From 37a620748bd3578eda1c74daad8df8451d13b989 Mon Sep 17 00:00:00 2001
From: MarcoFalke <falke.marco@gmail.com>
Date: Thu, 23 Apr 2020 14:04:02 -0400
Subject: test: Add unregister_validation_interface_race test

This commit is (intentionally) adding a broken test. The test is broken
because it registering a subscriber object that can go out of scope
while events are still being sent.

To run the broken test and reproduce the bug:
  - Remove comment /** and */
  - ./configure --with-sanitizers=address
  - export ASAN_OPTIONS=detect_leaks=0
  - make
  - while ./src/test/test_bitcoin -t validationinterface_tests/unregister_validation_interface_race --catch_system_errors=no  ; do true; done

Github-Pull: #18742
Rebased-From: fab6d060ce5f580db538070beec1c5518c8c777c
---
 src/test/validationinterface_tests.cpp | 36 ++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/src/test/validationinterface_tests.cpp b/src/test/validationinterface_tests.cpp
index 208be92852..14f09ae905 100644
--- a/src/test/validationinterface_tests.cpp
+++ b/src/test/validationinterface_tests.cpp
@@ -12,6 +12,42 @@
 
 BOOST_FIXTURE_TEST_SUITE(validationinterface_tests, TestingSetup)
 
+/**
+struct TestSubscriberNoop final : public CValidationInterface {
+    void BlockChecked(const CBlock&, const BlockValidationState&) override {}
+};
+
+BOOST_AUTO_TEST_CASE(unregister_validation_interface_race)
+{
+    std::atomic<bool> generate{true};
+
+    // Start thread to generate notifications
+    std::thread gen{[&] {
+        const CBlock block_dummy;
+        const BlockValidationState state_dummy;
+        while (generate) {
+            GetMainSignals().BlockChecked(block_dummy, state_dummy);
+        }
+    }};
+
+    // Start thread to consume notifications
+    std::thread sub{[&] {
+        // keep going for about 1 sec, which is 250k iterations
+        for (int i = 0; i < 250000; i++) {
+            TestSubscriberNoop sub{};
+            RegisterValidationInterface(&sub);
+            UnregisterValidationInterface(&sub);
+        }
+        // tell the other thread we are done
+        generate = false;
+    }};
+
+    gen.join();
+    sub.join();
+    BOOST_CHECK(!generate);
+}
+*/
+
 class TestInterface : public CValidationInterface
 {
 public:
-- 
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