From 61b91122b72d7a3a5c93b80b6fb6d3ac892619dc Mon Sep 17 00:00:00 2001
From: Eddielu <Eddie.Lu@quantatw.com>
Date: Mon, 1 Jun 2020 14:18:33 +0800
Subject: [PATCH] add sensors slow readings

---
 mainloop.cpp | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++++----
 mainloop.hpp |  3 +++
 sensor.cpp   | 76 +++++++++++++++++++++++++++++++++++++++++++++++++++++-------
 sensor.hpp   | 21 +++++++++++++++--
 4 files changed, 158 insertions(+), 15 deletions(-)

diff --git a/mainloop.cpp b/mainloop.cpp
index 1769e94..5094343 100644
--- a/mainloop.cpp
+++ b/mainloop.cpp
@@ -32,6 +32,7 @@
 #include <cassert>
 #include <cstdlib>
 #include <functional>
+#include <future>
 #include <iostream>
 #include <memory>
 #include <phosphor-logging/elog-errors.hpp>
@@ -296,7 +297,7 @@ std::optional<ObjectStateData>
     {
         // Add status interface based on _fault file being present
         sensorObj->addStatus(info);
-        valueInterface = sensorObj->addValue(retryIO, info);
+        valueInterface = sensorObj->addValue(retryIO, info, _timedoutMap);
     }
     catch (const std::system_error& e)
     {
@@ -542,10 +543,74 @@ void MainLoop::read()
                 // RAII object for GPIO unlock / lock
                 auto locker = sensor::gpioUnlock(sensor->getGpio());
 
-                // Retry for up to a second if device is busy
-                // or has a transient error.
-                value = _ioAccess->read(sensorSysfsType, sensorSysfsNum, input,
+                // For sensors with attribute ASYNC_READ_TIMEOUT,
+                // spawn a thread with timeout
+                auto asyncRead =
+                    env::getEnv("ASYNC_READ_TIMEOUT", sensorSetKey);
+                if (!asyncRead.empty())
+                {
+                    // Default async read timeout
+                    std::chrono::milliseconds asyncReadTimeout{
+                        std::stoi(asyncRead)};
+                    bool valueIsValid = false;
+                    std::future<SensorValueType> asyncThread;
+
+                    auto asyncIter = _timedoutMap.find(sensorSetKey);
+                    if (asyncIter == _timedoutMap.end())
+                    {
+                        // If sesnor not found in timedoutMap, spawn an async
+                        // thread
+                        asyncThread = std::async(
+                            std::launch::async,
+                            &hwmonio::HwmonIOInterface::read, _ioAccess,
+                            sensorSysfsType, sensorSysfsNum, input,
+                            hwmonio::retries, hwmonio::delay);
+                        valueIsValid = true;
+                    }
+                    else
+                    {
+                        // If we already have the async thread in the
+                        // timedoutMap, it means this sensor has already timed
+                        // out in the previous reads. No need to wait on
+                        // subsequent reads
+                        asyncReadTimeout = std::chrono::seconds(0);
+                        asyncThread = std::move(asyncIter->second);
+                    }
+
+                    std::future_status status =
+                        asyncThread.wait_for(asyncReadTimeout);
+                    switch (status)
+                    {
+                        // Read has finished
+                        case std::future_status::ready:
+                            // Read has finished
+                            if (valueIsValid)
+                            {
+                                value = asyncThread.get();
+                                break;
+                                // Good sensor reads should skip the code below
+                            }
+                            // Async read thread has completed, erase from
+                            // timedoutMap to allow retry then throw
+                            _timedoutMap.erase(sensorSetKey);
+                            throw sensor::AsyncSensorReadTimeOut();
+                        default:
+                            // Read timed out so add the thread to the
+                            // timedoutMap (if the entry already exists,
+                            // operator[] updates it)
+                            _timedoutMap[sensorSetKey] = std::move(asyncThread);
+                            throw sensor::AsyncSensorReadTimeOut();
+                    }
+                }
+                else
+                {
+                    // Retry for up to a second if device is busy
+                    // or has a transient error.
+                    value =
+                        _ioAccess->read(sensorSysfsType, sensorSysfsNum, input,
                                         hwmonio::retries, hwmonio::delay);
+                }
+
                 // Set functional property to true if we could read sensor
                 statusIface->functional(true);
 
diff --git a/mainloop.hpp b/mainloop.hpp
index 6c5b8e0..cfe34d5 100644
--- a/mainloop.hpp
+++ b/mainloop.hpp
@@ -9,6 +9,7 @@
 #include "types.hpp"
 
 #include <any>
+#include <future>
 #include <memory>
 #include <optional>
 #include <sdbusplus/server.hpp>
@@ -116,6 +117,8 @@ class MainLoop
     /** @brief Store the specifications of sensor objects */
     std::map<SensorSet::key_type, std::unique_ptr<sensor::Sensor>>
         _sensorObjects;
+    /** @brief Store the async futures of timed out sensor objects */
+    std::map<SensorSet::key_type, std::future<SensorValueType>> _timedoutMap;
 
     /**
      * @brief Map of removed sensors
diff --git a/sensor.cpp b/sensor.cpp
index 93bbb03..7b681e1 100644
--- a/sensor.cpp
+++ b/sensor.cpp
@@ -13,6 +13,7 @@
 #include <cmath>
 #include <cstring>
 #include <filesystem>
+#include <future>
 #include <phosphor-logging/elog-errors.hpp>
 #include <thread>
 #include <xyz/openbmc_project/Common/error.hpp>
@@ -135,8 +136,9 @@ SensorValueType Sensor::adjustValue(SensorValueType value)
     return value;
 }
 
