commit 50fe8ee363251f4a573f811fda88d3cb90122b89
author Andrei Kartashev <a.kartashev@yadro.com> Tue Jan 04 21:24:22 2022 +0300
committer Andrei Kartashev <a.kartashev@yadro.com> Tue Jan 11 10:08:58 2022 +0300
tree 7fa257d9536ff3562a45a5767f80b5656cdfee55
parent c46ebb493f0e0cc1ccc5525d5484465bba69551f

introduce PersistentState manager

This commit brings new mechanism to store application state over system
reboot. State is saved to json file and restored on application startup
by easy to use class.

Currently only PowerState is managed by this class but more states can
be added in future.

Tested: verify that power state saved to file and restored on startup
Change-Id: I91fb46f262827dda89f438eefea38d59e02ba25c
Signed-off-by: Andrei Kartashev <a.kartashev@yadro.com>

src/power_control.cpp

diff --git a/src/power_control.cpp b/src/power_control.cpp
index fbe1266..b99556a 100644
--- a/src/power_control.cpp
+++ b/src/power_control.cpp
@@ -13,6 +13,8 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 */
+#include "power_control.hpp"
+
 #include <sys/sysinfo.h>
 #include <systemd/sd-journal.h>
 
@@ -34,6 +36,7 @@
 {
 static boost::asio::io_service io;
 std::shared_ptr<sdbusplus::asio::connection> conn;
+PersistentState appState;
 
 static std::string node = "0";
 
@@ -135,8 +138,6 @@
     {"WarmResetCheckMs", 500},
     {"PowerOffSaveMs", 7000},
     {"SlotPowerCycleMs", 200}};
-const static std::filesystem::path powerControlDir = "/var/lib/power-control";
-const static constexpr std::string_view powerStateFile = "power-state";
 
 static bool nmiEnabled = true;
 static bool sioEnabled = true;
@@ -544,8 +545,8 @@
             }
             return;
         }
-        std::ofstream powerStateStream(powerControlDir / powerStateFile);
-        powerStateStream << getChassisState(state);
+        appState.set(PersistentState::Params::PowerState,
+                     std::string{getChassisState(state)});
     });
 }
 static void setPowerState(const PowerState state)
@@ -731,7 +732,7 @@
                     "OpenBMC.0.1.NMIDiagnosticInterrupt", NULL);
 }
 
-static int initializePowerStateStorage()
+PersistentState::PersistentState()
 {
     // create the power control directory if it doesn't exist
     std::error_code ec;
@@ -741,29 +742,90 @@
         {
             lg2::error("failed to create {DIR_NAME}: {ERROR_MSG}", "DIR_NAME",
                        powerControlDir.string(), "ERROR_MSG", ec.message());
-            return -1;
+            throw std::runtime_error("Failed to create state directory");
         }
     }
-    // Create the power state file if it doesn't exist
-    if (!std::filesystem::exists(powerControlDir / powerStateFile))
+
+    // read saved state, it's ok, if the file doesn't exists
+    std::ifstream appStateStream(powerControlDir / stateFile);
+    if (!appStateStream.is_open())
     {
-        std::ofstream powerStateStream(powerControlDir / powerStateFile);
-        powerStateStream << getChassisState(powerState);
+        lg2::info("Cannot open state file \'{PATH}\'", "PATH",
+                  std::string(powerControlDir / stateFile));
+        stateData = nlohmann::json({});
+        return;
     }
-    return 0;
+    try
+    {
+        appStateStream >> stateData;
+        if (stateData.is_discarded())
+        {
+            lg2::info("Cannot parse state file \'{PATH}\'", "PATH",
+                      std::string(powerControlDir / stateFile));
+            stateData = nlohmann::json({});
+            return;
+        }
+    }
+    catch (const std::exception& ex)
+    {
+        lg2::info("Cannot read state file \'{PATH}\'", "PATH",
+                  std::string(powerControlDir / stateFile));
+        stateData = nlohmann::json({});
+        return;
+    }
+}
+PersistentState::~PersistentState()
+{
+    saveState();
+}
+const std::string PersistentState::get(Params parameter)
+{
+    auto val = stateData.find(getName(parameter));
+    if (val != stateData.end())
+    {
+        return val->get<std::string>();
+    }
+    return getDefault(parameter);
+}
+void PersistentState::set(Params parameter, const std::string& value)
+{
+    stateData[getName(parameter)] = value;
+    saveState();
+}
+
+const std::string PersistentState::getName(const Params parameter)
+{
+    switch (parameter)
+    {
+        case Params::PowerState:
+            return "PowerState";
+    }
+    return "";
+}
+const std::string PersistentState::getDefault(const Params parameter)
+{
+    switch (parameter)
+    {
+        case Params::PowerState:
+            return "xyz.openbmc_project.State.Chassis.PowerState.Off";
+    }
+    return "";
+}
+void PersistentState::saveState()
+{
+    std::ofstream appStateStream(powerControlDir / stateFile, std::ios::trunc);
+    if (!appStateStream.is_open())
+    {
+        lg2::error("Cannot write state file \'{PATH}\'", "PATH",
+                   std::string(powerControlDir / stateFile));
+        return;
+    }
+    appStateStream << stateData.dump(indentationSize);
 }
 
 static bool wasPowerDropped()
 {
-    std::ifstream powerStateStream(powerControlDir / powerStateFile);
-    if (!powerStateStream.is_open())
-    {
-        lg2::error("Failed to open power state file");
-        return false;
-    }
-
-    std::string state;
-    std::getline(powerStateStream, state);
+    std::string state = appState.get(PersistentState::Params::PowerState);
     return state == "xyz.openbmc_project.State.Chassis.PowerState.On";
 }
 
@@ -2693,12 +2755,6 @@
             powerState = PowerState::on;
         }
     }
-    // Initialize the power state storage
-    if (initializePowerStateStorage() < 0)
-    {
-        return -1;
-    }
-
     // Check if we need to start the Power Restore policy
     powerRestorePolicyCheck();