Fix return value propagation through proxies

A slot with return values returns a PendingCall object on the replica.  If
such a replica is used in a proxy, a client would get an invalid QVariant
as the reply.  This was because the proxy would try to return the pending-
call, not wait for the slot return from the original source.  This change
fixes that issue.

Change-Id: I1a25ed49ce51729dde4fa4593845946041493ea1
Reviewed-by: Brett Stottlemyer <bstottle@ford.com>
 

2 files changed, 26 insertions, 3 deletions

diff --git a/src/remoteobjects/qremoteobjectsourceio.cpp b/src/remoteobjects/qremoteobjectsourceio.cpp
index c2dc70a..bde010b 100644
--- a/src/remoteobjects/qremoteobjectsourceio.cpp
+++ b/src/remoteobjects/qremoteobjectsourceio.cpp
@@ -42,6 +42,7 @@
 #include "qremoteobjectpacket_p.h"
 #include "qremoteobjectsource_p.h"
 #include "qremoteobjectnode_p.h"
+#include "qremoteobjectpendingcall.h"
 #include "qtremoteobjectglobal.h"
 
 #include <QtCore/qstringlist.h>
@@ -240,11 +241,28 @@ void QRemoteObjectSourceIo::onServerRead(QObject *conn)
                     if (!QMetaType(typeId).sizeOf())
                         typeId = QVariant::Invalid;
                     QVariant returnValue(typeId, nullptr);
+                    // If a Replica is used as a Source (which node->proxy() does) we can have a PendingCall return value.
+                    // In this case, we need to wait for the pending call and send that.
+                    if (source->m_api->typeName(index) == QByteArrayLiteral("QRemoteObjectPendingCall"))
+                        returnValue = QVariant::fromValue<QRemoteObjectPendingCall>(QRemoteObjectPendingCall());
                     source->invoke(QMetaObject::InvokeMetaMethod, index, m_rxArgs, &returnValue);
                     // send reply if wanted
                     if (serialId >= 0) {
-                        serializeInvokeReplyPacket(m_packet, m_rxName, serialId, returnValue);
-                        connection->write(m_packet.array, m_packet.size);
+                        if (returnValue.canConvert<QRemoteObjectPendingCall>()) {
+                            QRemoteObjectPendingCall call = returnValue.value<QRemoteObjectPendingCall>();
+                            // Watcher will be destroyed when connection is, or when the finished lambda is called
+                            QRemoteObjectPendingCallWatcher *watcher = new QRemoteObjectPendingCallWatcher(call, connection);
+                            QObject::connect(watcher, &QRemoteObjectPendingCallWatcher::finished, connection, [this, serialId, connection, watcher]() {
+                                if (watcher->error() == QRemoteObjectPendingCall::NoError) {
+                                    serializeInvokeReplyPacket(this->m_packet, this->m_rxName, serialId, watcher->returnValue());
+                                    connection->write(m_packet.array, m_packet.size);
+                                }
+                                watcher->deleteLater();
+                            });
+                        } else {
+                            serializeInvokeReplyPacket(m_packet, m_rxName, serialId, returnValue);
+                            connection->write(m_packet.array, m_packet.size);
+                        }
                     }
                 } else {
                     const int resolvedIndex = source->m_api->sourcePropertyIndex(index);
diff --git a/tests/auto/proxy_multiprocess/client/main.cpp b/tests/auto/proxy_multiprocess/client/main.cpp
index 4874fb1..f37821f 100644
--- a/tests/auto/proxy_multiprocess/client/main.cpp
+++ b/tests/auto/proxy_multiprocess/client/main.cpp
@@ -72,6 +72,8 @@ private Q_SLOTS:
         qDebug() << "Verified expected initial states, sending start.";
         auto reply = m_rep->start();
         QVERIFY(reply.waitForFinished());
+        QVERIFY(reply.error() == QRemoteObjectPendingCall::NoError);
+        QCOMPARE(reply.returnValue(), QVariant::fromValue(true));
 
         QSignalSpy advanceSpy(m_rep.data(), SIGNAL(advance()));
         QVERIFY(advanceSpy.wait());
@@ -87,7 +89,10 @@ private Q_SLOTS:
     void cleanupTestCase()
     {
         auto reply = m_rep->quit();
-        QVERIFY(reply.waitForFinished());
+        // Don't verify the wait result, depending on the timing of the server and proxy
+        // closing it may return false.  We just need this process to stay alive long
+        // enough for the packets to be sent.
+        reply.waitForFinished(5000);
     }
 
 private: