Fix crash in timeout of JavaScript locator filter

The timeout code may not access thread local state, because if it fires
on the main thread after the thread already finished, that state is
gone.

Change-Id: I3b9b432515ff6f0c46c46b1904bdd622a19960d2
Reviewed-by: Orgad Shaneh <orgads@gmail.com>
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/coreplugin/locator/javascriptfilter.cpp

@@ -28,7 +28,6 @@
 #include <QClipboard>
 #include <QGuiApplication>
 #include <QScriptEngine>
-#include <QTimer>
 
 namespace Core {
 namespace Internal {
@@ -45,6 +44,13 @@ JavaScriptFilter::JavaScriptFilter()
     setDisplayName(tr("Evaluate JavaScript"));
     setIncludedByDefault(false);
     setShortcutString("=");
+    m_abortTimer.setSingleShot(true);
+    m_abortTimer.setInterval(1000);
+    connect(&m_abortTimer, &QTimer::timeout, this, [this] {
+        m_aborted = true;
+        if (m_engine && m_engine->isEvaluating())
+            m_engine->abortEvaluation();
+    });
 }
 
 JavaScriptFilter::~JavaScriptFilter()
@@ -57,6 +63,8 @@ void JavaScriptFilter::prepareSearch(const QString &entry)
 
     if (!m_engine)
         setupEngine();
+    m_aborted = false;
+    m_abortTimer.start();
 }
 
 QList<LocatorFilterEntry> JavaScriptFilter::matchesFor(
@@ -68,16 +76,8 @@ QList<LocatorFilterEntry> JavaScriptFilter::matchesFor(
     if (entry.trimmed().isEmpty()) {
         entries.append({this, tr("Reset Engine"), QVariant(ResetEngine, nullptr)});
     } else {
-        bool aborted = false;
-
-        QTimer::singleShot(1000, this, [this, &aborted]() {
-            m_engine->abortEvaluation();
-            aborted = true;
-        });
-
         const QString result = m_engine->evaluate(entry).toString();
-
-        if (aborted) {
+        if (m_aborted) {
             const QString message = entry + " = " + tr("Engine aborted after timeout.");
             entries.append({this, message, QVariant(AbortEngine, nullptr)});
         } else {

src/plugins/coreplugin/locator/javascriptfilter.h

@@ -27,6 +27,8 @@
 
 #include <coreplugin/locator/ilocatorfilter.h>
 
+#include <QTimer>
+
 #include <memory>
 
 QT_BEGIN_NAMESPACE
@@ -54,6 +56,8 @@ private:
     void setupEngine();
 
     mutable std::unique_ptr<QScriptEngine> m_engine;
+    QTimer m_abortTimer;
+    bool m_aborted = false;
 };
 
 } // namespace Internal