update_manager: Make Prefs Variable async.
The update_engine prefs, while stored in disk, are private daemon
values changed by the daemon only. There was a 5 minutes delay between
changing this value and the update policy checking it again, and there
was a log spam every 5 minutes due to policy re-evaluations.
This patch makes these Prefs-based variables async by implementing an
observer pattern in the PrefsInterface and makes these variables async.
Bug: chromium:367333
Test: Added uniittest. No more log spam every 5 minutes.
Change-Id: I8b3f7072cc87515972c9f5b1ddcc54b865ffe238
diff --git a/update_manager/fake_updater_provider.h b/update_manager/fake_updater_provider.h
index 7d2d3f6..44389f4 100644
--- a/update_manager/fake_updater_provider.h
+++ b/update_manager/fake_updater_provider.h
@@ -106,10 +106,12 @@
"curr_channel", kVariableModePoll};
FakeVariable<std::string> var_new_channel_{ // NOLINT(whitespace/braces)
"new_channel", kVariableModePoll};
- FakeVariable<bool> var_p2p_enabled_{ // NOLINT(whitespace/braces)
- "p2p_enabled", kVariableModePoll};
- FakeVariable<bool> var_cellular_enabled_{ // NOLINT(whitespace/braces)
- "cellular_enabled", kVariableModePoll};
+ FakeVariable<bool> var_p2p_enabled_{// NOLINT(whitespace/braces)
+ "p2p_enabled",
+ kVariableModeAsync};
+ FakeVariable<bool> var_cellular_enabled_{// NOLINT(whitespace/braces)
+ "cellular_enabled",
+ kVariableModeAsync};
FakeVariable<unsigned int>
var_consecutive_failed_update_checks_{ // NOLINT(whitespace/braces)
"consecutive_failed_update_checks", kVariableModePoll};