3 files changed, 94 insertions, 1 deletions

diff --git a/async/autotests/asynctest.cpp b/async/autotests/asynctest.cpp
index 73026bb..7437608 100644
--- a/async/autotests/asynctest.cpp
+++ b/async/autotests/asynctest.cpp
@@ -59,6 +59,10 @@ private Q_SLOTS:
 
     void testErrorHandler();
 
+
+    void testChainingRunningJob();
+    void testChainingFinishedJob();
+
     void benchmarkSyncThenExecutor();
 
 private:
@@ -399,6 +403,74 @@ void AsyncTest::testErrorHandler()
 
 
 
+void AsyncTest::testChainingRunningJob()
+{
+    int check = 0;
+
+    auto job = Async::start<int>(
+        [&check](Async::Future<int> &future) {
+            QTimer *timer = new QTimer();
+            QObject::connect(timer, &QTimer::timeout,
+                             [&future, &check]() {
+                                 ++check;
+                                 future.setValue(42);
+                                 future.setFinished();
+                             });
+            QObject::connect(timer, &QTimer::timeout,
+                             timer, &QObject::deleteLater);
+            timer->setSingleShot(true);
+            timer->start(500);
+        });
+
+    auto future1 = job.exec();
+    QTest::qWait(200);
+
+    auto job2 = job.then<int, int>(
+        [&check](int in) -> int {
+            ++check;
+            return in * 2;
+        });
+
+    auto future2 = job2.exec();
+    QVERIFY(!future1.isFinished());
+    future2.waitForFinished();
+
+    QCOMPARE(check, 2);
+    QVERIFY(future1.isFinished());
+    QVERIFY(future2.isFinished());
+    QCOMPARE(future1.value(), 42);
+    QCOMPARE(future2.value(), 84);
+}
+
+void AsyncTest::testChainingFinishedJob()
+{
+    int check = 0;
+
+    auto job = Async::start<int>(
+        [&check]() -> int {
+            ++check;
+            return 42;
+        });
+
+    auto future1 = job.exec();
+    QVERIFY(future1.isFinished());
+
+    auto job2 = job.then<int, int>(
+        [&check](int in) -> int {
+            ++check;
+            return in * 2;
+        });
+
+    auto future2 = job2.exec();
+    QVERIFY(future2.isFinished());
+
+    QCOMPARE(check, 2);
+    QCOMPARE(future1.value(), 42);
+    QCOMPARE(future2.value(), 84);
+}
+
+
+
 
 
 void AsyncTest::benchmarkSyncThenExecutor()
diff --git a/async/src/async.cpp b/async/src/async.cpp
index c9fedc7..6eefd1b 100644
--- a/async/src/async.cpp
+++ b/async/src/async.cpp
@@ -27,6 +27,8 @@ using namespace Async;
 Private::ExecutorBase::ExecutorBase(const ExecutorBasePtr &parent)
     : mPrev(parent)
     , mResult(0)
+    , mIsRunning(false)
+    , mIsFinished(false)
 {
 }
 
diff --git a/async/src/async.h b/async/src/async.h
index d21caf8..8296fbc 100644
--- a/async/src/async.h
+++ b/async/src/async.h
@@ -90,6 +90,8 @@ protected:
 
     ExecutorBasePtr mPrev;
     FutureBase *mResult;
+    bool mIsRunning;
+    bool mIsFinished;
 };
 
 template<typename PrevOut, typename Out, typename ... In>
@@ -470,19 +472,35 @@ Future<PrevOut>* Executor<PrevOut, Out, In ...>::chainup()
 template<typename PrevOut, typename Out, typename ... In>
 void Executor<PrevOut, Out, In ...>::exec()
 {
-    mPrevFuture = chainup();
+    // Don't chain up to job that already is running (or is finished)
+    if (mPrev && !mPrev->mIsRunning & !mPrev->mIsFinished) {
+        mPrevFuture = chainup();
+    } else if (mPrev && !mPrevFuture) {
+        // If previous job is running or finished, just get it's future
+        mPrevFuture = static_cast<Async::Future<PrevOut>*>(mPrev->result());
+    }
+
     // Initialize our future
     mResult = new Async::Future<Out>();
+    auto fw = new Async::FutureWatcher<Out>();
+    QObject::connect(fw, &Async::FutureWatcher<Out>::futureReady,
+                     [&]() {
+                         mIsFinished = true;
+                         fw->deleteLater();
+                     });
+
     if (!mPrevFuture || mPrevFuture->isFinished()) {
         if (mPrevFuture && mPrevFuture->errorCode() != 0) {
             if (mErrorFunc) {
                 mErrorFunc(mPrevFuture->errorCode(), mPrevFuture->errorMessage());
                 mResult->setFinished();
+                mIsFinished = true;
                 return;
             } else {
                 // Propagate the error to next caller
             }
         }
+        mIsRunning = true;
         previousFutureReady();
     } else {
         auto futureWatcher = new Async::FutureWatcher<PrevOut>();
@@ -500,6 +518,7 @@ void Executor<PrevOut, Out, In ...>::exec()
                                      // Propagate the error to next caller
                                  }
                              }
+                             mIsRunning = true;
                              previousFutureReady();
                          });