Isolate strict warning counter to just the ongoing build (#2607)

Refactor to eliminate global state.
Fixes the issue with the webserver's warnings being able to abort the build.

mkdocs/__main__.py

@@ -72,11 +72,6 @@ def __init__(self, log_name='mkdocs', level=logging.INFO):
         self.stream.name = 'MkDocsStreamHandler'
         self.logger.addHandler(self.stream)
 
-        # Add CountHandler for strict mode
-        self.counter = utils.log_counter
-        self.counter.setLevel(logging.WARNING)
-        self.logger.addHandler(self.counter)
-
 
 pass_state = click.make_pass_decorator(State, ensure=True)
 

mkdocs/commands/build.py

@@ -240,8 +240,16 @@ def _build_page(page, config, doc_files, nav, env, dirty=False):
 
 def build(config, live_server=False, dirty=False):
     """ Perform a full site build. """
-    try:
 
+    logger = logging.getLogger('mkdocs')
+
+    # Add CountHandler for strict mode
+    warning_counter = utils.CountHandler()
+    warning_counter.setLevel(logging.WARNING)
+    if config['strict']:
+        logging.getLogger('mkdocs').addHandler(warning_counter)
+
+    try:
         from time import time
         start = time()
 
@@ -308,8 +316,8 @@ def build(config, live_server=False, dirty=False):
         # Run `post_build` plugin events.
         config['plugins'].run_event('post_build', config=config)
 
-        counts = utils.log_counter.get_counts()
-        if config['strict'] and len(counts):
+        counts = warning_counter.get_counts()
+        if counts:
             msg = ', '.join([f'{v} {k.lower()}s' for k, v in counts])
             raise Abort(f'\nAborted with {msg} in strict mode!')
 
@@ -323,6 +331,9 @@ def build(config, live_server=False, dirty=False):
             raise Abort('\nAborted with a BuildError!')
         raise
 
+    finally:
+        logger.removeHandler(warning_counter)
+
 
 def site_directory_contains_stale_files(site_directory):
     """ Check if the site directory contains stale files from a previous build. """

mkdocs/utils/__init__.py

@@ -442,9 +442,6 @@ def get_counts(self):
         return [(logging.getLevelName(k), v) for k, v in sorted(self.counts.items(), reverse=True)]
 
 
-# A global instance to use throughout package
-log_counter = CountHandler()
-
 # For backward compatibility as some plugins import it.
 # It is no longer necessary as all messages on the
 # `mkdocs` logger get counted automatically.