QKqueueFileSystemWatcherEngine: Unlock mutex before calling write(2).

Calls to write(2) potentially block, so make sure the application thread
unlocks the mutex before it writes to the pipe between itself and the
worker thread, so the latter can continue to process events and eventually
unblock the write call (if needed) by emptying the pipe.

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

1 files changed, 69 insertions, 65 deletions

diff --git a/src/corelib/io/qfilesystemwatcher_kqueue.cpp b/src/corelib/io/qfilesystemwatcher_kqueue.cpp
index 4d15519..8fba091 100644
--- a/src/corelib/io/qfilesystemwatcher_kqueue.cpp
+++ b/src/corelib/io/qfilesystemwatcher_kqueue.cpp
@@ -117,67 +117,69 @@ QStringList QKqueueFileSystemWatcherEngine::addPaths(const QStringList &paths,
                                                      QStringList *files,
                                                      QStringList *directories)
 {
-    QMutexLocker locker(&mutex);
-
     QStringList p = paths;
-    QMutableListIterator<QString> it(p);
-    while (it.hasNext()) {
-        QString path = it.next();
-        int fd;
+    {
+        QMutexLocker locker(&mutex);
+
+        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 == -1) {
+                perror("QKqueueFileSystemWatcherEngine::addPaths: open");
+                continue;
+            }
 
-        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)) {
+            QT_STATBUF st;
+            if (QT_FSTAT(fd, &st) == -1) {
+                perror("QKqueueFileSystemWatcherEngine::addPaths: fstat");
                 ::close(fd);
                 continue;
             }
-        } else {
-            if (files->contains(path)) {
+            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");
                 ::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");
-            ::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);
+            }
 
-        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);
         }
-
-        pathToID.insert(path, id);
-        idToPath.insert(id, path);
     }
 
     if (!isRunning())
@@ -192,31 +194,33 @@ QStringList QKqueueFileSystemWatcherEngine::removePaths(const QStringList &paths
                                                         QStringList *files,
                                                         QStringList *directories)
 {
-    QMutexLocker locker(&mutex);
-
+    bool isEmpty;
     QStringList p = paths;
-    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;
+    {
+        QMutexLocker locker(&mutex);
 
-        ::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;
+
+            ::close(id < 0 ? -id : id);
 
-        it.remove();
-        if (id < 0)
-            directories->removeAll(path);
-        else
-            files->removeAll(path);
+            it.remove();
+            if (id < 0)
+                directories->removeAll(path);
+            else
+                files->removeAll(path);
+        }
+        isEmpty = pathToID.isEmpty();
     }
 
-    if (pathToID.isEmpty()) {
+    if (isEmpty) {
         stop();
-        locker.unlock();
         wait();
-        locker.relock();
     } else {
         write(kqpipe[1], "@", 1);
     }