Clang: Suspend least recently used translation units

...to free some memory.

The translation units of the 7 most recently used documents ("hot
documents", tracked by document visibility) are kept in memory.
Translation units of other documents are suspended and will be resumed
once they become visible again.

The resumption of a translation unit needs the same time as reparse
(since it is a reparse effectively).

The number of hot documents can be modified by the run time environment
variable QTC_CLANG_HOT_DOCUMENTS=N. Visible documents are always hot.

Task-number: QTCREATORBUG-11640
Change-Id: I68ecd2b1373e303372300203e42d90f65a4b39b3
Reviewed-by: Ivan Donchevskii <ivan.donchevskii@qt.io>
Reviewed-by: Marco Bubke <marco.bubke@qt.io>

src/tools/clangbackend/ipcsource/clangbackend_global.h

@@ -25,6 +25,8 @@
 
 #pragma once
 
+#include <clang-c/Index.h>
+
 namespace ClangBackEnd {
 
 enum class PreferredTranslationUnit
@@ -34,4 +36,9 @@ enum class PreferredTranslationUnit
     LastUninitialized,
 };
 
+// CLANG-UPGRADE-CHECK: Remove IS_SUSPEND_SUPPORTED once we require clang >= 5.0
+#if defined(CINDEX_VERSION_HAS_BACKPORTED_SUSPEND) || CINDEX_VERSION_MINOR >= 41
+#  define IS_SUSPEND_SUPPORTED
+#endif
+
 } // namespace ClangBackEnd

src/tools/clangbackend/ipcsource/clangbackendclangipc-source.pri

@@ -12,6 +12,7 @@ HEADERS += \
     $$PWD/clangdocumentprocessor.h \
     $$PWD/clangdocumentprocessors.h \
     $$PWD/clangdocuments.h \
+    $$PWD/clangdocumentsuspenderresumer.h \
     $$PWD/clangexceptions.h \
     $$PWD/clangfilepath.h \
     $$PWD/clangfilesystemwatcher.h \
@@ -25,8 +26,10 @@ HEADERS += \
     $$PWD/clangreparsesupportivetranslationunitjob.h \
     $$PWD/clangrequestdocumentannotationsjob.h \
     $$PWD/clangrequestreferencesjob.h \
+    $$PWD/clangresumedocumentjob.h \
     $$PWD/clangstring.h \
     $$PWD/clangsupportivetranslationunitinitializer.h \
+    $$PWD/clangsuspenddocumentjob.h \
     $$PWD/clangtranslationunit.h \
     $$PWD/clangtranslationunits.h \
     $$PWD/clangtranslationunitupdater.h \
@@ -63,6 +66,7 @@ SOURCES += \
     $$PWD/clangdocumentprocessor.cpp \
     $$PWD/clangdocumentprocessors.cpp \
     $$PWD/clangdocuments.cpp \
+    $$PWD/clangdocumentsuspenderresumer.cpp \
     $$PWD/clangexceptions.cpp \
     $$PWD/clangfilepath.cpp \
     $$PWD/clangfilesystemwatcher.cpp \
@@ -72,10 +76,12 @@ SOURCES += \
     $$PWD/clangjobrequest.cpp \
     $$PWD/clangjobs.cpp \
     $$PWD/clangparsesupportivetranslationunitjob.cpp \
+    $$PWD/clangresumedocumentjob.cpp \
     $$PWD/clangreferencescollector.cpp \
     $$PWD/clangreparsesupportivetranslationunitjob.cpp \
     $$PWD/clangrequestdocumentannotationsjob.cpp \
     $$PWD/clangrequestreferencesjob.cpp \
+    $$PWD/clangsuspenddocumentjob.cpp  \
     $$PWD/clangsupportivetranslationunitinitializer.cpp \
     $$PWD/clangtranslationunit.cpp \
     $$PWD/clangtranslationunits.cpp \

src/tools/clangbackend/ipcsource/clangcodemodelserver.cpp

@@ -26,6 +26,7 @@
 #include "clangcodemodelserver.h"
 
 #include "clangdocuments.h"
+#include "clangdocumentsuspenderresumer.h"
 #include "clangfilesystemwatcher.h"
 #include "clangtranslationunits.h"
 #include "codecompleter.h"
@@ -89,6 +90,7 @@ void ClangCodeModelServer::registerTranslationUnitsForEditor(const ClangBackEnd:
         unsavedFiles.createOrUpdate(message.fileContainers());
         documents.setUsedByCurrentEditor(message.currentEditorFilePath());
         documents.setVisibleInEditors(message.visibleEditorFilePaths());
+        processSuspendResumeJobs(documents.documents());
 
         processInitialJobsForDocuments(createdDocuments);
     } catch (const std::exception &exception) {
@@ -264,6 +266,8 @@ void ClangCodeModelServer::updateVisibleTranslationUnits(const UpdateVisibleTran
     try {
         documents.setUsedByCurrentEditor(message.currentEditorFilePath());
         documents.setVisibleInEditors(message.visibleEditorFilePaths());
+        processSuspendResumeJobs(documents.documents());
+
         updateDocumentAnnotationsTimer.start(0);
     }  catch (const std::exception &exception) {
         qWarning() << "Error in ClangCodeModelServer::updateVisibleTranslationUnits:" << exception.what();
@@ -347,6 +351,16 @@ void ClangCodeModelServer::processJobsForDirtyAndVisibleButNotCurrentDocuments()
     addAndRunUpdateJobs(documents.dirtyAndVisibleButNotCurrentDocuments());
 }
 
