Simplify result handling

If we start collecting the results in run_parallel *immediately* after
starting the worker processes, we do not need another process to handle
the results. This also allows us to store all of the results on a the
FileChecker class and process results uniformly. This also means we can
count the number of errors and warnings in a run and use that to exit
appropriately (using SystemExit).

flake8/checker.py

@@ -173,22 +173,6 @@ class Manager(object):
                 physical_line=physical_line,
             )
 
-    def _report_after_parallel(self):
-        final_results = {}
-        for (filename, results) in self._results():
-            final_results[filename] = results
-
-        for checker in self.checkers:
-            filename = checker.filename
-            results = sorted(final_results.get(filename, []),
-                             key=lambda tup: (tup[1], tup[2]))
-            self._handle_results(filename, results)
-
-    def _report_after_serial(self):
-        for checker in self.checkers:
-            results = sorted(checker.results, key=lambda tup: (tup[2], tup[3]))
-            self._handle_results(checker.filename, results)
-
     def _run_checks_from_queue(self):
         LOG.info('Running checks in parallel')
         for checker in iter(self.process_queue.get, 'DONE'):
@@ -242,12 +226,16 @@ class Manager(object):
         This iterates over each of the checkers and reports the errors sorted
         by line number.
         """
-        if not self.using_multiprocessing:
-            self._report_after_serial()
+        results_found = 0
+        for checker in self.checkers:
+            results = sorted(checker.results, key=lambda tup: (tup[2], tup[3]))
+            self._handle_results(checker.filename, results)
+            results_found += len(results)
+        return results_found
 
     def run_parallel(self):
         """Run the checkers in parallel."""
-        LOG.info('Starting %d process workers', self.jobs - 1)
+        LOG.info('Starting %d process workers', self.jobs)
         for i in range(self.jobs):
             proc = multiprocessing.Process(
                 target=self._run_checks_from_queue
@@ -256,10 +244,14 @@ class Manager(object):
             proc.start()
             self.processes.append(proc)
 
-        proc = multiprocessing.Process(target=self._report_after_parallel)
-        proc.start()
-        LOG.info('Started process to report errors')
-        self.processes.append(proc)
+        final_results = {}
+        for (filename, results) in self._results():
+            final_results[filename] = results
+
+        for checker in self.checkers:
+            filename = checker.filename
+            checker.results = sorted(final_results.get(filename, []),
+                                     key=lambda tup: (tup[1], tup[2]))
 
     def run_serial(self):
         """Run the checkers in serial."""
@@ -299,11 +291,11 @@ class Manager(object):
         for checker in self.checkers:
             self.process_queue.put(checker)
 
-    def stop(self):
-        """Stop checking files."""
         for i in range(self.jobs):
             self.process_queue.put('DONE')
 
+    def stop(self):
+        """Stop checking files."""
         for proc in self.processes:
             LOG.info('Joining %s to the main process', proc.name)
             proc.join()

flake8/main/cli.py

@@ -195,6 +195,7 @@ class Application(object):
 
         self.options = None
         self.args = None
+        self.result_count = 0
 
     def find_plugins(self):
         # type: () -> NoneType
@@ -274,7 +275,7 @@ class Application(object):
         # type: () -> NoneType
         """Report all the errors found by flake8 3.0."""
         LOG.info('Reporting errors')
-        self.file_checker_manager.report()
+        self.result_count = self.file_checker_manager.report()
 
     def _run(self, argv):
         self.find_plugins()
@@ -289,7 +290,12 @@ class Application(object):
 
     def run(self, argv=None):
         # type: (Union[NoneType, List[str]]) -> NoneType
-        """Run our application."""
+        """Run our application.
+
+        This method will also handle KeyboardInterrupt exceptions for the
+        entirety of the flake8 application. If it sees a KeyboardInterrupt it
+        will forcibly clean up the :class:`~flake8.checker.Manager`.
+        """
         try:
             self._run(argv)
         except KeyboardInterrupt as exc:
@@ -303,3 +309,4 @@ def main(argv=None):
     """Main entry-point for the flake8 command-line tool."""
     app = Application()
     app.run(argv)
+    raise SystemExit(app.result_count > 0)