1 files changed, 97 insertions, 0 deletions
diff --git a/src/libs/solutions/tasking/barrier.h b/src/libs/solutions/tasking/barrier.h
new file mode 100644
index 0000000000..6939da5b36
--- /dev/null
+++ b/src/libs/solutions/tasking/barrier.h
@@ -0,0 +1,97 @@
+// Copyright (C) 2023 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+
+#pragma once
+
+#include "tasking_global.h"
+
+#include "tasktree.h"
+
+namespace Tasking {
+
+class TASKING_EXPORT Barrier final : public QObject
+{
+    Q_OBJECT
+
+public:
+    void setLimit(int value);
+    int limit() const { return m_limit; }
+
+    void start();
+    void advance(); // If limit reached, stops with true
+    void stopWithResult(bool success); // Ignores limit
+
+    bool isRunning() const { return m_current >= 0; }
+    int current() const { return m_current; }
+    std::optional<bool> result() const { return m_result; }
+
+signals:
+    void done(bool success);
+
+private:
+    std::optional<bool> m_result = {};
+    int m_limit = 1;
+    int m_current = -1;
+};
+
+class TASKING_EXPORT BarrierTaskAdapter : public Tasking::TaskAdapter<Barrier>
+{
+public:
+    BarrierTaskAdapter() { connect(task(), &Barrier::done, this, &TaskInterface::done); }
+    void start() final { task()->start(); }
+};
+
+} // namespace Tasking
+
+TASKING_DECLARE_TASK(BarrierTask, Tasking::BarrierTaskAdapter);
+
+namespace Tasking {
+
+template <int Limit = 1>
+class SharedBarrier
+{
+public:
+    static_assert(Limit > 0, "SharedBarrier's limit should be 1 or more.");
+    SharedBarrier() : m_barrier(new Barrier) {
+        m_barrier->setLimit(Limit);
+        m_barrier->start();
+    }
+    Barrier *barrier() const { return m_barrier.get(); }
+
+private:
+    std::shared_ptr<Barrier> m_barrier;
+};
+
+template <int Limit = 1>
+using MultiBarrier = TreeStorage<SharedBarrier<Limit>>;
+
+// Can't write: "MultiBarrier barrier;". Only "MultiBarrier<> barrier;" would work.
+// Can't have one alias with default type in C++17, getting the following error:
+// alias template deduction only available with C++20.
+using SingleBarrier = MultiBarrier<1>;
+
+class TASKING_EXPORT WaitForBarrierTask : public BarrierTask
+{
+public:
+    template <int Limit>
+    WaitForBarrierTask(const MultiBarrier<Limit> &sharedBarrier)
+        : BarrierTask([sharedBarrier](Barrier &barrier) {
+            SharedBarrier<Limit> *activeBarrier = sharedBarrier.activeStorage();
+            if (!activeBarrier) {
+                qWarning("The barrier referenced from WaitForBarrier element "
+                         "is not reachable in the running tree. "
+                         "It is possible that no barrier was added to the tree, "
+                         "or the storage is not reachable from where it is referenced. "
+                         "The WaitForBarrier task will finish with error. ");
+                return TaskAction::StopWithError;
+            }
+            Barrier *activeSharedBarrier = activeBarrier->barrier();
+            const std::optional<bool> result = activeSharedBarrier->result();
+            if (result.has_value())
+                return result.value() ? TaskAction::StopWithDone : TaskAction::StopWithError;
+            QObject::connect(activeSharedBarrier, &Barrier::done, &barrier, &Barrier::stopWithResult);
+            return TaskAction::Continue;
+        }) {}
+};
+
+} // namespace Tasking