Declare sphinxext.redirect_from parallel_read_safe

timhoffm · timhoffm · commit bf9352932599 · 2021-03-15T00:31:12.000+01:00
diff --git a/doc/sphinxext/redirect_from.py b/doc/sphinxext/redirect_from.py
@@ -48,33 +48,55 @@
 def setup(app):
     RedirectFrom.app = app
     app.add_directive("redirect-from", RedirectFrom)
+    app.connect("env-before-read-docs", _setup_redirects)
+    app.connect("env-merge-info", _merge_redirects)
+    app.connect("env-purge-doc", _purge_redirects)
     app.connect("build-finished", _generate_redirects)
 
+    metadata = {'parallel_read_safe': True}
+    return metadata
+
 
 class RedirectFrom(Directive):
     required_arguments = 1
-    redirects = {}
 
     def run(self):
         redirected_doc, = self.arguments
         env = self.app.env
         builder = self.app.builder
         current_doc = env.path2doc(self.state.document.current_source)
         redirected_reldoc, _ = env.relfn2path(redirected_doc, current_doc)
-        if redirected_reldoc in self.redirects:
+        if redirected_reldoc in env._redirects:
             raise ValueError(
                 f"{redirected_reldoc} is already noted as redirecting to "
-                f"{self.redirects[redirected_reldoc]}")
-        self.redirects[redirected_reldoc] = builder.get_relative_uri(
+                f"{env._redirects[redirected_reldoc]}")
+        env._redirects[redirected_reldoc] = builder.get_relative_uri(
             redirected_reldoc, current_doc)
         return []
 
 
+def _setup_redirects(app, env, docnames):
+    if not hasattr(env, "_redirects"):
+        env._redirects = {}
+
+
+def _merge_redirects(app, env, docnames, other):
+    for src, dst in other._redirects.items():
+        if src not in env._redirects:
+            env._redirects[src] = dst
+        elif env._redirects[src] != dst:
+            raise ValueError(f"{src} is already noted as redirecting to {dst}")
+
+
+def _purge_redirects(app, env, docname):
+    env._redirects.clear()
+
+
 def _generate_redirects(app, exception):
     builder = app.builder
     if builder.name != "html" or exception:
         return
-    for k, v in RedirectFrom.redirects.items():
+    for k, v in app.env._redirects.items():
         p = Path(app.outdir, k + builder.out_suffix)
         if p.is_file():
             logger.warning(f'A redirect-from directive is trying to create '
