Thread-safe cache

python/src/etos_api/library/validator.py

@@ -18,6 +18,7 @@
 import asyncio
 import time
 from typing import List, Union
+from threading import Lock
 from uuid import UUID
 
 import requests
@@ -32,10 +33,71 @@
 
 # pylint:disable=too-few-public-methods
 
-# Cache for lazy testrunner validation. Keys: container names, values: timestamp.
-# Only passed validations are cached.
-TESTRUNNER_VALIDATION_CACHE = {}
-TESTRUNNER_VALIDATION_WINDOW = 1800
+
+class TestRunnerValidationCache:
+    """Lazy test runner validation via in-memory cache."""
+
+    # Cache for lazy testrunner validation. Keys: container names, values: timestamp.
+    # Only passed validations are cached.
+    TESTRUNNER_VALIDATION_CACHE = {}
+    TESTRUNNER_VALIDATION_WINDOW = 1800  # seconds
+
+    lock = Lock()
+
+    @classmethod
+    def get_timestamp(cls, test_runner: str) -> Union[float, None]:
+        """Get latest passed validation timestamp for the given testrunner.
+
+        :param test_runner: test runner container name
+        :type test_runner: str
+        :return: validation timestamp or none if not found
+        :rtype: float or NoneType
+        """
+        with cls.lock:
+            if test_runner in cls.TESTRUNNER_VALIDATION_CACHE:
+                return cls.TESTRUNNER_VALIDATION_CACHE[test_runner]
+        return None
+
+    @classmethod
+    def set_timestamp(cls, test_runner: str, timestamp: float) -> None:
+        """Set passed validation timestamp for the given testrunner.
+
+        :param test_runner: test runner container name
+        :type test_runner: str
+        :param timestamp: test runner container name
+        :type timestamp: float
+        :return: none
+        :rtype: NoneType
+        """
+        with cls.lock:
+            cls.TESTRUNNER_VALIDATION_CACHE[test_runner] = timestamp
+
+    @classmethod
+    def remove(cls, test_runner: str) -> None:
+        """Remove the given test runner from the validation cache.
+
+        :param test_runner: test runner container name
+        :type test_runner: str
+        :return: none
+        :rtype: NoneType
+        """
+        with cls.lock:
+            if test_runner in cls.TESTRUNNER_VALIDATION_CACHE:
+                del cls.TESTRUNNER_VALIDATION_CACHE[test_runner]
+
+    @classmethod
+    def is_test_runner_valid(cls, test_runner: str) -> bool:
+        """Determine if the given test runner is valid.
+
+        :param test_runner: test runner container name
+        :type test_runner: str
+        :return: validation result from cache
+        :rtype: bool
+        """
+        timestamp = cls.get_timestamp(test_runner)
+        if timestamp is None:
+            return False
+        return (timestamp + cls.TESTRUNNER_VALIDATION_WINDOW) < time.time()
 
 
 class Environment(BaseModel):
@@ -203,15 +265,9 @@ async def validate(self, test_suite_url):
                         test_runners.add(constraint.value)
             docker = Docker()
             for test_runner in test_runners:
-                if test_runner in TESTRUNNER_VALIDATION_CACHE:
-                    timestamp = TESTRUNNER_VALIDATION_CACHE[test_runner]
-                    if (timestamp + TESTRUNNER_VALIDATION_WINDOW) > time.time():
-                        self.logger.info(
-                            "Using cached testrunner validation result: %s", test_runner
-                        )
-                        continue
-                    del TESTRUNNER_VALIDATION_CACHE[test_runner]
-
+                if TestRunnerValidationCache.is_test_runner_valid(test_runner):
+                    self.logger.info("Using cached test runner validation result: %s", test_runner)
+                    continue
                 for attempt in range(5):
                     if attempt > 0:
                         span.add_event(f"Test runner validation unsuccessful, retry #{attempt}")
@@ -223,7 +279,7 @@ async def validate(self, test_suite_url):
                     result = await docker.digest(test_runner)
                     if result:
                         # only passed validations shall be cached
-                        TESTRUNNER_VALIDATION_CACHE[test_runner] = time.time()
+                        TestRunnerValidationCache.set_timestamp(test_runner, time.time())
                         break
                     # Total wait time with 5 attempts: 55 seconds
                     sleep_time = (attempt + 1) ** 2