From b8a5f34b34b6c4e37684fe2782b8cf39c38cd928 Mon Sep 17 00:00:00 2001
From: Fabian Vogt <fabian@ritter-vogt.de>
Date: Mon, 14 Jan 2019 13:32:52 +0100
Subject: [PATCH 2/2] Revert "Refactor SlaveInterface::calcSpeed"

This reverts commit 4e2a815b9a107663a3d75e9d9d1be336adea888e.
This commit causes crashes due to improper division and there are some
outstanding code review issues as well.

BUG: 402665
---
 src/core/slaveinterface.cpp | 48 ++++++++++++++++++++++++-------------
 src/core/slaveinterface_p.h | 19 +++++++--------
 2 files changed, 39 insertions(+), 28 deletions(-)

diff --git a/src/core/slaveinterface.cpp b/src/core/slaveinterface.cpp
index 6eb2b08d..88f649c8 100644
--- a/src/core/slaveinterface.cpp
+++ b/src/core/slaveinterface.cpp
@@ -45,7 +45,6 @@ SlaveInterface::SlaveInterface(SlaveInterfacePrivate &dd, QObject *parent)
     : QObject(parent), d_ptr(&dd)
 {
     connect(&d_ptr->speed_timer, &QTimer::timeout, this, &SlaveInterface::calcSpeed);
-    d_ptr->transfer_details.reserve(max_count);
 }
 
 SlaveInterface::~SlaveInterface()
@@ -98,24 +97,36 @@ void SlaveInterface::calcSpeed()
         return;
     }
 
-    // Note for future reference: A list is maintained for sizes and times.
-    // Minimum list size is 1 and maximum list size is 8. Delta is calculated
-    // using first and last item from the list.
-
-    const qint64 elapsed_time = d->elapsed_timer.elapsed();
-    if (elapsed_time >= 900) {
-        if (d->transfer_details.count() == max_count) {
-            d->transfer_details.removeFirst();
+    const qint64 currentTime = QDateTime::currentMSecsSinceEpoch();
+    const qint64 diff = currentTime - d->start_time;
+    if (diff - d->last_time >= 900) {
+        d->last_time = diff;
+        if (d->nums == max_nums) {
+            // let's hope gcc can optimize that well enough
+            // otherwise I'd try memcpy :)
+            for (unsigned int i = 1; i < max_nums; ++i) {
+                d->times[i - 1] = d->times[i];
+                d->sizes[i - 1] = d->sizes[i];
+            }
+            d->nums--;
         }
+        d->times[d->nums] = diff;
+        d->sizes[d->nums++] = d->filesize - d->offset;
+
+        KIO::filesize_t lspeed = 1000 * (d->sizes[d->nums - 1] - d->sizes[0]) / (d->times[d->nums - 1] - d->times[0]);
+
+//qDebug() << (long)d->filesize << diff
+//          << long(d->sizes[d->nums-1] - d->sizes[0])
+//          << d->times[d->nums-1] - d->times[0]
+//          << long(lspeed) << double(d->filesize) / diff
+//          << convertSize(lspeed)
+//          << convertSize(long(double(d->filesize) / diff) * 1000);
 
-        const SlaveInterfacePrivate::TransferInfo first = d->transfer_details.first();
-        const SlaveInterfacePrivate::TransferInfo last = {elapsed_time, (d->filesize - d->offset)};
-        KIO::filesize_t lspeed = 1000 * (last.size - first.size) / (last.time - first.time);
         if (!lspeed) {
-            d->transfer_details.clear();
+            d->nums = 1;
+            d->times[0] = diff;
+            d->sizes[0] = d->filesize - d->offset;
         }
-        d->transfer_details.append(last);
-
         emit speed(lspeed);
     }
 }
@@ -198,10 +209,13 @@ bool SlaveInterface::dispatch(int _cmd, const QByteArray &rawdata)
     }
     case INF_TOTAL_SIZE: {
         KIO::filesize_t size = readFilesize_t(stream);
+        d->start_time = QDateTime::currentMSecsSinceEpoch();
+        d->last_time = 0;
         d->filesize = d->offset;
-        d->transfer_details.append({0, 0});
+        d->sizes[0] = d->filesize - d->offset;
+        d->times[0] = 0;
+        d->nums = 1;
         d->speed_timer.start(1000);
-        d->elapsed_timer.start();
         d->slave_calcs_speed = false;
         emit totalSize(size);
         break;
diff --git a/src/core/slaveinterface_p.h b/src/core/slaveinterface_p.h
index efb17d0f..a4cb5d3f 100644
--- a/src/core/slaveinterface_p.h
+++ b/src/core/slaveinterface_p.h
@@ -29,19 +29,17 @@
 #include <QTimer>
 #include <QPointer>
 #include <QHostInfo>
-#include <QVector>
-#include <QElapsedTimer>
 
 #include "kiocoredebug.h"
 
-static const unsigned int max_count = 8;
+static const unsigned int max_nums = 8;
 
 class KIO::SlaveInterfacePrivate
 {
 public:
     SlaveInterfacePrivate()
-        : connection(nullptr), filesize(0), offset(0),
-          slave_calcs_speed(false)
+        : connection(nullptr), filesize(0), offset(0), last_time(0), start_time(0),
+          nums(0), slave_calcs_speed(false)
     {
     }
     virtual ~SlaveInterfacePrivate()
@@ -55,14 +53,13 @@ public:
     // We need some metadata here for our SSL code in messageBox() and for sslMetaData().
     MetaData sslMetaData;
 
-    struct TransferInfo {
-        qint64 time;
-        KIO::filesize_t size;
-    };
-    QVector<TransferInfo> transfer_details;
-    QElapsedTimer elapsed_timer;
+    KIO::filesize_t sizes[max_nums];
+    qint64 times[max_nums];
 
     KIO::filesize_t filesize, offset;
+    size_t last_time;
+    qint64 start_time;
+    uint nums;
     bool slave_calcs_speed;
 
     void slotHostInfo(const QHostInfo &info);
-- 
2.20.1