From 0f2869fcdc0932478c0745bda6e6c70a57b8ad47 Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@kdab.com>
Date: Sat, 2 May 2020 23:03:39 +0200
Subject: [PATCH] QDirIterator: port visitedLinks from QSet to
 QDuplicateTracker

Apart from a more fitting, minimal, API, QDuplicateTracker also
transparently uses C++17 pmr::monotonic_buffer_resource to avoid, or
at least reduce, memory allocations.

The old code performed the visitedLinks check unconditionally, but
since we add entries to visitedLinks only when following symlinks (and
this property cannot be changed under iteration, as `iteratorFlags` is
a const member), the new code only performs the check conditionally,
with unchanged semantics.

Change-Id: Ia2c2dda16136ef5256e2c345b8ecba530883ee37
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
---
 src/corelib/io/qdiriterator.cpp | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/corelib/io/qdiriterator.cpp b/src/corelib/io/qdiriterator.cpp
index f6d337bb74..7128435aa4 100644
--- a/src/corelib/io/qdiriterator.cpp
+++ b/src/corelib/io/qdiriterator.cpp
@@ -108,6 +108,7 @@
 #include <QtCore/private/qfilesystemmetadata_p.h>
 #include <QtCore/private/qfilesystemengine_p.h>
 #include <QtCore/private/qfileinfo_p.h>
+#include <QtCore/private/qduplicatetracker_p.h>
 
 #include <memory>
 
@@ -159,7 +160,7 @@ public:
     QFileInfo nextFileInfo;
 
     // Loop protection
-    QSet<QString> visitedLinks;
+    QDuplicateTracker<QString> visitedLinks;
 };
 
 /*!
@@ -210,12 +211,11 @@ void QDirIteratorPrivate::pushDirectory(const QFileInfo &fileInfo)
         path = fileInfo.canonicalFilePath();
 #endif
 
-    // Stop link loops
-    if (visitedLinks.contains(fileInfo.canonicalFilePath()))
-        return;
-
-    if (iteratorFlags & QDirIterator::FollowSymlinks)
-        visitedLinks << fileInfo.canonicalFilePath();
+    if ((iteratorFlags & QDirIterator::FollowSymlinks)) {
+        // Stop link loops
+        if (visitedLinks.hasSeen(fileInfo.canonicalFilePath()))
+            return;
+    }
 
     if (engine) {
         engine->setFileName(path);