Compress responses with gzip.

frontends/ycdl_flask/backend/common.py

@@ -3,6 +3,8 @@ Do not execute this file directly.
 Use ycdl_launch.py to start the server with gevent.
 '''
 import flask; from flask import request
+import gzip
+import io
 import mimetypes
 import os
 import threading
@@ -37,6 +39,37 @@ site.jinja_env.add_extension('jinja2.ext.do')
 site.jinja_env.filters['seconds_to_hms'] = jinja_filters.seconds_to_hms
 site.debug = True
 
+gzip_minimum_size = 500
+gzip_level = 3
+@site.after_request
+def after_request(response):
+    '''
+    Thank you close.io.
+    https://github.com/closeio/Flask-gzip
+    '''
+    accept_encoding = request.headers.get('Accept-Encoding', '')
+
+    bail = False
+    bail = bail or response.status_code < 200
+    bail = bail or response.status_code >= 300
+    bail = bail or response.direct_passthrough
+    bail = bail or len(response.get_data()) < gzip_minimum_size
+    bail = bail or 'gzip' not in accept_encoding.lower()
+    bail = bail or 'Content-Encoding' in response.headers
+
+    if bail:
+        return response
+
+    gzip_buffer = io.BytesIO()
+    gzip_file = gzip.GzipFile(mode='wb', compresslevel=gzip_level, fileobj=gzip_buffer)
+    gzip_file.write(response.get_data())
+    gzip_file.close()
+    response.set_data(gzip_buffer.getvalue())
+    response.headers['Content-Encoding'] = 'gzip'
+    response.headers['Content-Length'] = len(response.get_data())
+
+    return response
+
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