Locator filters: Fix various thread-safety issues

Introduces a "prepareSearch" method for locator filters that is called on
the UI thread prior to the threaded matching.
Fix various small thread-safety issues in the various filters.

Change-Id: If5ae7d205e126d367420936a93f8d9a84496edb8
Reviewed-by: Daniel Teske <daniel.teske@digia.com>

src/plugins/help/helpindexfilter.cpp

@@ -59,16 +59,19 @@ HelpIndexFilter::~HelpIndexFilter()
 {
 }
 
+void HelpIndexFilter::prepareSearch(const QString &entry)
+{
+    if (entry.length() < 2)
+        m_keywords = Core::HelpManager::findKeywords(entry, caseSensitivity(entry), 200);
+    else
+        m_keywords = Core::HelpManager::findKeywords(entry, caseSensitivity(entry));
+}
+
 QList<LocatorFilterEntry> HelpIndexFilter::matchesFor(QFutureInterface<LocatorFilterEntry> &future, const QString &entry)
 {
-    QStringList keywords;
-    if (entry.length() < 2)
-        keywords = Core::HelpManager::findKeywords(entry, caseSensitivity(entry), 200);
-    else
-        keywords = Core::HelpManager::findKeywords(entry, caseSensitivity(entry));
-
+    Q_UNUSED(entry) // search is already done in the GUI thread in prepareSearch
     QList<LocatorFilterEntry> entries;
-    foreach (const QString &keyword, keywords) {
+    foreach (const QString &keyword, m_keywords) {
         if (future.isCanceled())
             break;
         entries.append(LocatorFilterEntry(this, keyword, QVariant(), m_icon));

src/plugins/help/helpindexfilter.h

@@ -46,6 +46,7 @@ public:
     ~HelpIndexFilter();
 
     // ILocatorFilter
+    void prepareSearch(const QString &entry);
     QList<Core::LocatorFilterEntry> matchesFor(QFutureInterface<Core::LocatorFilterEntry> &future, const QString &entry);
     void accept(Core::LocatorFilterEntry selection) const;
     void refresh(QFutureInterface<void> &future);
@@ -55,6 +56,7 @@ signals:
 
 private:
     QIcon m_icon;
+    QStringList m_keywords;
 };
 
 } // namespace Internal

src/plugins/help/remotehelpfilter.cpp

@@ -29,6 +29,7 @@
 
 #include "remotehelpfilter.h"
 
+#include <QMutexLocker>
 #include <QUrl>
 
 namespace Help {
@@ -99,7 +100,7 @@ RemoteHelpFilter::~RemoteHelpFilter()
 QList<Core::LocatorFilterEntry> RemoteHelpFilter::matchesFor(QFutureInterface<Core::LocatorFilterEntry> &future, const QString &pattern)
 {
     QList<Core::LocatorFilterEntry> entries;
-    foreach (const QString &url, m_remoteUrls) {
+    foreach (const QString &url, remoteUrls()) {
         if (future.isCanceled())
             break;
 
@@ -156,6 +157,7 @@ bool RemoteHelpFilter::openConfigDialog(QWidget *parent, bool &needsRefresh)
     Q_UNUSED(needsRefresh)
     RemoteFilterOptions optionsDialog(this, parent);
     if (optionsDialog.exec() == QDialog::Accepted) {
+        QMutexLocker lock(&m_mutex); Q_UNUSED(lock)
         m_remoteUrls.clear();
         setIncludedByDefault(!optionsDialog.m_ui.limitCheck->isChecked());
         setShortcutString(optionsDialog.m_ui.shortcutEdit->text().trimmed());
@@ -166,5 +168,11 @@ bool RemoteHelpFilter::openConfigDialog(QWidget *parent, bool &needsRefresh)
     return true;
 }
 
+QStringList RemoteHelpFilter::remoteUrls() const
+{
+    QMutexLocker lock(&m_mutex); Q_UNUSED(lock)
+    return m_remoteUrls;
+}
+
     } // namespace Internal
 } // namespace Help

src/plugins/help/remotehelpfilter.h

@@ -35,6 +35,7 @@
 #include <coreplugin/locator/ilocatorfilter.h>
 
 #include <QIcon>
+#include <QMutex>
 
 namespace Help {
     namespace Internal {
@@ -54,7 +55,7 @@ public:
     bool restoreState(const QByteArray &state);
     bool openConfigDialog(QWidget *parent, bool &needsRefresh);
 
-    QStringList remoteUrls() const { return m_remoteUrls; }
+    QStringList remoteUrls() const;
 
 signals:
     void linkActivated(const QUrl &url) const;
@@ -62,6 +63,7 @@ signals:
 private:
     QIcon m_icon;
     QStringList m_remoteUrls;
+    mutable QMutex m_mutex;
 };
 
 class RemoteFilterOptions : public QDialog