+void ClangCodeModelServer::processSuspendResumeJobs(const std::vector<Document> &documents)
+{
+    const SuspendResumeJobs suspendResumeJobs = createSuspendResumeJobs(documents);
+    for (const SuspendResumeJobsEntry &entry : suspendResumeJobs) {
+        DocumentProcessor processor = documentProcessors().processor(entry.document);
+        processor.addJob(entry.jobRequestType, entry.preferredTranslationUnit);
+        processor.process();
+    }
+}
+
 void ClangCodeModelServer::processInitialJobsForDocuments(const std::vector<Document> &documents)
 {
     for (const auto &document : documents) {

src/tools/clangbackend/ipcsource/clangcodemodelserver.h

@@ -77,6 +77,7 @@ private:
     void processJobsForDirtyCurrentDocument();
     void processTimerForVisibleButNotCurrentDocuments();
     void processJobsForDirtyAndVisibleButNotCurrentDocuments();
+    void processSuspendResumeJobs(const std::vector<Document> &documents);
 
     void addAndRunUpdateJobs(std::vector<Document> documents);
 

src/tools/clangbackend/ipcsource/clangdocument.cpp

@@ -80,6 +80,7 @@ public:
     bool isUsedByCurrentEditor = false;
     bool isVisibleInEditor = false;
     bool increaseResponsiveness = false;
+    bool isSuspended = false;
 };
 
 DocumentData::DocumentData(const Utf8String &filePath,
@@ -226,6 +227,20 @@ void Document::setResponsivenessIncreaseNeeded(bool responsivenessIncreaseNeeded
     d->increaseResponsiveness = responsivenessIncreaseNeeded;
 }
 
+bool Document::isSuspended() const
+{
+    checkIfNull();
+
+    return d->isSuspended;
+}
+
+void Document::setIsSuspended(bool isSuspended)
+{
+    checkIfNull();
+
+    d->isSuspended = isSuspended;
+}
+
 bool Document::isUsedByCurrentEditor() const
 {
     checkIfNull();

src/tools/clangbackend/ipcsource/clangdocument.h

@@ -93,6 +93,9 @@ public:
     bool isResponsivenessIncreaseNeeded() const;
     void setResponsivenessIncreaseNeeded(bool responsivenessIncreaseNeeded);
 
+    bool isSuspended() const;
+    void setIsSuspended(bool isSuspended);
+
     bool isUsedByCurrentEditor() const;
     void setIsUsedByCurrentEditor(bool isUsedByCurrentEditor);
 

src/tools/clangbackend/ipcsource/clangdocumentsuspenderresumer.cpp

@@ -0,0 +1,141 @@
+/****************************************************************************
+**
+** 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.
+**
+****************************************************************************/
+
+#include "clangdocumentsuspenderresumer.h"
+
+#include "clangbackendipc_global.h"
+#include "clangdocumentprocessors.h"
+#include "clangdocuments.h"
+
+#include <utils/algorithm.h>
+
+#include <algorithm>
+
+namespace ClangBackEnd {
+
+constexpr int DefaultHotDocumentsSize = 7;
+
+void categorizeHotColdDocuments(int hotDocumentsSize,
+                                const std::vector<Document> &inDocuments,
+                                std::vector<Document> &hotDocuments,
+                                std::vector<Document> &coldDocuments)
+{
+    // Sort documents, most recently used/visible at top
+    std::vector<Document> documents = inDocuments;
+    std::stable_sort(documents.begin(), documents.end(), [](const Document &a, const Document &b) {
+        return a.visibleTimePoint() > b.visibleTimePoint();
+    });
+
+    // Ensure that visible documents are always hot, otherwise not all visible
+    // documents will be resumed.
+    const auto isVisible = [](const Document &document) { return document.isVisibleInEditor(); };
+    const int visibleDocumentsSize = Utils::count(documents, isVisible);
+    hotDocumentsSize = std::max(hotDocumentsSize, visibleDocumentsSize);
+
+    if (documents.size() <= uint(hotDocumentsSize)) {
+        hotDocuments = documents;
+        coldDocuments.clear();
+    } else {
+        const auto firstColdIterator = documents.begin() + hotDocumentsSize;
+        hotDocuments = std::vector<Document>(documents.begin(), firstColdIterator);
+        coldDocuments = std::vector<Document>(firstColdIterator,  documents.end());
+    }
+}
+
+#ifdef IS_SUSPEND_SUPPORTED
+static int hotDocumentsSize()
+{
+    static int hotDocuments = -1;
+    if (hotDocuments == -1) {
+        bool ok = false;
+        const int fromEnvironment = qEnvironmentVariableIntValue("QTC_CLANG_HOT_DOCUMENTS", &ok);
+        hotDocuments = ok && fromEnvironment >= 1 ? fromEnvironment : DefaultHotDocumentsSize;
+    }
+
+    return hotDocuments;
+}
+
+static SuspendResumeJobs createJobs(const Document &document, JobRequest::Type type)
+{
+    SuspendResumeJobs jobs;
+
+    jobs.append({document, type, PreferredTranslationUnit::RecentlyParsed});
+    if (document.isResponsivenessIncreased())
+        jobs.append({document, type, PreferredTranslationUnit::PreviouslyParsed});
+
+    return jobs;
+}
+
+static bool isFineDocument(const Document &document)
+{
+    return !document.isNull() && document.isIntact();
+}
+
+static bool isSuspendable(const Document &document)
+{
+    return isFineDocument(document)
+        && !document.isSuspended()
+        && !document.isVisibleInEditor();
+}
+
+static bool isResumable(const Document &document)
+{
+    return isFineDocument(document)
+        && document.isSuspended()
+        && document.isVisibleInEditor();
+}
+
+#endif // IS_SUSPEND_SUPPORTED
+
+SuspendResumeJobs createSuspendResumeJobs(const std::vector<Document> &documents,
+                                          int customHotDocumentSize)
+{
+    Q_UNUSED(documents);
+    Q_UNUSED(customHotDocumentSize);
+
+    SuspendResumeJobs jobs;
+
+#ifdef IS_SUSPEND_SUPPORTED
+    std::vector<Document> hotDocuments;
+    std::vector<Document> coldDocuments;
+
+    const int size = (customHotDocumentSize == -1) ? hotDocumentsSize() : customHotDocumentSize;
+    categorizeHotColdDocuments(size, documents, hotDocuments, coldDocuments);
+
+    // Cold documents should be suspended...
+    const std::vector<Document> toSuspend = Utils::filtered(coldDocuments, &isSuspendable);
+    for (const Document &document : toSuspend)
+        jobs += createJobs(document, JobRequest::Type::SuspendDocument);
+
+    // ...and hot documents that were suspended should be resumed
+    const std::vector<Document> toResume = Utils::filtered(hotDocuments, &isResumable);
+    for (const Document &document : toResume)
+        jobs += createJobs(document, JobRequest::Type::ResumeDocument);
+#endif // IS_SUSPEND_SUPPORTED
+
+    return jobs;
+}
+
+} // namespace ClangBackEnd

