From d6413efc0aa61fd98a94da7b6c6fb774833fdec9 Mon Sep 17 00:00:00 2001
From: Daniel Baston <dbaston@gmail.com>
Date: Tue, 6 Dec 2022 22:10:51 -0500
Subject: [PATCH] Isolate interrupt requests to single thread

---
 src/util/Interrupt.cpp                |  6 ++--
 tests/unit/capi/GEOSInterruptTest.cpp | 50 +++++++++++++++++++++++++++
 2 files changed, 52 insertions(+), 4 deletions(-)

diff --git a/src/util/Interrupt.cpp b/src/util/Interrupt.cpp
index 0bc988221b..ce337e2ed2 100644
--- a/src/util/Interrupt.cpp
+++ b/src/util/Interrupt.cpp
@@ -16,10 +16,8 @@
 #include <geos/util/GEOSException.h> // for inheritance
 
 namespace {
-/* Could these be portably stored in thread-specific space ? */
-bool requested = false;
-
-geos::util::Interrupt::Callback* callback = nullptr;
+thread_local bool requested = false;
+thread_local geos::util::Interrupt::Callback* callback = nullptr;
 }
 
 namespace geos {
diff --git a/tests/unit/capi/GEOSInterruptTest.cpp b/tests/unit/capi/GEOSInterruptTest.cpp
index 0bd0301143..5b0e9ec71e 100644
--- a/tests/unit/capi/GEOSInterruptTest.cpp
+++ b/tests/unit/capi/GEOSInterruptTest.cpp
@@ -9,6 +9,7 @@
 #include <cstdio>
 #include <cstdlib>
 #include <memory>
+#include <thread>
 
 namespace tut {
 //
@@ -18,6 +19,7 @@ namespace tut {
 // Common data used in test cases.
 struct test_capiinterrupt_data {
     static int numcalls;
+    static int numcalls2;
     static GEOSInterruptCallback* nextcb;
 
     static void
@@ -56,9 +58,19 @@ struct test_capiinterrupt_data {
         }
     }
 
+    static void
+    countCalls2()
+    {
+        ++numcalls2;
+        if(nextcb) {
+            (*nextcb)();
+        }
+    }
+
 };
 
 int test_capiinterrupt_data::numcalls = 0;
+int test_capiinterrupt_data::numcalls2 = 0;
 GEOSInterruptCallback* test_capiinterrupt_data::nextcb = nullptr;
 
 typedef test_group<test_capiinterrupt_data> group;
@@ -221,5 +233,43 @@ void object::test<5>
 }
 
 
+// Test callback is thread-local
+template<>
+template<>
+void object::test<6>
+()
+{
+    numcalls = 0;
+    numcalls2 = 0;
+    nextcb = nullptr;
+
+    initGEOS(notice, notice);
+
+    auto buffer = [](GEOSInterruptCallback* cb) {
+        GEOSGeometry* geom1 = GEOSGeomFromWKT("LINESTRING (0 0, 1 0)");
+
+        GEOS_interruptRegisterCallback(cb);
+
+        GEOSGeometry* geom2 = GEOSBuffer(geom1, 1, 8);
+        GEOSGeom_destroy(geom2);
+        GEOSGeom_destroy(geom1);
+
+        GEOS_interruptRegisterCallback(nullptr);
+    };
+
+    std::thread t1(buffer, countCalls);
+    std::thread t2(buffer, countCalls2);
+
+    t1.join();
+    t2.join();
+
+    ensure("numcalls > 0", numcalls > 0);
+    ensure("numcalls2 > 0", numcalls2 > 0);
+    ensure_equals(numcalls, numcalls2);
+
+    finishGEOS();
+}
+
+
 } // namespace tut