Merge pull request #7725 from yorickvP/check-coro-gc

Disable GC during coroutine execution + test

2 files changed, 148 insertions, 1 deletions

diff --git a/src/libexpr/tests/coro-gc.cc b/src/libexpr/tests/coro-gc.cc
new file mode 100644
index 000000000..f848bc2f0
--- /dev/null
+++ b/src/libexpr/tests/coro-gc.cc
@@ -0,0 +1,147 @@
+#include <gtest/gtest.h>
+#if HAVE_BOEHMGC
+#include <gc/gc.h>
+
+#include "eval.hh"
+#include "serialise.hh"
+
+#endif
+
+
+namespace nix {
+#if HAVE_BOEHMGC
+
+    static void finalizer(void *obj, void *data) {
+        *((bool*)data) = true;
+    }
+
+    static bool* make_witness(volatile void* obj) {
+        /* We can't store the witnesses on the stack,
+           since they might be collected long afterwards */
+        bool* res = (bool*)GC_MALLOC_UNCOLLECTABLE(1);
+        *res = false;
+        GC_register_finalizer((void*)obj, finalizer, res, nullptr, nullptr);
+        return res;
+    }
+
+    // Generate 2 objects, discard one, run gc,
+    // see if one got collected and the other didn't
+    // GC is disabled inside coroutines on __APPLE__
+    static void testFinalizerCalls() {
+        volatile void* do_collect = GC_MALLOC_ATOMIC(128);
+        volatile void* dont_collect = GC_MALLOC_ATOMIC(128);
+
+        bool* do_collect_witness = make_witness(do_collect);
+        bool* dont_collect_witness = make_witness(dont_collect);
+        GC_gcollect();
+        GC_invoke_finalizers();
+
+        ASSERT_TRUE(GC_is_disabled() || *do_collect_witness);
+        ASSERT_FALSE(*dont_collect_witness);
+        ASSERT_NE(nullptr, dont_collect);
+    }
+
+    TEST(CoroGC, BasicFinalizers) {
+        initGC();
+        testFinalizerCalls();
+    }
+
+    // Run testFinalizerCalls inside a coroutine
+    // this tests that GC works as expected inside a coroutine
+    TEST(CoroGC, CoroFinalizers) {
+        initGC();
+
+        auto source = sinkToSource([&](Sink& sink) {
+            testFinalizerCalls();
+
+            // pass control to main
+            writeString("foo", sink);
+        });
+
+        // pass control to coroutine
+        std::string foo = readString(*source);
+        ASSERT_EQ(foo, "foo");
+    }
+
+#if __APPLE__
+    // This test tests that GC is disabled on darwin
+    // to work around the patch not being sufficient there,
+    // causing crashes whenever gc is invoked inside a coroutine
+    TEST(CoroGC, AppleCoroDisablesGC) {
+        initGC();
+        auto source = sinkToSource([&](Sink& sink) {
+            ASSERT_TRUE(GC_is_disabled());
+            // pass control to main
+            writeString("foo", sink);
+
+            ASSERT_TRUE(GC_is_disabled());
+
+            // pass control to main
+            writeString("bar", sink);
+        });
+
+        // pass control to coroutine
+        std::string foo = readString(*source);
+        ASSERT_EQ(foo, "foo");
+        ASSERT_FALSE(GC_is_disabled());
+        // pass control to coroutine
+        std::string bar = readString(*source);
+        ASSERT_EQ(bar, "bar");
+
+        ASSERT_FALSE(GC_is_disabled());
+    }
+#endif
+
+    // This test tests that boehm handles coroutine stacks correctly
+    // This test tests that coroutine stacks are registered to the GC,
+    // even when the coroutine is not running. It also tests that
+    // the main stack is still registered to the GC when the coroutine is running.
+    TEST(CoroGC, CoroutineStackNotGCd) {
+        initGC();
+
+        volatile void* do_collect = GC_MALLOC_ATOMIC(128);
+        volatile void* dont_collect = GC_MALLOC_ATOMIC(128);
+
+        bool* do_collect_witness = make_witness(do_collect);
+        bool* dont_collect_witness = make_witness(dont_collect);
+
+        do_collect = nullptr;
+
+        auto source = sinkToSource([&](Sink& sink) {
+            volatile void* dont_collect_inner = GC_MALLOC_ATOMIC(128);
+            volatile void* do_collect_inner = GC_MALLOC_ATOMIC(128);
+
+            bool* do_collect_inner_witness = make_witness(do_collect_inner);
+            bool* dont_collect_inner_witness = make_witness(dont_collect_inner);
+
+            do_collect_inner = nullptr;
+
+            // pass control to main
+            writeString("foo", sink);
+
+            ASSERT_FALSE(*dont_collect_inner_witness);
+            ASSERT_TRUE(*do_collect_inner_witness);
+            ASSERT_NE(nullptr, dont_collect_inner);
+
+            // pass control to main
+            writeString("bar", sink);
+        });
+
+        // pass control to coroutine
+        std::string foo = readString(*source);
+        ASSERT_EQ(foo, "foo");
+
+        ASSERT_FALSE(GC_is_disabled());
+        GC_gcollect();
+        GC_invoke_finalizers();
+
+        // pass control to coroutine
+        std::string bar = readString(*source);
+        ASSERT_EQ(bar, "bar");
+
+        ASSERT_FALSE(*dont_collect_witness);
+        ASSERT_TRUE(*do_collect_witness);
+        ASSERT_NE(nullptr, dont_collect);
+    }
+#endif
+}
diff --git a/src/libexpr/tests/local.mk b/src/libexpr/tests/local.mk
index 3e5504f71..c36d21bfe 100644
--- a/src/libexpr/tests/local.mk
+++ b/src/libexpr/tests/local.mk
@@ -16,4 +16,4 @@ libexpr-tests_CXXFLAGS += -I src/libexpr -I src/libutil -I src/libstore -I src/l
 
 libexpr-tests_LIBS = libstore-tests libutils-tests libexpr libutil libstore libfetchers
 
-libexpr-tests_LDFLAGS := $(GTEST_LIBS) -lgmock
+libexpr-tests_LDFLAGS := $(GTEST_LIBS) -lgmock -lboost_context