src/tools/clangbackend/ipcsource/clangdocumentsuspenderresumer.h

@@ -0,0 +1,62 @@
+/****************************************************************************
+**
+** 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 "clangdocument.h"
+#include "clangjobrequest.h"
+
+#include <vector>
+
+namespace ClangBackEnd {
+
+class SuspendResumeJobsEntry {
+public:
+    SuspendResumeJobsEntry() = default;
+    SuspendResumeJobsEntry(const Document &document,
+                           JobRequest::Type jobRequestType,
+                           PreferredTranslationUnit preferredTranslationUnit)
+        : document(document)
+        , jobRequestType(jobRequestType)
+        , preferredTranslationUnit(preferredTranslationUnit)
+    {
+    }
+
+    Document document;
+    JobRequest::Type jobRequestType = JobRequest::Type::SuspendDocument;
+    PreferredTranslationUnit preferredTranslationUnit = PreferredTranslationUnit::RecentlyParsed;
+};
+using SuspendResumeJobs = QVector<SuspendResumeJobsEntry>;
+
+SuspendResumeJobs createSuspendResumeJobs(const std::vector<Document> &documents,
+                                          int customHotDocumentCounts = -1);
+
+// for tests
+void categorizeHotColdDocuments(int hotDocumentsSize,
+                                const std::vector<Document> &inDocuments,
+                                std::vector<Document> &hotDocuments,
+                                std::vector<Document> &coldDocuments);
+
+} // namespace ClangBackEnd

src/tools/clangbackend/ipcsource/clangiasyncjob.cpp

@@ -31,6 +31,8 @@
 #include "clangreparsesupportivetranslationunitjob.h"
 #include "clangrequestdocumentannotationsjob.h"
 #include "clangrequestreferencesjob.h"
+#include "clangresumedocumentjob.h"
+#include "clangsuspenddocumentjob.h"
 #include "clangupdatedocumentannotationsjob.h"
 
 Q_LOGGING_CATEGORY(jobsLog, "qtc.clangbackend.jobs");
@@ -54,6 +56,10 @@ IAsyncJob *IAsyncJob::create(JobRequest::Type type)
         return new RequestDocumentAnnotationsJob();
     case JobRequest::Type::RequestReferences:
         return new RequestReferencesJob();
+    case JobRequest::Type::SuspendDocument:
+        return new SuspendDocumentJob();
+    case JobRequest::Type::ResumeDocument:
+        return new ResumeDocumentJob();
     }
 
     return nullptr;

src/tools/clangbackend/ipcsource/clangjobqueue.cpp

@@ -179,6 +179,16 @@ static bool passesPreconditions(const JobRequest &request, const Document &docum
     using Condition = JobRequest::Condition;
     const JobRequest::Conditions conditions = request.conditions;
 
+    if (conditions.testFlag(Condition::DocumentSuspended) && !document.isSuspended()) {
+        qCDebug(jobsLog) << "Not choosing due to unsuspended document:" << request;
+        return false;
+    }
+
+    if (conditions.testFlag(Condition::DocumentUnsuspended) && document.isSuspended()) {
+        qCDebug(jobsLog) << "Not choosing due to suspended document:" << request;
+        return false;
+    }
+
     if (conditions.testFlag(Condition::DocumentVisible) && !document.isVisibleInEditor()) {
         qCDebug(jobsLog) << "Not choosing due to invisble document:" << request;
         return false;

src/tools/clangbackend/ipcsource/clangjobrequest.cpp

@@ -40,6 +40,8 @@ static const char *JobRequestTypeToText(JobRequest::Type type)
         RETURN_TEXT_FOR_CASE(CompleteCode);
         RETURN_TEXT_FOR_CASE(RequestDocumentAnnotations);
         RETURN_TEXT_FOR_CASE(RequestReferences);
+        RETURN_TEXT_FOR_CASE(SuspendDocument);
+        RETURN_TEXT_FOR_CASE(ResumeDocument);
     }
 
     return "UnhandledJobRequestType";
@@ -121,7 +123,19 @@ JobRequest::ExpirationReasons JobRequest::expirationReasonsForType(Type type)
 
