Redefine CacheStatus.readRatio field.

Now it is defined as:
CacheStatus.readRatio = (blocks read from cache) / (blocks read from disk + blocks read from cache)
The 2 variables in denominator are counted separately and the formula before this change doesn't really make sense

Add percentage sign to "Read cache hits" stats
Also remove redundant header include

src/base/bittorrent/session.cpp

@@ -29,10 +29,10 @@
 
 #include "session.h"
 
+#include <algorithm>
 #include <cstdlib>
 #include <queue>
 #include <string>
-#include <vector>
 
 #include <QCoreApplication>
 #include <QDateTime>
@@ -4266,11 +4266,10 @@ void Session::handleSessionStatsAlert(libt::session_stats_alert *p)
     m_status.diskWriteQueue = p->values[m_metricIndices.peer.numPeersDownDisk];
     m_status.peersCount = p->values[m_metricIndices.peer.numPeersConnected];
 
-    const auto numBlocksRead = p->values[m_metricIndices.disk.numBlocksRead];
+    const int numBlocksRead = p->values[m_metricIndices.disk.numBlocksRead];
+    const int numBlocksCacheHits = p->values[m_metricIndices.disk.numBlocksCacheHits];
     m_cacheStatus.totalUsedBuffers = p->values[m_metricIndices.disk.diskBlocksInUse];
-    m_cacheStatus.readRatio = numBlocksRead > 0
-            ? static_cast<qreal>(p->values[m_metricIndices.disk.numBlocksCacheHits]) / numBlocksRead
-            : -1;
+    m_cacheStatus.readRatio = static_cast<qreal>(numBlocksCacheHits) / std::max(numBlocksCacheHits + numBlocksRead, 1);
     m_cacheStatus.jobQueueLength = p->values[m_metricIndices.disk.queuedDiskJobs];
 
     quint64 totalJobs = p->values[m_metricIndices.disk.writeJobs] + p->values[m_metricIndices.disk.readJobs]

src/gui/statsdialog.cpp

@@ -77,7 +77,10 @@ void StatsDialog::update()
                 : "-");
     // Cache hits
     qreal readRatio = cs.readRatio;
-    m_ui->labelCacheHits->setText((readRatio >= 0) ? Utils::String::fromDouble(100 * readRatio, 2) : "-");
+    m_ui->labelCacheHits->setText(QString("%1%").arg(
+        readRatio > 0
+        ? Utils::String::fromDouble(100 * readRatio, 2)
+        : "0"));
     // Buffers size
     m_ui->labelTotalBuf->setText(Utils::Misc::friendlyUnit(cs.totalUsedBuffers * 16 * 1024));
     // Disk overload (100%) equivalent