initialize markdown on a per-page basis

the footnote extra expects to only parse one document over the Markup's
lifetime, and writes the footnotes to the bottom of every page that is
rendered (again assuming only one) with links back to the reference

having one parser for the entire app, naturally, introduced
ever-increasing footnote links and every footnote on the site showing up
on every page. this was not intended

in some light testing, doing this per-request has a nominal effect on
performance

incorporealcms/__init__.py

@@ -3,7 +3,6 @@ import logging
 import os
 from logging.config import dictConfig
 
-import markdown
 from flask import Flask, request, send_from_directory
 
 from ._version import get_versions
@@ -32,10 +31,6 @@ def create_app(instance_path=None, test_config=None):
 
     logger.debug("instance path: %s", app.instance_path)
 
-    # initialize markdown parser from config, but include
-    # extensions our app depends on, like the meta extension
-    app.config['md'] = markdown.Markdown(extensions=app.config['MARKDOWN_EXTENSIONS'] + ['meta'])
-
     @app.before_request
     def log_request():
         logger.info("REQUEST:  %s %s", request.method, request.path)

incorporealcms/config.py

@@ -33,6 +33,7 @@ class Config(object):
     }
 
     MARKDOWN_EXTENSIONS = ['mdx_linkify', 'tables']
+    MARKDOWN_EXTENSION_CONFIGS = {}
 
     DEFAULT_PAGE_STYLE = 'light'
 

incorporealcms/lib.py

@@ -1,7 +1,21 @@
 """Miscellaneous helper functions and whatnot."""
+import markdown
 from flask import current_app as app
 
 
-def get_meta_str(key):
-    """Provide the page's metadata for the specified key, or '' if unset."""
-    return " ".join(app.config['md'].Meta.get(key)) if app.config['md'].Meta.get(key) else ""
+def get_meta_str(md, key):
+    """Provide the page's (parsed in Markup obj md) metadata for the specified key, or '' if unset."""
+    return " ".join(md.Meta.get(key)) if md.Meta.get(key) else ""
+
+
+def init_md():
+    """Initialize the Markdown parser.
+
+    This used to done at the app level in __init__, but extensions like footnotes apparently
+    assume the parser to only live for the length of parsing one document, and create double
+    footnote ref links if the one parser sees the same document multiple times.
+    """
+    # initialize markdown parser from config, but include
+    # extensions our app depends on, like the meta extension
+    return markdown.Markdown(extensions=app.config['MARKDOWN_EXTENSIONS'] + ['meta'],
+                             extension_configs=app.config['MARKDOWN_EXTENSION_CONFIGS'])

incorporealcms/pages.py

@@ -8,7 +8,7 @@ from flask import current_app as app
 from flask import make_response, redirect, render_template, request
 from tzlocal import get_localzone
 
-from incorporealcms.lib import get_meta_str
+from incorporealcms.lib import get_meta_str, init_md
 
 logger = logging.getLogger(__name__)
 
@@ -34,11 +34,12 @@ def display_page(path):
         logger.warning("requested path '%s' (resolved path '%s') not found!", path, resolved_path)
         abort(404)
     else:
-        content = Markup(app.config['md'].convert(entry))
-        logger.debug("file metadata: %s", app.config['md'].Meta)
+        md = init_md()
+        content = Markup(md.convert(entry))
+        logger.debug("file metadata: %s", md.Meta)
 
-        return render('base.html', title=get_meta_str('title'), description=get_meta_str('description'),
-                      image=get_meta_str('image'), base_url=request.base_url, content=content, navs=parent_navs,
+        return render('base.html', title=get_meta_str(md, 'title'), description=get_meta_str(md, 'description'),
+                      image=get_meta_str(md, 'image'), base_url=request.base_url, content=content, navs=parent_navs,
                       mtime=mtime.strftime('%Y-%m-%d %H:%M:%S %Z'))
 
 
@@ -111,6 +112,8 @@ def generate_parent_navs(path):
     else:
         with app.open_instance_resource(resolved_path, 'r') as entry_file:
             entry = entry_file.read()
-        _ = Markup(app.config['md'].convert(entry))
-        page_name = " ".join(app.config['md'].Meta.get('title')) if app.config['md'].Meta.get('title') else f'/{path}'
+        # for issues regarding parser reuse (see lib.init_md) we reinitialize the parser here
+        md = init_md()
+        _ = Markup(md.convert(entry))
+        page_name = " ".join(md.Meta.get('title')) if md.Meta.get('title') else f'/{path}'
         return generate_parent_navs(parent_path) + [(page_name, f'/{path}')]