Rename the PolicyManager to UpdateManager.
This change renames the PolicyManager class, directory, tests, etc,
to avoid confusion with libpolicy and its classes.
BUG=chromium:373551
TEST=emerged on link.
CQ-DEPEND=CL:I43081673c7ba409f02273197da7915537bde39c6
Change-Id: Iffa76caa3b95ecbbdba87ab01006d1d8ce35a27f
Reviewed-on: https://chromium-review.googlesource.com/201876
Tested-by: Alex Deymo <[email protected]>
Reviewed-by: David Zeuthen <[email protected]>
Commit-Queue: Alex Deymo <[email protected]>
diff --git a/update_manager/variable.h b/update_manager/variable.h
new file mode 100644
index 0000000..3b77d0a
--- /dev/null
+++ b/update_manager/variable.h
@@ -0,0 +1,203 @@
+// 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_UPDATE_MANAGER_VARIABLE_H_
+#define CHROMEOS_PLATFORM_UPDATE_ENGINE_UPDATE_MANAGER_VARIABLE_H_
+
+#include <algorithm>
+#include <list>
+#include <string>
+
+#include <base/bind.h>
+#include <base/logging.h>
+#include <base/time/time.h>
+#include <gtest/gtest_prod.h> // for FRIEND_TEST
+
+#include "update_engine/update_manager/event_loop.h"
+
+namespace chromeos_update_manager {
+
+// The VariableMode specifies important behavior of the variable in terms of
+// whether, how and when the value of the variable changes.
+enum VariableMode {
+ // Const variables never changes during the life of a policy request, so the
+ // EvaluationContext caches the value even between different evaluations of
+ // the same policy request.
+ kVariableModeConst,
+
+ // Poll variables, or synchronous variables, represent a variable with a value
+ // that can be queried at any time, but it is not known when the value
+ // changes on the source of information. In order to detect if the value of
+ // the variable changes, it has to be queried again.
+ kVariableModePoll,
+
+ // Async variables are able to produce a signal or callback whenever the
+ // value changes. This means that it's not required to poll the value to
+ // detect when it changes, instead, you should register an observer to get
+ // a notification when that happens.
+ kVariableModeAsync,
+};
+
+// This class is a base class with the common functionality that doesn't
+// deppend on the variable's type, implemented by all the variables.
+class BaseVariable {
+ public:
+ // Interface for observing changes on variable value.
+ class ObserverInterface {
+ public:
+ virtual ~ObserverInterface() {}
+
+ // Called when the value on the variable changes.
+ virtual void ValueChanged(BaseVariable* variable) = 0;
+ };
+
+ virtual ~BaseVariable() {
+ if (!observer_list_.empty()) {
+ LOG(WARNING) << "Variable " << name_ << " deleted with "
+ << observer_list_.size() << " observers.";
+ }
+ DCHECK(observer_list_.empty()) << "Don't destroy the variable without "
+ "removing the observers.";
+ }
+
+ // Returns the variable name as a string.
+ const std::string& GetName() const {
+ return name_;
+ }
+
+ // Returns the variable mode.
+ VariableMode GetMode() const {
+ return mode_;
+ }
+
+ // For VariableModePoll variables, it returns the polling interval of this
+ // variable. In other case, it returns 0.
+ base::TimeDelta GetPollInterval() const {
+ return poll_interval_;
+ }
+
+ // Adds and removes observers for value changes on the variable. This only
+ // works for kVariableAsync variables since the other modes don't track value
+ // changes. Adding the same observer twice has no effect.
+ virtual void AddObserver(BaseVariable::ObserverInterface* observer) {
+ if (std::find(observer_list_.begin(), observer_list_.end(), observer) ==
+ observer_list_.end()) {
+ observer_list_.push_back(observer);
+ }
+ }
+
+ virtual void RemoveObserver(BaseVariable::ObserverInterface* observer) {
+ observer_list_.remove(observer);
+ }
+
+ protected:
+ // Creates a BaseVariable using the default polling interval (5 minutes).
