FEATURE: extend duration allowed for download

Previously we would raise a warning in the logs if downloading
a file (from s3) takes longer than 60 seconds.

At scale this happens reasonably frequently.

1. Raised the duration to 3 minutes

2. Pulled the resizing mutex out of the downloading mutex
so we have less and clearer error logs

app/models/optimized_image.rb

@@ -56,6 +56,15 @@ class OptimizedImage < ActiveRecord::Base
 
     return thumbnail if thumbnail
 
+    # create the thumbnail otherwise
+    original_path = Discourse.store.path_for(upload)
+
+    if original_path.blank?
+      # download is protected with a DistributedMutex
+      external_copy = Discourse.store.download(upload) rescue nil
+      original_path = external_copy.try(:path)
+    end
+
     lock(upload.id, width, height) do
       # may have been generated since we got the lock
       thumbnail = find_by(upload_id: upload.id, width: width, height: height)
@@ -63,13 +72,6 @@ class OptimizedImage < ActiveRecord::Base
       # return the previous thumbnail if any
       return thumbnail if thumbnail
 
-      # create the thumbnail otherwise
-      original_path = Discourse.store.path_for(upload)
-      if original_path.blank?
-        external_copy = Discourse.store.download(upload) rescue nil
-        original_path = external_copy.try(:path)
-      end
-
       if original_path.blank?
         Rails.logger.error("Could not find file in the store located at url: #{upload.url}")
       else

lib/file_store/base_store.rb

@@ -77,7 +77,7 @@ module FileStore
     end
 
     def download(upload)
-      DistributedMutex.synchronize("download_#{upload.sha1}") do
+      DistributedMutex.synchronize("download_#{upload.sha1}", validity: 3.minutes) do
         filename = "#{upload.sha1}#{File.extname(upload.original_filename)}"
         file = get_from_cache(filename)