Linters are created per file

2 files changed, 86 insertions, 48 deletions

diff --git a/pylint/lint.py b/pylint/lint.py
index 390efa2d2..131a07e0c 100644
--- a/pylint/lint.py
+++ b/pylint/lint.py
@@ -107,6 +107,7 @@ def _get_python_path(filepath):
 def _merge_stats(stats):
     merged = {}
     by_msg = collections.Counter()
+    nested_keys = set()
     for stat in stats:
         message_stats = stat.pop("by_msg", {})
         by_msg.update(message_stats)
@@ -116,11 +117,17 @@ def _merge_stats(stats):
                 merged[key] = item
             else:
                 if isinstance(item, dict):
+                    nested_keys.add(key)
+                elif isinstance(item, set):
                     merged[key].update(item)
                 else:
                     merged[key] = merged[key] + item
 
-    merged["by_msg"] = by_msg
+    for key in nested_keys:
+        merged[key] = _merge_stats(stat.get(key, {}) for stat in stats)
+
+    if by_msg:
+        merged["by_msg"] = by_msg
     return merged
 
 
@@ -487,6 +494,19 @@ class PyLinter(utils.MessagesHandlerMixIn, checkers.BaseTokenChecker):
             },
         ),
         (
+            "limit-inference-results",
+            {
+                "type": "int",
+                "metavar": "<number-of-results>",
+                "default": 100,
+                "help": (
+                    "Control the amount of potential inferred values when inferring "
+                    "a single object. This can help the performance when dealing with "
+                    "large functions or complex, nested conditions. "
+                ),
+            },
+        ),
+        (
             "extension-pkg-whitelist",
             {
                 "type": "csv",
@@ -516,7 +536,8 @@ class PyLinter(utils.MessagesHandlerMixIn, checkers.BaseTokenChecker):
         (
             "exit-zero",
             {
-                "action": "store_true",
+                "type": "yn",
+                "default": False,
                 "help": (
                     "Always return a 0 (non-error) status code, even if "
                     "lint errors are found. This is primarily useful in "
@@ -775,18 +796,19 @@ class PyLinter(utils.MessagesHandlerMixIn, checkers.BaseTokenChecker):
         walker.walk(ast_node)
         return True
 
-    # IAstroidChecker interface #################################################
-
     def open(self):
-        """initialize counters"""
-        self.stats.clear()
-        self.stats["by_module"] = {}
-        self.stats["by_msg"] = {}
-        MANAGER.always_load_extensions = self.config.unsafe_load_any_extension
-        MANAGER.max_inferable_values = self.config.limit_inference_results
-        MANAGER.extension_package_whitelist.update(self.config.extension_pkg_whitelist)
-        for msg_cat in utils.MSG_TYPES.values():
-            self.stats[msg_cat] = 0
+        self._init_msg_states()
+
+    def add_stats(self, **kwargs):
+        """add some stats entries to the statistic dictionary
+        raise an AssertionError if there is a key conflict
+        """
+        for key, value in kwargs.items():
+            if key[-1] == "_":
+                key = key[:-1]
+            assert key not in self.stats
+            self.stats[key] = value
+        return self.stats
 
 
 # utilities ###################################################################
@@ -929,18 +951,21 @@ class PluginRegistry(utils.MessagesHandlerMixIn, ReportRegistry):
         :raises InvalidCheckerError: If the priority of the checker is
             invalid.
         """
+        # Allow instances to be passed for backwards compatibility
+        if isinstance(checker, checkers.BaseChecker):
+            checker = checker.__class__
+
         existing_checker_types = set(
-            type(existing_checker)
+            existing_checker
             for name_checkers in self._checkers.values()
             for existing_checker in name_checkers
         )
-        checker_type = type(checker)
-        if checker_type in existing_checker_types:
+        if checker in existing_checker_types:
             msg_fmt = (
                 "Not registering checker {}. A checker of type {} has "
                 "already been registered."
             )
-            msg = msg_fmt.format(checker.name, checker_type.__name__)
+            msg = msg_fmt.format(checker.name, checker.__name__)
             warnings.warn(msg)
             return
 
@@ -1367,7 +1392,7 @@ group are mutually exclusive.",
 
             self.generate_reports(base_name)
 
-        if self._global_config.config.exit_zero:
+        if self._global_config.exit_zero:
             sys.exit(0)
         else:
             sys.exit(status_code)
@@ -1569,35 +1594,26 @@ group are mutually exclusive.",
 
     # pylint: enable=unused-argument
 
+    def close_registration(self):
+        """Stop registering plugins and prepare everything for checking."""
+        MANAGER.always_load_extensions = self._global_config.unsafe_load_any_extension
+        MANAGER.max_inferable_values = self._global_config.limit_inference_results
+        MANAGER.extension_package_whitelist.update(
+            self._global_config.extension_pkg_whitelist
+        )
+
     def check(self, files_or_modules, checkers_):
         """main checking entry: check a list of files or modules from their
         name.
         """
-        # initialize msgs_state now that all messages have been registered into
-        # the store
-        self._plugin_registry.init_msg_states()
+        # initialize msgs_state now that all messages have been registered into the store
+        self.close_registration()
 
         if not isinstance(files_or_modules, (list, tuple)):
             files_or_modules = (files_or_modules,)
 
