✨ Make the binfile export process more resilent to errors

The current binfile export process uses a streaming technique. The
major problem with the streaming approach is the case when an error
happens on the middle of generation, because we have no way to
notify the user about the error (because the response is already
is sent and contents are streaming directly to the user
client/browser).

This commit replaces the streaming with temporal files and SSE
encoded response for emit the export progress events; once the
exportation is finished, a temporal uri to the exported artifact
is emited to the user via "end" event and the frontend code
will automatically trigger the download.

Using the SSE approach removes possible transport timeouts on export
large files by sending progress data over the open connection.

This commit also removes obsolete code related to old binfile
formats.

backend/src/app/binfile/v3.clj

@@ -255,6 +255,8 @@
 
         (write-entry! output path params)
 
+        (events/tap :progress {:section :storage-object :id id})
+
         (with-open [input (sto/get-object-data storage sobject)]
           (.putNextEntry ^ZipOutputStream output (ZipEntry. (str "objects/" id ext)))
           (io/copy input output :size (:size sobject))
@@ -279,6 +281,8 @@
 
         thumbnails   (bfc/get-file-object-thumbnails cfg file-id)]
 
+    (events/tap :progress {:section :file :id file-id})
+
     (vswap! bfc/*state* update :files assoc file-id
             {:id file-id
              :name (:name file)

backend/src/app/rpc/commands/binfile.clj

@@ -11,9 +11,9 @@
    [app.binfile.v1 :as bf.v1]
    [app.binfile.v3 :as bf.v3]
    [app.common.features :as cfeat]
-   [app.common.logging :as l]
    [app.common.schema :as sm]
    [app.common.time :as ct]
+   [app.common.uri :as u]
    [app.config :as cf]
    [app.db :as db]
    [app.http.sse :as sse]
@@ -25,10 +25,12 @@
    [app.rpc.commands.projects :as projects]
    [app.rpc.commands.teams :as teams]
    [app.rpc.doc :as-alias doc]
-   [app.rpc.helpers :as rph]
+   [app.storage :as sto]
+   [app.storage.tmp :as tmp]
    [app.tasks.file-gc]
    [app.util.services :as sv]
-   [app.worker :as-alias wrk]))
+   [app.worker :as-alias wrk]
+   [datoteka.fs :as fs]))
 
 (set! *warn-on-reflection* true)
 
@@ -38,52 +40,42 @@
   schema:export-binfile
   [:map {:title "export-binfile"}
    [:file-id ::sm/uuid]
-   [:version {:optional true} ::sm/int]
    [:include-libraries ::sm/boolean]
    [:embed-assets ::sm/boolean]])
 
-(defn stream-export-v1
-  [cfg {:keys [file-id include-libraries embed-assets] :as params}]
-  (rph/stream
-   (fn [_ output-stream]
-     (try
-       (-> cfg
-           (assoc ::bfc/ids #{file-id})
-           (assoc ::bfc/embed-assets embed-assets)
-           (assoc ::bfc/include-libraries include-libraries)
-           (bf.v1/export-files! output-stream))
-       (catch Throwable cause
-         (l/err :hint "exception on exporting file"
-                :file-id (str file-id)
-                :cause cause))))))
+(defn- export-binfile
+  [{:keys [::sto/storage] :as cfg} {:keys [file-id include-libraries embed-assets]}]
+  (let [output  (tmp/tempfile*)]
+    (try
+      (-> cfg
+          (assoc ::bfc/ids #{file-id})
+          (assoc ::bfc/embed-assets embed-assets)
+          (assoc ::bfc/include-libraries include-libraries)
+          (bf.v3/export-files! output))
 
-(defn stream-export-v3
-  [cfg {:keys [file-id include-libraries embed-assets] :as params}]
-  (rph/stream
-   (fn [_ output-stream]
-     (try
-       (-> cfg
-           (assoc ::bfc/ids #{file-id})
-           (assoc ::bfc/embed-assets embed-assets)
-           (assoc ::bfc/include-libraries include-libraries)
-           (bf.v3/export-files! output-stream))
-       (catch Throwable cause
-         (l/err :hint "exception on exporting file"
-                :file-id (str file-id)
-                :cause cause))))))
+      (let [data   (sto/content output)
+            object (sto/put-object! storage
+                                    {::sto/content data
+                                     ::sto/touched-at (ct/in-future {:minutes 60})
+                                     :content-type "application/zip"
+                                     :bucket "tempfile"})]
+
+        (-> (cf/get :public-uri)
+            (u/join "/assets/by-id/")
+            (u/join (str (:id object)))))
+
+      (finally
+        (fs/delete output)))))
 
 (sv/defmethod ::export-binfile
   "Export a penpot file in a binary format."
   {::doc/added "1.15"
+   ::doc/changes [["2.12" "Remove version parameter, only one version is supported"]]
    ::webhooks/event? true
    ::sm/params schema:export-binfile}
-  [{:keys [::db/pool] :as cfg} {:keys [::rpc/profile-id version file-id] :as params}]
+  [{:keys [::db/pool] :as cfg} {:keys [::rpc/profile-id file-id] :as params}]
   (files/check-read-permissions! pool profile-id file-id)
-  (let [version (or version 1)]
-    (case (int version)
-      1 (stream-export-v1 cfg params)
-      2 (throw (ex-info "not-implemented" {}))
-      3 (stream-export-v3 cfg params))))
+  (sse/response (partial export-binfile cfg params)))
 
 ;; --- Command: import-binfile
 

backend/src/app/util/services.clj

@@ -27,7 +27,7 @@
       (throw (IllegalArgumentException. "Missing arguments on `defmethod` macro.")))
 
     (let [mdata (assoc mdata
-                       ::docstring (some-> docs str/<<-)
+                       ::docstring (some-> docs str/unindent)
                        ::spec sname
                        ::name (name sname))