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penpot/frontend/src/app/worker.cljs

155 lines
4.7 KiB
Clojure

;; This Source Code Form is subject to the terms of the Mozilla Public
;; License, v. 2.0. If a copy of the MPL was not distributed with this
;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
;;
;; Copyright (c) UXBOX Labs SL
(ns app.worker
(:require
[cljs.spec.alpha :as s]
[promesa.core :as p]
[beicon.core :as rx]
[cuerdas.core :as str]
[app.common.exceptions :as ex]
[app.common.spec :as us]
[app.common.uuid :as uuid]
[app.worker.impl :as impl]
[app.worker.selection]
[app.worker.thumbnails]
[app.worker.snaps]
[app.util.object :as obj]
[app.util.transit :as t]
[app.util.worker :as w]))
;; --- Messages Handling
(s/def ::cmd keyword?)
(s/def ::payload
(s/keys :req-un [::cmd]))
(s/def ::sender-id uuid?)
(s/def ::buffer? boolean?)
(s/def ::message
(s/keys
:req-opt [::buffer?]
:req-un [::payload ::sender-id]))
(def buffer (rx/subject))
(defn- handle-message
"Process the message and returns to the client"
[{:keys [sender-id payload] :as message}]
(us/assert ::message message)
(try
(let [result (impl/handler payload)]
(cond
(p/promise? result)
(p/handle result
(fn [msg]
(.postMessage js/self (t/encode
{:reply-to sender-id
:payload msg})))
(fn [err]
(.postMessage js/self (t/encode
{:reply-to sender-id
:error {:data (ex-data err)
:message (ex-message err)}}))))
(or (rx/observable? result)
(rx/subject? result))
(throw (ex-info "not implemented" {}))
:else
(.postMessage js/self (t/encode
{:reply-to sender-id
:payload result}))))
(catch :default e
(.error js/console "error" e)
(let [message {:reply-to sender-id
:error {:data (ex-data e)
:message (ex-message e)}}]
(.postMessage js/self (t/encode message))))))
(defn- drop-message
"Sends to the client a notifiction that its messages have been dropped"
[{:keys [sender-id payload] :as message}]
(us/assert ::message message)
(.postMessage js/self (t/encode {:reply-to sender-id
:dropped true})))
(defn subscribe-buffer-messages
"Creates a subscription to process the buffer messages"
[]
(let [empty [{} [] ::clear]]
(->> buffer
;; We want async processing to not block the main loop
(rx/observe-on :async)
;; This scan will store the last message per type in `messages`
;; when a previous message is dropped is stored in `dropped`
;; we also store the last message processed in order to detect
;; posible infinite loops
(rx/scan
(fn [[messages dropped last] message]
(let [cmd (get-in message [:payload :cmd])
;; The previous message is dropped
dropped
(cond-> dropped
(contains? messages cmd)
(conj (get messages cmd)))
;; This is the new "head" for its type
messages
(assoc messages cmd message)]
;; When a "clear" message is detected we empty the buffer
(if (= message ::clear)
empty
[messages dropped message])))
empty)
;; 1ms debounce, after 1ms without messages will process the buffer
(rx/debounce 1)
(rx/subs (fn [[messages dropped last]]
;; Send back the dropped messages replies
(doseq [msg dropped]
(drop-message msg))
;; Process the message
(doseq [msg (vals messages)]
(handle-message msg))
;; After process the buffer we send a clear
(when-not (= last ::clear)
(rx/push! buffer ::clear)))))))
(defonce process-message-sub (subscribe-buffer-messages))
(defn- on-message
[event]
(when (nil? (.-source event))
(let [message (.-data event)
message (t/decode message)]
(if (:buffer? message)
(rx/push! buffer message)
(handle-message message)))))
(.addEventListener js/self "message" on-message)
(defn ^:dev/before-load stop []
(rx/-dispose process-message-sub)
(.removeEventListener js/self "message" on-message))
(defn ^:dev/after-load start []
[]
(set! process-message-sub (subscribe-buffer-messages))
(.addEventListener js/self "message" on-message))