Git: Avoid main loop blocking in instant blame

Query the author and encoding information asynchronous
after the current repository is changed.

Set the default codec to UTF-8, which should cover most
configurations (i.e. almost never be different).

In case requesting the information takes longer, the blame
mark is already created with the cached information.

In case the author or encoding changed, the blame mark
has to be recreated.

The call to refreshWorkingDirectory() is moved after the
widget checks in setupInstantBlame() to avoid requesting
these information in VCS editors.

Fixes: QTCREATORBUG-29151
Change-Id: I6feccbbed67c877f1015295f630dd63cf3ccf4a0
Reviewed-by: Orgad Shaneh <orgads@gmail.com>

src/plugins/git/gitclient.cpp

@@ -822,14 +822,19 @@ FilePaths GitClient::unmanagedFiles(const FilePaths &filePaths) const
     return res;
 }
 
+QTextCodec *GitClient::defaultCommitEncoding() const
+{
+    // Set default commit encoding to 'UTF-8', when it's not set,
+    // to solve displaying error of commit log with non-latin characters.
+    return QTextCodec::codecForName("UTF-8");
+}
+
 QTextCodec *GitClient::encoding(GitClient::EncodingType encodingType, const FilePath &source) const
 {
     auto codec = [this](const FilePath &workingDirectory, const QString &configVar) {
         const QString codecName = readConfigValue(workingDirectory, configVar).trimmed();
-        // Set default commit encoding to 'UTF-8', when it's not set,
-        // to solve displaying error of commit log with non-latin characters.
         if (codecName.isEmpty())
-            return QTextCodec::codecForName("UTF-8");
+            return defaultCommitEncoding();
         return QTextCodec::codecForName(codecName.toUtf8());
     };
 
@@ -2618,11 +2623,10 @@ bool GitClient::readDataFromCommit(const FilePath &repoDirectory, const QString
     return true;
 }
 
-Author GitClient::getAuthor(const Utils::FilePath &workingDirectory)
+Author GitClient::parseAuthor(const QString &authorInfo)
 {
     // The format is:
     // Joe Developer <joedev@example.com> unixtimestamp +HHMM
-    const QString authorInfo = readGitVar(workingDirectory, "GIT_AUTHOR_IDENT");
     int lt = authorInfo.lastIndexOf('<');
     int gt = authorInfo.lastIndexOf('>');
     if (gt == -1 || uint(lt) > uint(gt)) {
@@ -2634,6 +2638,12 @@ Author GitClient::getAuthor(const Utils::FilePath &workingDirectory)
     return result;
 }
 
+Author GitClient::getAuthor(const Utils::FilePath &workingDirectory)
+{
+    const QString authorInfo = readGitVar(workingDirectory, "GIT_AUTHOR_IDENT");
+    return parseAuthor(authorInfo);
+}
+
 bool GitClient::getCommitData(const FilePath &workingDirectory,
                               QString *commitTemplate,
                               CommitData &commitData,
@@ -3425,21 +3435,33 @@ QString GitClient::readGitVar(const FilePath &workingDirectory, const QString &c
     return readOneLine(workingDirectory, {"var", configVar});
 }
 
-QString GitClient::readOneLine(const FilePath &workingDirectory, const QStringList &arguments) const
+static QTextCodec *configFileCodec()
 {
     // Git for Windows always uses UTF-8 for configuration:
     // https://github.com/msysgit/msysgit/wiki/Git-for-Windows-Unicode-Support#convert-config-files
     static QTextCodec *codec = HostOsInfo::isWindowsHost()
             ? QTextCodec::codecForName("UTF-8")
             : QTextCodec::codecForLocale();
+    return codec;
+}
 
+QString GitClient::readOneLine(const FilePath &workingDirectory, const QStringList &arguments) const
+{
     const CommandResult result = vcsSynchronousExec(workingDirectory, arguments,
-                                                    RunFlags::NoOutput, vcsTimeoutS(), codec);
+                                                    RunFlags::NoOutput, vcsTimeoutS(),
+                                                    configFileCodec());
     if (result.result() == ProcessResult::FinishedWithSuccess)
         return result.cleanedStdOut().trimmed();
     return {};
 }
 
+void GitClient::readConfigAsync(const FilePath &workingDirectory, const QStringList &arguments,
+                                const CommandHandler &handler) const
+{
+    vcsExecWithHandler(workingDirectory, arguments, this, handler, RunFlags::NoOutput,
+                       configFileCodec());
+}
+
 static unsigned parseGitVersion(const QString &output)
 {
     // cut 'git version 1.6.5.1.sha'

src/plugins/git/gitclient.h

@@ -79,6 +79,12 @@ public:
 };
 
 struct Author {
+    bool operator==(const Author &other) const {
+        return name == other.name && email == other.email;
+    }
+    bool operator!=(const Author &other) const {
+        return !operator==(other);
+    }
     QString name;
     QString email;
 };
@@ -343,11 +349,16 @@ public:
     Core::IEditor *openShowEditor(const Utils::FilePath &workingDirectory, const QString &ref,
                                   const Utils::FilePath &path, ShowEditor showSetting = ShowEditor::Always);
 
