dart-sdk/runtime/vm/stack_trace.cc
Alexander Markov 2ad557a892 [vm] Cleanup more async-related code
This change continues cleanup of async implementation in the VM.

TEST=ci

Issue: https://github.com/dart-lang/sdk/issues/48378
Change-Id: Icdaeab18bcdc0d6974bc45841b630822cd1ac114
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/251441
Reviewed-by: Martin Kustermann <kustermann@google.com>
Commit-Queue: Alexander Markov <alexmarkov@google.com>
2022-07-14 16:04:54 +00:00

550 lines
21 KiB
C++

// Copyright (c) 2017, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
#include "vm/stack_trace.h"
#include "vm/dart_api_impl.h"
#include "vm/object_store.h"
#include "vm/stack_frame.h"
#include "vm/symbols.h"
namespace dart {
// Keep in sync with:
// - sdk/lib/async/stream_controller.dart:_StreamController._STATE_SUBSCRIBED.
const intptr_t k_StreamController__STATE_SUBSCRIBED = 1;
// - sdk/lib/async/future_impl.dart:_FutureListener.stateThen.
const intptr_t k_FutureListener_stateThen = 1;
// - sdk/lib/async/future_impl.dart:_FutureListener.stateCatchError.
const intptr_t k_FutureListener_stateCatchError = 2;
// - sdk/lib/async/future_impl.dart:_FutureListener.stateWhenComplete.
const intptr_t k_FutureListener_stateWhenComplete = 8;
// Keep in sync with sdk/lib/async/future_impl.dart:_FutureListener.handleValue.
const intptr_t kNumArgsFutureListenerHandleValue = 1;
// Instance caches library and field references.
// This way we don't have to do the look-ups for every frame in the stack.
CallerClosureFinder::CallerClosureFinder(Zone* zone)
: closure_(Closure::Handle(zone)),
receiver_context_(Context::Handle(zone)),
receiver_function_(Function::Handle(zone)),
parent_function_(Function::Handle(zone)),
suspend_state_(SuspendState::Handle(zone)),
context_entry_(Object::Handle(zone)),
future_(Object::Handle(zone)),
listener_(Object::Handle(zone)),
callback_(Object::Handle(zone)),
controller_(Object::Handle(zone)),
state_(Object::Handle(zone)),
var_data_(Object::Handle(zone)),
callback_instance_(Object::Handle(zone)),
future_impl_class(Class::Handle(zone)),
future_listener_class(Class::Handle(zone)),
async_star_stream_controller_class(Class::Handle(zone)),
stream_controller_class(Class::Handle(zone)),
sync_stream_controller_class(Class::Handle(zone)),
controller_subscription_class(Class::Handle(zone)),
buffering_stream_subscription_class(Class::Handle(zone)),
stream_iterator_class(Class::Handle(zone)),
future_result_or_listeners_field(Field::Handle(zone)),
callback_field(Field::Handle(zone)),
future_listener_state_field(Field::Handle(zone)),
future_listener_result_field(Field::Handle(zone)),
controller_controller_field(Field::Handle(zone)),
var_data_field(Field::Handle(zone)),
state_field(Field::Handle(zone)),
on_data_field(Field::Handle(zone)),
state_data_field(Field::Handle(zone)),
has_value_field(Field::Handle(zone)) {
const auto& async_lib = Library::Handle(zone, Library::AsyncLibrary());
// Look up classes:
// - async:
future_impl_class = async_lib.LookupClassAllowPrivate(Symbols::FutureImpl());
ASSERT(!future_impl_class.IsNull());
future_listener_class =
async_lib.LookupClassAllowPrivate(Symbols::_FutureListener());
ASSERT(!future_listener_class.IsNull());
// - async*:
async_star_stream_controller_class =
async_lib.LookupClassAllowPrivate(Symbols::_AsyncStarStreamController());
ASSERT(!async_star_stream_controller_class.IsNull());
stream_controller_class =
async_lib.LookupClassAllowPrivate(Symbols::_StreamController());
ASSERT(!stream_controller_class.IsNull());
sync_stream_controller_class =
async_lib.LookupClassAllowPrivate(Symbols::_SyncStreamController());
ASSERT(!sync_stream_controller_class.IsNull());
controller_subscription_class =
async_lib.LookupClassAllowPrivate(Symbols::_ControllerSubscription());
ASSERT(!controller_subscription_class.IsNull());
buffering_stream_subscription_class = async_lib.LookupClassAllowPrivate(
