*(minor): small refactor

passbook/policies/process.py

@@ -0,0 +1,49 @@
+"""passbook policy task"""
+from multiprocessing import Process
+from multiprocessing.connection import Connection
+
+from django.core.cache import cache
+from structlog import get_logger
+
+from passbook.core.models import Policy
+from passbook.policies.exceptions import PolicyException
+from passbook.policies.struct import PolicyRequest, PolicyResult
+
+LOGGER = get_logger()
+
+
+def cache_key(policy, user):
+    """Generate Cache key for policy"""
+    return f"policy_{policy.pk}#{user.pk}"
+
+class PolicyProcess(Process):
+    """Evaluate a single policy within a seprate process"""
+
+    connection: Connection
+    policy: Policy
+    request: PolicyRequest
+
+    def __init__(self, policy: Policy, request: PolicyRequest, connection: Connection):
+        super().__init__()
+        self.policy = policy
+        self.request = request
+        self.connection = connection
+
+    def run(self):
+        """Task wrapper to run policy checking"""
+        LOGGER.debug("Running policy", policy=self.policy,
+                     user=self.request.user, process="PolicyProcess")
+        try:
+            policy_result = self.policy.passes(self.request)
+        except PolicyException as exc:
+            LOGGER.debug(exc)
+            policy_result = PolicyResult(False, str(exc))
+        # Invert result if policy.negate is set
+        if self.policy.negate:
+            policy_result = not policy_result
+        LOGGER.debug("Got result", policy=self.policy, result=policy_result,
+                     process="PolicyProcess")
+        key = cache_key(self.policy, self.request.user)
+        cache.set(key, policy_result)
+        LOGGER.debug("Cached policy evaluation", key=key)
+        self.connection.send(policy_result)