-        walker = utils.PyLintASTWalker(self._plugin_registry)
-        tokencheckers = [
-            c for c in checkers_ if interfaces.implements(c, interfaces.ITokenChecker)
-        ]
-        rawcheckers = [
-            c for c in checkers_ if interfaces.implements(c, interfaces.IRawChecker)
-        ]
         # notify global begin
-        linter = PyLinter(self._global_config)
-        linter.config = self._global_config
-        linter.msgs_store = self._plugin_registry.msgs_store
-        linter.stats = self._plugin_registry.stats
-        linter.open()
-        for checker in checkers_:
-            checker.linter = linter
-            checker.open()
-            if interfaces.implements(checker, interfaces.IAstroidChecker):
-                walker.add_checker(checker)
+        all_stats = [self._plugin_registry.stats]
         # build ast and check modules or packages
         expanded_files = utils.expand_files(
             files_or_modules,
@@ -1606,6 +1622,26 @@ group are mutually exclusive.",
             self._global_config.black_list_re,
         )
         for module_desc in expanded_files:
+            linter = PyLinter(self._global_config)
+            linter.msgs_store = self._plugin_registry.msgs_store
+            linter.open()
+
+            walker = utils.PyLintASTWalker(self._plugin_registry)
+            allcheckers = []
+            tokencheckers = [linter]
+            rawcheckers = []
+            for checker_cls in checkers_:
+                checker = checker_cls(linter)
+                checker.linter = linter
+                checker.open()
+                allcheckers.append(checker)
+                if interfaces.implements(checker, interfaces.ITokenChecker):
+                    tokencheckers.append(checker)
+                if interfaces.implements(checker, interfaces.IRawChecker):
+                    rawcheckers.append(checker)
+                if interfaces.implements(checker, interfaces.IAstroidChecker):
+                    walker.add_checker(checker)
+
             modname = module_desc.name
             filepath = module_desc.path
             if not module_desc.isarg and not self.should_analyze_file(
@@ -1615,12 +1651,13 @@ group are mutually exclusive.",
 
             linter.reporter = self._reporter
             linter.check(module_desc, walker, rawcheckers, tokencheckers)
+            self._plugin_registry.stats["statement"] += walker.nbstatements
+            all_stats.append(linter.stats)
+
+            for checker in reversed(allcheckers):
+                checker.close()
 
-        # notify global end
-        self._plugin_registry.stats["statement"] = walker.nbstatements
-        for checker in reversed(checkers_):
-            checker.close()
-        linter.close()
+        self._plugin_registry.stats = _merge_stats(all_stats)
 
         return module_desc.basename, linter.msg_status
 
diff --git a/pylint/utils.py b/pylint/utils.py
index 4a5966656..88c1100c5 100644
--- a/pylint/utils.py
+++ b/pylint/utils.py
@@ -203,13 +203,12 @@ def build_message_def(checker, msgid, msg_tuple):
         )
         symbol = None
     options.setdefault("scope", default_scope)
-    return MessageDefinition(checker, msgid, msg, descr, symbol, **options)
+    return MessageDefinition(msgid, msg, descr, symbol, **options)
 
 
 class MessageDefinition:
     def __init__(
         self,
-        checker,
         msgid,
         msg,
         descr,
@@ -219,7 +218,6 @@ class MessageDefinition:
         maxversion=None,
         old_names=None,
     ):
-        self.checker = checker
         if len(msgid) != 5:
             raise InvalidMessageError("Invalid message id %r" % msgid)
         if not msgid[0] in MSG_TYPES:
@@ -287,7 +285,7 @@ class MessagesHandlerMixIn:
         self.msg_status = 0
         self.msgs_store = MessagesStore()
         self.reporter = None
-        self.stats = {"by_module": {}, "by_msg": {}}
+        self.stats = {"by_module": {}, "by_msg": {}, "statement": 0}
         super().__init__()
 
     def _checker_messages(self, checker):
@@ -418,11 +416,14 @@ class MessagesHandlerMixIn:
                 for msgid in msgids:
                     self.disable(msgid)
 
-    def init_msg_states(self):
+    def _init_msg_states(self):
         for msg in self.msgs_store.messages:
             if not msg.may_be_emitted():
                 self._msgs_state[msg.msgid] = False
 
+        for msg_cat in MSG_TYPES.values():
+            self.stats[msg_cat] = 0
+
     def get_message_state_scope(self, msgid, line=None, confidence=UNDEFINED):
         """Returns the scope at which a message was enabled/disabled."""
         if self.config.confidence and confidence.name not in self.config.confidence: