Clang: Reuse thread based pipeline for pch creation

The pch creation so far used signal and slots but there was no explicit
pipeline. This patch is introducing the same architecture like the
refactoring plugin. It is filtering out older project parts from the
pipeline.

Change-Id: Iaa6bd2ca1272231b97ebe1f5f7b2ce8e43bc590c
Task-number: QTCREATORBUG-21111
Reviewed-by: Ivan Donchevskii <ivan.donchevskii@qt.io>

16 files changed, 102 insertions, 576 deletions

diff --git a/src/tools/clangrefactoringbackend/clangrefactoringbackend.pro b/src/tools/clangrefactoringbackend/clangrefactoringbackend.pro
index 072d254728..ea66a43b61 100644
--- a/src/tools/clangrefactoringbackend/clangrefactoringbackend.pro
+++ b/src/tools/clangrefactoringbackend/clangrefactoringbackend.pro
@@ -17,6 +17,7 @@ QT -= gui
 
 LIBS += $$LIBTOOLING_LIBS
 INCLUDEPATH += $$LLVM_INCLUDEPATH
+INCLUDEPATH += ../clangpchmanagerbackend/source
 
 QMAKE_CXXFLAGS += $$LLVM_CXXFLAGS
 
diff --git a/src/tools/clangrefactoringbackend/source/clangrefactoringbackend-source.pri b/src/tools/clangrefactoringbackend/source/clangrefactoringbackend-source.pri
index d15e0f625d..26fa44aa68 100644
--- a/src/tools/clangrefactoringbackend/source/clangrefactoringbackend-source.pri
+++ b/src/tools/clangrefactoringbackend/source/clangrefactoringbackend-source.pri
@@ -24,11 +24,7 @@ HEADERS += \
     $$PWD/indexdataconsumer.h \
     $$PWD/sourcesmanager.h \
     $$PWD/symbolindexertaskqueue.h \
-    $$PWD/symbolindexertaskscheduler.h \
-    $$PWD/symbolscollectormanagerinterface.h \
     $$PWD/symbolindexertaskqueueinterface.h \
-    $$PWD/symbolindexertaskschedulerinterface.h \
-    $$PWD/symbolscollectormanager.h \
     $$PWD/symbolindexertask.h
 
 !isEmpty(LIBTOOLING_LIBS) {
@@ -74,6 +70,4 @@ SOURCES += \
     $$PWD/sourcerangefilter.cpp \
     $$PWD/symbolindexer.cpp \
     $$PWD/projectpartartefact.cpp \
-    $$PWD/filestatuscache.cpp \
-    $$PWD/symbolindexertaskqueue.cpp \
-    $$PWD/symbolindexertaskscheduler.cpp
+    $$PWD/filestatuscache.cpp
diff --git a/src/tools/clangrefactoringbackend/source/symbolindexer.cpp b/src/tools/clangrefactoringbackend/source/symbolindexer.cpp
index 5c9f0cbccc..272e89fa89 100644
--- a/src/tools/clangrefactoringbackend/source/symbolindexer.cpp
+++ b/src/tools/clangrefactoringbackend/source/symbolindexer.cpp
@@ -101,27 +101,25 @@ void SymbolIndexer::updateProjectPart(V2::ProjectPartContainer &&projectPart)
     std::vector<SymbolIndexerTask> symbolIndexerTask;
     symbolIndexerTask.reserve(projectPart.sourcePathIds.size());
     for (FilePathId sourcePathId : projectPart.sourcePathIds) {
-        auto indexing = [projectPartId, arguments, sourcePathId]
-                (SymbolsCollectorInterface &symbolsCollector,
-                SymbolStorageInterface &symbolStorage,
-                Sqlite::TransactionInterface &transactionInterface) {
+        auto indexing = [projectPartId, arguments, sourcePathId, this]
+                (SymbolsCollectorInterface &symbolsCollector) {
             symbolsCollector.setFile(sourcePathId, arguments);
 
             symbolsCollector.collectSymbols();
 
-            Sqlite::ImmediateTransaction transaction{transactionInterface};
+            Sqlite::ImmediateTransaction transaction{m_transactionInterface};
 
-            symbolStorage.addSymbolsAndSourceLocations(symbolsCollector.symbols(),
-                                                       symbolsCollector.sourceLocations());
+            m_symbolStorage.addSymbolsAndSourceLocations(symbolsCollector.symbols(),
+                                                         symbolsCollector.sourceLocations());
 
-            symbolStorage.updateProjectPartSources(projectPartId,
-                                                   symbolsCollector.sourceFiles());
+            m_symbolStorage.updateProjectPartSources(projectPartId,
+                                                     symbolsCollector.sourceFiles());
 
-            symbolStorage.insertOrUpdateUsedMacros(symbolsCollector.usedMacros());
+            m_symbolStorage.insertOrUpdateUsedMacros(symbolsCollector.usedMacros());
 
-            symbolStorage.insertFileStatuses(symbolsCollector.fileStatuses());
+            m_symbolStorage.insertFileStatuses(symbolsCollector.fileStatuses());
 
-            symbolStorage.insertOrUpdateSourceDependencies(symbolsCollector.sourceDependencies());
+            m_symbolStorage.insertOrUpdateSourceDependencies(symbolsCollector.sourceDependencies());
 
             transaction.commit();
         };
@@ -130,7 +128,7 @@ void SymbolIndexer::updateProjectPart(V2::ProjectPartContainer &&projectPart)
     }
 
     m_symbolIndexerTaskQueue.addOrUpdateTasks(std::move(symbolIndexerTask));
-    m_symbolIndexerTaskQueue.processTasks();
+    m_symbolIndexerTaskQueue.processEntries();
 }
 
 void SymbolIndexer::pathsWithIdsChanged(const Utils::SmallStringVector &)
@@ -146,7 +144,7 @@ void SymbolIndexer::pathsChanged(const FilePathIds &filePathIds)
         updateChangedPath(filePathId, symbolIndexerTask);
 
     m_symbolIndexerTaskQueue.addOrUpdateTasks(std::move(symbolIndexerTask));
-    m_symbolIndexerTaskQueue.processTasks();
+    m_symbolIndexerTaskQueue.processEntries();
 }
 
 void SymbolIndexer::updateChangedPath(FilePathId filePathId,
@@ -169,26 +167,24 @@ void SymbolIndexer::updateChangedPath(FilePathId filePathId,
         const Utils::SmallStringVector arguments = compilerArguments(artefact.compilerArguments,
                                                                      optionalProjectPartPch);
 
-        auto indexing = [projectPartId=artefact.projectPartId, arguments, filePathId]
-                (SymbolsCollectorInterface &symbolsCollector,
-                SymbolStorageInterface &symbolStorage,
-                Sqlite::TransactionInterface &transactionInterface) {
+        auto indexing = [projectPartId=artefact.projectPartId, arguments, filePathId, this]
+                (SymbolsCollectorInterface &symbolsCollector) {
             symbolsCollector.setFile(filePathId, arguments);
 
             symbolsCollector.collectSymbols();
 
-            Sqlite::ImmediateTransaction transaction{transactionInterface};
+            Sqlite::ImmediateTransaction transaction{m_transactionInterface};
 
-            symbolStorage.addSymbolsAndSourceLocations(symbolsCollector.symbols(),
-                                                       symbolsCollector.sourceLocations());
+            m_symbolStorage.addSymbolsAndSourceLocations(symbolsCollector.symbols(),
+                                                         symbolsCollector.sourceLocations());
 
-            symbolStorage.updateProjectPartSources(projectPartId, symbolsCollector.sourceFiles());
+            m_symbolStorage.updateProjectPartSources(projectPartId, symbolsCollector.sourceFiles());
 
-            symbolStorage.insertOrUpdateUsedMacros(symbolsCollector.usedMacros());
+            m_symbolStorage.insertOrUpdateUsedMacros(symbolsCollector.usedMacros());
 
-            symbolStorage.insertFileStatuses(symbolsCollector.fileStatuses());
+            m_symbolStorage.insertFileStatuses(symbolsCollector.fileStatuses());
 
-            symbolStorage.insertOrUpdateSourceDependencies(symbolsCollector.sourceDependencies());
+            m_symbolStorage.insertOrUpdateSourceDependencies(symbolsCollector.sourceDependencies());
 
             transaction.commit();
         };
diff --git a/src/tools/clangrefactoringbackend/source/symbolindexertask.h b/src/tools/clangrefactoringbackend/source/symbolindexertask.h
index 3b18681e07..de3303815d 100644
--- a/src/tools/clangrefactoringbackend/source/symbolindexertask.h
+++ b/src/tools/clangrefactoringbackend/source/symbolindexertask.h
@@ -35,16 +35,13 @@ class TransactionInterface;
 
 namespace ClangBackEnd {
 
-class SymbolIndexerTaskSchedulerInterface;
 class SymbolsCollectorInterface;
 class SymbolStorageInterface;
 
 class SymbolIndexerTask
 {
 public:
-    using Callable = std::function<void(SymbolsCollectorInterface &symbolsCollector,
-                                        SymbolStorageInterface &symbolStorage,
-                                        Sqlite::TransactionInterface &transaction)>;
+    using Callable = std::function<void(SymbolsCollectorInterface &symbolsCollector)>;
 