 JobRequest::Conditions JobRequest::conditionsForType(JobRequest::Type type)
 {
-    Conditions conditions = Condition::DocumentVisible;
+    if (type == Type::SuspendDocument) {
+        return Conditions(Condition::DocumentUnsuspended)
+             | Conditions(Condition::DocumentNotVisible);
+    }
+
+    if (type == Type::ResumeDocument) {
+        return Conditions(Condition::DocumentSuspended)
+             | Conditions(Condition::DocumentVisible);
+    }
+
+    Conditions conditions = Conditions(Condition::DocumentUnsuspended)
+                          | Conditions(Condition::DocumentVisible);
+
     if (type == Type::RequestReferences)
         conditions |= Condition::CurrentDocumentRevision;
 

src/tools/clangbackend/ipcsource/clangjobrequest.h

@@ -53,13 +53,18 @@ public:
         CompleteCode,
         RequestDocumentAnnotations,
         RequestReferences,
+
+        SuspendDocument,
+        ResumeDocument,
     };
 
     enum class Condition {
         NoCondition             = 1 << 0,
         DocumentVisible         = 1 << 1,
         DocumentNotVisible      = 1 << 2,
-        CurrentDocumentRevision = 1 << 3,
+        DocumentSuspended       = 1 << 3,
+        DocumentUnsuspended     = 1 << 4,
+        CurrentDocumentRevision = 1 << 5,
     };
     Q_DECLARE_FLAGS(Conditions, Condition)
 

src/tools/clangbackend/ipcsource/clangresumedocumentjob.cpp

@@ -0,0 +1,54 @@
+/****************************************************************************
+**
+** 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.
+**
+****************************************************************************/
+
+#include "clangresumedocumentjob.h"
+
+#include <utils/qtcassert.h>
+
+namespace ClangBackEnd {
+
+void ResumeDocumentJob::finalizeAsyncRun()
+{
+    if (context().isDocumentOpen()) {
+        if (QTC_GUARD(asyncResult().updateResult.hasReparsed()))
+            m_pinnedDocument.setIsSuspended(false);
+    }
+
+    UpdateDocumentAnnotationsJob::finalizeAsyncRun();
+}
+
+bool ResumeDocumentJob::isExpectedJobRequestType(const JobRequest &jobRequest) const
+{
+    return jobRequest.type == JobRequest::Type::ResumeDocument;
+}
+
+TranslationUnitUpdateInput ResumeDocumentJob::createUpdateInput(const Document &document) const
+{
+    TranslationUnitUpdateInput input = UpdateDocumentAnnotationsJob::createUpdateInput(document);
+    input.reparseNeeded = true;
+    return input;
+}
+
+} // namespace ClangBackEnd

src/tools/clangbackend/ipcsource/clangresumedocumentjob.h

@@ -0,0 +1,44 @@
+/****************************************************************************
+**
+** 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 "clangasyncjob.h"
+#include "clangdocument.h"
+#include "clangupdatedocumentannotationsjob.h"
+
+namespace ClangBackEnd {
+
+class ResumeDocumentJob : public UpdateDocumentAnnotationsJob
+{
+public:
+    void finalizeAsyncRun() override;
+
+private:
+    bool isExpectedJobRequestType(const JobRequest &jobRequest) const override;
+    TranslationUnitUpdateInput createUpdateInput(const Document &document) const override;
+};
+
+} // namespace ClangBackEnd

src/tools/clangbackend/ipcsource/clangsuspenddocumentjob.cpp

@@ -0,0 +1,73 @@
+/****************************************************************************
+**
+** 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.
+**
+****************************************************************************/
+
+#include "clangsuspenddocumentjob.h"
+
+#include <clangbackendipc/clangbackendipcdebugutils.h>
+
+#include <utils/qtcassert.h>
+
+namespace ClangBackEnd {
+
+static bool runAsyncHelper(const TranslationUnit &translationUnit)
+{
+    TIME_SCOPE_DURATION("SuspendDocumentJobRunner");
+
+    return translationUnit.suspend();
+}
+
+IAsyncJob::AsyncPrepareResult SuspendDocumentJob::prepareAsyncRun()
+{
+    const JobRequest jobRequest = context().jobRequest;
+    QTC_ASSERT(jobRequest.type == JobRequest::Type::SuspendDocument, return AsyncPrepareResult());
+
+    try {
+        m_pinnedDocument = context().documentForJobRequest();
+        m_pinnedFileContainer = m_pinnedDocument.fileContainer();
+
+        TranslationUnit translationUnit
+                = m_pinnedDocument.translationUnit(jobRequest.preferredTranslationUnit);
+        setRunner([translationUnit]() {
+            return runAsyncHelper(translationUnit);
+        });
+        return AsyncPrepareResult{translationUnit.id()};
+
+    } catch (const std::exception &exception) {
+        qWarning() << "Error in SuspendDocumentJob::prepareAsyncRun:" << exception.what();
+        return AsyncPrepareResult();
+    }
+}
+
+void SuspendDocumentJob::finalizeAsyncRun()
+{
+    if (context().isDocumentOpen()) {
+        const bool suspendSucceeded = asyncResult();
+        if (QTC_GUARD(suspendSucceeded)) {
+            m_pinnedDocument.setIsSuspended(true);
+        }
+    }
+}
+
+} // namespace ClangBackEnd

src/tools/clangbackend/ipcsource/clangsuspenddocumentjob.h

@@ -0,0 +1,44 @@
+/****************************************************************************
+**
+** 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 "clangasyncjob.h"
+#include "clangdocument.h"
+
+namespace ClangBackEnd {
+
+class SuspendDocumentJob : public AsyncJob<bool>
+{
+public:
+    AsyncPrepareResult prepareAsyncRun() override;
+    void finalizeAsyncRun() override;
+
+private:
+    Document m_pinnedDocument;
+    FileContainer m_pinnedFileContainer;
+};
+
+} // namespace ClangBackEnd

src/tools/clangbackend/ipcsource/clangtranslationunit.cpp

@@ -25,6 +25,7 @@
 
 #include "clangtranslationunit.h"
 
