logger: dedupe equal RedactionFilters on register_callback

acai_aws/common/logger/common_logger.py

@@ -34,6 +34,8 @@ def __init__(self):
 
     @classmethod
     def register_callback(cls, callback):
+        if callback in cls._callbacks:
+            return
         cls._callbacks.append(callback)
 
     @classmethod

acai_aws/common/logger/redaction.py

@@ -7,9 +7,22 @@ class RedactionFilter:
 
     def __init__(self, **kwargs):
         self._keys = {str(key).lower() for key in kwargs.get('keys') or []}
-        self._patterns = [re.compile(pattern) for pattern in kwargs.get('patterns') or []]
+        self._pattern_sources = tuple(kwargs.get('patterns') or [])
+        self._patterns = [re.compile(pattern) for pattern in self._pattern_sources]
         self._redact_with = kwargs.get('redact_with', self.DEFAULT_REDACTION)
 
+    def __eq__(self, other):
+        if not isinstance(other, RedactionFilter):
+            return NotImplemented
+        return (
+            self._keys == other._keys
+            and self._pattern_sources == other._pattern_sources
+            and self._redact_with == other._redact_with
+        )
+
+    def __hash__(self):
+        return hash((frozenset(self._keys), self._pattern_sources, self._redact_with))
+
     def __call__(self, record):
         if isinstance(record, dict) and 'log' in record:
             record['log'] = self._scrub(record['log'])

tests/acai_aws/common/test_logger.py

@@ -212,5 +212,15 @@ def test_reset_callbacks_clears_registry(self):
         CommonLogger.reset_callbacks()
         self.assertEqual(0, len(CommonLogger._callbacks))
 
+    def test_register_callback_dedupes_equal_filters(self):
+        CommonLogger.register_callback(RedactionFilter(keys=['email']))
+        CommonLogger.register_callback(RedactionFilter(keys=['email']))
+        self.assertEqual(1, len(CommonLogger._callbacks))
+
+    def test_register_callback_keeps_distinct_filters(self):
+        CommonLogger.register_callback(RedactionFilter(keys=['email']))
+        CommonLogger.register_callback(RedactionFilter(keys=['phone']))
+        self.assertEqual(2, len(CommonLogger._callbacks))
+
     def test_common_logger_is_singleton(self):
         self.assertIs(CommonLogger(), CommonLogger())

tests/acai_aws/common/test_redaction.py

@@ -60,3 +60,18 @@ def test_keys_and_patterns_together(self):
         self.assertEqual('[REDACTED]', log['email'])
         self.assertNotIn('123-45-6789', log['message'])
         self.assertNotIn('ada@example.com', log['message'])
+
+    def test_equal_filters_compare_equal_and_hash_equal(self):
+        one = RedactionFilter(keys=['email', 'ssn'], patterns=[r'\d{3}'], redact_with='*')
+        two = RedactionFilter(keys=['ssn', 'email'], patterns=[r'\d{3}'], redact_with='*')
+        self.assertEqual(one, two)
+        self.assertEqual(hash(one), hash(two))
+
+    def test_filters_with_different_config_are_not_equal(self):
+        base = RedactionFilter(keys=['email'], patterns=[r'\d{3}'])
+        self.assertNotEqual(base, RedactionFilter(keys=['email'], patterns=[r'\d{4}']))
+        self.assertNotEqual(base, RedactionFilter(keys=['phone'], patterns=[r'\d{3}']))
+        self.assertNotEqual(base, RedactionFilter(keys=['email'], patterns=[r'\d{3}'], redact_with='*'))
+
+    def test_not_equal_to_non_filter(self):
+        self.assertNotEqual(RedactionFilter(keys=['email']), 'not-a-filter')