Fix pixmap cache profiling for multiple pixmaps with equal URLs

Apply a heuristic to figure out which pixmaps are causing which
events. As the only means of identification we can get from the
application is the URL this will never be perfect. However, using
some knowledge about the inner workings of pixmap loading we can
get usable results.

Change-Id: I42d7af7499ed7692ed87e68e8fd12c7528e08b3e
Reviewed-by: Kai Koehne <kai.koehne@digia.com>

2 files changed, 263 insertions, 56 deletions

diff --git a/plugins/qmlprofilerextension/pixmapcachemodel.cpp b/plugins/qmlprofilerextension/pixmapcachemodel.cpp
index 1ff6e6ab99..f5d08083e8 100644
--- a/plugins/qmlprofilerextension/pixmapcachemodel.cpp
+++ b/plugins/qmlprofilerextension/pixmapcachemodel.cpp
@@ -23,12 +23,45 @@
 #include "qmlprofiler/singlecategorytimelinemodel_p.h"
 
 #include <QDebug>
+#include <QSize>
 
 namespace QmlProfilerExtension {
 namespace Internal {
 
 using namespace QmlProfiler;
 
+enum CacheState {
+    Uncached,    // After loading started (or some other proof of existence) or after uncaching
+    ToBeCached,  // After determining the pixmap is to be cached but before knowing its size
+    Cached,      // After caching a pixmap or determining the size of a ToBeCached pixmap
+    Uncacheable, // If loading failed without ToBeCached or after a corrupt pixmap has been uncached
+    Corrupt      // If after ToBeCached we learn that loading failed
+};
+
+enum LoadState {
+    Initial,
+    Loading,
+    Finished,
+    Error
+};
+
+struct PixmapState {
+    PixmapState(int width, int height, CacheState cache = Uncached) :
+        size(width, height), started(-1), loadState(Initial), cacheState(cache) {}
+    PixmapState(CacheState cache = Uncached) : started(-1), loadState(Initial), cacheState(cache) {}
+    QSize size;
+    int started;
+    LoadState loadState;
+    CacheState cacheState;
+};
+
+struct Pixmap {
+    Pixmap() {}
+    Pixmap(const QString &url) : url(url), sizes(1) {}
+    QString url;
+    QVector<PixmapState> sizes;
+};
+
 class PixmapCacheModel::PixmapCacheModelPrivate :
         public SortedTimelineModel<PixmapCacheEvent,
                                    SingleCategoryTimelineModel::SingleCategoryTimelineModelPrivate>
@@ -38,9 +71,10 @@ public:
     void resizeUnfinishedLoads();
     void flattenLoads();
     void computeRowCounts();
+    int updateCacheCount(int lastCacheSizeEvent, qint64 startTime, qint64 pixSize,
+                         PixmapCacheEvent &newEvent);
 
-    QVector < QString > pixmapUrls;
-    QVector < QPair<int, int> > pixmapSizes;
+    QVector<Pixmap> pixmaps;
     int expandedRowCount;
     int collapsedRowCount;
     void addVP(QVariantList &l, QString label, qint64 time) const;
@@ -129,11 +163,13 @@ const QVariantList PixmapCacheModel::getLabelsForCategory(int category) const
             result << element;
         }
 
-        for (int i=0; i < d->pixmapUrls.count(); i++) {
+        for (int i=0; i < d->pixmaps.count(); i++) {
             // Loading
             QVariantMap element;
-            element.insert(QLatin1String("displayName"), QVariant(getFilenameOnly(d->pixmapUrls[i])));
-            element.insert(QLatin1String("description"), QVariant(getFilenameOnly(d->pixmapUrls[i])));
+            element.insert(QLatin1String("displayName"),
+                           QVariant(getFilenameOnly(d->pixmaps[i].url)));
+            element.insert(QLatin1String("description"),
+                           QVariant(getFilenameOnly(d->pixmaps[i].url)));
 
             element.insert(QLatin1String("id"), QVariant(i+1));
             result << element;
@@ -173,20 +209,23 @@ const QVariantList PixmapCacheModel::getEventDetails(int index) const
 
     {
         QVariantMap res;
-        res.insert(tr("File"), QVariant(getFilenameOnly(d->pixmapUrls[ev->urlIndex])));
+        res.insert(tr("File"), QVariant(getFilenameOnly(d->pixmaps[ev->urlIndex].url)));
         result << res;
     }
 