-std::shared_ptr<ValueObject> Sensor::addValue(const RetryIO& retryIO,
-                                              ObjectInfo& info)
+std::shared_ptr<ValueObject> Sensor::addValue(
+    const RetryIO& retryIO, ObjectInfo& info,
+    std::map<SensorSet::key_type, std::future<SensorValueType>>& timedoutMap)
 {
     static constexpr bool deferSignals = true;
 
@@ -163,13 +165,69 @@ std::shared_ptr<ValueObject> Sensor::addValue(const RetryIO& retryIO,
             // RAII object for GPIO unlock / lock
             auto locker = gpioUnlock(getGpio());
 
-            // Retry for up to a second if device is busy
-            // or has a transient error.
-            val =
-                _ioAccess->read(_sensor.first, _sensor.second,
-                                hwmon::entry::cinput, std::get<size_t>(retryIO),
-                                std::get<std::chrono::milliseconds>(retryIO));
-
+            // For sensors with attribute ASYNC_READ_TIMEOUT,
+            // spawn a thread with timeout
+            auto asyncRead = env::getEnv("ASYNC_READ_TIMEOUT", _sensor);
+            if (!asyncRead.empty())
+            {
+                // Default async read timeout
+                std::chrono::milliseconds asyncReadTimeout{
+                    std::stoi(asyncRead)};
+                bool valueIsValid = false;
+                std::future<SensorValueType> asyncThread;
+
+                auto asyncIter = timedoutMap.find(_sensor);
+                if (asyncIter == timedoutMap.end())
+                {
+                    // If sesnor not found in timedoutMap, spawn an async thread
+                    asyncThread = std::async(
+                        std::launch::async, &hwmonio::HwmonIOInterface::read,
+                        _ioAccess, _sensor.first, _sensor.second,
+                        hwmon::entry::cinput, std::get<size_t>(retryIO),
+                        std::get<std::chrono::milliseconds>(retryIO));
+                    valueIsValid = true;
+                }
+                else
+                {
+                    // If we already have the async thread in the timedoutMap,
+                    // it means this sensor has already timed out in the
+                    // previous reads. No need to wait on subsequent reads
+                    asyncReadTimeout = std::chrono::seconds(0);
+                    asyncThread = std::move(asyncIter->second);
+                }
+
+                std::future_status status =
+                    asyncThread.wait_for(asyncReadTimeout);
+                switch (status)
+                {
+                    case std::future_status::ready:
+                        // Read has finished
+                        if (valueIsValid)
+                        {
+                            val = asyncThread.get();
+                            break;
+                            // Good sensor reads should skip the code below
+                        }
+                        // Async read thread has completed, erase from
+                        // timedoutMap to allow retry then throw
+                        timedoutMap.erase(_sensor);
+                        throw AsyncSensorReadTimeOut();
+                    default:
+                        // Read timed out so add the thread to the timedoutMap
+                        // (if the entry already exists, operator[] updates it)
+                        timedoutMap[_sensor] = std::move(asyncThread);
+                        throw AsyncSensorReadTimeOut();
+                }
+            }
+            else
+            {
+                // Retry for up to a second if device is busy
+                // or has a transient error.
+                val = _ioAccess->read(
+                    _sensor.first, _sensor.second, hwmon::entry::cinput,
+                    std::get<size_t>(retryIO),
+                    std::get<std::chrono::milliseconds>(retryIO));
+            }
             val = adjustValue(val);
         }
 #ifdef UPDATE_FUNCTIONAL_ON_FAIL
diff --git a/sensor.hpp b/sensor.hpp
index 369a252..d1d6730 100644
--- a/sensor.hpp
+++ b/sensor.hpp
@@ -4,6 +4,8 @@
 #include "sensorset.hpp"
 #include "types.hpp"
 
+#include <cerrno>
+#include <future>
 #include <gpioplus/handle.hpp>
 #include <memory>
 #include <optional>
@@ -20,6 +22,17 @@ struct valueAdjust
     std::unordered_set<int> rmRCs;
 };
 
+/** @brief Custom exception for async sensor reading timeout
+ */
+struct AsyncSensorReadTimeOut : public std::system_error
+{
+    AsyncSensorReadTimeOut() :
+        system_error(std::error_code(ETIMEDOUT, std::system_category()),
+                     "Async sensor read timed out")
+    {
+    }
+};
+
 /** @class Sensor
  *  @brief Sensor object based on a SensorSet container's key type
  *  @details Sensor object to create and modify an associated device's sensor
@@ -87,10 +100,14 @@ class Sensor
      *                      (number of and delay between)
      * @param[in] info - Sensor object information
      *
+     * @param[in] timedoutMap - Map to track timed out threads
+     *
      * @return - Shared pointer to the value object
      */
-    std::shared_ptr<ValueObject> addValue(const RetryIO& retryIO,
-                                          ObjectInfo& info);
+    std::shared_ptr<ValueObject>
+        addValue(const RetryIO& retryIO, ObjectInfo& info,
+                 std::map<SensorSet::key_type, std::future<SensorValueType>>&
+                     timedoutMap);
 
     /**
      * @brief Add status interface and functional property for sensor
-- 
2.7.4