QSocketNotifier: extend API to provide more flexible startup

Technically, having a single constructor limits the use-cases for this
class. We should take into account that:

  - an opened socket descriptor must be available at the moment of
    construction;
  - the constructor unconditionally enables the notifier (the possible
    solution

        notifier = new QSocketNotifier(...);
        notifier->setEnabled(false);

    is suboptimal due to heavy operations inside the event dispatcher);
  - for these reasons, QSocketNotifier most often cannot be a member of
    another class (we have an extra allocation and indirect access).

This patch addresses this shortcoming by making it possible to set the
socket descriptor at a later point:

[ChangeLog][QtCore][QSocketNotifier] Added setSocket() and an additional
constructor which requires no socket.

Change-Id: I2eb2edf33ddafe99e528aac7d3774ade40795e7a
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>

1 files changed, 46 insertions, 0 deletions

diff --git a/tests/auto/corelib/kernel/qsocketnotifier/tst_qsocketnotifier.cpp b/tests/auto/corelib/kernel/qsocketnotifier/tst_qsocketnotifier.cpp
index 9ab540cdf2..79ee7da5b6 100644
--- a/tests/auto/corelib/kernel/qsocketnotifier/tst_qsocketnotifier.cpp
+++ b/tests/auto/corelib/kernel/qsocketnotifier/tst_qsocketnotifier.cpp
@@ -54,6 +54,7 @@ class tst_QSocketNotifier : public QObject
 {
     Q_OBJECT
 private slots:
+    void constructing();
     void unexpectedDisconnection();
     void mixingWithTimers();
 #ifdef Q_OS_UNIX
@@ -85,6 +86,51 @@ static QHostAddress makeNonAny(const QHostAddress &address,
     return address;
 }
 
+void tst_QSocketNotifier::constructing()
+{
+    const qintptr fd = 15;
+
+    // Test constructing with no descriptor assigned.
+    {
+        QSocketNotifier notifier(QSocketNotifier::Read);
+
+        QVERIFY(!notifier.isValid());
+        QCOMPARE(notifier.socket(), Q_INT64_C(-1));
+        QCOMPARE(notifier.type(), QSocketNotifier::Read);
+        QVERIFY(!notifier.isEnabled());
+
+        notifier.setEnabled(true);
+        QVERIFY(!notifier.isEnabled());
+
+        notifier.setSocket(fd, true);
+        QVERIFY(notifier.isValid());
+        QCOMPARE(notifier.socket(), fd);
+        QVERIFY(notifier.isEnabled());
+        notifier.setEnabled(false);
+        QVERIFY(!notifier.isEnabled());
+    }
+
+    // Test constructing with the notifications enabled by default.
+    {
+        QSocketNotifier notifier(fd, QSocketNotifier::Write);
+
+        QVERIFY(notifier.isValid());
+        QCOMPARE(notifier.socket(), fd);
+        QCOMPARE(notifier.type(), QSocketNotifier::Write);
+        QVERIFY(notifier.isEnabled());
+
+        notifier.setSocket(fd, false);
+        QVERIFY(!notifier.isEnabled());
+
+        notifier.setEnabled(true);
+        QVERIFY(notifier.isEnabled());
+        notifier.setSocket(-1, true);
+        QVERIFY(!notifier.isValid());
+        QCOMPARE(notifier.socket(), Q_INT64_C(-1));
+        QVERIFY(!notifier.isEnabled());
+    }
+}
+
 class UnexpectedDisconnectTester : public QObject
 {
     Q_OBJECT