update_manager/evaluation_context-inl.h

// 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 UPDATE_ENGINE_UPDATE_MANAGER_EVALUATION_CONTEXT_INL_H_
#define UPDATE_ENGINE_UPDATE_MANAGER_EVALUATION_CONTEXT_INL_H_

#include <string>

#include <base/logging.h>

namespace chromeos_update_manager {

template<typename T>
const T* EvaluationContext::GetValue(Variable<T>* var) {
  if (var == nullptr) {
    LOG(ERROR) << "GetValue received an uninitialized variable.";
    return nullptr;
  }

  // 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 == nullptr) {
    LOG(WARNING) << "Error reading Variable " << var->GetName() << ": \""
        << errmsg << "\"";
  }
  // 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_update_manager

#endif  // UPDATE_ENGINE_UPDATE_MANAGER_EVALUATION_CONTEXT_INL_H_