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authorLangonda Agag <namezero@afim.info>2019-11-25 07:25:46 +0000
committerLangonda Agag <namezero@afim.info>2019-11-25 08:44:56 +0000
commit0e0793ca590439bd437310f1e80507d21be3f14d (patch)
tree8f9d22839d67dc62189b9127a477a43833094c1c /src/gui
parent59a705e3710b0ba93bb698e3223241cfac932948 (diff)
Improve QTextDocumentPrivate cursor performance
The cursors in QTextDocumentPrivate are held in a QList. This becomes a serious performance problem with lots of extra selections due to a call to QTextDocumentPrivate::removeCursor() from the QTextCursor destructor. Given the following test program: QPlainTextEdit *editor = ... std::list< QTextCursor> list; for(int i = 0; i < 100000; ++i) { QTextCursor c(editor->document()); c.setPosition(std::rand()%100); list.push_front(c); } list.clear(); // <-- clear calls hangs for 3+ seconds // due to time spent in // QTextDocumentPrivate::removeCursor() // due to QList::removeAll() call Note the push_front because it exacerbates the issue because the entire list will be traversed. The change submitted changes the structure to a set, removing the issue. In theory, this limits that a cursors cannot be in the structure twice, but this neither happens nor would it make sense. Change-Id: I817dc5d1bda1d98c6725a531b32d1c711a029a34 Reviewed-by: Langonda Agag <namezero@afim.info> Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io> Reviewed-by: Simon Hausmann <simon.hausmann@qt.io> Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io> Reviewed-by: Jesus Fernandez <jsfdez@gmail.com>
Diffstat (limited to 'src/gui')
-rw-r--r--src/gui/text/qtextdocument_p.cpp2
-rw-r--r--src/gui/text/qtextdocument_p.h6
2 files changed, 4 insertions, 4 deletions
diff --git a/src/gui/text/qtextdocument_p.cpp b/src/gui/text/qtextdocument_p.cpp
index a1b1c2e92b..2f02f62a57 100644
--- a/src/gui/text/qtextdocument_p.cpp
+++ b/src/gui/text/qtextdocument_p.cpp
@@ -243,7 +243,7 @@ void QTextDocumentPrivate::clear()
curs->adjusted_anchor = 0;
}
- QList<QTextCursorPrivate *>oldCursors = cursors;
+ QSet<QTextCursorPrivate *> oldCursors = cursors;
QT_TRY{
cursors.clear();
diff --git a/src/gui/text/qtextdocument_p.h b/src/gui/text/qtextdocument_p.h
index f4e7a25f22..94c67b3264 100644
--- a/src/gui/text/qtextdocument_p.h
+++ b/src/gui/text/qtextdocument_p.h
@@ -277,8 +277,8 @@ private:
public:
void documentChange(int from, int length);
- inline void addCursor(QTextCursorPrivate *c) { cursors.append(c); }
- inline void removeCursor(QTextCursorPrivate *c) { cursors.removeAll(c); }
+ inline void addCursor(QTextCursorPrivate *c) { cursors.insert(c); }
+ inline void removeCursor(QTextCursorPrivate *c) { cursors.remove(c); }
QTextFrame *frameAt(int pos) const;
QTextFrame *rootFrame() const;
@@ -330,7 +330,7 @@ private:
BlockMap blocks;
int initialBlockCharFormatIndex;
- QList<QTextCursorPrivate *> cursors;
+ QSet<QTextCursorPrivate *> cursors;
QMap<int, QTextObject *> objects;
QMap<QUrl, QVariant> resources;
QMap<QUrl, QVariant> cachedResources;