     SymbolIndexerTask(FilePathId filePathId,
                       int projectPartId,
diff --git a/src/tools/clangrefactoringbackend/source/symbolindexertaskqueue.cpp b/src/tools/clangrefactoringbackend/source/symbolindexertaskqueue.cpp
deleted file mode 100644
index bb891467a6..0000000000
--- a/src/tools/clangrefactoringbackend/source/symbolindexertaskqueue.cpp
+++ /dev/null
@@ -1,71 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2018 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.
-**
-****************************************************************************/
-
-#include "symbolindexertaskqueue.h"
-
-#include <symbolindexertaskschedulerinterface.h>
-
-#include <utils/algorithm.h>
-
-namespace ClangBackEnd {
-
-void SymbolIndexerTaskQueue::addOrUpdateTasks(std::vector<SymbolIndexerTask> &&tasks)
-{
-    auto merge = [] (SymbolIndexerTask &&first, SymbolIndexerTask &&second) {
-        first.callable = std::move(second.callable);
-
-        return std::move(first);
-    };
-
-    m_tasks = Utils::setUnionMerge<std::vector<SymbolIndexerTask>>(tasks, m_tasks, merge);
-}
-
-void SymbolIndexerTaskQueue::removeTasks(const std::vector<int> &projectPartIds)
-{
-    auto shouldBeRemoved = [&] (const SymbolIndexerTask& task) {
-        return std::binary_search(projectPartIds.begin(), projectPartIds.end(), task.projectPartId);
-    };
-
-    auto newEnd = std::remove_if(m_tasks.begin(), m_tasks.end(), shouldBeRemoved);
-
-    m_tasks.erase(newEnd, m_tasks.end());
-}
-
-const std::vector<SymbolIndexerTask> &SymbolIndexerTaskQueue::tasks() const
-{
-    return m_tasks;
-}
-
-void SymbolIndexerTaskQueue::processTasks()
-{
-    int taskCount = m_symbolIndexerScheduler.freeSlots();
-
-    auto newEnd = std::prev(m_tasks.end(), std::min<int>(taskCount, int(m_tasks.size())));
-    m_symbolIndexerScheduler.addTasks({std::make_move_iterator(newEnd),
-                                       std::make_move_iterator(m_tasks.end())});
-    m_tasks.erase(newEnd, m_tasks.end());
-}
-
-} // namespace ClangBackEnd
diff --git a/src/tools/clangrefactoringbackend/source/symbolindexertaskqueue.h b/src/tools/clangrefactoringbackend/source/symbolindexertaskqueue.h
index 6a627e8865..3dc54998d0 100644
--- a/src/tools/clangrefactoringbackend/source/symbolindexertaskqueue.h
+++ b/src/tools/clangrefactoringbackend/source/symbolindexertaskqueue.h
@@ -29,7 +29,9 @@
 #include "symbolindexertask.h"
 
 #include <filepathid.h>
+#include <taskschedulerinterface.h>
 
+#include <utils/algorithm.h>
 #include <utils/smallstringvector.h>
 
 #include <functional>
@@ -41,29 +43,59 @@ class TransactionInterface;
 
 namespace ClangBackEnd {
 
-class SymbolIndexerTaskSchedulerInterface;
 class SymbolsCollectorInterface;
 class SymbolStorageInterface;
 
 class SymbolIndexerTaskQueue final : public SymbolIndexerTaskQueueInterface
 {
 public:
-    SymbolIndexerTaskQueue(SymbolIndexerTaskSchedulerInterface &symbolIndexerTaskScheduler)
+    using Task = SymbolIndexerTask::Callable;
+
+    SymbolIndexerTaskQueue(TaskSchedulerInterface<Task> &symbolIndexerTaskScheduler)
         : m_symbolIndexerScheduler(symbolIndexerTaskScheduler)
     {}
 
