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web3_events.cljs
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web3_events.cljs
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(ns district.server.web3-events
(:require
[cljs-node-io.core :refer [slurp spit]]
[cljs-web3.core :as web3]
[cljs-web3.eth :as web3-eth]
[cljs.nodejs :as nodejs]
[cljs.reader :as reader]
[clojure.string :as string]
[district.server.config :refer [config]]
[district.server.logging]
[district.server.smart-contracts :refer [create-event-filter replay-past-events-in-order]]
[district.server.web3 :refer [web3]]
[medley.core :as medley]
[mount.core :as mount :refer [defstate]]
[taoensso.timbre :as log]))
(defonce fs (nodejs/require "fs"))
(declare start)
(declare stop)
(def default-file-path "web3-events.log")
(defstate ^{:on-reload :noop} web3-events
:start (start (merge (:web3-events @config)
(:web3-events (mount/args))))
:stop (stop web3-events))
(defn register-callback! [event-key callback & [callback-id]]
(let [[contract-key event] (if-not (= event-key ::after-past-events-dummy-key)
(get (:events @web3-events) event-key)
[::after-past-events-dummy-contract ::after-past-events-dummy-event])
callback-id (or callback-id (rand-int 999999999))]
(when-not contract-key
(throw (js/Error. "Trying to register callback for non existing event " event-key)))
(swap! (:callbacks @web3-events) (fn [callbacks]
(-> callbacks
(assoc-in [contract-key event callback-id] callback)
(assoc-in [:callback-id->path callback-id] [contract-key event])))))
callback-id)
(defn register-after-past-events-dispatched-callback! [callback]
(register-callback! ::after-past-events-dummy-key callback))
(defn unregister-callbacks! [callback-ids]
(doseq [callback-id callback-ids]
(let [path (get-in @(:callbacks @web3-events) [:callback-id->path callback-id])]
(swap! (:callbacks @web3-events) (fn [callbacks]
(-> callbacks
(medley/dissoc-in (into path [callback-id]))
(medley/dissoc-in [:callback-id->path callback-id]))))))
callback-ids)
(defn- read-events-from-file [file-path]
(try
(reader/read-string {:readers {'object (fn [[t v]]
(if (= "BigNumber" (str t))
(web3/to-big-number v)
nil))}}
(str "[" (slurp file-path) "]"))
(catch js/Error e
(log/error "Could not read events from file" {:error (ex-message e) :file-path file-path})
nil)))
(defn- append-line-into-file! [file-path line]
(.appendFileSync fs file-path (str line "\n")))
(defn- clear-file! [file-path]
(.writeFile fs file-path "" (fn [err]
(when err
(log/error "Failed to clear file"
{:error (ex-message err)
:file-path file-path})))))
(defn dispatch [err {:keys [:contract :event] :as evt}]
(if err
(log/error "Error Dispatching" {:err err :event evt} ::event-dispatch)
(when-not (:disable-dispatch-logging? @web3-events)
(log/info "Dispatching event" {:err err :event evt} ::event-dispatch)))
(when (or (not err)
(and err (:dispatch-on-error? @web3-events)))
(doseq [callback (vals (get-in @(:callbacks @web3-events) [(:contract-key contract) event]))]
(callback err evt)))
(when (and (:write-events-into-file? @web3-events)
(not err))
(append-line-into-file! (:file-path @web3-events) (str evt))))
(defn- create-past-event-filters [events last-block-number]
(->> events
(medley/remove-vals #(= (last %) "latest"))
(medley/map-vals (fn [[contract event filter-opts block-opts]]
(let [block-opts (assoc block-opts :to-block last-block-number)]
(create-event-filter contract event filter-opts block-opts))))))
(defn- create-latest-event-filters [events last-block-number]
(->> events
(medley/filter-vals #(or (= (last %) "latest")
(= (:to-block (last %)) "latest")))
(medley/map-vals (fn [[contract event filter-opts]]
(let [block-opts {:from-block last-block-number :to-block "latest"}]
(create-event-filter contract event filter-opts block-opts
(fn [err event]
(dispatch err (assoc event :latest-event? true)))))))
doall))
(defn- get-block-opts-from-event-filter [event-filter]
(let [options (aget event-filter "options")
to-dec (fn [option]
(if (and option (string/starts-with? option "0x"))
(web3/to-decimal option)
option))]
{:from-block (to-dec (aget options "fromBlock"))
:to-block (to-dec (aget options "toBlock"))}))
(defn- log-event-filters-start! [event-filters]
(js/setTimeout
(fn []
(log/info "Started dispatching event filters:"
{:event-filters
(medley/map-vals (fn [event-filter]
(merge {:id (aget event-filter "filterId")}
(get-block-opts-from-event-filter event-filter)))
event-filters)}))
700))
(defn- start-dispatching-latest-events! [events last-block-number]
(let [event-filters (create-latest-event-filters events last-block-number)]
(swap! (:event-filters @web3-events) #(into % event-filters))
(log-event-filters-start! event-filters)
event-filters))
(defn- dispatch-after-past-events-callbacks! []
(let [callbacks (get-in @(:callbacks @web3-events) [::after-past-events-dummy-contract ::after-past-events-dummy-event])
callback-fns (vals callbacks)
callback-ids (keys callbacks)]
(doseq [callback callback-fns]
(callback))
(unregister-callbacks! callback-ids)))
(defn- uninstall-filter [filter]
(web3-eth/stop-watching!
filter (fn [err]
(let [id (aget filter "filterId")]
(when err
(log/error "Error uninstalling event filter" {:error err :filter-id id}))))))
(defn start [{:keys [:events :read-past-events-from-file? :write-events-into-file? :file-path] :as opts
:or {file-path default-file-path}}]
(when-not (web3/connected? @web3)
(throw (js/Error. "Can't connect to Ethereum node")))
(let [last-block-number (web3-eth/block-number @web3)
past-event-filters (if-not read-past-events-from-file?
(create-past-event-filters events (dec last-block-number))
[])
past-events-from-file (when read-past-events-from-file?
(read-events-from-file file-path))]
(when write-events-into-file?
(clear-file! file-path))
(if-not read-past-events-from-file?
(do
(replay-past-events-in-order
(vals past-event-filters)
dispatch
{:on-finish (fn []
(dispatch-after-past-events-callbacks!)
(start-dispatching-latest-events! events last-block-number))})
(log-event-filters-start! past-event-filters))
(js/setTimeout ;; other mount components need to start first
(fn []
(doseq [event past-events-from-file]
(dispatch nil event))
(start-dispatching-latest-events! events last-block-number))
0))
(merge opts {:callbacks (atom {})
:event-filters (atom past-event-filters)
:past-events-from-file past-events-from-file
:file-path file-path})))
(defn stop [web3-events]
(let [filters @(:event-filters @web3-events)]
(log/warn "Stopping web3-events" {:event-filters (medley/map-vals #(aget % "filterId") filters)})
(doseq [filter (remove nil? (vals filters))]
(uninstall-filter filter))))