+    Author parseAuthor(const QString &authorInfo);
     Author getAuthor(const Utils::FilePath &workingDirectory);
 
+    QTextCodec *defaultCommitEncoding() const;
     enum EncodingType { EncodingSource, EncodingLogOutput, EncodingCommit, EncodingDefault };
     QTextCodec *encoding(EncodingType encodingType, const Utils::FilePath &source = {}) const;
 
+    void readConfigAsync(const Utils::FilePath &workingDirectory, const QStringList &arguments,
+                         const VcsBase::CommandHandler &handler) const;
+
 private:
     static GitSettings &settings();
 

src/plugins/git/gitplugin.cpp

@@ -392,6 +392,7 @@ public:
 
     void setupInstantBlame();
     void instantBlameOnce();
+    void forceInstantBlame();
     void instantBlame();
     void stopInstantBlame();
     bool refreshWorkingDirectory(const FilePath &workingDirectory);
@@ -705,6 +706,7 @@ GitPluginPrivate::GitPluginPrivate()
     m_fileActions.reserve(10);
     m_projectActions.reserve(10);
     m_repositoryActions.reserve(50);
+    m_codec = GitClient::instance()->defaultCommitEncoding();
 
     Context context(Constants::GIT_CONTEXT);
 
@@ -1441,10 +1443,6 @@ void GitPluginPrivate::setupInstantBlame()
             return;
         }
 
-        const Utils::FilePath workingDirectory = GitPlugin::currentState().currentFileTopLevel();
-        if (!refreshWorkingDirectory(workingDirectory))
-            return;
-
         const TextEditorWidget *widget = TextEditorWidget::fromEditor(editor);
         if (!widget)
             return;
@@ -1452,6 +1450,10 @@ void GitPluginPrivate::setupInstantBlame()
         if (qobject_cast<const VcsBaseEditorWidget *>(widget))
             return; // Skip in VCS editors like log or blame
 
+        const Utils::FilePath workingDirectory = GitPlugin::currentState().currentFileTopLevel();
+        if (!refreshWorkingDirectory(workingDirectory))
+            return;
+
         m_blameCursorPosConn = connect(widget, &QPlainTextEdit::cursorPositionChanged, this,
                                 [this] {
             if (!settings().instantBlame.value()) {
@@ -1461,8 +1463,7 @@ void GitPluginPrivate::setupInstantBlame()
             m_cursorPositionChangedTimer->start(500);
         });
 
-        m_lastVisitedEditorLine = -1;
+        forceInstantBlame();
-        instantBlame();
     };
 
     connect(&settings().instantBlame, &BoolAspect::valueChanged, this,
@@ -1530,6 +1531,11 @@ void GitPluginPrivate::instantBlameOnce()
             return;
     }
 
+    forceInstantBlame();
+}
+
+void GitPluginPrivate::forceInstantBlame()
+{
     m_lastVisitedEditorLine = -1;
     instantBlame();
 }
@@ -1596,8 +1602,38 @@ bool GitPluginPrivate::refreshWorkingDirectory(const FilePath &workingDirectory)
         return true;
 
     m_workingDirectory = workingDirectory;
-    m_author = GitClient::instance()->getAuthor(workingDirectory);
+
-    m_codec = GitClient::instance()->encoding(GitClient::EncodingCommit, workingDirectory);
+    const auto commitCodecHandler = [this, workingDirectory](const CommandResult &result) {
+        QTextCodec *codec = nullptr;
+
+        if (result.result() == ProcessResult::FinishedWithSuccess) {
+            const QString codecName = result.cleanedStdOut().trimmed();
+            codec = QTextCodec::codecForName(codecName.toUtf8());
+        } else {
+            codec = GitClient::instance()->defaultCommitEncoding();
+        }
+
+        if (m_codec != codec) {
+            m_codec = codec;
+            forceInstantBlame();
+        }
+    };
+    GitClient::instance()->readConfigAsync(workingDirectory, {"config", "i18n.commitEncoding"},
+                                           commitCodecHandler);
+
+    const auto authorHandler = [this, workingDirectory](const CommandResult &result) {
+        if (result.result() == ProcessResult::FinishedWithSuccess) {
+            const QString authorInfo = result.cleanedStdOut().trimmed();
+            const Author author = GitClient::instance()->parseAuthor(authorInfo);
+
+            if (m_author != author) {
+                m_author = author;
+                forceInstantBlame();
+            }
+        }
+    };
+    GitClient::instance()->readConfigAsync(workingDirectory, {"var", "GIT_AUTHOR_IDENT"},
+                                           authorHandler);
 
     return true;
 }