presence: Add fallback redundancy policy
Add a fallback redundancy implementation of the RedundancyPolicy
interface.
The fallback policy associates multiple PresenceSensor instances
to a single fan, and "falls-back" on secondary sensor implementations
when the primary sensor cannot see the fan.
Change-Id: I6468d77d97b8916b3ff33bcd0cd28a102d1aaba1
Signed-off-by: Brad Bishop <bradleyb@fuzziesquirrel.com>
diff --git a/presence/fallback.cpp b/presence/fallback.cpp
new file mode 100644
index 0000000..625d74a
--- /dev/null
+++ b/presence/fallback.cpp
@@ -0,0 +1,101 @@
+/**
+ * Copyright © 2017 IBM Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include <algorithm>
+#include <phosphor-logging/log.hpp>
+#include "fan.hpp"
+#include "fallback.hpp"
+#include "psensor.hpp"
+
+namespace phosphor
+{
+namespace fan
+{
+namespace presence
+{
+
+void Fallback::stateChanged(bool present)
+{
+ if (!present)
+ {
+ // Starting with the first backup, find the first
+ // sensor that reports the fan as present, if any.
+ auto it = std::find_if(
+ std::next(activeSensor),
+ sensors.end(),
+ [](auto& s){return s.get().present();});
+
+ if (it != sensors.end())
+ {
+ // A backup sensor disagrees with the active sensor.
+ // Switch to the backup.
+ activeSensor->get().stop();
+ present = it->get().start();
+
+ while (activeSensor != it)
+ {
+ // Callout the broken sensors.
+ activeSensor->get().fail();
+ ++activeSensor;
+ }
+ phosphor::logging::log<phosphor::logging::level::INFO>(
+ "Using backup presence sensor.",
+ phosphor::logging::entry(
+ "FAN=%s", std::get<1>(fan)));
+ activeSensor = it;
+ }
+ }
+
+ setPresence(fan, present);
+}
+
+void Fallback::monitor()
+{
+ // Find the first sensor that says the fan is present
+ // and set it as the active sensor.
+ activeSensor = std::find_if(
+ sensors.begin(),
+ sensors.end(),
+ [](auto& s){return s.get().present();});
+ if (activeSensor == sensors.end())
+ {
+ // The first sensor is working or all sensors
+ // agree the fan isn't present. Use the first sensor.
+ activeSensor = sensors.begin();
+ }
+
+ if (activeSensor != sensors.begin())
+ {
+ phosphor::logging::log<phosphor::logging::level::INFO>(
+ "Using backup presence sensor.",
+ phosphor::logging::entry(
+ "FAN=%s", std::get<1>(fan)));
+ }
+
+ // Callout the broken sensors.
+ auto it = sensors.begin();
+ while (it != activeSensor)
+ {
+ it->get().fail();
+ ++it;
+ }
+
+ // Start the active sensor and set the initial state.
+ setPresence(fan, activeSensor->get().start());
+}
+
+} // namespace presence
+} // namespace fan
+} // namespace phosphor