-    void addOrUpdateTasks(std::vector<SymbolIndexerTask> &&tasks);
-    void removeTasks(const std::vector<int> &projectPartIds);
+    void addOrUpdateTasks(std::vector<SymbolIndexerTask> &&tasks)
+    {
+        auto merge = [] (SymbolIndexerTask &&first, SymbolIndexerTask &&second) {
+            first.callable = std::move(second.callable);
+
+            return std::move(first);
+        };
+
+        m_tasks = Utils::setUnionMerge<std::vector<SymbolIndexerTask>>(tasks, m_tasks, merge);
+    }
+    void removeTasks(const std::vector<int> &projectPartIds)
+    {
+        auto shouldBeRemoved = [&] (const SymbolIndexerTask& task) {
+            return std::binary_search(projectPartIds.begin(), projectPartIds.end(), task.projectPartId);
+        };
+
+        auto newEnd = std::remove_if(m_tasks.begin(), m_tasks.end(), shouldBeRemoved);
+
+        m_tasks.erase(newEnd, m_tasks.end());
+    }
+
+    const std::vector<SymbolIndexerTask> &tasks() const
+    {
+        return m_tasks;
+    }
 
-    const std::vector<SymbolIndexerTask> &tasks() const;
+    void processEntries()
+    {
+        uint taskCount = m_symbolIndexerScheduler.freeSlots();
 
-    void processTasks();
+        auto newEnd = std::prev(m_tasks.end(), std::min<int>(int(taskCount), int(m_tasks.size())));
+        m_symbolIndexerScheduler.addTasks({std::make_move_iterator(newEnd),
+                                           std::make_move_iterator(m_tasks.end())});
+        m_tasks.erase(newEnd, m_tasks.end());
+    }
     void syncTasks();
 
 private:
     std::vector<Utils::SmallString> m_projectPartIds;
     std::vector<SymbolIndexerTask> m_tasks;
-    SymbolIndexerTaskSchedulerInterface &m_symbolIndexerScheduler;
+    TaskSchedulerInterface<Task> &m_symbolIndexerScheduler;
 };
 
 } // namespace ClangBackEnd
diff --git a/src/tools/clangrefactoringbackend/source/symbolindexertaskqueueinterface.h b/src/tools/clangrefactoringbackend/source/symbolindexertaskqueueinterface.h
index 9e96a79e6c..dfcc78bd23 100644
--- a/src/tools/clangrefactoringbackend/source/symbolindexertaskqueueinterface.h
+++ b/src/tools/clangrefactoringbackend/source/symbolindexertaskqueueinterface.h
@@ -25,24 +25,21 @@
 
 #pragma once
 
+#include <queueinterface.h>
+
 #include <utils/smallstringvector.h>
 
 namespace ClangBackEnd {
 
 class SymbolIndexerTask;
 
-class SymbolIndexerTaskQueueInterface
+class SymbolIndexerTaskQueueInterface : public QueueInterface
 {
 public:
-    SymbolIndexerTaskQueueInterface() = default;
-    SymbolIndexerTaskQueueInterface(const SymbolIndexerTaskQueueInterface &) = delete;
-    SymbolIndexerTaskQueueInterface &operator=(const SymbolIndexerTaskQueueInterface &) = delete;
-
     virtual void addOrUpdateTasks(std::vector<SymbolIndexerTask> &&tasks) = 0
     /* [[expects: std::is_sorted(tasks)]] */;
     virtual void removeTasks(const std::vector<int> &projectPartIds) = 0
     /* [[expects: std::is_sorted(projectPartIds)]] */;
-    virtual void processTasks() = 0;
 
