Remove threads

This converts phosphor-pid-control into an async
single threaded application. The reason for doing this
is on our systems phosphor-pid-control had the largest
VSZ when viewed under top. Before this patch the VSZ
was at 50720, after it is at 7760.

Tested-by: Could still interact with all interfaces
under rest-dbus and sensor override worked to ramp fans
when changing cpu temps.

Change-Id: Ie0a837bdf0d1b1df61dc7aff87e5d503b9e0e875
Signed-off-by: James Feist <james.feist@linux.intel.com>

9 files changed, 167 insertions, 197 deletions

diff --git a/Makefile.am b/Makefile.am
index 9375ea6..241878c 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -55,11 +55,9 @@ setsensor_CXXFLAGS = \
 swampd_SOURCES = main.cpp util.cpp
 swampd_LDADD = \
 	$(SDBUSPLUS_LIBS) \
-	$(PTHREAD_LIBS) \
 	libswampd.la
 swampd_CXXFLAGS = \
 	$(SDBUSPLUS_CFLAGS) \
-	$(PTHREAD_CFLAGS) \
 	$(CODE_COVERAGE_CXXFLAGS)
 
 noinst_LTLIBRARIES = libswampd.la
@@ -102,9 +100,8 @@ libswampd_la_SOURCES = \
 	pid/buildjson.cpp \
 	pid/zone.cpp \
 	pid/util.cpp \
-	pid/pidthread.cpp \
+	pid/pidloop.cpp \
 	pid/tuning.cpp \
-	threads/busthread.cpp \
 	build/buildjson.cpp \
 	experiments/drive.cpp
 
diff --git a/configure.ac b/configure.ac
index df031b0..b216837 100644
--- a/configure.ac
+++ b/configure.ac
@@ -56,7 +56,22 @@ AC_CHECK_HEADERS(
     [],
     [AC_MSG_ERROR([Could not find CLI11 CLI/CLI.hpp])]
 )
-AX_PTHREAD([], [AC_MSG_ERROR(["pthread required and not found"])])
+
+# check for boost headers
+AC_CHECK_HEADER(
+    boost/asio/io_context.hpp,
+    [],
+    [AC_MSG_ERROR([Could not find boost/asio/io_context.hpp])]
+)
+AC_CHECK_HEADER(
+    boost/asio/steady_timer.hpp,
+    [],
+    [AC_MSG_ERROR([Could not find boost/asio/steady_timer.hpp])]
+)
+AX_APPEND_COMPILE_FLAGS(["-DBOOST_ASIO_DISABLE_THREADS"], [CPPFLAGS])
+AX_APPEND_COMPILE_FLAGS(["-DBOOST_ERROR_CODE_HEADER_ONLY"], [CPPFLAGS])
+AX_APPEND_COMPILE_FLAGS(["-DBOOST_SYSTEM_NO_DEPRECATED"], [CPPFLAGS])
+AX_APPEND_COMPILE_FLAGS(["-DBOOST_ASIO_NO_DEPRECATED"], [CPPFLAGS])
 
 # Checks for library functions.
 LT_INIT # Required for systemd linking
diff --git a/main.cpp b/main.cpp
index 2db1ff9..6dca309 100644
--- a/main.cpp
+++ b/main.cpp
@@ -21,20 +21,23 @@
 #include "interfaces.hpp"
 #include "pid/builder.hpp"
 #include "pid/buildjson.hpp"
-#include "pid/pidthread.hpp"
+#include "pid/pidloop.hpp"
 #include "pid/tuning.hpp"
 #include "pid/zone.hpp"
 #include "sensors/builder.hpp"
 #include "sensors/buildjson.hpp"
 #include "sensors/manager.hpp"
-#include "threads/busthread.hpp"
 #include "util.hpp"
 
 #include <CLI/CLI.hpp>
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/steady_timer.hpp>
 #include <chrono>
 #include <iostream>
+#include <list>
 #include <map>
 #include <memory>
+#include <sdbusplus/asio/connection.hpp>
 #include <sdbusplus/bus.hpp>
 #include <thread>
 #include <unordered_map>
@@ -123,42 +126,24 @@ int main(int argc, char* argv[])
     auto& hostSensorBus = mgmr.getHostBus();
     auto& passiveListeningBus = mgmr.getPassiveBus();
 
-    std::cerr << "Starting threads\n";
+    boost::asio::io_context io;
+    sdbusplus::asio::connection passiveBus(io, passiveListeningBus.release());
 
-    /* TODO(venture): Ask SensorManager if we have any passive sensors. */
-    struct ThreadParams p = {std::ref(passiveListeningBus), ""};
-    std::thread l(busThread, std::ref(p));
+    sdbusplus::asio::connection hostBus(io, hostSensorBus.release());
+    hostBus.request_name("xyz.openbmc_project.Hwmon.external");
 
-    /* TODO(venture): Ask SensorManager if we have any host sensors. */
-    static constexpr auto hostBus = "xyz.openbmc_project.Hwmon.external";
-    struct ThreadParams e = {std::ref(hostSensorBus), hostBus};
-    std::thread te(busThread, std::ref(e));
+    sdbusplus::asio::connection modeBus(io, modeControlBus.release());
+    modeBus.request_name("xyz.openbmc_project.State.FanCtrl");
 
