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Merge pull request #8012 from NixOS/revert-7725-check-coro-gc

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Revert "Disable GC during coroutine execution + test"
This commit is contained in:
Eelco Dolstra 2023-03-09 12:37:38 +01:00 committed by GitHub
commit 1ba40e959b
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GPG key ID: 4AEE18F83AFDEB23
6 changed files with 9 additions and 232 deletions
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22
boehmgc-coroutine-sp-fallback.diff
View file

@ -1,8 +1,8 @@
diff --git a/darwin_stop_world.c b/darwin_stop_world.c
index 0468aaec..b348d869 100644
index 3dbaa3fb..36a1d1f7 100644
--- a/darwin_stop_world.c
+++ b/darwin_stop_world.c
@@ -356,6 +356,7 @@ GC_INNER void GC_push_all_stacks(void)
@@ -352,6 +352,7 @@ GC_INNER void GC_push_all_stacks(void)
int nthreads = 0;
word total_size = 0;
mach_msg_type_number_t listcount = (mach_msg_type_number_t)THREAD_TABLE_SZ;
@ -10,7 +10,7 @@ index 0468aaec..b348d869 100644
if (!EXPECT(GC_thr_initialized, TRUE))
GC_thr_init();
@@ -411,6 +412,19 @@ GC_INNER void GC_push_all_stacks(void)
@@ -407,6 +408,19 @@ GC_INNER void GC_push_all_stacks(void)
GC_push_all_stack_sections(lo, hi, p->traced_stack_sect);
}
if (altstack_lo) {
@ -30,22 +30,6 @@ index 0468aaec..b348d869 100644
total_size += altstack_hi - altstack_lo;
GC_push_all_stack(altstack_lo, altstack_hi);
}
diff --git a/include/gc.h b/include/gc.h
index edab6c22..f2c61282 100644
--- a/include/gc.h
+++ b/include/gc.h
@@ -2172,6 +2172,11 @@ GC_API void GC_CALL GC_win32_free_heap(void);
(*GC_amiga_allocwrapper_do)(a,GC_malloc_atomic_ignore_off_page)
#endif /* _AMIGA && !GC_AMIGA_MAKINGLIB */
+#if !__APPLE__
+/* Patch doesn't work on apple */
+#define NIX_BOEHM_PATCH_VERSION 1
+#endif
+
#ifdef __cplusplus
} /* extern "C" */
#endif
diff --git a/pthread_stop_world.c b/pthread_stop_world.c
index b5d71e62..aed7b0bf 100644
--- a/pthread_stop_world.c

25
src/libexpr/eval.cc
View file

@ -325,22 +325,6 @@ static Symbol getName(const AttrName & name, EvalState & state, Env & env)
}
}
#if HAVE_BOEHMGC
/* Disable GC while this object lives. Used by CoroutineContext.
*
* Boehm keeps a count of GC_disable() and GC_enable() calls,
* and only enables GC when the count matches.
*/
class BoehmDisableGC {
public:
BoehmDisableGC() {
GC_disable();
};
~BoehmDisableGC() {
GC_enable();
};
};
#endif
static bool gcInitialised = false;
@ -365,15 +349,6 @@ void initGC()
StackAllocator::defaultAllocator = &boehmGCStackAllocator;
#if NIX_BOEHM_PATCH_VERSION != 1
printTalkative("Unpatched BoehmGC, disabling GC inside coroutines");
/* Used to disable GC when entering coroutines on macOS */
create_coro_gc_hook = []() -> std::shared_ptr<void> {
return std::make_shared<BoehmDisableGC>();
};
#endif
/* Set the initial heap size to something fairly big (25% of
physical RAM, up to a maximum of 384 MiB) so that in most cases
we don't need to garbage collect at all. (Collection has a

147
src/libexpr/tests/coro-gc.cc
View file

@ -1,147 +0,0 @@
#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
}

2
src/libexpr/tests/local.mk
View file

@ -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 -lboost_context
libexpr-tests_LDFLAGS := $(GTEST_LIBS) -lgmock

39
src/libutil/serialise.cc
View file

@ -186,22 +186,6 @@ static DefaultStackAllocator defaultAllocatorSingleton;
StackAllocator *StackAllocator::defaultAllocator = &defaultAllocatorSingleton;
std::shared_ptr<void> (*create_coro_gc_hook)() = []() -> std::shared_ptr<void> {
return {};
};
/* This class is used for entry and exit hooks on coroutines */
class CoroutineContext {
/* Disable GC when entering the coroutine without the boehm patch,
* since it doesn't find the main thread stack in this case.
* std::shared_ptr<void> performs type-erasure, so it will call the right
* deleter. */
const std::shared_ptr<void> coro_gc_hook = create_coro_gc_hook();
public:
CoroutineContext() {};
~CoroutineContext() {};
};
std::unique_ptr<FinishSink> sourceToSink(std::function<void(Source &)> fun)
{
struct SourceToSink : FinishSink
@ -222,8 +206,7 @@ std::unique_ptr<FinishSink> sourceToSink(std::function<void(Source &)> fun)
if (in.empty()) return;
cur = in;
if (!coro) {
CoroutineContext ctx;
if (!coro)
coro = coro_t::push_type(VirtualStackAllocator{}, [&](coro_t::pull_type & yield) {
LambdaSource source([&](char *out, size_t out_len) {
if (cur.empty()) {
@ -240,24 +223,17 @@ std::unique_ptr<FinishSink> sourceToSink(std::function<void(Source &)> fun)
});
fun(source);
});
}
if (!*coro) { abort(); }
if (!cur.empty()) {
CoroutineContext ctx;
(*coro)(false);
}
if (!cur.empty()) (*coro)(false);
}
void finish() override
{
if (!coro) return;
if (!*coro) abort();
{
CoroutineContext ctx;
(*coro)(true);
}
(*coro)(true);
if (*coro) abort();
}
};
@ -288,23 +264,18 @@ std::unique_ptr<Source> sinkToSource(
size_t read(char * data, size_t len) override
{
if (!coro) {
CoroutineContext ctx;
if (!coro)
coro = coro_t::pull_type(VirtualStackAllocator{}, [&](coro_t::push_type & yield) {
LambdaSink sink([&](std::string_view data) {
if (!data.empty()) yield(std::string(data));
});
fun(sink);
});
}
if (!*coro) { eof(); abort(); }
if (pos == cur.size()) {
if (!cur.empty()) {
CoroutineContext ctx;
(*coro)();
}
if (!cur.empty()) (*coro)();
cur = coro->get();
pos = 0;
}

6
src/libutil/serialise.hh
View file

@ -501,10 +501,4 @@ struct StackAllocator {
static StackAllocator *defaultAllocator;
};
/* Disabling GC when entering a coroutine (without the boehm patch).
mutable to avoid boehm gc dependency in libutil.
*/
extern std::shared_ptr<void> (*create_coro_gc_hook)();
}