     {
         QVariantMap res;
-        res.insert(tr("Width"), QVariant(QString::fromLatin1("%1 px").arg(d->pixmapSizes[ev->urlIndex].first)));
+        res.insert(tr("Width"), QVariant(QString::fromLatin1("%1 px")
+                .arg(d->pixmaps[ev->urlIndex].sizes[ev->sizeIndex].size.width())));
         result << res;
         res.clear();
-        res.insert(tr("Height"), QVariant(QString::fromLatin1("%1 px").arg(d->pixmapSizes[ev->urlIndex].second)));
+        res.insert(tr("Height"), QVariant(QString::fromLatin1("%1 px")
+                .arg(d->pixmaps[ev->urlIndex].sizes[ev->sizeIndex].size.height())));
         result << res;
     }
 
-    if (ev->pixmapEventType == PixmapLoadingStarted && ev->cacheSize == -1) {
+    if (ev->pixmapEventType == PixmapLoadingStarted &&
+            d->pixmaps[ev->urlIndex].sizes[ev->sizeIndex].loadState != Finished) {
         QVariantMap res;
         res.insert(tr("Result"), QVariant(QLatin1String("Load Error")));
         result << res;
@@ -195,6 +234,36 @@ const QVariantList PixmapCacheModel::getEventDetails(int index) const
     return result;
 }
 
+/* Ultimately there is no way to know which cache entry a given event refers to as long as we only
+ * receive the pixmap URL from the application. Multiple copies of different sizes may be cached
+ * for each URL. However, we can apply some heuristics to make the result somewhat plausible by
+ * using the following assumptions:
+ *
+ * - PixmapSizeKnown will happen at most once for every cache entry.
+ * - PixmapSizeKnown cannot happen for entries with PixmapLoadingError and vice versa.
+ * - PixmapCacheCountChanged can happen for entries with PixmapLoadingError but doesn't have to.
+ * - Decreasing PixmapCacheCountChanged events can only happen for entries that have seen an
+ *   increasing PixmapCacheCountChanged (but that may have happened before the trace).
+ * - PixmapCacheCountChanged can happen before or after PixmapSizeKnown.
+ * - For every PixmapLoadingFinished or PixmapLoadingError there is exactly one
+ *   PixmapLoadingStarted event, but it may be before the trace.
+ * - For every PixmapLoadingStarted there is exactly one PixmapLoadingFinished or
+ *   PixmapLoadingError, but it may be after the trace.
+ * - Decreasing PixmapCacheCountChanged events in the presence of corrupt cache entries are more
+ *   likely to clear those entries than other, correctly loaded ones.
+ * - Increasing PixmapCacheCountChanged events are more likely to refer to correctly loaded entries
+ *   than to ones with PixmapLoadingError.
+ * - PixmapLoadingFinished and PixmapLoadingError are more likely to refer to cache entries that
+ *   have seen a PixmapLoadingStarted than to ones that haven't.
+ *
+ * For each URL we keep an ordered list of pixmaps possibly being loaded and assign new events to
+ * the first entry that "fits". If multiple sizes of the same pixmap are being loaded concurrently
+ * we generally assume that the PixmapLoadingFinished and PixmapLoadingError events occur in the
+ * order we learn about the existence of these sizes, subject to the above constraints. This is not
+ * necessarily the order the pixmaps are really loaded but it's the best we can do with the given
+ * information. If they're loaded sequentially the representation is correct.
+ */
+
 void PixmapCacheModel::loadData()
 {
     Q_D(PixmapCacheModel);
@@ -205,8 +274,6 @@ void PixmapCacheModel::loadData()
 
     int lastCacheSizeEvent = -1;
     int cumulatedCount = 0;
-    QVector < int > pixmapStartPoints;
-    QVector < int > pixmapCachePoints;
 
     foreach (const QmlProfilerDataModel::QmlEventData &event, simpleModel->getEvents()) {
         if (!eventAccepted(event))
@@ -216,69 +283,192 @@ void PixmapCacheModel::loadData()
         newEvent.pixmapEventType = event.bindingType;
         qint64 startTime = event.startTime;
 