Symbols::_BufferingStreamSubscription());
ASSERT(!buffering_stream_subscription_class.IsNull());
stream_iterator_class =
async_lib.LookupClassAllowPrivate(Symbols::_StreamIterator());
ASSERT(!stream_iterator_class.IsNull());
// Look up fields:
// - async:
future_result_or_listeners_field =
future_impl_class.LookupFieldAllowPrivate(Symbols::_resultOrListeners());
ASSERT(!future_result_or_listeners_field.IsNull());
callback_field =
future_listener_class.LookupFieldAllowPrivate(Symbols::callback());
ASSERT(!callback_field.IsNull());
future_listener_state_field =
future_listener_class.LookupFieldAllowPrivate(Symbols::state());
ASSERT(!future_listener_state_field.IsNull());
future_listener_result_field =
future_listener_class.LookupFieldAllowPrivate(Symbols::result());
ASSERT(!future_listener_result_field.IsNull());
// - async*:
controller_controller_field =
async_star_stream_controller_class.LookupFieldAllowPrivate(
Symbols::controller());
ASSERT(!controller_controller_field.IsNull());
state_field =
stream_controller_class.LookupFieldAllowPrivate(Symbols::_state());
ASSERT(!state_field.IsNull());
var_data_field =
stream_controller_class.LookupFieldAllowPrivate(Symbols::_varData());
ASSERT(!var_data_field.IsNull());
on_data_field = buffering_stream_subscription_class.LookupFieldAllowPrivate(
Symbols::_onData());
ASSERT(!on_data_field.IsNull());
state_data_field =
stream_iterator_class.LookupFieldAllowPrivate(Symbols::_stateData());
ASSERT(!state_data_field.IsNull());
has_value_field =
stream_iterator_class.LookupFieldAllowPrivate(Symbols::_hasValue());
ASSERT(!has_value_field.IsNull());
}
ClosurePtr CallerClosureFinder::GetCallerInFutureImpl(const Object& future) {
ASSERT(!future.IsNull());
ASSERT(future.GetClassId() == future_impl_class.id());
// Since this function is recursive, we have to keep a local ref.
auto& listener = Object::Handle(GetFutureFutureListener(future));
if (listener.IsNull()) {
return Closure::null();
}
return GetCallerInFutureListener(listener);
}
ClosurePtr CallerClosureFinder::FindCallerInAsyncStarStreamController(
const Object& async_star_stream_controller) {
ASSERT(async_star_stream_controller.IsInstance());
ASSERT(async_star_stream_controller.GetClassId() ==
async_star_stream_controller_class.id());
controller_ = Instance::Cast(async_star_stream_controller)
.GetField(controller_controller_field);
ASSERT(!controller_.IsNull());
ASSERT(controller_.GetClassId() == sync_stream_controller_class.id());
// Get the _StreamController._state field.
state_ = Instance::Cast(controller_).GetField(state_field);
ASSERT(state_.IsSmi());
if (Smi::Cast(state_).Value() != k_StreamController__STATE_SUBSCRIBED) {
return Closure::null();
}
// Get the _StreamController._varData field.
var_data_ = Instance::Cast(controller_).GetField(var_data_field);
ASSERT(var_data_.GetClassId() == controller_subscription_class.id());
// _ControllerSubscription<T>/_BufferingStreamSubscription.<T>_onData
callback_ = Instance::Cast(var_data_).GetField(on_data_field);
ASSERT(callback_.IsClosure());
// If this is not the "_StreamIterator._onData" tear-off, we return the
// callback we found.
receiver_function_ = Closure::Cast(callback_).function();
if (!receiver_function_.IsImplicitInstanceClosureFunction() ||
receiver_function_.Owner() != stream_iterator_class.ptr()) {
return Closure::Cast(callback_).ptr();
}
// All implicit closure functions (tear-offs) have the "this" receiver
// captured.
receiver_context_ = Closure::Cast(callback_).context();
ASSERT(receiver_context_.num_variables() == 1);
callback_instance_ = receiver_context_.At(0);
ASSERT(callback_instance_.IsInstance());
// If the async* stream is await-for'd:
if (callback_instance_.GetClassId() == stream_iterator_class.id()) {
// If `_hasValue` is true then the `StreamIterator._stateData` field
// contains the iterator's value. In that case we cannot unwind anymore.
