PolicyManager: New EvaluationContext class.
The EvaluationContext class handles the life of a policy request
evaluation caching all the results and tracking the variables used
by a the policy implementation.
This patch adds the first part of the EvaluationContex class with
its public interface and minimal support.
BUG=chromium:338590
TEST=Unit test added and passing.
Change-Id: I70e04e7e10ea30ddfb887b494b2b40557565b2da
Reviewed-on: https://chromium-review.googlesource.com/185106
Reviewed-by: Alex Deymo <deymo@chromium.org>
Commit-Queue: Alex Deymo <deymo@chromium.org>
Tested-by: Alex Deymo <deymo@chromium.org>
diff --git a/policy_manager/evaluation_context-inl.h b/policy_manager/evaluation_context-inl.h
new file mode 100644
index 0000000..1413059
--- /dev/null
+++ b/policy_manager/evaluation_context-inl.h
@@ -0,0 +1,42 @@
+// Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_POLICY_MANAGER_EVALUATION_CONTEXT_INL_H
+#define CHROMEOS_PLATFORM_UPDATE_ENGINE_POLICY_MANAGER_EVALUATION_CONTEXT_INL_H
+
+#include <base/logging.h>
+
+namespace chromeos_policy_manager {
+
+template<typename T>
+const T* EvaluationContext::GetValue(Variable<T>* var) {
+ if (var == NULL) {
+ LOG(ERROR) << "GetValue received an uninitialized variable.";
+ return NULL;
+ }
+
+ // Search for the value on the cache first.
+ ValueCacheMap::iterator it = value_cache_.find(var);
+ if (it != value_cache_.end())
+ return reinterpret_cast<const T*>(it->second.value());
+
+ // Get the value from the variable if not found on the cache.
+ std::string errmsg;
+ const T* result = var->GetValue(RemainingTime(), &errmsg);
+ if (result == NULL) {
+ LOG(WARNING) << "Error reading Variable " << var->GetName() << ": \""
+ << errmsg << "\"";
+ } else {
+ // Cache the value for the next time. The map of CachedValues keeps the
+ // ownership of the pointer until the map is destroyed.
+ value_cache_.emplace(
+ static_cast<BaseVariable*>(var),
+ std::move(BoxedValue(result)));
+ }
+ return result;
+}
+
+} // namespace chromeos_policy_manager
+
+#endif // CHROMEOS_PLATFORM_UPDATE_ENGINE_POLICY_MANAGER_EVALUATION_CONTEXT_INL_H