Clang: Fix canceling of clang query

Every AST unit is created and queried asynchronously, like before, but
we don't wait anymore but use a timer to process new sources. So the server
will not be blocked and can process other messages like cancel.

Change-Id: If0e69466c78f628190f59fd32a03cab1c3a4d0a3
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

src/tools/clangrefactoringbackend/source/clangquerygatherer.h

@@ -0,0 +1,76 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt Creator.
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+****************************************************************************/
+
+#pragma once
+
+#include <sourcerangesanddiagnosticsforquerymessage.h>
+#include <filecontainerv2.h>
+
+#include <future>
+
+namespace ClangBackEnd {
+
+class ClangQueryGatherer
+{
+public:
+    using Future = std::future<SourceRangesAndDiagnosticsForQueryMessage>;
+
+    ClangQueryGatherer() = default;
+    ClangQueryGatherer(std::vector<V2::FileContainer> &&sources,
+                       std::vector<V2::FileContainer> &&unsaved,
+                       Utils::SmallString &&query);
+
+    static
+    SourceRangesAndDiagnosticsForQueryMessage createSourceRangesAndDiagnosticsForSource(
+            V2::FileContainer &&source,
+            const std::vector<V2::FileContainer> &unsaved,
+            Utils::SmallString &&query);
+
+    bool canCreateSourceRangesAndDiagnostics() const;
+    SourceRangesAndDiagnosticsForQueryMessage createNextSourceRangesAndDiagnostics();
+    Future startCreateNextSourceRangesAndDiagnosticsMessage();
+    void startCreateNextSourceRangesAndDiagnosticsMessages();
+    void waitForFinished();
+    bool isFinished() const;
+
+    const std::vector<V2::FileContainer> &sources() const;
+    const std::vector<Future> &sourceFutures() const;
+    std::vector<SourceRangesAndDiagnosticsForQueryMessage> allCurrentProcessedMessages();
+    std::vector<SourceRangesAndDiagnosticsForQueryMessage> finishedMessages();
+
+    void setProcessingSlotCount(uint count);
+
+protected:
+    std::vector<Future> finishedFutures();
+
+private:
+    std::vector<V2::FileContainer> m_sources;
+    std::vector<V2::FileContainer> m_unsaved;
+    Utils::SmallString m_query;
+    uint m_processingSlotCount = 1;
+    std::vector<Future> m_sourceFutures;
+};
+
+} // namespace ClangBackEnd