//
// Notice: With correct async* semantics this may never be true: The async*
// generator should only be invoked to produce a value if there's an
// in-progress `await streamIterator.moveNext()` call. Once such call has
// finished the async* generator should be paused/yielded until the next
// such call - and being paused/yielded means it should not appear in stack
// traces.
//
// See dartbug.com/48695.
const auto& stream_iterator = Instance::Cast(callback_instance_);
if (stream_iterator.GetField(has_value_field) ==
Object::bool_true().ptr()) {
return Closure::null();
}
// If we have an await'er for `await streamIterator.moveNext()` we continue
// unwinding there.
//
// Notice: With correct async* semantics this may always contain a Future
// See also comment above as well as dartbug.com/48695.
future_ = stream_iterator.GetField(state_data_field);
if (future_.GetClassId() == future_impl_class.id()) {
return GetCallerInFutureImpl(future_);
}
return Closure::null();
}
UNREACHABLE(); // If no onData is found we have a bug.
}
ClosurePtr CallerClosureFinder::GetCallerInFutureListener(
const Object& future_listener) {
auto value = GetFutureListenerState(future_listener);
// If the _FutureListener is a `then`, `catchError`, or `whenComplete`
// listener, follow the Future being completed, `result`, instead of the
// dangling whenComplete `callback`.
if (value == k_FutureListener_stateThen ||
value == k_FutureListener_stateCatchError ||
value == k_FutureListener_stateWhenComplete) {
future_ = GetFutureListenerResult(future_listener);
return GetCallerInFutureImpl(future_);
}
// If no chained futures, fall back on _FutureListener.callback.
return GetFutureListenerCallback(future_listener);
}
ClosurePtr CallerClosureFinder::FindCallerFromSuspendState(
const SuspendState& suspend_state) {
context_entry_ = suspend_state.function_data();
if (context_entry_.GetClassId() == future_impl_class.id()) {
return GetCallerInFutureImpl(context_entry_);
} else if (context_entry_.GetClassId() ==
async_star_stream_controller_class.id()) {
return FindCallerInAsyncStarStreamController(context_entry_);
} else {
UNREACHABLE();
}
}
bool CallerClosureFinder::IsAsyncCallback(const Function& function) {
parent_function_ = function.parent_function();
auto kind = parent_function_.recognized_kind();
return (kind == MethodRecognizer::kSuspendState_createAsyncCallbacks) ||
(kind == MethodRecognizer::kSuspendState_createAsyncStarCallback);
}
SuspendStatePtr CallerClosureFinder::GetSuspendStateFromAsyncCallback(
const Closure& closure) {
ASSERT(IsAsyncCallback(Function::Handle(closure.function())));
// Async/async* handler only captures the receiver (SuspendState).
receiver_context_ = closure.context();
RELEASE_ASSERT(receiver_context_.num_variables() == 1);
return SuspendState::RawCast(receiver_context_.At(0));
}
ClosurePtr CallerClosureFinder::FindCaller(const Closure& receiver_closure) {
receiver_function_ = receiver_closure.function();
receiver_context_ = receiver_closure.context();
if (IsAsyncCallback(receiver_function_)) {
suspend_state_ = GetSuspendStateFromAsyncCallback(receiver_closure);
return FindCallerFromSuspendState(suspend_state_);
}
if (receiver_function_.HasParent()) {
parent_function_ = receiver_function_.parent_function();
if (parent_function_.recognized_kind() ==
MethodRecognizer::kFutureTimeout) {
ASSERT(IsolateGroup::Current()
->object_store()
->future_timeout_future_index() != Object::null());
const intptr_t future_index =
Smi::Value(IsolateGroup::Current()
->object_store()
->future_timeout_future_index());
context_entry_ = receiver_context_.At(future_index);
return GetCallerInFutureImpl(context_entry_);
}
if (parent_function_.recognized_kind() == MethodRecognizer::kFutureWait) {
receiver_context_ = receiver_context_.parent();
ASSERT(!receiver_context_.IsNull());
ASSERT(
IsolateGroup::Current()->object_store()->future_wait_future_index() !=
Object::null());
const intptr_t future_index = Smi::Value(
IsolateGroup::Current()->object_store()->future_wait_future_index());
context_entry_ = receiver_context_.At(future_index);
return GetCallerInFutureImpl(context_entry_);
}
}
return Closure::null();
}
ObjectPtr CallerClosureFinder::GetFutureFutureListener(const Object& future) {
ASSERT(future.GetClassId() == future_impl_class.id());
auto& listener = Object::Handle(
Instance::Cast(future).GetField(future_result_or_listeners_field));
// This field can either hold a _FutureListener, Future, or the Future result.
