribing:" namespace view-id parameters
"e:" e "msg:" (.getMessage e))))))))
(defn remove-from-subscribers
[view-system view-sig subscriber-key]