 protected:
     ~SymbolIndexerTaskQueueInterface() = default;
diff --git a/src/tools/clangrefactoringbackend/source/symbolindexertaskscheduler.cpp b/src/tools/clangrefactoringbackend/source/symbolindexertaskscheduler.cpp
deleted file mode 100644
index e9f5cbe285..0000000000
--- a/src/tools/clangrefactoringbackend/source/symbolindexertaskscheduler.cpp
+++ /dev/null
@@ -1,146 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2018 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.
-**
-****************************************************************************/
-
-#include "symbolindexertaskscheduler.h"
-
-#include <symbolindexertaskqueueinterface.h>
-#include <symbolscollectormanagerinterface.h>
-#include <symbolscollectorinterface.h>
-
-#include <QAbstractEventDispatcher>
-#include <QCoreApplication>
-#include <QMetaObject>
-#include <QThread>
-
-#include <algorithm>
-#include <thread>
-
-namespace ClangBackEnd {
-namespace {
-#if QT_VERSION < QT_VERSION_CHECK(5, 10, 0)
-template <typename CallableType>
-class CallableEvent : public QEvent {
-public:
-   using Callable = std::decay_t<CallableType>;
-   CallableEvent(Callable &&callable)
-       : QEvent(QEvent::None),
-         callable(std::move(callable))
-   {}
-   CallableEvent(const Callable &callable)
-       : QEvent(QEvent::None),
-         callable(callable)
-   {}
-
-   ~CallableEvent()
-   {
-       callable();
-   }
-public:
-   Callable callable;
-};
-
-template <typename Callable>
-void executeInLoop(Callable &&callable, QObject *object = QCoreApplication::instance()) {
-   if (QThread *thread = qobject_cast<QThread*>(object))
-       object = QAbstractEventDispatcher::instance(thread);
-
-   QCoreApplication::postEvent(object,
-                               new CallableEvent<Callable>(std::forward<Callable>(callable)),
-                               Qt::HighEventPriority);
-}
-#else
-template <typename Callable>
-void executeInLoop(Callable &&callable, QObject *object = QCoreApplication::instance()) {
-   if (QThread *thread = qobject_cast<QThread*>(object))
-       object = QAbstractEventDispatcher::instance(thread);
-
-   QMetaObject::invokeMethod(object, std::forward<Callable>(callable));
-}
-#endif
-}
-
-void SymbolIndexerTaskScheduler::addTasks(std::vector<Task> &&tasks)
-{
-    for (auto &task : tasks) {
-        auto callWrapper = [&, task=std::move(task)] (
-                std::reference_wrapper<SymbolsCollectorInterface> symbolsCollector)
-                -> SymbolsCollectorInterface& {
-            task(symbolsCollector.get(), m_symbolStorage, m_transactionInterface);
-            executeInLoop([&] {
-                m_symbolIndexerTaskQueue.processTasks();
-            });
-
-            return symbolsCollector;
-        };
-        m_futures.emplace_back(std::async(m_launchPolicy,
-                                          std::move(callWrapper),
-                                          std::ref(m_symbolsCollectorManager.unusedSymbolsCollector())));
-    }
-}
-
-const std::vector<SymbolIndexerTaskScheduler::Future> &SymbolIndexerTaskScheduler::futures() const
-{
-    return m_futures;
-}
-
-uint SymbolIndexerTaskScheduler::freeSlots()
-{
-    removeFinishedFutures();
-
-    if (m_isDisabled)
-        return 0;
-
-    return uint(std::max(int(m_hardware_concurrency) - int(m_futures.size()), 0));
-}
-
-void SymbolIndexerTaskScheduler::syncTasks()
-{
-    for (auto &future : m_futures)
-        future.wait();
-}
-
-void SymbolIndexerTaskScheduler::disable()
-{
-    m_isDisabled = true;
-}
-
-void SymbolIndexerTaskScheduler::removeFinishedFutures()
-{
-    auto notReady = [] (Future &future) {
-        return future.wait_for(std::chrono::duration<int>::zero()) != std::future_status::ready;
-    };
-
-    auto split = std::partition(m_futures.begin(), m_futures.end(), notReady);
-
-    std::for_each(split, m_futures.end(), [] (Future &future) {
-        SymbolsCollectorInterface &symbolCollector = future.get();
-        symbolCollector.setIsUsed(false);
-        symbolCollector.clear();
-    });
-
-    m_futures.erase(split, m_futures.end());
-}
-
-} // namespace ClangBackEnd
diff --git a/src/tools/clangrefactoringbackend/source/symbolindexertaskscheduler.h b/src/tools/clangrefactoringbackend/source/symbolindexertaskscheduler.h
deleted file mode 100644
