modify summary_watcher to reduce cyclomatic complexity

mindinsight/datavisual/common/exceptions.py

@@ -81,3 +81,12 @@ class NodeNotInGraphError(MindInsightException):
         super(NodeNotInGraphError, self).__init__(DataVisualErrors.NODE_NOT_IN_GRAPH_ERROR,
                                                   error_msg,
                                                   http_code=400)
+
+
+class MaxCountExceededException(MindInsightException):
+    """Count is out of limit."""
+    def __init__(self):
+        error_msg = "Count is out of limit."
+        super(MaxCountExceededException, self).__init__(DataVisualErrors.NODE_NOT_IN_GRAPH_ERROR,
+                                                        error_msg,
+                                                        http_code=400)

mindinsight/datavisual/data_transform/summary_watcher.py

@@ -21,6 +21,8 @@ from pathlib import Path
 
 from mindinsight.datavisual.common.log import logger
 from mindinsight.datavisual.common.validation import Validation
+from mindinsight.datavisual.utils.tools import Counter
+from mindinsight.utils.exceptions import ParamValueError
 from mindinsight.utils.exceptions import FileSystemPermissionError
 
 
@@ -42,6 +44,7 @@ class SummaryWatcher:
 
         Args:
             summary_base_dir (str): Path of summary base directory.
+            overall (bool): Limit the total num of scanning if overall is False.
 
         Returns:
             list, list of summary directory info, each of which including the following attributes.
@@ -67,7 +70,11 @@ class SummaryWatcher:
             return []
 
         summary_dict = {}
-        scan_count = 0
+
+        if not overall:
+            counter = Counter(max_count=self.MAX_SCAN_COUNT)
+        else:
+            counter = Counter()
 
         try:
             entries = os.scandir(summary_base_dir)
@@ -78,6 +85,12 @@ class SummaryWatcher:
         for entry in entries:
             if len(summary_dict) == self.MAX_SUMMARY_DIR_COUNT:
                 break
+            try:
+                counter.add()
+            except ParamValueError:
+                logger.info('Stop further scanning due to overall is False and '
+                            'number of scanned files exceeds upper limit.')
+                break
             relative_path = os.path.join('.', '')
             if entry.is_symlink():
                 pass
@@ -85,30 +98,12 @@ class SummaryWatcher:
                 self._update_summary_dict(summary_dict, relative_path, entry)
             elif entry.is_dir():
                 full_path = os.path.realpath(os.path.join(summary_base_dir, entry.name))
-
                 try:
                     subdir_entries = os.scandir(full_path)
                 except PermissionError:
                     logger.warning('Path of %s under summary base directory is not accessible.', entry.name)
-                else:
-                    for subdir_entry in subdir_entries:
-                        if len(summary_dict) == self.MAX_SUMMARY_DIR_COUNT:
-                            break
-                        subdir_relative_path = os.path.join('.', entry.name)
-                        if subdir_entry.is_symlink():
-                            pass
-                        elif subdir_entry.is_file():
-                            self._update_summary_dict(summary_dict, subdir_relative_path, subdir_entry)
-
-                        scan_count += 1
-                        if not overall and scan_count >= self.MAX_SCAN_COUNT:
-                            break
-
-            scan_count += 1
-            if not overall and scan_count >= self.MAX_SCAN_COUNT:
-                logger.info('Stop further scanning due to overall is False and '
-                            'number of scanned files exceeds upper limit.')
-                break
+                    continue
+                self._scan_subdir_entries(summary_dict, subdir_entries, entry.name, counter)
 
         directories = [{
             'relative_path': key,
@@ -121,6 +116,32 @@ class SummaryWatcher:
 
         return directories
 
+    def _scan_subdir_entries(self, summary_dict, subdir_entries, entry_name, counter):
+        """
+        Scan subdir entries.
+
+        Args:
+            summary_dict (dict): Temporary data structure to hold summary directory info.
+            subdir_entries(DirEntry): Directory entry instance.
+            entry_name (str): Name of entry.
+            counter (Counter): An instance of CountLimiter.
+
+        """
+        for subdir_entry in subdir_entries:
+            if len(summary_dict) == self.MAX_SUMMARY_DIR_COUNT:
+                break
+            try:
+                counter.add()
+            except ParamValueError:
+                logger.info('Stop further scanning due to overall is False and '
+                            'number of scanned files exceeds upper limit.')
+                break
+            subdir_relative_path = os.path.join('.', entry_name)
+            if subdir_entry.is_symlink():
+                pass
+            elif subdir_entry.is_file():
+                self._update_summary_dict(summary_dict, subdir_relative_path, subdir_entry)
+
     def _contains_null_byte(self, **kwargs):
         """
         Check if arg contains null byte.

mindinsight/datavisual/utils/tools.py

@@ -20,6 +20,7 @@ import os
 from numbers import Number
 from urllib.parse import unquote
 
+from mindinsight.datavisual.common.exceptions import MaxCountExceededException
 from mindinsight.utils import exceptions
 
 _IMG_EXT_TO_MIMETYPE = {
@@ -153,3 +154,16 @@ def if_nan_inf_to_none(name, value):
     if math.isnan(value) or math.isinf(value):
         value = None
     return value
+
+
+class Counter:
+    """Count accumulator with limit checking."""
+    def __init__(self, max_count=None, init_count=0):
+        self._count = init_count
+        self._max_count = max_count
+
+    def add(self, value=1):
+        """Add value."""
+        if self._max_count is not None and self._count + value > self._max_count:
+            raise MaxCountExceededException()
+        self._count += value