if (listener.GetClassId() != future_listener_class.id()) {
return Closure::null();
}
return listener.ptr();
}
intptr_t CallerClosureFinder::GetFutureListenerState(
const Object& future_listener) {
ASSERT(future_listener.GetClassId() == future_listener_class.id());
state_ =
Instance::Cast(future_listener).GetField(future_listener_state_field);
return Smi::Cast(state_).Value();
}
ClosurePtr CallerClosureFinder::GetFutureListenerCallback(
const Object& future_listener) {
ASSERT(future_listener.GetClassId() == future_listener_class.id());
return Closure::RawCast(
Instance::Cast(future_listener).GetField(callback_field));
}
ObjectPtr CallerClosureFinder::GetFutureListenerResult(
const Object& future_listener) {
ASSERT(future_listener.GetClassId() == future_listener_class.id());
return Instance::Cast(future_listener).GetField(future_listener_result_field);
}
bool CallerClosureFinder::HasCatchError(const Object& future_listener) {
ASSERT(future_listener.GetClassId() == future_listener_class.id());
listener_ = future_listener.ptr();
Object& result = Object::Handle();
// Iterate through any `.then()` chain.
while (!listener_.IsNull()) {
if (GetFutureListenerState(listener_) == k_FutureListener_stateCatchError) {
return true;
}
result = GetFutureListenerResult(listener_);
RELEASE_ASSERT(!result.IsNull());
listener_ = GetFutureFutureListener(result);
}
return false;
}
bool CallerClosureFinder::WasPreviouslySuspended(
const Function& function,
const Object& suspend_state_var) {
if (!suspend_state_var.IsSuspendState()) {
return false;
}
if (function.IsAsyncFunction()) {
// Error callback is set after both 'then' and 'error' callbacks are
// registered with the Zone. Callback registration may query
// stack trace and should still collect the synchronous stack trace.
return SuspendState::Cast(suspend_state_var).error_callback() !=
Object::null();
} else if (function.IsAsyncGenerator()) {
return true;
} else {
UNREACHABLE();
}
}
ClosurePtr StackTraceUtils::ClosureFromFrameFunction(
Zone* zone,
CallerClosureFinder* caller_closure_finder,
const DartFrameIterator& frames,
StackFrame* frame,
bool* skip_frame,
bool* is_async) {
auto& function = Function::Handle(zone);
function = frame->LookupDartFunction();
if (function.IsNull()) {
return Closure::null();
}
if (function.IsAsyncFunction() || function.IsAsyncGenerator()) {
auto& suspend_state = Object::Handle(
zone, *reinterpret_cast<ObjectPtr*>(LocalVarAddress(
frame->fp(), runtime_frame_layout.FrameSlotForVariableIndex(
SuspendState::kSuspendStateVarIndex))));
if (caller_closure_finder->WasPreviouslySuspended(function,
suspend_state)) {
*is_async = true;
return caller_closure_finder->FindCallerFromSuspendState(
SuspendState::Cast(suspend_state));
}
// Still running the sync part before the first await.
return Closure::null();
}
// May have been called from `_FutureListener.handleValue`, which means its
// receiver holds the Future chain.
DartFrameIterator future_frames(frames);
if (function.recognized_kind() == MethodRecognizer::kRootZoneRunUnary) {
frame = future_frames.NextFrame();
function = frame->LookupDartFunction();
if (function.recognized_kind() !=
MethodRecognizer::kFutureListenerHandleValue) {
return Closure::null();
}
}
if (function.recognized_kind() ==
MethodRecognizer::kFutureListenerHandleValue) {
*is_async = true;
*skip_frame = true;
// The _FutureListener receiver is at the top of the previous frame, right
// before the arguments to the call.
