Stop SystemMonitor updates when all reporting is disabled

When all reports are disabled, stop updating the model
since there's no work to be done. Once reporting is
enabled back again, reset the model and restart the update
timer.

The previous behavior would keep the update timer running,
filling the model with blank data row-by-row until the model
was completely empty, at which point it would finally stop the
update timer. That was a waste of resources and caused many
unnecessary wake ups.

Task-number: AUTOSUITE-688
Change-Id: I41a56b0cab7516b2e4545ca5faeae84c8c015d0d
Reviewed-by: Robert Griebl <robert.griebl@pelagicore.com>

2 files changed, 90 insertions, 123 deletions

diff --git a/src/monitor-lib/systemmonitor.cpp b/src/monitor-lib/systemmonitor.cpp
index 694d502a..b2d695f4 100644
--- a/src/monitor-lib/systemmonitor.cpp
+++ b/src/monitor-lib/systemmonitor.cpp
@@ -45,6 +45,7 @@
 #include <QTimerEvent>
 #include <QElapsedTimer>
 #include <vector>
+#include <QtQml/qqmlinfo.h>
 #if !defined(AM_HEADLESS)
 #  include <QGuiApplication>
 #  include <QQuickView>
@@ -384,80 +385,50 @@ void SystemMonitorPrivate::setupFpsReporting()
 #endif
 }
 
-void SystemMonitorPrivate::setupTimer(int newInterval)
+void SystemMonitorPrivate::setupTimer()
 {
-    bool useNewInterval = (newInterval != -1) && (newInterval != reportingInterval);
-    bool shouldBeOn = reportCpu || reportGpu || reportMem || reportFps || !ioHash.isEmpty()
-        || cpuTail > 0 || memTail > 0 || fpsTail > 0 || !ioTails.isEmpty();
+    bool shouldBeOn = reportCpu || reportGpu || reportMem || reportFps || !ioHash.isEmpty();
 
-    if (useNewInterval)
-        reportingInterval = newInterval;
-
-    if (!shouldBeOn) {
-        if (reportingTimerId) {
-            killTimer(reportingTimerId);
-            reportingTimerId = 0;
-        }
-    } else {
-        if (reportingTimerId) {
-            if (useNewInterval) {
-                killTimer(reportingTimerId);
-                reportingTimerId = 0;
-            }
-        }
-        if (!reportingTimerId && reportingInterval >= 0)
-            reportingTimerId = startTimer(reportingInterval);
+    if (!shouldBeOn && reportingTimerId) {
+        killTimer(reportingTimerId);
+        reportingTimerId = 0;
+    } else if (shouldBeOn && !reportingTimerId) {
+        updateModel(true /* clear */);
+        reportingTimerId = startTimer(reportingInterval);
     }
 }
 
-void SystemMonitorPrivate::timerEvent(QTimerEvent *te)
+void SystemMonitorPrivate::makeNewReport()
 {
     Q_Q(SystemMonitor);
 
-    if (te && te->timerId() == reportingTimerId) {
-        Report r;
-        QVector<int> roles;
+    Report r;
+    QVector<int> changedRoles;
+    {
+        const Report &currentReport = reports.at(reportPos);
 
-        if (reportCpu) {
+        if (reportCpu)
             r.cpuLoad = cpu->readLoadValue();
-            roles.append(CpuLoad);
-        } else if (cpuTail > 0) {
-            --cpuTail;
-            roles.append(CpuLoad);
-        }
+        if (currentReport.cpuLoad != r.cpuLoad)
+            changedRoles.append(CpuLoad);
 
-        if (reportGpu) {
+        if (reportGpu)
             r.gpuLoad = gpu->readLoadValue();
-            roles.append(GpuLoad);
-        } else if (gpuTail > 0) {
-            --gpuTail;
-            roles.append(GpuLoad);
-        }
+        if (currentReport.gpuLoad != r.gpuLoad)
+            changedRoles.append(GpuLoad);
 
-        if (reportMem) {
+        if (reportMem)
             r.memoryUsed = memory->readUsedValue();
-            roles.append(MemoryUsed);
-        } else if (memTail > 0) {
-            --memTail;
-            roles.append(MemoryUsed);
-        }
+        if (currentReport.memoryUsed != r.memoryUsed)
+            changedRoles.append(MemoryUsed);
 
         for (auto it = ioHash.cbegin(); it != ioHash.cend(); ++it) {
             qreal ioVal = it.value()->readLoadValue();
             emit q->ioLoadReportingChanged(it.key(), ioVal);
             r.ioLoad.insert(it.key(), ioVal);
         }
-        if (!r.ioLoad.isEmpty())
-            roles.append(IoLoad);
-        if (!ioTails.isEmpty()) {
-            if (r.ioLoad.isEmpty())
-                roles.append(IoLoad);
-            for (const auto &it : ioTails.keys()) {
-                r.ioLoad.insert(it, 0.0);
-                if (--ioTails[it] == 0)
-                    ioTails.remove(it);
-            }
-        }
+        if (currentReport.ioLoad != r.ioLoad)
+            changedRoles.append(IoLoad);
 
