Remove unnecessary QMutexes in QFileSystemWatcher implementations

The polling, inotify, and kqueue implementations are no longer threaded,
and as such, do not need mutexes to protect their internal data (since
QFileSystemWatcher itself is not documented as a thread-safe API).

The Windows implementation is unchanged as it uses multiple threads
explicitly.

Change-Id: Ia82510397e576bf704ce3aed3d776b58b39f7ff3
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>
Reviewed-by: João Abecasis <joao.abecasis@nokia.com>

1 files changed, 69 insertions, 77 deletions

diff --git a/src/corelib/io/qfilesystemwatcher_kqueue.cpp b/src/corelib/io/qfilesystemwatcher_kqueue.cpp
index 1f16f6a226..8070af5e18 100644
--- a/src/corelib/io/qfilesystemwatcher_kqueue.cpp
+++ b/src/corelib/io/qfilesystemwatcher_kqueue.cpp
@@ -98,76 +98,72 @@ QStringList QKqueueFileSystemWatcherEngine::addPaths(const QStringList &paths,
                                                      QStringList *directories)
 {
     QStringList p = paths;
-    {
-        QMutexLocker locker(&mutex);
-
-        QMutableListIterator<QString> it(p);
-        while (it.hasNext()) {
-            QString path = it.next();
-            int fd;
+    QMutableListIterator<QString> it(p);
+    while (it.hasNext()) {
+        QString path = it.next();
+        int fd;
 #if defined(O_EVTONLY)
-            fd = qt_safe_open(QFile::encodeName(path), O_EVTONLY);
+        fd = qt_safe_open(QFile::encodeName(path), O_EVTONLY);
 #else
-            fd = qt_safe_open(QFile::encodeName(path), O_RDONLY);
+        fd = qt_safe_open(QFile::encodeName(path), O_RDONLY);
 #endif
-            if (fd == -1) {
-                perror("QKqueueFileSystemWatcherEngine::addPaths: open");
-                continue;
-            }
-            if (fd >= (int)FD_SETSIZE / 2 && fd < (int)FD_SETSIZE) {
-                int fddup = fcntl(fd, F_DUPFD, FD_SETSIZE);
-                if (fddup != -1) {
-                    ::close(fd);
-                    fd = fddup;
-                }
+        if (fd == -1) {
+            perror("QKqueueFileSystemWatcherEngine::addPaths: open");
+            continue;
+        }
+        if (fd >= (int)FD_SETSIZE / 2 && fd < (int)FD_SETSIZE) {
+            int fddup = fcntl(fd, F_DUPFD, FD_SETSIZE);
+            if (fddup != -1) {
+                ::close(fd);
+                fd = fddup;
             }
-            fcntl(fd, F_SETFD, FD_CLOEXEC);
+        }
+        fcntl(fd, F_SETFD, FD_CLOEXEC);
 
-            QT_STATBUF st;
-            if (QT_FSTAT(fd, &st) == -1) {
-                perror("QKqueueFileSystemWatcherEngine::addPaths: fstat");
+        QT_STATBUF st;
+        if (QT_FSTAT(fd, &st) == -1) {
+            perror("QKqueueFileSystemWatcherEngine::addPaths: fstat");
+            ::close(fd);
+            continue;
+        }
+        int id = (S_ISDIR(st.st_mode)) ? -fd : fd;
+        if (id < 0) {
+            if (directories->contains(path)) {
                 ::close(fd);
                 continue;
             }
-            int id = (S_ISDIR(st.st_mode)) ? -fd : fd;
-            if (id < 0) {
-                if (directories->contains(path)) {
-                    ::close(fd);
-                    continue;
-                }
-            } else {
-                if (files->contains(path)) {
-                    ::close(fd);
-                    continue;
-                }
-            }
-
-            struct kevent kev;
-            EV_SET(&kev,
-                   fd,
-                   EVFILT_VNODE,
-                   EV_ADD | EV_ENABLE | EV_CLEAR,
-                   NOTE_DELETE | NOTE_WRITE | NOTE_EXTEND | NOTE_ATTRIB | NOTE_RENAME | NOTE_REVOKE,
-                   0,
-                   0);
-            if (kevent(kqfd, &kev, 1, 0, 0, 0) == -1) {
-                perror("QKqueueFileSystemWatcherEngine::addPaths: kevent");
+        } else {
+            if (files->contains(path)) {
                 ::close(fd);
                 continue;
             }
+        }
 
-            it.remove();
-            if (id < 0) {
-                DEBUG() << "QKqueueFileSystemWatcherEngine: added directory path" << path;
-                directories->append(path);
-            } else {
-                DEBUG() << "QKqueueFileSystemWatcherEngine: added file path" << path;
-                files->append(path);
-            }
+        struct kevent kev;
+        EV_SET(&kev,
+               fd,
+               EVFILT_VNODE,
+               EV_ADD | EV_ENABLE | EV_CLEAR,
+               NOTE_DELETE | NOTE_WRITE | NOTE_EXTEND | NOTE_ATTRIB | NOTE_RENAME | NOTE_REVOKE,
+               0,
+               0);
+        if (kevent(kqfd, &kev, 1, 0, 0, 0) == -1) {
+            perror("QKqueueFileSystemWatcherEngine::addPaths: kevent");
+            ::close(fd);
+            continue;
+        }
 
-            pathToID.insert(path, id);
-            idToPath.insert(id, path);
+        it.remove();
+        if (id < 0) {
+            DEBUG() << "QKqueueFileSystemWatcherEngine: added directory path" << path;
+            directories->append(path);
+        } else {
+            DEBUG() << "QKqueueFileSystemWatcherEngine: added file path" << path;
+            files->append(path);
         }
+
+        pathToID.insert(path, id);
+        idToPath.insert(id, path);
     }
 
     return p;
@@ -179,29 +175,26 @@ QStringList QKqueueFileSystemWatcherEngine::removePaths(const QStringList &paths
 {
     bool isEmpty;
     QStringList p = paths;
-    {
-        QMutexLocker locker(&mutex);
-        if (pathToID.isEmpty())
-            return p;
-
-        QMutableListIterator<QString> it(p);
-        while (it.hasNext()) {
-            QString path = it.next();
-            int id = pathToID.take(path);
-            QString x = idToPath.take(id);
-            if (x.isEmpty() || x != path)
-                continue;
+    if (pathToID.isEmpty())
+        return p;
 
-            ::close(id < 0 ? -id : id);
+    QMutableListIterator<QString> it(p);
+    while (it.hasNext()) {
+        QString path = it.next();
+        int id = pathToID.take(path);
+        QString x = idToPath.take(id);
+        if (x.isEmpty() || x != path)
+            continue;
 
-            it.remove();
-            if (id < 0)
-                directories->removeAll(path);
-            else
-                files->removeAll(path);
-        }
-        isEmpty = pathToID.isEmpty();
+        ::close(id < 0 ? -id : id);
+
+        it.remove();
+        if (id < 0)
+            directories->removeAll(path);
+        else
+            files->removeAll(path);
     }
+    isEmpty = pathToID.isEmpty();
 
     return p;
 }
@@ -224,7 +217,6 @@ void QKqueueFileSystemWatcherEngine::readFromKqueue()
             int fd = kev.ident;
 
             DEBUG() << "QKqueueFileSystemWatcherEngine: processing kevent" << kev.ident << kev.filter;
-            QMutexLocker locker(&mutex);
 
             int id = fd;
             QString path = idToPath.value(id);