Git: Do not run 'git --version' synchronously at startup

We can easily delay this, and if git acts up for some reason, we don't
have to block startup.

Task-number: QTCREATORBUG-27765
Change-Id: I25aa6f8d04d1fd4b9d87f8ccf7ffd591f7bbe519
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Jarek Kobus <jaroslaw.kobus@qt.io>

src/plugins/git/gitclient.cpp

@@ -648,7 +648,7 @@ public:
 
 static bool gitHasRgbColors()
 {
-    const unsigned gitVersion = GitClient::instance()->gitVersion();
+    const unsigned gitVersion = GitClient::instance()->gitVersion().result();
     return gitVersion >= 0x020300U;
 }
 
@@ -3611,36 +3611,10 @@ QString GitClient::readOneLine(const FilePath &workingDirectory, const QStringLi
     return proc.cleanedStdOut().trimmed();
 }
 
-// determine version as '(major << 16) + (minor << 8) + patch' or 0.
+static unsigned parseGitVersion(const QString &output)
-unsigned GitClient::gitVersion(QString *errorMessage) const
 {
-    const FilePath newGitBinary = vcsBinary();
-    if (m_gitVersionForBinary != newGitBinary && !newGitBinary.isEmpty()) {
-        // Do not execute repeatedly if that fails (due to git
-        // not being installed) until settings are changed.
-        m_cachedGitVersion = synchronousGitVersion(errorMessage);
-        m_gitVersionForBinary = newGitBinary;
-    }
-    return m_cachedGitVersion;
-}
-
-// determine version as '(major << 16) + (minor << 8) + patch' or 0.
-unsigned GitClient::synchronousGitVersion(QString *errorMessage) const
-{
-    if (vcsBinary().isEmpty())
-        return 0;
-
-    // run git --version
-    QtcProcess proc;
-    vcsSynchronousExec(proc, {}, {"--version"}, silentFlags);
-    if (proc.result() != ProcessResult::FinishedWithSuccess) {
-        msgCannotRun(tr("Cannot determine Git version: %1").arg(proc.cleanedStdErr()), errorMessage);
-        return 0;
-    }
-
     // cut 'git version 1.6.5.1.sha'
     // another form: 'git version 1.9.rc1'
-    const QString output = proc.cleanedStdOut();
     const QRegularExpression versionPattern("^[^\\d]+(\\d+)\\.(\\d+)\\.(\\d+|rc\\d).*$");
     QTC_ASSERT(versionPattern.isValid(), return 0);
     const QRegularExpressionMatch match = versionPattern.match(output);
@@ -3651,6 +3625,41 @@ unsigned GitClient::synchronousGitVersion(QString *errorMessage) const
     return version(majorV, minorV, patchV);
 }
 
+// determine version as '(major << 16) + (minor << 8) + patch' or 0.
+QFuture<unsigned> GitClient::gitVersion() const
+{
+    QFutureInterface<unsigned> fi;
+    fi.reportStarted();
+
+    // Do not execute repeatedly if that fails (due to git
+    // not being installed) until settings are changed.
+    const FilePath newGitBinary = vcsBinary();
+    const bool needToRunGit = m_gitVersionForBinary != newGitBinary && !newGitBinary.isEmpty();
+    if (needToRunGit) {
+        auto proc = new QtcProcess(const_cast<GitClient *>(this));
+        connect(proc, &QtcProcess::done, this, [this, proc, fi, newGitBinary]() mutable {
+            if (proc->result() == ProcessResult::FinishedWithSuccess) {
+                m_cachedGitVersion = parseGitVersion(proc->cleanedStdOut());
+                m_gitVersionForBinary = newGitBinary;
+                fi.reportResult(m_cachedGitVersion);
+                fi.reportFinished();
+            }
+            proc->deleteLater();
+        });
+
+        proc->setTimeoutS(vcsTimeoutS());
+        proc->setEnvironment(processEnvironment());
+        proc->setCommand({newGitBinary, {"--version"}});
+        proc->start();
+    } else {
+        // already cached
+        fi.reportResult(m_cachedGitVersion);
+        fi.reportFinished();
+    }
+
+    return fi.future();
+}
+
 bool GitClient::StashInfo::init(const FilePath &workingDirectory, const QString &command,
                                 StashFlag flag, PushAction pushAction)
 {

src/plugins/git/gitclient.h

@@ -145,7 +145,7 @@ public:
     static GitSettings &settings();
 