+#include "clangbackend_global.h"
 #include "clangreferencescollector.h"
 #include "clangtranslationunitupdater.h"
 
@@ -38,6 +39,8 @@
 #include <sourcelocation.h>
 #include <sourcerange.h>
 
+#include <utils/qtcassert.h>
+
 namespace ClangBackEnd {
 
 TranslationUnit::TranslationUnit(const Utf8String &id,
@@ -100,6 +103,16 @@ TranslationUnitUpdateResult TranslationUnit::reparse(
     return updater.update(TranslationUnitUpdater::UpdateMode::ForceReparse);
 }
 
+bool TranslationUnit::suspend() const
+{
+#ifdef IS_SUSPEND_SUPPORTED
+    return clang_suspendTranslationUnit(cxTranslationUnit());
+#else
+    QTC_CHECK(false && "clang_suspendTranslationUnit() not supported.");
+    return false;
+#endif
+}
+
 TranslationUnit::CodeCompletionResult TranslationUnit::complete(
         UnsavedFiles &unsavedFiles,
         uint line,

src/tools/clangbackend/ipcsource/clangtranslationunit.h

@@ -71,6 +71,8 @@ public:
     CXIndex &cxIndex() const;
     CXTranslationUnit &cxTranslationUnit() const;
 
+    bool suspend() const;
+
     TranslationUnitUpdateResult update(const TranslationUnitUpdateInput &parseInput) const;
     TranslationUnitUpdateResult parse(const TranslationUnitUpdateInput &parseInput) const;
     TranslationUnitUpdateResult reparse(const TranslationUnitUpdateInput &parseInput) const;

src/tools/clangbackend/ipcsource/clangupdatedocumentannotationsjob.cpp

@@ -56,8 +56,7 @@ static UpdateDocumentAnnotationsJob::AsyncResult runAsyncHelper(
 IAsyncJob::AsyncPrepareResult UpdateDocumentAnnotationsJob::prepareAsyncRun()
 {
     const JobRequest jobRequest = context().jobRequest;
-    QTC_ASSERT(jobRequest.type == JobRequest::Type::UpdateDocumentAnnotations,
+    QTC_ASSERT(isExpectedJobRequestType(jobRequest), return AsyncPrepareResult());
-               return AsyncPrepareResult());
 
     try {
         m_pinnedDocument = context().documentForJobRequest();
@@ -65,7 +64,7 @@ IAsyncJob::AsyncPrepareResult UpdateDocumentAnnotationsJob::prepareAsyncRun()
 
         const TranslationUnit translationUnit
                 = m_pinnedDocument.translationUnit(jobRequest.preferredTranslationUnit);
-        const TranslationUnitUpdateInput updateInput = m_pinnedDocument.createUpdateInput();
+        const TranslationUnitUpdateInput updateInput = createUpdateInput(m_pinnedDocument);
         setRunner([translationUnit, updateInput]() {
             return runAsyncHelper(translationUnit, updateInput);
         });
@@ -87,6 +86,17 @@ void UpdateDocumentAnnotationsJob::finalizeAsyncRun()
     }
 }
 
+bool UpdateDocumentAnnotationsJob::isExpectedJobRequestType(const JobRequest &jobRequest) const
+{
+    return jobRequest.type == JobRequest::Type::UpdateDocumentAnnotations;
+}
+
+TranslationUnitUpdateInput
+UpdateDocumentAnnotationsJob::createUpdateInput(const Document &document) const
+{
+    return document.createUpdateInput();
+}
+
 void UpdateDocumentAnnotationsJob::incorporateUpdaterResult(const AsyncResult &result)
 {
     m_pinnedDocument.incorporateUpdaterResult(result.updateResult);

src/tools/clangbackend/ipcsource/clangupdatedocumentannotationsjob.h

@@ -53,12 +53,18 @@ public:
     AsyncPrepareResult prepareAsyncRun() override;
     void finalizeAsyncRun() override;
 
+protected:
+    virtual bool isExpectedJobRequestType(const JobRequest &jobRequest) const;
+    virtual TranslationUnitUpdateInput createUpdateInput(const Document &document) const;
+
 private:
     void incorporateUpdaterResult(const AsyncResult &result);
     void sendAnnotations(const AsyncResult &result);
 
-private:
+protected:
     Document m_pinnedDocument;
+
+private:
     FileContainer m_pinnedFileContainer;
 };
 