         if (reportFps) {
             if (FrameTimer *ft = frameTimer.value(nullptr)) {
@@ -467,39 +438,43 @@ void SystemMonitorPrivate::timerEvent(QTimerEvent *te)
                 r.fpsJitter = ft->jitterFps();
                 ft->reset();
                 emit q->fpsReportingChanged(r.fpsAvg, r.fpsMin, r.fpsMax, r.fpsJitter);
-                roles.append(AverageFps);
-                roles.append(MinimumFps);
-                roles.append(MaximumFps);
-                roles.append(FpsJitter);
             }
-        } else if (fpsTail > 0){
-            --fpsTail;
-            roles.append(AverageFps);
-            roles.append(MinimumFps);
-            roles.append(MaximumFps);
-            roles.append(FpsJitter);
         }
+        if (currentReport.fpsAvg != r.fpsAvg)
+            changedRoles.append(AverageFps);
+        if (currentReport.fpsMin != r.fpsMin)
+            changedRoles.append(MinimumFps);
+        if (currentReport.fpsMax != r.fpsMax)
+            changedRoles.append(MaximumFps);
+        if (currentReport.fpsJitter != r.fpsJitter)
+            changedRoles.append(FpsJitter);
+    }
 
-        // ring buffer handling
-        // optimization: instead of sending a dataChanged for every item, we always move the
-        // last item to the front and change its data only
-        int last = reports.size() - 1;
-        q->beginMoveRows(QModelIndex(), last, last, QModelIndex(), 0);
-        reports[reportPos++] = r;
-        if (reportPos > last)
-            reportPos = 0;
-        q->endMoveRows();
-        q->dataChanged(q->index(0), q->index(0), roles);
+    // ring buffer handling
+    // optimization: instead of sending a dataChanged for every item, we always move the
+    // last item to the front and change its data only
+    int last = reports.size() - 1;
+    q->beginMoveRows(QModelIndex(), last, last, QModelIndex(), 0);
+    reports[reportPos++] = r;
+    if (reportPos > last)
+        reportPos = 0;
+    q->endMoveRows();
+    q->dataChanged(q->index(0), q->index(0), changedRoles);
 
-        if (reportMem)
-            emit q->memoryReportingChanged(r.memoryUsed);
-        if (reportCpu)
-            emit q->cpuLoadReportingChanged(r.cpuLoad);
-        if (reportGpu)
-            emit q->gpuLoadReportingChanged(r.gpuLoad);
+    if (reportMem)
+        emit q->memoryReportingChanged(r.memoryUsed);
+    if (reportCpu)
+        emit q->cpuLoadReportingChanged(r.cpuLoad);
+    if (reportGpu)
+        emit q->gpuLoadReportingChanged(r.gpuLoad);
+}
 
-        setupTimer();  // we might be able to stop this timer, when end of tail reached
+void SystemMonitorPrivate::timerEvent(QTimerEvent *te)
+{
+    Q_Q(SystemMonitor);
 
+    if (te && te->timerId() == reportingTimerId) {
+        makeNewReport();
     } else if (te && te->timerId() == idleTimerId) {
         qreal idleVal = idleCpu->readLoadValue();
         bool nowIdle = (idleVal <= idleThreshold);
@@ -531,8 +506,6 @@ void SystemMonitorPrivate::updateModel(bool clear)
         reports.clear();
         reports.resize(count);
         reportPos = 0;
-        cpuTail = memTail = fpsTail = 0;
-        ioTails.clear();
     } else {
         int oldCount = reports.size();
         int diff = count - oldCount;
@@ -549,15 +522,6 @@ void SystemMonitorPrivate::updateModel(bool clear)
                 reportPos = 0;
             }
         }
-
-        if (cpuTail > 0)
-            cpuTail += diff;
-        if (memTail > 0)
-            memTail += diff;
-        if (fpsTail > 0)
-            fpsTail += diff;
-        for (const auto &it : ioTails.keys())
-            ioTails[it] += diff;
     }
     q->endResetModel();
 }
@@ -808,10 +772,7 @@ void SystemMonitor::setMemoryReportingEnabled(bool enabled)
 
     if (enabled != d->reportMem) {
         d->reportMem = enabled;
-        if (!enabled)
-            d->memTail = d->count;
-        else
-            d->setupTimer();
+        d->setupTimer();
         emit memoryReportingEnabledChanged();
     }
 }
@@ -829,10 +790,7 @@ void SystemMonitor::setCpuLoadReportingEnabled(bool enabled)
 