+ BaseVariable(const std::string& name, VariableMode mode)
+ : BaseVariable(name, mode,
+ base::TimeDelta::FromMinutes(kDefaultPollMinutes)) {}
+
+ // Creates a BaseVariable with mode kVariableModePoll and the provided
+ // polling interval.
+ BaseVariable(const std::string& name, base::TimeDelta poll_interval)
+ : BaseVariable(name, kVariableModePoll, poll_interval) {}
+
+ // Calls ValueChanged on all the observers.
+ void NotifyValueChanged() {
+ // Fire all the observer methods from the main loop as single call. In order
+ // to avoid scheduling these callbacks when it is not needed, we check
+ // first the list of observers.
+ if (!observer_list_.empty()) {
+ RunFromMainLoop(base::Bind(&BaseVariable::OnValueChangedNotification,
+ base::Unretained(this)));
+ }
+ }
+
+ private:
+ friend class UmEvaluationContextTest;
+ FRIEND_TEST(UmBaseVariableTest, RepeatedObserverTest);
+ FRIEND_TEST(UmBaseVariableTest, NotifyValueChangedTest);
+ FRIEND_TEST(UmBaseVariableTest, NotifyValueRemovesObserversTest);
+
+ BaseVariable(const std::string& name, VariableMode mode,
+ base::TimeDelta poll_interval)
+ : name_(name), mode_(mode),
+ poll_interval_(mode == kVariableModePoll ?
+ poll_interval : base::TimeDelta()) {}
+
+ void OnValueChangedNotification() {
+ // A ValueChanged() method can change the list of observers, for example
+ // removing itself and invalidating the iterator, so we create a snapshot
+ // of the observers first. Also, to support the case when *another* observer
+ // is removed, we check for them.
+ std::list<BaseVariable::ObserverInterface*> observer_list_copy(
+ observer_list_);
+
+ for (auto& observer : observer_list_copy) {
+ if (std::find(observer_list_.begin(), observer_list_.end(), observer) !=
+ observer_list_.end()) {
+ observer->ValueChanged(this);
+ }
+ }
+ }
+
+ // The default PollInterval in minutes.
+ static constexpr int kDefaultPollMinutes = 5;
+
+ // The variable's name as a string.
+ const std::string name_;
+
+ // The variable's mode.
+ const VariableMode mode_;
+
+ // The variable's polling interval for VariableModePoll variable and 0 for
+ // other modes.
+ const base::TimeDelta poll_interval_;
+
+ // The list of value changes observers.
+ std::list<BaseVariable::ObserverInterface*> observer_list_;
+
+ DISALLOW_COPY_AND_ASSIGN(BaseVariable);
+};
+
+// Interface to an Update Manager variable of a given type. Implementation
+// internals are hidden as protected members, since policies should not be
+// using them directly.
+template<typename T>
+class Variable : public BaseVariable {
+ public:
+ virtual ~Variable() {}
+
+ protected:
+ // Only allow to get values through the EvaluationContext class and not
+ // directly from the variable.
+ friend class EvaluationContext;
+
+ // Needed to be able to verify variable contents during unit testing.
+ friend class UmTestUtils;
+ FRIEND_TEST(UmRealRandomProviderTest, GetRandomValues);
+
+ Variable(const std::string& name, VariableMode mode)
+ : BaseVariable(name, mode) {}
+
+ Variable(const std::string& name, const base::TimeDelta poll_interval)
+ : BaseVariable(name, poll_interval) {}
+
+ // Gets the current value of the variable. The current value is copied to a
+ // new object and returned. The caller of this method owns the object and
+ // should delete it.
+ //
+ // In case of and error getting the current value or the |timeout| timeout is
+ // exceeded, a NULL value is returned and the |errmsg| is set.
+ //
+ // The caller can pass a NULL value for |errmsg|, in which case the error
+ // message won't be set.
+ virtual const T* GetValue(base::TimeDelta timeout, std::string* errmsg) = 0;
+
+ private:
+ DISALLOW_COPY_AND_ASSIGN(Variable);
+};
+
+} // namespace chromeos_update_manager
+
+#endif // CHROMEOS_PLATFORM_UPDATE_ENGINE_UPDATE_MANAGER_VARIABLE_H_
