async parsing + tex caching

Plugins/ZShell/Llm/segment.cpp

@@ -2,7 +2,10 @@
 
 #include "markdownparser.hpp"
 
+#include <QCoreApplication>
 #include <QDateTime>
+#include <QPointer>
+#include <QThreadPool>
 
 namespace ZShell::llm {
 
@@ -19,8 +22,10 @@ LlmSegment::LlmSegment(Type type, qint64 timestamp, QObject* parent)
 		&m_markdownTimer, &QTimer::timeout, this, [this]() {
 			if (!m_markdownDirty)
 				return;
-			m_markdownDirty = false;
-			parseMarkdown();
+			// A parse may still be running; leave the dirty flag set so
+			// it re-parses the newest text when that one completes.
+			if (parseMarkdown())
+				m_markdownDirty = false;
 		});
 }
 
@@ -53,7 +58,8 @@ void LlmSegment::close() {
 	// out the debounce.
 	if (m_type == Type::Content && m_markdownDirty) {
 		m_markdownTimer.stop();
-		parseMarkdown();
+		if (parseMarkdown())
+			m_markdownDirty = false;
 	}
 }
 
@@ -130,9 +136,33 @@ void LlmSegment::scheduleMarkdown() {
 		m_markdownTimer.start();
 }
 
-void LlmSegment::parseMarkdown() {
-	m_markdown = MarkdownParser::parse(m_text);
-	Q_EMIT markdownChanged();
+bool LlmSegment::parseMarkdown() {
+	if (m_parseInFlight)
+		return false;
+	m_parseInFlight = true;
+	const QString text = m_text;
+	QThreadPool::globalInstance()->start([this, text]() {
+		const QVariantList blocks = MarkdownParser::parse(text);
+		// Deliver through qApp (never destroyed) and re-check the
+		// pointer on the GUI thread: posting to `this` from the pool
+		// thread would race with its destruction.
+		QPointer<LlmSegment> guard(this);
+		QMetaObject::invokeMethod(
+			QCoreApplication::instance(),
+			[guard, blocks]() {
+				LlmSegment* seg = guard;
+				if (!seg)
+					return;
+				seg->m_parseInFlight = false;
+				seg->m_markdown = blocks;
+				Q_EMIT seg->markdownChanged();
+				// Text arrived while the worker was running; parse it.
+				if (seg->m_markdownDirty)
+					seg->parseMarkdown();
+			},
+			Qt::QueuedConnection);
+	});
+	return true;
 }
 
 } // namespace ZShell::llm