Debugger: Simplify removal of outdated L&E items

This removes the need of bookkeeping on the engine side. It's
basically a kind of mark-and-sweep: On update begin mark items
that are expected to change as outdated, while data arrives, undo
that marking, and update end remove all remaining marked items.

Change-Id: I739b84869033d511d5c9a80605c079e87ef4f6a7
Reviewed-by: David Schulz <david.schulz@theqtcompany.com>

src/plugins/debugger/cdb/cdbengine.cpp

@@ -1340,7 +1340,7 @@ void CdbEngine::doUpdateLocals(const UpdateParameters &updateParameters)
         return;
     }
 
-    watchHandler()->notifyUpdateStarted();
+    watchHandler()->notifyUpdateStarted(updateParameters.partialVariables());
 
     /* Watchers: Forcibly discard old symbol group as switching from
      * thread 0/frame 0 -> thread 1/assembly -> thread 0/frame 0 will otherwise re-use it
@@ -1775,7 +1775,6 @@ void CdbEngine::handleRegistersExt(const CdbResponse &response)
 
 void CdbEngine::handleLocals(const CdbResponse &response, bool partialUpdate)
 {
-    watchHandler()->notifyUpdateFinished();
     if (response.success) {
         if (boolSetting(VerboseLog))
             showMessage(QLatin1String("Locals: ") + QString::fromLatin1(response.extensionReply), LogDebug);
@@ -1796,6 +1795,7 @@ void CdbEngine::handleLocals(const CdbResponse &response, bool partialUpdate)
     } else {
         showMessage(QString::fromLatin1(response.errorMessage), LogWarning);
     }
+    watchHandler()->notifyUpdateFinished();
 }
 
 void CdbEngine::handleExpandLocals(const CdbResponse &response)

src/plugins/debugger/debuggerengine.cpp

@@ -1944,12 +1944,6 @@ void DebuggerEngine::updateLocalsView(const GdbMi &all)
         }
     }
 
-    QSet<QByteArray> toDelete;
-    if (!partial) {
-        foreach (WatchItem *item, handler->model()->itemsAtLevel<WatchItem *>(2))
-            toDelete.insert(item->iname);
-    }
-
     GdbMi data = all["data"];
     foreach (const GdbMi &child, data.children()) {
         WatchItem *item = new WatchItem(child);
@@ -1958,7 +1952,6 @@ void DebuggerEngine::updateLocalsView(const GdbMi &all)
             item->size = ti.size;
 
         handler->insertItem(item);
-        toDelete.remove(item->iname);
     }
 
     GdbMi ns = all["qtnamespace"];
@@ -1967,8 +1960,6 @@ void DebuggerEngine::updateLocalsView(const GdbMi &all)
         showMessage(_("FOUND NAMESPACED QT: " + ns.data()));
     }
 
-    handler->purgeOutdatedItems(toDelete);
-
     static int count = 0;
     showMessage(_("<Rebuild Watchmodel %1 @ %2 >")
                 .arg(++count).arg(LogWindow::logTimeStamp()), LogMiscInput);

src/plugins/debugger/debuggerengine.h

@@ -120,6 +120,14 @@ class UpdateParameters
 public:
     UpdateParameters() {}
 
+    QList<QByteArray> partialVariables() const
+    {
+        QList<QByteArray> result;
+        if (!partialVariable.isEmpty())
+            result.append(partialVariable);
+        return result;
+    }
+
     QByteArray partialVariable;
 };
 

src/plugins/debugger/gdb/gdbengine.cpp

@@ -4660,7 +4660,7 @@ void GdbEngine::doUpdateLocals(const UpdateParameters &params)
 {
     m_pendingBreakpointRequests = 0;
 
-    watchHandler()->notifyUpdateStarted();
+    watchHandler()->notifyUpdateStarted(params.partialVariables());
 
     DebuggerCommand cmd("showData");
     watchHandler()->appendFormatRequests(&cmd);
@@ -4716,7 +4716,6 @@ void GdbEngine::doUpdateLocals(const UpdateParameters &params)
 
 void GdbEngine::handleStackFrame(const DebuggerResponse &response)
 {
-    watchHandler()->notifyUpdateFinished();
     if (response.resultClass == ResultDone) {
         QByteArray out = response.consoleStreamOutput;
         while (out.endsWith(' ') || out.endsWith('\n'))
@@ -4735,6 +4734,7 @@ void GdbEngine::handleStackFrame(const DebuggerResponse &response)
     } else {
         showMessage(_("DUMPER FAILED: " + response.toString()));
     }
+    watchHandler()->notifyUpdateFinished();
 }
 
 QString GdbEngine::msgPtraceError(DebuggerStartMode sm)

src/plugins/debugger/lldb/lldbengine.cpp

@@ -447,8 +447,8 @@ void LldbEngine::handleResponse(const QByteArray &response)
     foreach (const GdbMi &item, all.children()) {
         const QByteArray name = item.name();
         if (name == "all") {
-            watchHandler()->notifyUpdateFinished();
             updateLocalsView(item);
+            watchHandler()->notifyUpdateFinished();
         } else if (name == "dumpers") {
             watchHandler()->addDumpers(item);
             setupInferiorStage2();
@@ -864,7 +864,7 @@ void LldbEngine::doUpdateLocals(const UpdateParameters &params)
         return;
     }
 
