Create metric_tool to deal with metric definitions

infra/tools/metric_tool/metric_tool.py

Index: infra/tools/metric_tool/metric_tool.py
diff --git a/infra/tools/metric_tool/metric_tool.py b/infra/tools/metric_tool/metric_tool.py
new file mode 100644
index 0000000000000000000000000000000000000000..bcf2b22fe9b789459a186df6d81e56e8c7bd488f
--- /dev/null
+++ b/infra/tools/metric_tool/metric_tool.py
@@ -0,0 +1,120 @@
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+"""Main implementation of metric_tool."""
+
+import ast
+import os
+import logging
+
+
+# https://chromium.googlesource.com/infra/infra/+/master/infra_libs/logs/README.md
+LOGGER = logging.getLogger(__name__)
+
+METRICS_NAMES = set(('StringMetric', 'BooleanMetric',
+                     'CounterMetric', 'GaugeMetric', 'CumulativeMetric',
+                     'FloatMetric', 'CumulativeDistributionMetric',
+                     'NonCumulativeDistributionMetric'))
+
+
+def extract_metrics_descriptions(filepath):
+  """Parse a python file and return all metrics descriptions it can find.
+
+  A metric description is the value of the 'description' keyword passed to a
+  metric definition (classes deriving from ts_mon.Metric)
+
+  Args:
+    filepath (str): path to a Python file.
+
+  Returns:
+    description (list of tuples): each tuple being
+       (metric name, description string). Metric name is 'DYNAMIC' it something
+       different than a static string is used in the metric creation.
+       If a metric is instanciated without a description, return None.
+  """
+  descriptions = []
+  try:
+    with open(filepath, 'r') as f:
+      content = f.read()  # pragma: no branch
+  except IOError:
+    return descriptions
+
+  try:
+    root = ast.parse(content)
+  except SyntaxError:  # just ignore invalid / python3 files.
+    return descriptions
+
+  for node in ast.walk(root):
+    if not isinstance(node, ast.Call):
+      continue
+
+    # Look for metrics definitions
+    calls = []
+    if isinstance(node.func, ast.Name):
+      if node.func.id in METRICS_NAMES:
+        LOGGER.debug('Method %s found line %d', node.func.id, node.func.lineno)
+        calls.append(node)
+    elif isinstance(node.func, ast.Attribute):  # pragma: no branch
+      if node.func.attr in METRICS_NAMES:
+        LOGGER.debug('Method %s found line %d',
+                     node.func.attr, node.func.lineno)
+        calls.append(node)
+
+    # Extract parameters from function call
+    for fcall in calls:
+      # Metric name
+      metric_name = 'DYNAMIC'
+      if fcall.args and isinstance(fcall.args[0], ast.Str):
+        metric_name = fcall.args[0].s
+
+      # Getting descriptions
+      description = None
+      for keyword in fcall.keywords:
+        if keyword.arg == 'description' and isinstance(keyword.value, ast.Str):
+          description = keyword.value.s
+
+      descriptions.append((filepath, fcall.lineno, metric_name, description))
+
+  return descriptions
+
+
+def main(path):
+  """Recursively walk a directory structure and print metrics documentation.
+
+  For all instanciated metrics in any Python file found under the directory
+  passed as argument, if a 'description' keyword is provided print it
+  alongside the metric name.
+
+  Args:
+    path (str): directory.
+  """
+  documented = []
+  non_documented = []
+
+  for (dirpath, _, filenames) in os.walk(path):
+    for filename in filenames:
+
+      if (not filename.endswith('.py')  # pragma: no branch
+          or filename.endswith('_test.py')):
+        continue  # pragma: no cover
+
+      full_filename = os.path.join(dirpath, filename)
+      LOGGER.debug('Scanning file %s', full_filename)
+      descriptions = extract_metrics_descriptions(full_filename)
+
+      for description in descriptions:
+        # TODO(pgervais): use namedtuple here instead
+        if description[3]:
+          documented.append(description)
+        else:
+          non_documented.append(description)
+
+  if documented:  # pragma: no branch
+    print('\nDocumented metrics found:')
+    for description in documented:
+      print('/chrome/infra/{2} \t"{3}" at {0}:{1}'.format(*description))
+
+  if non_documented:  # pragma: no branch
+    print('\nUndocumented metrics found:')
+    for description in non_documented:
+      print('/chrome/infra/{2} \t at {0}:{1}'.format(*description))