tests/unit/unittest/clangdocumentsuspenderresumer-test.cpp

@@ -0,0 +1,295 @@
+/****************************************************************************
+**
+** 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.
+**
+****************************************************************************/
+
+#include "googletest.h"
+
+#include "dummyclangipcclient.h"
+
+#include <clangclock.h>
+#include <clangdocument.h>
+#include <clangdocumentprocessors.h>
+#include <clangdocuments.h>
+#include <clangdocumentsuspenderresumer.h>
+#include <clangtranslationunits.h>
+#include <projects.h>
+#include <unsavedfiles.h>
+#include <utf8string.h>
+
+#include <utils/algorithm.h>
+
+#include <clang-c/Index.h>
+
+using ClangBackEnd::Clock;
+using ClangBackEnd::Document;
+using ClangBackEnd::JobRequest;
+using ClangBackEnd::PreferredTranslationUnit;
+using ClangBackEnd::SuspendResumeJobs;
+using ClangBackEnd::SuspendResumeJobsEntry;
+using ClangBackEnd::TimePoint;
+
+using testing::ContainerEq;
+using testing::ElementsAre;
+using testing::IsEmpty;
+
+namespace ClangBackEnd {
+
+bool operator==(const SuspendResumeJobsEntry &a, const SuspendResumeJobsEntry &b)
+{
+    return a.document == b.document
+        && a.jobRequestType == b.jobRequestType
+        && a.preferredTranslationUnit == b.preferredTranslationUnit;
+}
+
+} // ClangBackEnd
+
+namespace {
+
+class DocumentSuspenderResumer : public ::testing::Test
+{
+protected:
+    void SetUp() override;
+    Document getDocument(const Utf8String &filePath);
+    void categorizeDocuments(int hotDocumentsSize);
+    SuspendResumeJobs createSuspendResumeJobs(int hotDocumentsSize = -1);
+
+protected:
+    ClangBackEnd::ProjectParts projects;
+    ClangBackEnd::UnsavedFiles unsavedFiles;
+    ClangBackEnd::Documents documents{projects, unsavedFiles};
+    DummyIpcClient dummyIpcClient;
+    ClangBackEnd::DocumentProcessors documentProcessors{documents, unsavedFiles, projects,
+                                                        dummyIpcClient};
+
+    const Utf8String projectPartId = Utf8StringLiteral("projectPartId");
+
+    const Utf8String filePath1 = Utf8StringLiteral(TESTDATA_DIR"/empty1.cpp");
+    const ClangBackEnd::FileContainer fileContainer1{filePath1, projectPartId, Utf8String(), true};
+
+    const Utf8String filePath2 = Utf8StringLiteral(TESTDATA_DIR"/empty2.cpp");
+    const ClangBackEnd::FileContainer fileContainer2{filePath2, projectPartId, Utf8String(), true};
+
+    const Utf8String filePath3 = Utf8StringLiteral(TESTDATA_DIR"/empty3.cpp");
+    const ClangBackEnd::FileContainer fileContainer3{filePath3, projectPartId, Utf8String(), true};
+
+    std::vector<Document> hotDocuments;
+    std::vector<Document> coldDocuments;
+};
+
+TEST_F(DocumentSuspenderResumer, CategorizeNoDocuments)
+{
+    categorizeDocuments(99);
+
+    ASSERT_THAT(hotDocuments, IsEmpty());
+    ASSERT_THAT(coldDocuments, IsEmpty());
+}
+
+TEST_F(DocumentSuspenderResumer, CategorizeSingleDocument)
+{
+    documents.create({fileContainer1});
+
+    categorizeDocuments(99);
+
+    ASSERT_THAT(hotDocuments, ElementsAre(getDocument(filePath1)));
+    ASSERT_THAT(coldDocuments, IsEmpty());
+}
+
+TEST_F(DocumentSuspenderResumer, CategorizeKeepsStableOrder)
+{
+    documents.create({fileContainer1, fileContainer2});
+
+    categorizeDocuments(99);
+
+    ASSERT_THAT(hotDocuments, ElementsAre(getDocument(filePath1),
+                                          getDocument(filePath2)));
+}
+
+TEST_F(DocumentSuspenderResumer, CategorizePutsLastVisibleToTopOfHotDocuments)
+{
+    documents.create({fileContainer1, fileContainer2});
+    documents.setVisibleInEditors({filePath1});
+    documents.setVisibleInEditors({filePath2});
+
+    categorizeDocuments(99);
+
+    ASSERT_THAT(hotDocuments, ElementsAre(getDocument(filePath2),
+                                          getDocument(filePath1)));
+}
+
+TEST_F(DocumentSuspenderResumer, CategorizeWithLessDocumentsThanWeCareFor)
+{
+    documents.create({fileContainer1});
+
+    categorizeDocuments(2);
+
+    ASSERT_THAT(hotDocuments, ElementsAre(getDocument(filePath1)));
+    ASSERT_THAT(coldDocuments, IsEmpty());
+}
+
+TEST_F(DocumentSuspenderResumer, CategorizeWithZeroHotDocuments)
+{
+    documents.create({fileContainer1});
+
+    categorizeDocuments(0);
+
+    ASSERT_THAT(hotDocuments, IsEmpty());
+    ASSERT_THAT(coldDocuments, ElementsAre(getDocument(filePath1)));
+}
+
+TEST_F(DocumentSuspenderResumer, CategorizeWithMoreVisibleDocumentsThanHotDocuments)
+{
+    const TimePoint timePoint = Clock::now();
+    Document document1 = documents.create({fileContainer1})[0];
+    document1.setIsVisibleInEditor(true, timePoint);
+    Document document2 = documents.create({fileContainer2})[0];
+    document2.setIsVisibleInEditor(true, timePoint);
+
+    categorizeDocuments(1);