index 6182376dab..0000000000
--- a/src/tools/clangrefactoringbackend/source/symbolindexertaskscheduler.h
+++ /dev/null
@@ -1,91 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2018 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 "symbolindexertaskschedulerinterface.h"
-#include "symbolindexertask.h"
-
-#include <functional>
-#include <future>
-#include <vector>
-
-namespace Sqlite {
-class TransactionInterface;
-};
-
-namespace ClangBackEnd {
-
-class FilePathCachingInterface;
-class SymbolsCollectorInterface;
-class SymbolsCollectorManagerInterface;
-class SymbolIndexerTaskQueueInterface;
-class SymbolStorageInterface;
-
-class SymbolIndexerTaskScheduler final : public SymbolIndexerTaskSchedulerInterface
-{
-public:
-    using Task = SymbolIndexerTask::Callable;
-    using Future = std::future<SymbolsCollectorInterface&>;
-
-    SymbolIndexerTaskScheduler(SymbolsCollectorManagerInterface &symbolsCollectorManager,
-                               SymbolStorageInterface &symbolStorage,
-                               Sqlite::TransactionInterface &transactionInterface,
-                               SymbolIndexerTaskQueueInterface &symbolIndexerTaskQueue,
-                               uint hardware_concurrency,
-                               std::launch launchPolicy = std::launch::async)
-        : m_symbolsCollectorManager(symbolsCollectorManager),
-          m_symbolStorage(symbolStorage),
-          m_transactionInterface(transactionInterface),
-          m_symbolIndexerTaskQueue(symbolIndexerTaskQueue),
-          m_hardware_concurrency(hardware_concurrency),
-          m_launchPolicy(launchPolicy)
-    {}
-
-    void addTasks(std::vector<Task> &&tasks);
-
-    const std::vector<Future> &futures() const;
-
-    uint freeSlots();
-
-    void syncTasks();
-
-    void disable();
-
-private:
-    void removeFinishedFutures();
-
-private:
-    std::vector<Future> m_futures;
-    SymbolsCollectorManagerInterface &m_symbolsCollectorManager;
-    SymbolStorageInterface &m_symbolStorage;
-    Sqlite::TransactionInterface &m_transactionInterface;
-    SymbolIndexerTaskQueueInterface &m_symbolIndexerTaskQueue;
-    uint m_hardware_concurrency;
-    std::launch m_launchPolicy;
-    bool m_isDisabled = false;
-};
-
-} // namespace ClangBackEnd
diff --git a/src/tools/clangrefactoringbackend/source/symbolindexertaskschedulerinterface.h b/src/tools/clangrefactoringbackend/source/symbolindexertaskschedulerinterface.h
deleted file mode 100644
index c71454df3d..0000000000
--- a/src/tools/clangrefactoringbackend/source/symbolindexertaskschedulerinterface.h
+++ /dev/null
@@ -1,60 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2018 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 <functional>
-#include <vector>
-
-namespace Sqlite {
-class TransactionInterface;
-}
-
-namespace ClangBackEnd {
-
-class SymbolsCollectorInterface;
-class SymbolStorageInterface;
-
-using uint = unsigned int;
-
-class SymbolIndexerTaskSchedulerInterface
-{
-public:
-    using Task = std::function<void(SymbolsCollectorInterface &symbolsCollector,
-                                    SymbolStorageInterface &symbolStorage,
-                                    Sqlite::TransactionInterface &transaction)>;
-
-    SymbolIndexerTaskSchedulerInterface() = default;
-    SymbolIndexerTaskSchedulerInterface(const SymbolIndexerTaskSchedulerInterface &) = delete;
-    SymbolIndexerTaskSchedulerInterface &operator=(const SymbolIndexerTaskSchedulerInterface &) = delete;
-
-    virtual void addTasks(std::vector<Task> &&tasks) = 0;
-    virtual uint freeSlots() = 0;
-
-protected:
-    ~SymbolIndexerTaskSchedulerInterface() = default;
-};
-
-} // namespace ClangBackEnd
diff --git a/src/tools/clangrefactoringbackend/source/symbolindexing.h b/src/tools/clangrefactoringbackend/source/symbolindexing.h
index 8f7821bddb..918edb626a 100644
--- a/src/tools/clangrefactoringbackend/source/symbolindexing.h
+++ b/src/tools/clangrefactoringbackend/source/symbolindexing.h
@@ -30,9 +30,9 @@
 #include "storagesqlitestatementfactory.h"
 #include "symbolindexer.h"
 #include "symbolscollector.h"
-#include "symbolscollectormanager.h"
+#include "processormanager.h"
 #include "symbolindexertaskqueue.h"
-#include "symbolindexertaskscheduler.h"
+#include "taskscheduler.h"
 #include "symbolstorage.h"
 