-        bool isNewEntry = false;
-        newEvent.urlIndex = d->pixmapUrls.indexOf(event.location.filename);
+        newEvent.urlIndex = -1;
+        for (QVector<Pixmap>::const_iterator it(d->pixmaps.cend()); it != d->pixmaps.cbegin();) {
+            if ((--it)->url == event.location.filename) {
+                newEvent.urlIndex = it - d->pixmaps.cbegin();
+                break;
+            }
+        }
+
+        newEvent.sizeIndex = -1;
         if (newEvent.urlIndex == -1) {
-            isNewEntry = true;
-            newEvent.urlIndex = d->pixmapUrls.count();
-            d->pixmapUrls << event.location.filename;
-            d->pixmapSizes << QPair<int, int>(0,0); // default value
-            pixmapStartPoints << -1; // dummy value to be filled by load event
-            pixmapCachePoints << -1; // dummy value to be filled by cache event
+            newEvent.urlIndex = d->pixmaps.count();
+            d->pixmaps << Pixmap(event.location.filename);
         }
 
         newEvent.eventId = newEvent.urlIndex + 1;
         newEvent.rowNumberExpanded = newEvent.urlIndex + 2;
 
+        Pixmap &pixmap = d->pixmaps[newEvent.urlIndex];
         switch (newEvent.pixmapEventType) {
-        case PixmapSizeKnown: // pixmap size
-            d->pixmapSizes[newEvent.urlIndex] = QPair<int,int>((int)event.numericData1, (int)event.numericData2);
-            if (pixmapCachePoints[newEvent.urlIndex] == -1)
+        case PixmapSizeKnown: {// pixmap size
+            // Look for pixmaps for which we don't know the size, yet and which have actually been
+            // loaded.
+            for (QVector<PixmapState>::iterator i(pixmap.sizes.begin());
+                    i != pixmap.sizes.end(); ++i) {
+                if (i->size.isValid() || i->cacheState == Uncacheable || i->cacheState == Corrupt)
+                    continue;
+
+                // We can't have cached it before we knew the size
+                Q_ASSERT(i->cacheState != Cached);
+
+                i->size.setWidth(event.numericData1);
+                i->size.setHeight(event.numericData2);
+                newEvent.sizeIndex = i - pixmap.sizes.begin();
                 break;
-            // else fall through and update cache size
-            newEvent.pixmapEventType = PixmapCacheCountChanged;
+            }
+
+            if (newEvent.sizeIndex == -1) {
+                newEvent.sizeIndex = pixmap.sizes.length();
+                pixmap.sizes << PixmapState(event.numericData1, event.numericData2);
+            }
+
+            PixmapState &state = pixmap.sizes[newEvent.sizeIndex];
+            if (state.cacheState == ToBeCached) {
+                lastCacheSizeEvent = d->updateCacheCount(lastCacheSizeEvent, startTime,
+                                              state.size.width() * state.size.height(), newEvent);
+                state.cacheState = Cached;
+            }
+            break;
+        }
         case PixmapCacheCountChanged: {// Cache Size Changed Event
             startTime = event.startTime + 1; // delay 1 ns for proper sorting
-            newEvent.eventId = 0;
-            newEvent.rowNumberExpanded = 1;
-            newEvent.rowNumberCollapsed = 1;
-
-            qint64 pixSize = d->pixmapSizes[newEvent.urlIndex].first * d->pixmapSizes[newEvent.urlIndex].second;
-            qint64 prevSize = 0;
-            if (lastCacheSizeEvent != -1) {
-                prevSize = d->range(lastCacheSizeEvent).cacheSize;
-                if (pixmapCachePoints[newEvent.urlIndex] == -1) {
-                    // else it's a synthesized update and doesn't have a valid cache count
-                    if (event.numericData3 < cumulatedCount)
-                        pixSize = -pixSize;
-                    cumulatedCount = event.numericData3;
+
+            bool uncache = cumulatedCount > event.numericData3;
+            cumulatedCount = event.numericData3;
+            qint64 pixSize = 0;
+
+            // First try to find a preferred pixmap, which either is Corrupt and will be uncached
+            // or is uncached and will be cached.
+            for (QVector<PixmapState>::iterator i(pixmap.sizes.begin());
+                    i != pixmap.sizes.end(); ++i) {
+                if (uncache && i->cacheState == Corrupt) {
+                    newEvent.sizeIndex = i - pixmap.sizes.begin();
+                    i->cacheState = Uncacheable;
+                    break;
+                } else if (!uncache && i->cacheState == Uncached) {
+                    newEvent.sizeIndex = i - pixmap.sizes.begin();
+                    if (i->size.isValid()) {
+                        pixSize = i->size.width() * i->size.height();
+                        i->cacheState = Cached;
+                    } else {
+                        i->cacheState = ToBeCached;
+                    }
+                    break;
+                }
+            }
+
+            // If none found, check for cached or ToBeCached pixmaps that shall be uncached or
+            // Error pixmaps that become corrupt cache entries. We also accept Initial to be
+            // uncached as we may have missed the matching PixmapCacheCountChanged that cached it.
+            if (newEvent.sizeIndex == -1) {
+                for (QVector<PixmapState>::iterator i(pixmap.sizes.begin());
+                        i != pixmap.sizes.end(); ++i) {
+                    if (uncache && (i->cacheState == Cached || i->cacheState == ToBeCached ||
+                                    i->cacheState == Uncached)) {
+                        newEvent.sizeIndex = i - pixmap.sizes.begin();
+                        if (i->size.isValid())
+                            pixSize = -i->size.width() * i->size.height();
+                        i->cacheState = Uncached;
+                        break;
+                    } else if (!uncache && i->cacheState == Uncacheable) {