+
+    ASSERT_THAT(hotDocuments, ElementsAre(getDocument(filePath1), getDocument(filePath2)));
+    ASSERT_THAT(coldDocuments, IsEmpty());
+}
+
+TEST_F(DocumentSuspenderResumer, CreateSuspendJobForInvisible)
+{
+    Document document = documents.create({fileContainer1})[0];
+    document.setIsSuspended(false);
+    document.setIsVisibleInEditor(false, Clock::now());
+    const SuspendResumeJobs expectedJobs = {
+        {document, JobRequest::Type::SuspendDocument, PreferredTranslationUnit::RecentlyParsed}
+    };
+
+    const SuspendResumeJobs jobs = createSuspendResumeJobs(/*hotDocumentsSize=*/ 0);
+
+    ASSERT_THAT(jobs, ContainerEq(expectedJobs));
+}
+
+TEST_F(DocumentSuspenderResumer, DoNotCreateSuspendJobForVisible)
+{
+    Document document = documents.create({fileContainer1})[0];
+    document.setIsSuspended(false);
+    document.setIsVisibleInEditor(true, Clock::now());
+
+    const SuspendResumeJobs jobs = createSuspendResumeJobs(/*hotDocumentsSize=*/ 0);
+
+    ASSERT_THAT(jobs, ContainerEq(SuspendResumeJobs()));
+}
+
+TEST_F(DocumentSuspenderResumer, CreateSuspendJobsForDocumentWithSupportiveTranslationUnit)
+{
+    Document document = documents.create({fileContainer1})[0];
+    document.setIsSuspended(false);
+    document.setIsVisibleInEditor(false, Clock::now());
+    document.translationUnits().createAndAppend(); // Add supportive translation unit
+    const SuspendResumeJobs expectedJobs = {
+        {document, JobRequest::Type::SuspendDocument, PreferredTranslationUnit::RecentlyParsed},
+        {document, JobRequest::Type::SuspendDocument, PreferredTranslationUnit::PreviouslyParsed},
+    };
+
+    const SuspendResumeJobs jobs = createSuspendResumeJobs(/*hotDocumentsSize=*/ 0);
+
+    ASSERT_THAT(jobs, ContainerEq(expectedJobs));
+}
+
+TEST_F(DocumentSuspenderResumer, CreateResumeJob)
+{
+    Document document = documents.create({fileContainer1})[0];
+    document.setIsSuspended(true);
+    document.setIsVisibleInEditor(true, Clock::now());
+    const SuspendResumeJobs expectedJobs = {
+        {document, JobRequest::Type::ResumeDocument, PreferredTranslationUnit::RecentlyParsed}
+    };
+
+    const SuspendResumeJobs jobs = createSuspendResumeJobs();
+
+    ASSERT_THAT(jobs, ContainerEq(expectedJobs));
+}
+
+TEST_F(DocumentSuspenderResumer, DoNotCreateResumeJobForInvisible)
+{
+    Document document = documents.create({fileContainer1})[0];
+    document.setIsSuspended(true);
+    document.setIsVisibleInEditor(false, Clock::now());
+
+    const SuspendResumeJobs jobs = createSuspendResumeJobs(/*hotDocumentsSize=*/ 0);
+
+    ASSERT_THAT(jobs, ContainerEq(SuspendResumeJobs()));
+}
+
+TEST_F(DocumentSuspenderResumer, CreateResumeJobsForDocumentWithSupportiveTranslationUnit)
+{
+    Document document = documents.create({fileContainer1})[0];
+    document.setIsSuspended(true);
+    document.setIsVisibleInEditor(true, Clock::now());
+    document.translationUnits().createAndAppend(); // Add supportive translation unit
+    const SuspendResumeJobs expectedJobs = {
+        {document, JobRequest::Type::ResumeDocument, PreferredTranslationUnit::RecentlyParsed},
+        {document, JobRequest::Type::ResumeDocument, PreferredTranslationUnit::PreviouslyParsed},
+    };
+
+    const SuspendResumeJobs jobs = createSuspendResumeJobs();
+
+    ASSERT_THAT(jobs, ContainerEq(expectedJobs));
+}
+
+TEST_F(DocumentSuspenderResumer, CreateSuspendAndResumeJobs)
+{
+    Document hotDocument = documents.create({fileContainer1})[0];
+    hotDocument.setIsSuspended(true);
+    Document coldDocument = documents.create({fileContainer2})[0];
+    coldDocument.setIsSuspended(false);
+    documents.setVisibleInEditors({filePath1});
+    const SuspendResumeJobs expectedJobs = {
+        {coldDocument, JobRequest::Type::SuspendDocument, PreferredTranslationUnit::RecentlyParsed},
+        {hotDocument, JobRequest::Type::ResumeDocument, PreferredTranslationUnit::RecentlyParsed},
+    };
+
+    const SuspendResumeJobs jobs = createSuspendResumeJobs(/*hotDocumentsSize=*/ 1);
+
+    ASSERT_THAT(jobs, ContainerEq(expectedJobs));
+}
+
+void DocumentSuspenderResumer::SetUp()
+{
+    projects.createOrUpdate({ClangBackEnd::ProjectPartContainer(projectPartId)});
+}
+
+ClangBackEnd::Document DocumentSuspenderResumer::getDocument(const Utf8String &filePath)
+{
+    return documents.document(filePath, projectPartId);
+}
+
+void DocumentSuspenderResumer::categorizeDocuments(int hotDocumentsSize)
+{
+    categorizeHotColdDocuments(hotDocumentsSize, documents.documents(), hotDocuments,
+                               coldDocuments);
+}
+
+ClangBackEnd::SuspendResumeJobs
+DocumentSuspenderResumer::createSuspendResumeJobs(int hotDocumentsSize)
+{
+    return ClangBackEnd::createSuspendResumeJobs(documents.documents(), hotDocumentsSize);
+}
+
+} // anonymous