 #include <refactoringdatabaseinitializer.h>
@@ -48,19 +48,40 @@
 
 namespace ClangBackEnd {
 
+class SymbolsCollectorManager;
+
+class SymbolsCollectorManager final : public ClangBackEnd::ProcessorManager<SymbolsCollector>
+{
+public:
+    using Processor = SymbolsCollector;
+    SymbolsCollectorManager(const ClangBackEnd::GeneratedFiles &generatedFiles,
+                            Sqlite::Database &database)
+        : ProcessorManager(generatedFiles),
+          m_database(database)
+    {}
+
+protected:
+    std::unique_ptr<SymbolsCollector> createProcessor() const
+    {
+        return  std::make_unique<SymbolsCollector>(m_database);
+    }
+
+private:
+    Sqlite::Database &m_database;
+};
+
 class SymbolIndexing final : public SymbolIndexingInterface
 {
 public:
     using StatementFactory = ClangBackEnd::StorageSqliteStatementFactory<Sqlite::Database>;
     using Storage = ClangBackEnd::SymbolStorage<StatementFactory>;
-
     SymbolIndexing(Sqlite::Database &database,
                    FilePathCachingInterface &filePathCache,
                    const GeneratedFiles &generatedFiles)
         : m_filePathCache(filePathCache),
           m_statementFactory(database),
-          m_collectorManger(database, generatedFiles),
-          m_indexerScheduler(m_collectorManger, m_symbolStorage, database, m_indexerQueue, std::thread::hardware_concurrency())
+          m_collectorManger(generatedFiles, database),
+          m_indexerScheduler(m_collectorManger, m_indexerQueue, std::thread::hardware_concurrency())
     {
     }
 
@@ -86,12 +107,13 @@ public:
     void updateProjectParts(V2::ProjectPartContainers &&projectParts) override;
 
 private:
+    using SymbolIndexerTaskScheduler = TaskScheduler<SymbolsCollectorManager, SymbolIndexerTask::Callable>;
     FilePathCachingInterface &m_filePathCache;
     StatementFactory m_statementFactory;
     Storage m_symbolStorage{m_statementFactory};
     ClangPathWatcher<QFileSystemWatcher, QTimer> m_sourceWatcher{m_filePathCache};
     FileStatusCache m_fileStatusCache{m_filePathCache};
-    SymbolsCollectorManager<SymbolsCollector> m_collectorManger;
+    SymbolsCollectorManager m_collectorManger;
     SymbolIndexerTaskScheduler m_indexerScheduler;
     SymbolIndexerTaskQueue m_indexerQueue{m_indexerScheduler};
     SymbolIndexer m_indexer{m_indexerQueue,
diff --git a/src/tools/clangrefactoringbackend/source/symbolscollector.cpp b/src/tools/clangrefactoringbackend/source/symbolscollector.cpp
index 53e0bbba6e..afa01de2e9 100644
--- a/src/tools/clangrefactoringbackend/source/symbolscollector.cpp
+++ b/src/tools/clangrefactoringbackend/source/symbolscollector.cpp
@@ -129,6 +129,10 @@ void SymbolsCollector::collectSymbols()
                                                     &m_collectMacrosSourceFileCallbacks).get());
 }
 
+void SymbolsCollector::doInMainThreadAfterFinished()
+{
+}
+
 const SymbolEntries &SymbolsCollector::symbols() const
 {
     return m_symbolEntries;
diff --git a/src/tools/clangrefactoringbackend/source/symbolscollector.h b/src/tools/clangrefactoringbackend/source/symbolscollector.h
index 70213555d6..beb610d190 100644
--- a/src/tools/clangrefactoringbackend/source/symbolscollector.h
+++ b/src/tools/clangrefactoringbackend/source/symbolscollector.h
@@ -54,6 +54,8 @@ public:
 
     void collectSymbols() override;
 
+    void doInMainThreadAfterFinished() override;
+
     const SymbolEntries &symbols() const override;
     const SourceLocationEntries &sourceLocations() const override;
     const FilePathIds &sourceFiles() const override;
diff --git a/src/tools/clangrefactoringbackend/source/symbolscollectorinterface.h b/src/tools/clangrefactoringbackend/source/symbolscollectorinterface.h
index 540866630f..0b7e00509d 100644
--- a/src/tools/clangrefactoringbackend/source/symbolscollectorinterface.h
+++ b/src/tools/clangrefactoringbackend/source/symbolscollectorinterface.h
@@ -31,7 +31,7 @@
 #include "sourcelocationentry.h"
 #include "usedmacro.h"
 
