QKqueueFileSystemWatcherEngine: Unlock mutex between two events.

In the worker thread unlock the mutex between processing two events.
Otherwise it's possible for the worker thread to block the application
thread when many events occur. Also, there's no need to lock the mutex
when processing a pipe event. Generally the worker thread should hamper
the application thread as little as possible, so only lock the mutex
where needed.

Merge-request: 2425
Reviewed-by: João Abecasis <joao.abecasis@nokia.com>

1 files changed, 6 insertions, 13 deletions

diff --git a/src/corelib/io/qfilesystemwatcher_kqueue.cpp b/src/corelib/io/qfilesystemwatcher_kqueue.cpp
index 644831b..29cd111 100644
--- a/src/corelib/io/qfilesystemwatcher_kqueue.cpp
+++ b/src/corelib/io/qfilesystemwatcher_kqueue.cpp
@@ -237,8 +237,6 @@ void QKqueueFileSystemWatcherEngine::stop()
 
 void QKqueueFileSystemWatcherEngine::run()
 {
-    static const struct timespec ZeroTimeout = { 0, 0 };
-
     forever {
         int r;
         struct kevent kev;
@@ -247,10 +245,7 @@ void QKqueueFileSystemWatcherEngine::run()
         if (r < 0) {
             perror("QKqueueFileSystemWatcherEngine: error during kevent wait");
             return;
-        }
-
-        QMutexLocker locker(&mutex);
-        do {
+        } else {
             int fd = kev.ident;
 
             DEBUG() << "QKqueueFileSystemWatcherEngine: processing kevent" << kev.ident << kev.filter;
@@ -282,6 +277,8 @@ void QKqueueFileSystemWatcherEngine::run()
                     break;
                 }
             } else {
+                QMutexLocker locker(&mutex);
+
                 int id = fd;
                 QString path = idToPath.value(id);
                 if (path.isEmpty()) {
@@ -290,12 +287,12 @@ void QKqueueFileSystemWatcherEngine::run()
                     path = idToPath.value(id);
                     if (path.isEmpty()) {
                         DEBUG() << "QKqueueFileSystemWatcherEngine: received a kevent for a file we're not watching";
-                        goto process_next_event;
+                        continue;
                     }
                 }
                 if (kev.filter != EVFILT_VNODE) {
                     DEBUG() << "QKqueueFileSystemWatcherEngine: received a kevent with the wrong filter";
-                    goto process_next_event;
+                    continue;
                 }
 
                 if ((kev.fflags & (NOTE_DELETE | NOTE_REVOKE | NOTE_RENAME)) != 0) {
@@ -318,11 +315,7 @@ void QKqueueFileSystemWatcherEngine::run()
                         emit fileChanged(path, false);
                 }
             }
-
-            // are there any more?
-process_next_event:
-            r = kevent(kqfd, 0, 0, &kev, 1, &ZeroTimeout);
-        } while (r > 0);
+        }
     }
 }