tests/unit/unittest/clangjobqueue-test.cpp

@@ -430,6 +430,28 @@ TEST_F(JobQueue, RequestReferencesOutdatableByDocumentClose)
     ASSERT_THAT(jobQueue.size(), Eq(0));
 }
 
+TEST_F(JobQueue, RequestReferencesDoesNotRunOnSuspendedDocument)
+{
+    jobQueue.add(createJobRequest(filePath1, JobRequest::Type::RequestReferences));
+    document.setIsSuspended(true);
+
+    const JobRequests jobsToStart = jobQueue.processQueue();
+
+    ASSERT_THAT(jobsToStart.size(), Eq(0));
+    ASSERT_THAT(jobQueue.size(), Eq(1));
+}
+
+TEST_F(JobQueue, ResumeDocumentDoesNotRunOnUnsuspended)
+{
+    jobQueue.add(createJobRequest(filePath1, JobRequest::Type::ResumeDocument));
+    document.setIsSuspended(false);
+
+    const JobRequests jobsToStart = jobQueue.processQueue();
+
+    ASSERT_THAT(jobsToStart.size(), Eq(0));
+    ASSERT_THAT(jobQueue.size(), Eq(1));
+}
+
 void JobQueue::SetUp()
 {
     projects.createOrUpdate({ProjectPartContainer(projectPartId)});

tests/unit/unittest/clangresumedocumentjob-test.cpp

@@ -0,0 +1,92 @@
+/****************************************************************************
+**
+** 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.
+**
+****************************************************************************/
+
+#include "clangasyncjob-base.h"
+
+#include <clangresumedocumentjob.h>
+
+using namespace ClangBackEnd;
+
+using testing::_;
+
+namespace {
+
+class ResumeDocumentJob : public ClangAsyncJobTest
+{
+protected:
+    void SetUp() override { BaseSetUp(JobRequest::Type::ResumeDocument, job); }
+    void suspendDocument()
+    {
+        document.parse();
+        document.translationUnit().suspend();
+        document.setIsSuspended(true);
+    }
+
+protected:
+    ClangBackEnd::ResumeDocumentJob job;
+};
+
+TEST_F(ResumeDocumentJob, PrepareAsyncRun)
+{
+    job.setContext(jobContext);
+
+    ASSERT_TRUE(job.prepareAsyncRun());
+}
+
+TEST_F(ResumeDocumentJob, RunAsync)
+{
+    suspendDocument();
+    job.setContext(jobContext);
+    job.prepareAsyncRun();
+
+    job.runAsync();
+
+    ASSERT_TRUE(waitUntilJobFinished(job));
+}
+
+TEST_F(ResumeDocumentJob, DocumentIsResumedAfterRun)
+{
+    suspendDocument();
+    job.setContext(jobContext);
+    job.prepareAsyncRun();
+
+    job.runAsync();
+    ASSERT_TRUE(waitUntilJobFinished(job));
+
+    ASSERT_FALSE(document.isSuspended());
+}
+
+TEST_F(ResumeDocumentJob, SendsAnnotationsAfterResume)
+{
+    suspendDocument();
+    job.setContext(jobContextWithMockClient);
+    job.prepareAsyncRun();
+    EXPECT_CALL(mockIpcClient, documentAnnotationsChanged(_)).Times(1);
+
+    job.runAsync();
+    ASSERT_TRUE(waitUntilJobFinished(job));
+}
+
+} // anonymous

tests/unit/unittest/clangsuspenddocumentjob-test.cpp

@@ -0,0 +1,73 @@
+/****************************************************************************
+**
+** 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.
+**
+****************************************************************************/
+
+#include "clangasyncjob-base.h"
+
+#include <clangsuspenddocumentjob.h>
+
+using namespace ClangBackEnd;
+
+namespace {
+
+class SuspendDocumentJob : public ClangAsyncJobTest
+{
+protected:
+    void SetUp() override { BaseSetUp(JobRequest::Type::SuspendDocument, job); }
+
+protected:
+    ClangBackEnd::SuspendDocumentJob job;
+};
+
+TEST_F(SuspendDocumentJob, PrepareAsyncRun)
+{
+    job.setContext(jobContext);
+
+    ASSERT_TRUE(job.prepareAsyncRun());
+}
+
+TEST_F(SuspendDocumentJob, RunAsync)
+{
+    document.parse();
+    job.setContext(jobContext);
+    job.prepareAsyncRun();
+
+    job.runAsync();
+
+    ASSERT_TRUE(waitUntilJobFinished(job));
+}
+
+TEST_F(SuspendDocumentJob, DocumentIsSuspendedAfterRun)
+{
+    document.parse();
+    job.setContext(jobContext);
+    job.prepareAsyncRun();
+
+    job.runAsync();
+    ASSERT_TRUE(waitUntilJobFinished(job));
+
+    ASSERT_TRUE(document.isSuspended());
+}
+
+} // anonymous

tests/unit/unittest/unittest.pro

@@ -84,6 +84,7 @@ SOURCES += \
     clangdocumentprocessors-test.cpp \
     clangdocumentprocessor-test.cpp \
     clangdocuments-test.cpp \
+    clangdocumentsuspenderresumer-test.cpp \
     clangdocument-test.cpp \
     clangfixitoperation-test.cpp \
     clangisdiagnosticrelatedtolocation-test.cpp \
@@ -94,8 +95,10 @@ SOURCES += \
     clangreparsesupportivetranslationunitjob-test.cpp \
     clangrequestdocumentannotationsjob-test.cpp \
     clangrequestreferencesjob-test.cpp \
+    clangresumedocumentjob-test.cpp \
     clangstring-test.cpp \
     clangsupportivetranslationunitinitializer-test.cpp \
+    clangsuspenddocumentjob-test.cpp \
     clangtranslationunits-test.cpp \
     clangtranslationunit-test.cpp \
     clangupdatedocumentannotationsjob-test.cpp \