-#include <filecontainerv2.h>
+#include <processorinterface.h>
 
 #include <utils/smallstringvector.h>
 
@@ -40,20 +40,10 @@
 
 namespace ClangBackEnd {
 
-class SymbolsCollectorInterface
+class SymbolsCollectorInterface : public ProcessorInterface
 {
 public:
-    SymbolsCollectorInterface() = default;
-    virtual ~SymbolsCollectorInterface() = default;
-    SymbolsCollectorInterface(const SymbolsCollectorInterface &) = delete;
-    SymbolsCollectorInterface &operator=(const SymbolsCollectorInterface &) = delete;
-
     virtual void setFile(FilePathId filePathId, const Utils::SmallStringVector &arguments) = 0;
-
-    virtual void setUnsavedFiles(const V2::FileContainers &unsavedFiles) = 0;
-
-    virtual void clear() = 0;
-
     virtual void collectSymbols() = 0;
 
     virtual const SymbolEntries &symbols() const = 0;
@@ -62,9 +52,6 @@ public:
     virtual const UsedMacros &usedMacros() const = 0;
     virtual const FileStatuses &fileStatuses() const = 0;
     virtual const SourceDependencies &sourceDependencies() const = 0;
-
-    virtual bool isUsed() const = 0;
-    virtual void setIsUsed(bool isUsed) = 0;
 };
 
 } // namespace ClangBackEnd
diff --git a/src/tools/clangrefactoringbackend/source/symbolscollectormanager.h b/src/tools/clangrefactoringbackend/source/symbolscollectormanager.h
deleted file mode 100644
index d5a020904f..0000000000
--- a/src/tools/clangrefactoringbackend/source/symbolscollectormanager.h
+++ /dev/null
@@ -1,89 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2018 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 "symbolscollectormanagerinterface.h"
-#include "symbolscollectorinterface.h"
-#include "generatedfiles.h"
-
-#include <memory>
-
-namespace Sqlite {
-class Database;
-}
-
-namespace ClangBackEnd {
-
-class GeneratedFiles;
-class SymbolsCollector;
-template<typename SymbolsCollector>
-class SymbolsCollectorManager final : public SymbolsCollectorManagerInterface
-{
-public:
-    SymbolsCollectorManager(Sqlite::Database &database,
-                            const GeneratedFiles &generatedFiles)
-        : m_database(database),
-          m_generatedFiles(generatedFiles)
-    {}
-
-    SymbolsCollector &unusedSymbolsCollector() override
-    {
-        auto split = std::partition(m_collectors.begin(),
-                                    m_collectors.end(),
-                                    [] (const auto &collector) {
-            return collector->isUsed();
-        });
-
-        auto freeCollectors = std::distance(split, m_collectors.end());
-
-        if (freeCollectors > 0)
-            return initializedCollector(*split->get());
-
-        m_collectors.emplace_back(std::make_unique<SymbolsCollector>(m_database));
-
-        return  initializedCollector(*m_collectors.back().get());
-    }
-
-    const std::vector<std::unique_ptr<SymbolsCollector>> &collectors() const
-    {
-        return m_collectors;
-    }
-
-private:
-    SymbolsCollector &initializedCollector(SymbolsCollector &collector)
-    {
-        collector.setIsUsed(true);
-        collector.setUnsavedFiles(m_generatedFiles.fileContainers());
-        return collector;
-    }
-
-private:
-    std::vector<std::unique_ptr<SymbolsCollector>> m_collectors;
-    Sqlite::Database &m_database;
-    const GeneratedFiles &m_generatedFiles;
-};
-
-} // namespace ClangBackEnd
diff --git a/src/tools/clangrefactoringbackend/source/symbolscollectormanagerinterface.h b/src/tools/clangrefactoringbackend/source/symbolscollectormanagerinterface.h
deleted file mode 100644
index b0cb3a0332..0000000000
--- a/src/tools/clangrefactoringbackend/source/symbolscollectormanagerinterface.h
+++ /dev/null
@@ -1,49 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2018 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 <filecontainerv2.h>
-
-#include <vector>
-
-namespace ClangBackEnd {
-
-class SymbolsCollectorInterface;
-
-class SymbolsCollectorManagerInterface
-{
-public:
-    SymbolsCollectorManagerInterface() = default;
-    SymbolsCollectorManagerInterface(const SymbolsCollectorManagerInterface &) = delete;
-    SymbolsCollectorManagerInterface &operator=(const SymbolsCollectorManagerInterface &) = delete;
-
-    virtual SymbolsCollectorInterface &unusedSymbolsCollector() = 0;
-
-protected:
-    ~SymbolsCollectorManagerInterface() = default;
-};
-
-} // namespace ClangBackEnd