Darwin: correct state restore when FSEventsStream starting fails

The previous state was not restored completely when adding/removing
paths resulted in a stream start failure.

It also removes an autoreleasepool in restartStream, because both
stopStream and startStream do already create an autoreleasepool of their
own. (So, this pool will always be empty.)

Change-Id: Idc674e9c040f346703ab3ec256957e787a0ade73
Reviewed-by: Marc Mutz <marc.mutz@kdab.com>
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

1 files changed, 15 insertions, 4 deletions

diff --git a/src/corelib/io/qfilesystemwatcher_fsevents_p.h b/src/corelib/io/qfilesystemwatcher_fsevents_p.h
index b4640afc4e..b99c026fad 100644
--- a/src/corelib/io/qfilesystemwatcher_fsevents_p.h
+++ b/src/corelib/io/qfilesystemwatcher_fsevents_p.h
@@ -81,7 +81,7 @@ Q_SIGNALS:
 private slots:
     void doEmitFileChanged(const QString &path, bool removed);
     void doEmitDirectoryChanged(const QString &path, bool removed);
-    void restartStream();
+    bool restartStream();
 
 private:
     struct Info {
@@ -112,6 +112,19 @@ private:
     typedef QHash<QString, DirInfo> DirsByName;
     typedef QHash<QString, qint64> PathRefCounts;
 
+    struct WatchingState {
+        // These fields go hand-in-hand. FSEvents watches paths, and there is no use in watching
+        // the same path multiple times. So, the "refcount" on a path is the number of watched
+        // files that have the same path, plus the number of directories that have the same path.
+        //
+        // If the stream fails to start after adding files/directories, the watcher will try to
+        // keep watching files/directories that it was already watching. It does that by restoring
+        // the previous WatchingState and restarting the stream.
+        FilesByPath watchedFiles;
+        DirsByName watchedDirectories;
+        PathRefCounts watchedPaths;
+    };
+
     QFseventsFileSystemWatcherEngine(QObject *parent);
     bool startStream();
     void stopStream(bool isStopped = false);
@@ -125,10 +138,8 @@ private:
     QMutex lock;
     dispatch_queue_t queue;
     FSEventStreamRef stream;
-    FilesByPath watchedFiles;
-    DirsByName watchedDirectories;
-    PathRefCounts watchedPaths;
     FSEventStreamEventId lastReceivedEvent;
+    WatchingState watchingState;
 };
 
 QT_END_NAMESPACE