-    static constexpr auto modeBus = "xyz.openbmc_project.State.FanCtrl";
-    struct ThreadParams m = {std::ref(modeControlBus), modeBus};
-    std::thread tm(busThread, std::ref(m));
+    std::list<boost::asio::steady_timer> timers;
 
-    std::vector<std::thread> zoneThreads;
-
-    /* TODO(venture): This was designed to have one thread per zone, but really
-     * it could have one thread for all the zones and iterate through each
-     * sequentially as it goes -- and it'd probably be fast enough to do that,
-     * however, a system isn't likely going to have more than a couple zones.
-     * If it only has a couple zones, then this is fine.
-     */
     for (const auto& i : zones)
     {
+        auto& timer = timers.emplace_back(io);
         std::cerr << "pushing zone" << std::endl;
-        zoneThreads.push_back(std::thread(pidControlThread, i.second.get()));
-    }
-
-    l.join();
-    te.join();
-    tm.join();
-    for (auto& t : zoneThreads)
-    {
-        t.join();
+        pidControlLoop(i.second.get(), timer);
     }
 
+    io.run();
     return rc;
 }
diff --git a/pid/pidloop.cpp b/pid/pidloop.cpp
new file mode 100644
index 0000000..b684747
--- /dev/null
+++ b/pid/pidloop.cpp
@@ -0,0 +1,117 @@
+/**
+ * Copyright 2017 Google Inc.
+ *
+ * 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 "pidloop.hpp"
+
+#include "pid/pidcontroller.hpp"
+#include "pid/tuning.hpp"
+#include "sensors/sensor.hpp"
+
+#include <boost/asio/steady_timer.hpp>
+#include <chrono>
+#include <map>
+#include <memory>
+#include <thread>
+#include <vector>
+
+static void processThermals(PIDZone* zone)
+{
+    // Get the latest margins.
+    zone->updateSensors();
+    // Zero out the RPM set point goals.
+    zone->clearRPMSetPoints();
+    zone->clearRPMCeilings();
+    // Run the margin PIDs.
+    zone->processThermals();
+    // Get the maximum RPM setpoint.
+    zone->determineMaxRPMRequest();
+}
+
+void pidControlLoop(PIDZone* zone, boost::asio::steady_timer& timer, bool first,
+                    int ms100cnt)
+{
+    if (first)
+    {
+        if (tuningLoggingEnabled)
+        {
+            zone->initializeLog();
+        }
+
+        zone->initializeCache();
+        processThermals(zone);
+    }
+
+    timer.expires_after(std::chrono::milliseconds(100));
+    timer.async_wait(
+        [zone, &timer, ms100cnt](const boost::system::error_code& ec) mutable {
+            /*
+             * This should sleep on the conditional wait for the listen thread
+             * to tell us it's in sync.  But then we also need a timeout option
+             * in case phosphor-hwmon is down, we can go into some weird failure
+             * more.
+             *
+             * Another approach would be to start all sensors in worst-case
+             * values, and fail-safe mode and then clear out of fail-safe mode
+             * once we start getting values.  Which I think it is a solid
+             * approach.
+             *
+             * For now this runs before it necessarily has any sensor values.
+             * For the host sensors they start out in fail-safe mode.  For the
+             * fans, they start out as 0 as input and then are adjusted once
+             * they have values.
+             *
+             * If a fan has failed, it's value will be whatever we're told or
+             * however we retrieve it.  This program disregards fan values of 0,
+             * so any code providing a fan speed can set to 0 on failure and
+             * that fan value will be effectively ignored.  The PID algorithm
+             * will be unhappy but nothing bad will happen.
+             *
+             * TODO(venture): If the fan value is 0 should that loop just be
+             * skipped? Right now, a 0 value is ignored in
+             * FanController::inputProc()
+             */
+
+            // Check if we should just go back to sleep.
+            if (zone->getManualMode())
+            {
+                pidControlLoop(zone, timer, false, ms100cnt);
+                return;
+            }
+
+            // Get the latest fan speeds.
+            zone->updateFanTelemetry();
+
+            if (10 <= ms100cnt)
+            {
+                ms100cnt = 0;
+
+                processThermals(zone);
+            }
+
+            // Run the fan PIDs every iteration.
+            zone->processFans();
+
+            if (tuningLoggingEnabled)
+            {
+                zone->getLogHandle() << "," << zone->getFailSafeMode();
+                zone->getLogHandle() << std::endl;
+            }
+
+            ms100cnt += 1;
+
+            pidControlLoop(zone, timer, false, ms100cnt);
+        });
+}
diff --git a/pid/pidloop.hpp b/pid/pidloop.hpp
new file mode 100644
index 0000000..3a67954
--- /dev/null
+++ b/pid/pidloop.hpp
@@ -0,0 +1,18 @@
+#pragma once
