From 5a518074bef01fea1cf5fdb3086097cc8668ae93 Mon Sep 17 00:00:00 2001
From: Chris Cooper <chris@propelleraero.com.au>
Date: Wed, 22 Jun 2016 12:22:02 +1000
Subject: [PATCH] lock GDALTiler constructor otherwise transformed bounds can
 vary between threads

---
 src/GDALTiler.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/GDALTiler.cpp b/src/GDALTiler.cpp
index 56d2bc0..041b77a 100644
--- a/src/GDALTiler.cpp
+++ b/src/GDALTiler.cpp
@@ -22,6 +22,7 @@
 #include <cmath>                // std::abs
 #include <algorithm>            // std::minmax
 #include <string.h>             // strlen
+#include <mutex>
 
 #include "gdal_priv.h"
 #include "gdalwarper.h"
@@ -39,6 +40,11 @@ GDALTiler::GDALTiler(GDALDataset *poDataset, const Grid &grid, const TilerOption
   poDataset(poDataset),
   options(options)
 {
+
+  // Transformed bounds can give slightly different results on different threads unless mutexed
+  static std::mutex mutex;
+  std::lock_guard<std::mutex> lock(mutex);
+
   // if the dataset is set we need to initialise the tile bounds and raster
   // resolution from it.
   if (poDataset != NULL) {