+                        newEvent.sizeIndex = i - pixmap.sizes.begin();
+                        i->cacheState = Corrupt;
+                        break;
+                    }
                 }
-                d->insertEnd(lastCacheSizeEvent, startTime - d->range(lastCacheSizeEvent).start);
             }
-            newEvent.cacheSize = prevSize + pixSize;
-            lastCacheSizeEvent = d->insertStart(startTime, newEvent);
-            pixmapCachePoints[newEvent.urlIndex] = lastCacheSizeEvent;
+
+            // If that does't work, create a new entry.
+            if (newEvent.sizeIndex == -1) {
+                newEvent.sizeIndex = pixmap.sizes.length();
+                pixmap.sizes << PixmapState(uncache ? Uncached : ToBeCached);
+            }
+
+            lastCacheSizeEvent = d->updateCacheCount(lastCacheSizeEvent, startTime, pixSize,
+                                                     newEvent);
             break;
         }
         case PixmapLoadingStarted: // Load
-            pixmapStartPoints[newEvent.urlIndex] = d->insertStart(startTime, newEvent);
+            // Look for a pixmap that hasn't been started, yet. There may have been a refcount
+            // event, which we ignore.
+            for (QVector<PixmapState>::const_iterator i(pixmap.sizes.cbegin());
+                    i != pixmap.sizes.cend(); ++i) {
+                if (i->loadState == Initial) {
+                    newEvent.sizeIndex = i - pixmap.sizes.cbegin();
+                    break;
+                }
+            }
+            if (newEvent.sizeIndex == -1) {
+                newEvent.sizeIndex = pixmap.sizes.length();
+                pixmap.sizes << PixmapState();
+            }
+            pixmap.sizes[newEvent.sizeIndex].started = d->insertStart(startTime, newEvent);
+            pixmap.sizes[newEvent.sizeIndex].loadState = Loading;
             break;
         case PixmapLoadingFinished:
         case PixmapLoadingError: {
-            int loadIndex = pixmapStartPoints[newEvent.urlIndex];
-            if (!isNewEntry && loadIndex != -1) {
-                d->insertEnd(loadIndex, startTime - d->range(loadIndex).start);
-            } else {
-                // if it's a new entry it means that we don't have a corresponding start
+            // First try to find one that has already started
+            for (QVector<PixmapState>::const_iterator i(pixmap.sizes.cbegin());
+                    i != pixmap.sizes.cend(); ++i) {
+                if (i->loadState != Loading)
+                    continue;
+                // Pixmaps with known size cannot be errors and vice versa
+                if (newEvent.pixmapEventType == PixmapLoadingError && i->size.isValid())
+                    continue;
+
+                newEvent.sizeIndex = i - pixmap.sizes.cbegin();
+                break;
+            }
+
+            // If none was found use any other compatible one
+            if (newEvent.sizeIndex == -1) {
+                for (QVector<PixmapState>::const_iterator i(pixmap.sizes.cbegin());
+                        i != pixmap.sizes.cend(); ++i) {
+                    if (i->loadState != Initial)
+                        continue;
+                    // Pixmaps with known size cannot be errors and vice versa
+                    if (newEvent.pixmapEventType == PixmapLoadingError && i->size.isValid())
+                        continue;
+
+                    newEvent.sizeIndex = i - pixmap.sizes.cbegin();
+                    break;
+                }
+            }
+
+            // If again none was found, create one.
+            if (newEvent.sizeIndex == -1) {
+                newEvent.sizeIndex = pixmap.sizes.length();
+                pixmap.sizes << PixmapState();
+            }
+
+            PixmapState &state = pixmap.sizes[newEvent.sizeIndex];
+            // If the pixmap loading wasn't started, start it at traceStartTime()
+            if (state.loadState == Initial) {
                 newEvent.pixmapEventType = PixmapLoadingStarted;
-                newEvent.rowNumberExpanded = newEvent.urlIndex + 2;
-                loadIndex = d->insert(traceStartTime(), startTime - traceStartTime(), newEvent);
-                pixmapStartPoints[newEvent.urlIndex] = loadIndex;
+                state.started = d->insert(traceStartTime(), startTime - traceStartTime(), newEvent);
+            }
+
+            d->insertEnd(state.started, startTime - d->range(state.started).start);
+            if (newEvent.pixmapEventType == PixmapLoadingError) {
+                state.loadState = Error;
+                switch (state.cacheState) {
+                case Uncached:
+                    state.cacheState = Uncacheable;
+                    break;
+                case ToBeCached:
+                    state.cacheState = Corrupt;
+                    break;
+                default:
+                    // Cached cannot happen as size would have to be known and Corrupt or
+                    // Uncacheable cannot happen as we only accept one finish or error event per
+                    // pixmap.
+                    Q_ASSERT(false);
+                }
+            } else {
+                state.loadState = Finished;
             }
-            if (event.bindingType == PixmapLoadingFinished)
-                d->data(loadIndex).cacheSize = 1;  // use count to mark success
-            else
-                d->data(loadIndex).cacheSize = -1; // ... or failure
             break;
         }
         default:
@@ -306,8 +496,7 @@ void PixmapCacheModel::clear()
 {
     Q_D(PixmapCacheModel);
     d->SortedTimelineModel::clear();
-    d->pixmapUrls.clear();
-    d->pixmapSizes.clear();
+    d->pixmaps.clear();
     d->collapsedRowCount = 1;
     d->expandedRowCount = 1;
     d->expanded = false;
@@ -380,6 +569,23 @@ void PixmapCacheModel::PixmapCacheModelPrivate::computeRowCounts()
     collapsedRowCount++;
 }
 