     Utils::FilePath vcsBinary() const override;
-    unsigned gitVersion(QString *errorMessage = nullptr) const;
+    QFuture<unsigned> gitVersion() const;
 
     VcsBase::VcsCommand *vcsExecAbortable(const Utils::FilePath &workingDirectory,
                                           const QStringList &arguments,
@@ -387,9 +387,6 @@ private:
                        const Utils::FilePath &workingDirectory,
                        std::function<GitBaseDiffEditorController *(Core::IDocument *)> factory) const;
 
-    // determine version as '(major << 16) + (minor << 8) + patch' or 0.
-    unsigned synchronousGitVersion(QString *errorMessage = nullptr) const;
-
     QString readOneLine(const Utils::FilePath &workingDirectory, const QStringList &arguments) const;
 
     enum RevertResult { RevertOk, RevertUnchanged, RevertCanceled, RevertFailed };

src/plugins/git/gitgrep.cpp

@@ -247,10 +247,15 @@ GitGrep::GitGrep(GitClient *client)
     const QRegularExpression refExpression("[\\S]*");
     m_treeLineEdit->setValidator(new QRegularExpressionValidator(refExpression, this));
     layout->addWidget(m_treeLineEdit);
-    if (client->gitVersion() >= 0x021300) {
+    // asynchronously check git version, add "recurse submodules" option if available
-        m_recurseSubmodules = new QCheckBox(tr("Recurse submodules"));
+    Utils::onResultReady(client->gitVersion(),
-        layout->addWidget(m_recurseSubmodules);
+                         this,
-    }
+                         [this, pLayout = QPointer<QHBoxLayout>(layout)](unsigned version) {
+                             if (version >= 0x021300 && pLayout) {
+                                 m_recurseSubmodules = new QCheckBox(tr("Recurse submodules"));
+                                 pLayout->addWidget(m_recurseSubmodules);
+                             }
+                         });
     TextEditor::FindInFiles *findInFiles = TextEditor::FindInFiles::instance();
     QTC_ASSERT(findInFiles, return);
     connect(findInFiles, &TextEditor::FindInFiles::pathChanged,

src/plugins/git/gitplugin.cpp

@@ -66,6 +66,7 @@
 #include <utils/parameteraction.h>
 #include <utils/pathchooser.h>
 #include <utils/qtcassert.h>
+#include <utils/runextensions.h>
 #include <utils/stringutils.h>
 #include <utils/utilsicons.h>
 
@@ -1367,20 +1368,22 @@ void GitPluginPrivate::startCommit(CommitType commitType)
 
 void GitPluginPrivate::updateVersionWarning()
 {
-    unsigned version = m_gitClient.gitVersion();
+    QPointer<IDocument> curDocument = EditorManager::currentDocument();
-    if (!version || version >= minimumRequiredVersion)
-        return;
-    IDocument *curDocument = EditorManager::currentDocument();
     if (!curDocument)
         return;
-    InfoBar *infoBar = curDocument->infoBar();
+    Utils::onResultReady(m_gitClient.gitVersion(), this, [curDocument](unsigned version) {
-    Id gitVersionWarning("GitVersionWarning");
+        if (!curDocument || !version || version >= minimumRequiredVersion)
-    if (!infoBar->canInfoBeAdded(gitVersionWarning))
+            return;
-        return;
+        InfoBar *infoBar = curDocument->infoBar();
-    infoBar->addInfo(InfoBarEntry(gitVersionWarning,
+        Id gitVersionWarning("GitVersionWarning");
-                        tr("Unsupported version of Git found. Git %1 or later required.")
+        if (!infoBar->canInfoBeAdded(gitVersionWarning))
-                        .arg(versionString(minimumRequiredVersion)),
+            return;
-                        InfoBarEntry::GlobalSuppression::Enabled));
+        infoBar->addInfo(
+            InfoBarEntry(gitVersionWarning,
+                         tr("Unsupported version of Git found. Git %1 or later required.")
+                             .arg(versionString(minimumRequiredVersion)),
+                         InfoBarEntry::GlobalSuppression::Enabled));
+    });
 }
 
 IEditor *GitPluginPrivate::openSubmitEditor(const QString &fileName, const CommitData &cd)