Object& receiver =
Object::Handle(*(reinterpret_cast<ObjectPtr*>(frame->GetCallerSp()) +
kNumArgsFutureListenerHandleValue));
if (receiver.ptr() == Symbols::OptimizedOut().ptr()) {
// In the very rare case that _FutureListener.handleValue has deoptimized
// it may override the receiver slot in the caller frame with "<optimized
// out>" due to the `this` no longer being needed.
return Closure::null();
}
return caller_closure_finder->GetCallerInFutureListener(receiver);
}
return Closure::null();
}
void StackTraceUtils::UnwindAwaiterChain(
Zone* zone,
const GrowableObjectArray& code_array,
GrowableArray<uword>* pc_offset_array,
CallerClosureFinder* caller_closure_finder,
const Closure& leaf_closure) {
auto& code = Code::Handle(zone);
auto& function = Function::Handle(zone);
auto& closure = Closure::Handle(zone, leaf_closure.ptr());
auto& pc_descs = PcDescriptors::Handle(zone);
auto& suspend_state = SuspendState::Handle(zone);
// Inject async suspension marker.
code_array.Add(StubCode::AsynchronousGapMarker());
pc_offset_array->Add(0);
// Traverse the trail of async futures all the way up.
for (; !closure.IsNull();
closure = caller_closure_finder->FindCaller(closure)) {
function = closure.function();
if (function.IsNull()) {
continue;
}
if (caller_closure_finder->IsAsyncCallback(function)) {
suspend_state =
caller_closure_finder->GetSuspendStateFromAsyncCallback(closure);
const uword pc = suspend_state.pc();
if (pc == 0) {
// Async function is already resumed.
continue;
}
code = suspend_state.GetCodeObject();
code_array.Add(code);
const uword pc_offset = pc - code.PayloadStart();
ASSERT(pc_offset > 0 && pc_offset <= code.Size());
pc_offset_array->Add(pc_offset);
} else {
// In hot-reload-test-mode we sometimes have to do this:
code = function.EnsureHasCode();
RELEASE_ASSERT(!code.IsNull());
code_array.Add(code);
pc_descs = code.pc_descriptors();
// We reached a non-async closure receiving the yielded value.
pc_offset_array->Add(0);
}
// Inject async suspension marker.
code_array.Add(StubCode::AsynchronousGapMarker());
pc_offset_array->Add(0);
}
}
void StackTraceUtils::CollectFrames(
Thread* thread,
const GrowableObjectArray& code_array,
GrowableArray<uword>* pc_offset_array,
int skip_frames,
std::function<void(StackFrame*)>* on_sync_frames,
bool* has_async) {
if (has_async != nullptr) {
*has_async = false;
}
Zone* zone = thread->zone();
DartFrameIterator frames(thread, StackFrameIterator::kNoCrossThreadIteration);
StackFrame* frame = frames.NextFrame();
// If e.g. the isolate is paused before executing anything, we might not get
// any frames at all. Bail:
if (frame == nullptr) {
return;
}
auto& code = Code::Handle(zone);
auto& closure = Closure::Handle(zone);
CallerClosureFinder caller_closure_finder(zone);
// Start by traversing the sync. part of the stack.
for (; frame != nullptr; frame = frames.NextFrame()) {
if (skip_frames > 0) {
skip_frames--;
continue;
}
// If we encounter a known part of the async/Future mechanism, unwind the
// awaiter chain from the closures.
bool skip_frame = false;
bool is_async = false;
closure = ClosureFromFrameFunction(zone, &caller_closure_finder, frames,
frame, &skip_frame, &is_async);
// This isn't a special (async) frame we should skip.
if (!skip_frame) {
// Add the current synchronous frame.
code = frame->LookupDartCode();
code_array.Add(code);
const uword pc_offset = frame->pc() - code.PayloadStart();
ASSERT(pc_offset > 0 && pc_offset <= code.Size());
pc_offset_array->Add(pc_offset);
// Callback for sync frame.
if (on_sync_frames != nullptr) {
(*on_sync_frames)(frame);
}
}
// This frame is running async.
// Note: The closure might still be null in case it's an unawaited future.
if (is_async) {
UnwindAwaiterChain(zone, code_array, pc_offset_array,
&caller_closure_finder, closure);
if (has_async != nullptr) {
*has_async = true;
}
// Ignore the rest of the stack; already unwound all async calls.
return;
}
}
return;
}
} // namespace dart