commit 53556eccd206bacd5c9c8bb6605bcceb1bcb6190
author Alex Deymo <deymo@chromium.org> Mon Mar 17 10:05:57 2014 -0700
committer chrome-internal-fetch <chrome-internal-fetch@google.com> Fri Mar 21 23:59:36 2014 +0000
tree 81f5537eebc863cb88eaa18a1cae638b42021720
parent 6f079a8d7507dee7ce954f480672793a5923184f

PolicyManager: Schedule re-evaluations based on variable usage.

This patch makes the EvaluationContext re-schedule a policy request
based on the variables used by that method, waiting for the Async
variables and polling the Poll variables on the suggested interval.

In order to use the main loop functions from the EvaluationContext
they were moved to its own file called event_loop.h.

BUG=chromium:340871
TEST=Unit tests added.

Change-Id: Ibfc52e4dfd12c5e1ef87b5ad9cc318f9821dcfdd
Reviewed-on: https://chromium-review.googlesource.com/190424
Reviewed-by: Gilad Arnold <garnold@chromium.org>
Commit-Queue: Alex Deymo <deymo@chromium.org>
Tested-by: Alex Deymo <deymo@chromium.org>

policy_manager/variable.h

diff --git a/policy_manager/variable.h b/policy_manager/variable.h
index b00eca4..7111a99 100644
--- a/policy_manager/variable.h
+++ b/policy_manager/variable.h
@@ -9,9 +9,13 @@
 #include <list>
 #include <string>
 
+#include <base/bind.h>
+#include <base/logging.h>
 #include <base/time.h>
 #include <gtest/gtest_prod.h>  // for FRIEND_TEST
 
+#include "update_engine/policy_manager/event_loop.h"
+
 namespace chromeos_policy_manager {
 
 // The VariableMode specifies important behavior of the variable in terms of
@@ -40,15 +44,20 @@
 class BaseVariable {
  public:
   // Interface for observing changes on variable value.
-  class Observer {
+  class ObserverInterface {
    public:
-    virtual ~Observer() {}
+    virtual ~ObserverInterface() {}
 
     // Called when the value on the variable changes.
     virtual void ValueChanged(BaseVariable* variable) = 0;
   };
 
-  virtual ~BaseVariable() {}
+  virtual ~BaseVariable() {
+    if (!observer_list_.empty()) {
+      LOG(WARNING) << "Variable " << name_ << " deleted with "
+                   << observer_list_.size() << " observers.";
+    }
+  }
 
   // Returns the variable name as a string.
   const std::string& GetName() const {
@@ -69,14 +78,14 @@
   // 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::Observer* observer) {
+  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::Observer* observer) {
+  virtual void RemoveObserver(BaseVariable::ObserverInterface* observer) {
     observer_list_.remove(observer);
   }
 
@@ -93,11 +102,14 @@
 
   // Calls ValueChanged on all the observers.
   void NotifyValueChanged() {
-    for (auto& observer : observer_list_)
-      observer->ValueChanged(this);
+    for (auto& observer : observer_list_) {
+      RunFromMainLoop(base::Bind(&BaseVariable::ObserverInterface::ValueChanged,
+                                 base::Unretained(observer), this));
+    }
   }
 
  private:
+  friend class PmEvaluationContextTest;
   friend class PmBaseVariableTest;
   FRIEND_TEST(PmBaseVariableTest, RepeatedObserverTest);
   FRIEND_TEST(PmBaseVariableTest, NotifyValueChangedTest);
@@ -122,7 +134,7 @@
   const base::TimeDelta poll_interval_;
 
   // The list of value changes observers.
-  std::list<BaseVariable::Observer*> observer_list_;
+  std::list<BaseVariable::ObserverInterface*> observer_list_;
 };
 
 // Interface to a Policy Manager variable of a given type. Implementation