ProjectExplorer: Move BuildSystem owership to BuildConfiguration

... or Target.

This patch moves build system from conceptually "one per project"
to "one per target (i.e. per project-and-kit)" or "per
BuildConfigurations" for targets where the builds differ
significantly.

Building requires usually items from the kit (Qt version, compiler,
...) so a target-agnostic build is practically almost always wrong.

Moving the build system to the target also has the potential
to solve issues caused by switching targets while parsing, that
used Project::activeTarget() regularly, with potentially different
results before and after the switch.

This patch might create performance/size regressions when several
targets are set up per project as the build system implementation's
internal data are duplicated in this case.

The idea is to fix that by sharing per-project pieces again in
the project implementation once these problems occur.

Change-Id: I87f640ce418b93175b5029124eaa55f3b8721dca
Reviewed-by: Christian Stenger <christian.stenger@qt.io>
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

4 files changed, 73 insertions, 54 deletions

diff --git a/src/plugins/compilationdatabaseprojectmanager/compilationdatabaseproject.cpp b/src/plugins/compilationdatabaseprojectmanager/compilationdatabaseproject.cpp
index d9bf685f08..89f82a780f 100644
--- a/src/plugins/compilationdatabaseprojectmanager/compilationdatabaseproject.cpp
+++ b/src/plugins/compilationdatabaseprojectmanager/compilationdatabaseproject.cpp
@@ -337,9 +337,46 @@ void createTree(std::unique_ptr<ProjectNode> &root,
 
 } // anonymous namespace
 
-void CompilationDatabaseProject::buildTreeAndProjectParts()
+CompilationDatabaseBuildSystem::CompilationDatabaseBuildSystem(Target *target)
+    : BuildSystem(target)
+    , m_cppCodeModelUpdater(std::make_unique<CppTools::CppProjectUpdater>())
+    , m_parseDelay(new QTimer(this))
+    , m_deployFileWatcher(new FileSystemWatcher(this))
+{
+    connect(target->project(), &CompilationDatabaseProject::rootProjectDirectoryChanged,
+            this, [this] {
+        m_projectFileHash.clear();
+        m_parseDelay->start();
+    });
+
+    connect(m_parseDelay, &QTimer::timeout, this, &CompilationDatabaseBuildSystem::reparseProject);
+
+    m_parseDelay->setSingleShot(true);
+    m_parseDelay->setInterval(1000);
+    m_parseDelay->start();
+
+    connect(project(), &Project::projectFileIsDirty, this, &CompilationDatabaseBuildSystem::reparseProject);
+
+    connect(m_deployFileWatcher, &FileSystemWatcher::fileChanged,
+            this, &CompilationDatabaseBuildSystem::updateDeploymentData);
+    connect(target->project(), &Project::activeTargetChanged,
+            this, &CompilationDatabaseBuildSystem::updateDeploymentData);
+}
+
+CompilationDatabaseBuildSystem::~CompilationDatabaseBuildSystem()
+{
+    m_parserWatcher.cancel();
+    m_parserWatcher.waitForFinished();
+}
+
+void CompilationDatabaseBuildSystem::triggerParsing()
+{
+    reparseProject();
+}
+
+void CompilationDatabaseBuildSystem::buildTreeAndProjectParts()
 {
-    ProjectExplorer::KitInfo kitInfo(this);
+    ProjectExplorer::KitInfo kitInfo(project());
     QTC_ASSERT(kitInfo.isValid(), return);
     // Reset toolchains to pick them based on the database entries.
     kitInfo.cToolChain = nullptr;
@@ -349,6 +386,7 @@ void CompilationDatabaseProject::buildTreeAndProjectParts()
     QTC_ASSERT(m_parser, return);
     const DbContents dbContents = m_parser->dbContents();
     const DbEntry *prevEntry = nullptr;
+    Kit *kit = static_cast<CompilationDatabaseProject *>(project())->kit();
     for (const DbEntry &entry : dbContents.entries) {
         if (prevEntry && prevEntry->flags == entry.flags) {
             rpps.back().files.append(entry.fileName.toString());
@@ -358,7 +396,7 @@ void CompilationDatabaseProject::buildTreeAndProjectParts()
         prevEntry = &entry;
 
         RawProjectPart rpp = makeRawProjectPart(projectFilePath(),
-                                                m_kit.get(),
+                                                kit,
                                                 kitInfo,
                                                 entry.workingDir,
                                                 entry.fileName,
@@ -381,7 +419,7 @@ void CompilationDatabaseProject::buildTreeAndProjectParts()
 
 
     auto root = std::make_unique<ProjectNode>(projectDirectory());
-    createTree(root, rootProjectDirectory(), rpps, m_parser->scannedFiles());
+    createTree(root, project()->rootProjectDirectory(), rpps, m_parser->scannedFiles());
 
     root->addNode(std::make_unique<FileNode>(projectFilePath(), FileType::Project));
 