     if (enabled != d->reportCpu) {
         d->reportCpu = enabled;
-        if (!enabled)
-            d->cpuTail = d->count;
-        else
-            d->setupTimer();
+        d->setupTimer();
         emit cpuLoadReportingEnabledChanged();
     }
 }
@@ -850,10 +808,7 @@ void SystemMonitor::setGpuLoadReportingEnabled(bool enabled)
 
     if (enabled != d->reportGpu) {
         d->reportGpu = enabled;
-        if (!enabled)
-            d->gpuTail = d->count;
-        else
-            d->setupTimer();
+        d->setupTimer();
         d->gpu->setActive(enabled);
         emit gpuLoadReportingEnabledChanged();
     }
@@ -885,8 +840,6 @@ bool SystemMonitor::addIoLoadReporting(const QString &deviceName)
     if (d->ioHash.contains(deviceName))
         return false;
 
-    d->ioTails.remove(deviceName);
-
     IoReader *ior = new IoReader(deviceName.toLocal8Bit().constData());
     d->ioHash.insert(deviceName, ior);
     if (d->reportingInterval >= 0)
@@ -905,7 +858,6 @@ void SystemMonitor::removeIoLoadReporting(const QString &deviceName)
     Q_D(SystemMonitor);
 
     delete d->ioHash.take(deviceName);
-    d->ioTails.insert(deviceName, d->count);
 }
 
 /*!
@@ -926,10 +878,7 @@ void SystemMonitor::setFpsReportingEnabled(bool enabled)
 
     if (enabled != d->reportFps) {
         d->reportFps = enabled;
-        if (!enabled)
-            d->fpsTail = d->count;
-        else
-            d->setupTimer();
+        d->setupTimer();
         d->setupFpsReporting();
         emit fpsReportingEnabledChanged();
     }
@@ -945,14 +894,31 @@ bool SystemMonitor::isFpsReportingEnabled() const
 void SystemMonitor::setReportingInterval(int intervalInMSec)
 {
     Q_D(SystemMonitor);
+    d->setReportingInterval(intervalInMSec);
+}
+
+void SystemMonitorPrivate::setReportingInterval(int intervalInMSec)
+{
+    Q_Q(SystemMonitor);
+
+    if (reportingInterval == intervalInMSec)
+        return; // NOOP
+
+    if (intervalInMSec <= 0) {
+        qmlWarning(q) << "Cannot set a reportingInterval <= 0";
+        return;
+    }
 
-    if (d->reportingInterval != intervalInMSec && intervalInMSec > 0) {
-        for (auto it = d->ioHash.cbegin(); it != d->ioHash.cend(); ++it)
-            it.value()->readLoadValue();   // for initialization only
-        d->updateModel(true);
-        d->setupTimer(intervalInMSec);
-        emit reportingIntervalChanged(intervalInMSec);
+    for (auto it = ioHash.cbegin(); it != ioHash.cend(); ++it)
+        it.value()->readLoadValue();   // for initialization only
+    updateModel(true);
+    reportingInterval = intervalInMSec;
+    if (reportingTimerId) {
+        killTimer(reportingTimerId);
+        reportingTimerId = 0;
     }
+    setupTimer();
+    emit q->reportingIntervalChanged(intervalInMSec);
 }
 
 int SystemMonitor::reportingInterval() const
diff --git a/src/monitor-lib/systemmonitor_p.h b/src/monitor-lib/systemmonitor_p.h
index d61f4433..b5b35a6b 100644
--- a/src/monitor-lib/systemmonitor_p.h
+++ b/src/monitor-lib/systemmonitor_p.h
@@ -61,6 +61,8 @@ public:
         : q_ptr(q)
     { }
 
+    static const SystemMonitorPrivate* get(const SystemMonitor *sysMon) { return sysMon->d_func(); }
+
     SystemMonitor *q_ptr;
     Q_DECLARE_PUBLIC(SystemMonitor)
 
@@ -90,11 +92,6 @@ public:
     bool reportGpu = false;
     bool reportMem = false;
     bool reportFps = false;
-    int cpuTail = 0;
-    int gpuTail = 0;
-    int memTail = 0;
-    int fpsTail = 0;
-    QMap<QString, int> ioTails;
     bool windowManagerConnectionCreated = false;
 
     struct Report
@@ -114,6 +111,8 @@ public:
     // model
     QHash<int, QByteArray> roleNames;
 
+    void makeNewReport();
+
     int latestReportPos() const;
 
 #if !defined(AM_HEADLESS)
@@ -121,13 +120,15 @@ public:
 #endif
 
     void setupFpsReporting();
-    void setupTimer(int newInterval = -1);
+    void setupTimer();
 
     void timerEvent(QTimerEvent *te) override;
 
     const Report &reportForRow(int row) const;
 
     void updateModel(bool clear);
+
+    void setReportingInterval(int intervalInMSec);
 };
 
 QT_END_NAMESPACE_AM