+
+#include "pid/zone.hpp"
+
+#include <boost/asio/steady_timer.hpp>
+
+/**
+ * Main pid control loop for a given zone.
+ * This function calls itself indefinitely in an async loop to calculate
+ * fan outputs based on thermal inputs.
+ *
+ * @param[in] zone - ptr to the PIDZone for this loop.
+ * @param[in] timer - boost timer used for async callback.
+ * @param[in] first - boolean to denote if initialization needs to be run.
+ * @param[in] ms100cnt - loop timer counter.
+ */
+void pidControlLoop(PIDZone* zone, boost::asio::steady_timer& timer,
+                    bool first = true, int ms100cnt = 0);
diff --git a/pid/pidthread.cpp b/pid/pidthread.cpp
deleted file mode 100644
index f8d7fd9..0000000
--- a/pid/pidthread.cpp
+++ /dev/null
@@ -1,109 +0,0 @@
-/**
- * Copyright 2017 Google Inc.
- *
- * 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 "pidthread.hpp"
-
-#include "pid/pidcontroller.hpp"
-#include "pid/tuning.hpp"
-#include "sensors/sensor.hpp"
-
-#include <chrono>
-#include <map>
-#include <memory>
-#include <thread>
-#include <vector>
-
-static void processThermals(PIDZone* zone)
-{
-    // Get the latest margins.
-    zone->updateSensors();
-    // Zero out the RPM set point goals.
-    zone->clearRPMSetPoints();
-    zone->clearRPMCeilings();
-    // Run the margin PIDs.
-    zone->processThermals();
-    // Get the maximum RPM setpoint.
-    zone->determineMaxRPMRequest();
-}
-
-void pidControlThread(PIDZone* zone)
-{
-    int ms100cnt = 0;
-    /*
-     * This should sleep on the conditional wait for the listen thread to tell
-     * us it's in sync.  But then we also need a timeout option in case
-     * phosphor-hwmon is down, we can go into some weird failure more.
-     *
-     * Another approach would be to start all sensors in worst-case values,
-     * and fail-safe mode and then clear out of fail-safe mode once we start
-     * getting values.  Which I think it is a solid approach.
-     *
-     * For now this runs before it necessarily has any sensor values.  For the
-     * host sensors they start out in fail-safe mode.  For the fans, they start
-     * out as 0 as input and then are adjusted once they have values.
-     *
-     * If a fan has failed, it's value will be whatever we're told or however
-     * we retrieve it.  This program disregards fan values of 0, so any code
-     * providing a fan speed can set to 0 on failure and that fan value will be
-     * effectively ignored.  The PID algorithm will be unhappy but nothing bad
-     * will happen.
-     *
-     * TODO(venture): If the fan value is 0 should that loop just be skipped?
-     * Right now, a 0 value is ignored in FanController::inputProc()
-     */
-    if (tuningLoggingEnabled)
-    {
-        zone->initializeLog();
-    }
-
-    zone->initializeCache();
-    processThermals(zone);
-
-    while (true)
-    {
-        using namespace std::literals::chrono_literals;
-        std::this_thread::sleep_for(0.1s);
-
-        // Check if we should just go back to sleep.
-        if (zone->getManualMode())
-        {
-            continue;
-        }
-
-        // Get the latest fan speeds.
-        zone->updateFanTelemetry();
-
-        if (10 <= ms100cnt)
-        {
-            ms100cnt = 0;
-
-            processThermals(zone);
-        }
-
-        // Run the fan PIDs every iteration.
-        zone->processFans();
-
-        if (tuningLoggingEnabled)
-        {
-            zone->getLogHandle() << "," << zone->getFailSafeMode();
-            zone->getLogHandle() << std::endl;
-        }
-
-        ms100cnt += 1;
-    }
-
-    return;
-}
diff --git a/pid/pidthread.hpp b/pid/pidthread.hpp
deleted file mode 100644
index 94865c0..0000000
--- a/pid/pidthread.hpp
+++ /dev/null
@@ -1,6 +0,0 @@
-#pragma once
-
-#include "pid/zone.hpp"
-
-/* Given a zone, run through the loops. */
-void pidControlThread(PIDZone* zone);
diff --git a/threads/busthread.cpp b/threads/busthread.cpp
deleted file mode 100644
index 6cfb08c..0000000
--- a/threads/busthread.cpp
+++ /dev/null
@@ -1,36 +0,0 @@
-/**
- * Copyright 2017 Google Inc.
- *
- * 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 "busthread.hpp"
-
-#include <string>
-
-void busThread(struct ThreadParams& params)
-{
-    if (params.name.length() > 0)
-    {
-        params.bus.request_name(params.name.c_str());
-    }
-
-    while (true)
-    {
-        params.bus.process_discard();
-        /* block indefinitely for updates. */
-        params.bus.wait();
-    }
-
-    return;
-}
diff --git a/threads/busthread.hpp b/threads/busthread.hpp
deleted file mode 100644
index df875f5..0000000
--- a/threads/busthread.hpp
+++ /dev/null
@@ -1,11 +0,0 @@
-#pragma once
-
-#include <sdbusplus/bus.hpp>
-
-struct ThreadParams
-{
-    sdbusplus::bus::bus& bus;
-    std::string name;
-};
-
-void busThread(struct ThreadParams& params);