don't offer brotli content encoding

That was good while we still had files saved brotli-compressed, but now
it adds more overhead.

1 files changed, 9 insertions, 11 deletions

diff --git a/fietsboek/views/detail.py b/fietsboek/views/detail.py
index 8ca7836..4af7994 100644
--- a/fietsboek/views/detail.py
+++ b/fietsboek/views/detail.py
@@ -6,7 +6,6 @@ import io
 import logging
 from html.parser import HTMLParser
 
-import brotli
 from markupsafe import Markup
 from pyramid.httpexceptions import (
     HTTPFound,
@@ -134,18 +133,17 @@ def gpx(request):
         wanted_filename = f"{track.id}.gpx"
     content_disposition = f'attachment; filename="{wanted_filename}"'
     gpx_data = track.gpx_xml()
-    # We can be nice to the client if they support it, and deliver the gzipped
-    # data straight. This saves decompression time on the server and saves a
-    # lot of bandwidth.
-    accepted = request.accept_encoding.acceptable_offers(["br", "gzip", "identity"])
+    # We used to offer brotli compression here as well, but brotli is too
+    # inefficient to do on-the-fly. That was only useful while we had the data
+    # stored brotli-compressed. For comparison, a track with ~50k points:
+    # identity -- 2.4s -- 5.49 MiB
+    # gzip     -- 2.5s -- 657.53 KiB
+    # brotli   -- 12s  -- 389.45 KiB
+    # So yes, brotli does give better compression than gzip, but the time is
+    # not worth paying for.
+    accepted = request.accept_encoding.acceptable_offers(["gzip", "identity"])
     for encoding, _qvalue in accepted:
-        if encoding == "br":
-            data = brotli.compress(gpx_data)
-            response = Response(data, content_type="application/gpx+xml", content_encoding="br")
-            break
         if encoding == "gzip":
-            # gzip'ed GPX files are so much smaller than uncompressed ones, it
-            # is worth re-compressing them for the client
             data = gzip.compress(gpx_data)
             response = Response(data, content_type="application/gpx+xml", content_encoding="gzip")
             break