-    watchHandler()->notifyUpdateStarted();
+    watchHandler()->notifyUpdateStarted(params.partialVariables());
 
     DebuggerCommand cmd("updateData");
     cmd.arg("nativeMixed", isNativeMixedActive());

src/plugins/debugger/pdb/pdbengine.cpp

@@ -572,17 +572,10 @@ void PdbEngine::refreshLocals(const GdbMi &vars)
     WatchHandler *handler = watchHandler();
     handler->resetValueCache();
 
-    QSet<QByteArray> toDelete;
-    foreach (WatchItem *item, handler->model()->itemsAtLevel<WatchItem *>(2))
-        toDelete.insert(item->iname);
+    foreach (const GdbMi &child, vars.children())
+        handler->insertItem(new WatchItem(child));
 
-    foreach (const GdbMi &child, vars.children()) {
-        WatchItem *item = new WatchItem(child);
-        handler->insertItem(item);
-        toDelete.remove(item->iname);
-    }
-
-    handler->purgeOutdatedItems(toDelete);
+    handler->notifyUpdateFinished();
 
     DebuggerToolTipManager::updateEngine(this);
 }

src/plugins/debugger/watchdata.cpp

@@ -131,7 +131,8 @@ WatchData::WatchData() :
     elided(0),
     wantsChildren(false),
     valueEnabled(true),
-    valueEditable(true)
+    valueEditable(true),
+    outdated(false)
 {
 }
 

src/plugins/debugger/watchdata.h

@@ -119,6 +119,7 @@ public:
     bool            wantsChildren;
     bool            valueEnabled;  // Value will be enabled or not
     bool            valueEditable; // Value will be editable
+    bool            outdated;      // \internal item is to be removed.
 
     Q_DECLARE_TR_FUNCTIONS(Debugger::Internal::WatchHandler)
 };

src/plugins/debugger/watchhandler.cpp

@@ -1221,8 +1221,20 @@ void WatchHandler::resetWatchers()
     loadSessionData();
 }
 
-void WatchHandler::notifyUpdateStarted()
+void WatchHandler::notifyUpdateStarted(const QList<QByteArray> &inames)
 {
+    auto marker = [](TreeItem *it) { static_cast<WatchItem *>(it)->outdated = true; };
+
+    if (inames.isEmpty()) {
+        foreach (auto item, m_model->itemsAtLevel<WatchItem *>(2))
+            item->walkTree(marker);
+    } else {
+        foreach (auto iname, inames) {
+            if (WatchItem *item = m_model->findItem(iname))
+                item->walkTree(marker);
+        }
+    }
+
     m_model->m_requestUpdateTimer.start(80);
     m_model->m_contentsValid = false;
     updateWatchersWindow();
@@ -1230,25 +1242,32 @@ void WatchHandler::notifyUpdateStarted()
 
 void WatchHandler::notifyUpdateFinished()
 {
+    struct OutDatedItemsFinder : public TreeItemVisitor
+    {
+        bool preVisit(TreeItem *item)
+        {
+            auto watchItem = static_cast<WatchItem *>(item);
+            if (level() <= 1 || !watchItem->outdated)
+                return true;
+            toRemove.append(watchItem);
+            return false;
+        }
+
+        QList<WatchItem *> toRemove;
+    } finder;
+
+    m_model->root()->walkTree(&finder);
+
+    foreach (auto item, finder.toRemove)
+        delete m_model->takeItem(item);
+
     m_model->m_contentsValid = true;
     updateWatchersWindow();
+    m_model->reexpandItems();
     m_model->m_requestUpdateTimer.stop();
     emit m_model->updateFinished();
 }
 
-void WatchHandler::purgeOutdatedItems(const QSet<QByteArray> &inames)
-{
-    foreach (const QByteArray &iname, inames) {
-        WatchItem *item = findItem(iname);
-        delete m_model->takeItem(item);
-    }
-
-    m_model->layoutChanged();
-    m_model->reexpandItems();
-    m_model->m_contentsValid = true;
-    updateWatchersWindow();
-}
-
 void WatchHandler::removeItemByIName(const QByteArray &iname)
 {
     WatchItem *item = m_model->findItem(iname);

src/plugins/debugger/watchhandler.h

@@ -197,9 +197,9 @@ public:
     void removeAllData(bool includeInspectData = false);
     void resetValueCache();
     void resetWatchers();
-    void notifyUpdateStarted();
+
+    void notifyUpdateStarted(const QList<QByteArray> &inames = {});
     void notifyUpdateFinished();
-    void purgeOutdatedItems(const QSet<QByteArray> &inames);
 
 private:
     WatchModel *m_model; // Owned.