+int PixmapCacheModel::PixmapCacheModelPrivate::updateCacheCount(int lastCacheSizeEvent,
+        qint64 startTime, qint64 pixSize, PixmapCacheEvent &newEvent)
+{
+    newEvent.pixmapEventType = PixmapCacheCountChanged;
+    newEvent.eventId = 0;
+    newEvent.rowNumberExpanded = 1;
+    newEvent.rowNumberCollapsed = 1;
+
+    qint64 prevSize = 0;
+    if (lastCacheSizeEvent != -1) {
+        prevSize = range(lastCacheSizeEvent).cacheSize;
+        insertEnd(lastCacheSizeEvent, startTime - range(lastCacheSizeEvent).start);
+    }
+
+    newEvent.cacheSize = prevSize + pixSize;
+    return insertStart(startTime, newEvent);
+}
 
 
 } // namespace Internal
diff --git a/plugins/qmlprofilerextension/pixmapcachemodel.h b/plugins/qmlprofilerextension/pixmapcachemodel.h
index b0470f3713..cbebf71d0d 100644
--- a/plugins/qmlprofilerextension/pixmapcachemodel.h
+++ b/plugins/qmlprofilerextension/pixmapcachemodel.h
@@ -38,6 +38,7 @@ public:
         int eventId;
         int pixmapEventType;
         int urlIndex;
+        int sizeIndex;
         qint64 cacheSize;
         int rowNumberExpanded;
         int rowNumberCollapsed;