@@ -389,43 +427,26 @@ void CompilationDatabaseProject::buildTreeAndProjectParts()
         root->addNode(std::make_unique<FileNode>(Utils::FilePath::fromString(dbContents.extraFileName),
                                                  FileType::Project));
 
-    setRootProjectNode(std::move(root));
+    project()->setRootProjectNode(std::move(root));
 
-    m_cppCodeModelUpdater->update({this, kitInfo, activeParseEnvironment(), rpps});
+    m_cppCodeModelUpdater->update({project(), kitInfo, activeParseEnvironment(), rpps});
     updateDeploymentData();
 }
 
 CompilationDatabaseProject::CompilationDatabaseProject(const Utils::FilePath &projectFile)
     : Project(Constants::COMPILATIONDATABASEMIMETYPE, projectFile)
-    , m_cppCodeModelUpdater(std::make_unique<CppTools::CppProjectUpdater>())
-    , m_parseDelay(new QTimer(this))
-    , m_deployFileWatcher(new FileSystemWatcher(this))
 {
     setId(Constants::COMPILATIONDATABASEPROJECT_ID);
     setProjectLanguages(Core::Context(ProjectExplorer::Constants::CXX_LANGUAGE_ID));
     setDisplayName(projectDirectory().fileName());
 
+    setBuildSystemCreator([](Target *t) { return new CompilationDatabaseBuildSystem(t); });
+
     m_kit.reset(KitManager::defaultKit()->clone());
     addTargetForKit(m_kit.get());
 
-    connect(this, &CompilationDatabaseProject::rootProjectDirectoryChanged,
-            this, [this] {
-        m_projectFileHash.clear();
-        m_parseDelay->start();
-    });
-
     setExtraProjectFiles(
         {projectFile.stringAppended(Constants::COMPILATIONDATABASEPROJECT_FILES_SUFFIX)});
-    connect(m_parseDelay, &QTimer::timeout, this, &CompilationDatabaseProject::reparseProject);
-
-    m_parseDelay->setSingleShot(true);
-    m_parseDelay->setInterval(1000);
-
-    connect(this, &Project::projectFileIsDirty, this, &CompilationDatabaseProject::reparseProject);
-    connect(m_deployFileWatcher, &FileSystemWatcher::fileChanged,
-            this, &CompilationDatabaseProject::updateDeploymentData);
-    connect(this, &Project::activeTargetChanged,
-            this, &CompilationDatabaseProject::updateDeploymentData);
 }
 
 Utils::FilePath CompilationDatabaseProject::rootPathFromSettings() const
@@ -442,26 +463,19 @@ Project::RestoreResult CompilationDatabaseProject::fromMap(const QVariantMap &ma
                                                            QString *errorMessage)
 {
     Project::RestoreResult result = Project::fromMap(map, errorMessage);
-    if (result == Project::RestoreResult::Ok) {
-        const Utils::FilePath rootPath = rootPathFromSettings();
-        if (rootPath.isEmpty())
-            changeRootProjectDirectory(); // This triggers reparse itself.
-        else
-            reparseProject();
-    }
-
     return result;
 }
 
-void CompilationDatabaseProject::reparseProject()
+void CompilationDatabaseBuildSystem::reparseProject()
 {
     if (m_parser) {
         QTC_CHECK(isParsing());
         m_parser->stop();
     }
-    m_parser = new CompilationDbParser(displayName(),
+    const FilePath rootPath = static_cast<CompilationDatabaseProject *>(project())->rootPathFromSettings();
+    m_parser = new CompilationDbParser(project()->displayName(),
                                        projectFilePath(),
-                                       rootPathFromSettings(),
+                                       rootPath,
                                        m_mimeBinaryCache,
                                        guardParsingRun(),
                                        this);
@@ -475,17 +489,14 @@ void CompilationDatabaseProject::reparseProject()
     m_parser->start();
 }
 
-void CompilationDatabaseProject::updateDeploymentData()
+void CompilationDatabaseBuildSystem::updateDeploymentData()
 {
-    Target * const target = activeTarget();
-    if (!target)
-        return;
     const Utils::FilePath deploymentFilePath = projectDirectory()
             .pathAppended("QtCreatorDeployment.txt");
     DeploymentData deploymentData;
     deploymentData.addFilesFromDeploymentFile(deploymentFilePath.toString(),
                                               projectDirectory().toString());
-    target->setDeploymentData(deploymentData);
+    setDeploymentData(deploymentData);
     if (m_deployFileWatcher->files() != QStringList(deploymentFilePath.toString())) {
         m_deployFileWatcher->removeFiles(m_deployFileWatcher->files());
         m_deployFileWatcher->addFile(deploymentFilePath.toString(),
@@ -493,12 +504,6 @@ void CompilationDatabaseProject::updateDeploymentData()
     }
 }
 
