From e5de77084e92436c0fc75615002bdcb92f112deb Mon Sep 17 00:00:00 2001
From: Volker Krause <vkrause@kde.org>
Date: Thu, 16 Jul 2020 17:27:56 +0200
Subject: [PATCH] Add a simple reentrancy guard

Due to the use of sub-processes during the tile generation we re-enter the
event loop, and thus might receive another socket notification while the
previous one is still being processed.
---
 tools/vectorosm-tilecreator/tirexbackend.cpp | 6 ++++++
 tools/vectorosm-tilecreator/tirexbackend.h   | 1 +
 2 files changed, 7 insertions(+)

diff --git a/tools/vectorosm-tilecreator/tirexbackend.cpp b/tools/vectorosm-tilecreator/tirexbackend.cpp
index 7bc1ddabf..2798aa679 100644
--- a/tools/vectorosm-tilecreator/tirexbackend.cpp
+++ b/tools/vectorosm-tilecreator/tirexbackend.cpp
@@ -7,6 +7,7 @@
 #include "tirexbackend.h"
 
 #include <QDir>
+#include <QScopedValueRollback>
 #include <QSettings>
 #include <QSocketNotifier>
 
@@ -50,6 +51,11 @@ TirexBackend::~TirexBackend() = default;
 
 void TirexBackend::commandReadyRead()
 {
+    if (m_recursionLock) {
+        return;
+    }
+    QScopedValueRollback<bool> lock(m_recursionLock, true);
+
     while (true) {
         m_renderTime.restart();
         TirexMetatileRequest req;
diff --git a/tools/vectorosm-tilecreator/tirexbackend.h b/tools/vectorosm-tilecreator/tirexbackend.h
index 5d8658910..3e136b00d 100644
--- a/tools/vectorosm-tilecreator/tirexbackend.h
+++ b/tools/vectorosm-tilecreator/tirexbackend.h
@@ -86,6 +86,7 @@ private:
     QString m_tileDir;
     QElapsedTimer m_renderTime;
     int m_heartbeatFd = -1;
+    bool m_recursionLock = false;
     static constexpr const int m_metatileRows = 8; // TODO read from config eventually
     static constexpr const int m_metatileCols = 8;
 };
-- 
GitLab