-CompilationDatabaseProject::~CompilationDatabaseProject()
-{
-    m_parserWatcher.cancel();
-    m_parserWatcher.waitForFinished();
-}
-
 static TextEditor::TextDocument *createCompilationDatabaseDocument()
 {
     auto doc = new TextEditor::TextDocument;
diff --git a/src/plugins/compilationdatabaseprojectmanager/compilationdatabaseproject.h b/src/plugins/compilationdatabaseprojectmanager/compilationdatabaseproject.h
index 900f7d3675..98ff726a19 100644
--- a/src/plugins/compilationdatabaseprojectmanager/compilationdatabaseproject.h
+++ b/src/plugins/compilationdatabaseprojectmanager/compilationdatabaseproject.h
@@ -28,8 +28,11 @@
 #include "compilationdatabaseutils.h"
 
 #include <projectexplorer/buildconfiguration.h>
+#include <projectexplorer/buildsystem.h>
 #include <projectexplorer/project.h>
+
 #include <texteditor/texteditor.h>
+
 #include <utils/filesystemwatcher.h>
 
 #include <QFutureWatcher>
@@ -52,20 +55,31 @@ class CompilationDatabaseProject : public ProjectExplorer::Project
 
 public:
     explicit CompilationDatabaseProject(const Utils::FilePath &filename);
-    ~CompilationDatabaseProject() override;
+
     bool needsConfiguration() const override { return false; }
 
+    Utils::FilePath rootPathFromSettings() const;
+    ProjectExplorer::Kit *kit() const { return m_kit.get(); }
+
 private:
     RestoreResult fromMap(const QVariantMap &map, QString *errorMessage) override;
+    std::unique_ptr<ProjectExplorer::Kit> m_kit;
+};
+
+class CompilationDatabaseBuildSystem : public ProjectExplorer::BuildSystem
+{
+public:
+    explicit CompilationDatabaseBuildSystem(ProjectExplorer::Target *target);
+    ~CompilationDatabaseBuildSystem();
+
+    void triggerParsing() final;
 
     void reparseProject();
     void updateDeploymentData();
     void buildTreeAndProjectParts();
-    Utils::FilePath rootPathFromSettings() const;
 
     QFutureWatcher<void> m_parserWatcher;
     std::unique_ptr<CppTools::CppProjectUpdater> m_cppCodeModelUpdater;
-    std::unique_ptr<ProjectExplorer::Kit> m_kit;
     MimeBinaryCache m_mimeBinaryCache;
     QByteArray m_projectFileHash;
     QTimer * const m_parseDelay;
diff --git a/src/plugins/compilationdatabaseprojectmanager/compilationdbparser.cpp b/src/plugins/compilationdatabaseprojectmanager/compilationdbparser.cpp
index 374c245b23..1505dffa1a 100644
--- a/src/plugins/compilationdatabaseprojectmanager/compilationdbparser.cpp
+++ b/src/plugins/compilationdatabaseprojectmanager/compilationdbparser.cpp
@@ -48,7 +48,7 @@ CompilationDbParser::CompilationDbParser(const QString &projectName,
                                          const FilePath &projectPath,
                                          const FilePath &rootPath,
                                          MimeBinaryCache &mimeBinaryCache,
-                                         ProjectExplorer::Project::ParseGuard &&guard,
+                                         BuildSystem::ParseGuard &&guard,
                                          QObject *parent)
     : QObject(parent)
     , m_projectName(projectName)
diff --git a/src/plugins/compilationdatabaseprojectmanager/compilationdbparser.h b/src/plugins/compilationdatabaseprojectmanager/compilationdbparser.h
index ac5fbb0afb..dd126d9fd1 100644
--- a/src/plugins/compilationdatabaseprojectmanager/compilationdbparser.h
+++ b/src/plugins/compilationdatabaseprojectmanager/compilationdbparser.h
@@ -27,7 +27,7 @@
 
 #include "compilationdatabaseutils.h"
 
-#include <projectexplorer/project.h>
+#include <projectexplorer/buildsystem.h>
 
 #include <utils/fileutils.h>
 
@@ -56,7 +56,7 @@ public:
                                  const Utils::FilePath &projectPath,
                                  const Utils::FilePath &rootPath,
                                  MimeBinaryCache &mimeBinaryCache,
-                                 ProjectExplorer::Project::ParseGuard &&guard,
+                                 ProjectExplorer::BuildSystem::ParseGuard &&guard,
                                  QObject *parent = nullptr);
 
 
@@ -91,7 +91,7 @@ private:
     QByteArray m_projectFileContents;
     QByteArray m_projectFileHash;
 
-    ProjectExplorer::Project::ParseGuard m_guard;
+    ProjectExplorer::BuildSystem::ParseGuard m_guard;
 };
 
 } // namespace Internal