dart-sdk/runtime/vm/thread_registry.h
John McCutchan a0ee5b24db Track async causal stack traces
This CL improves the stack traces that accompany exceptions. Whenever an
async function is entered, we remember how we got there. This is similar
in spirit to package:stack_trace but the implementation is more efficient
and memory usage can be more easily reasoned about.

Tracking causal stack traces:

- [x] Upon entry to an async function, capture the synchronous stack trace prefix and store it into the closure.
- [x] Upon entry to an async* function, capture the synchronous stack trace prefix and store it into the closure.
- [x] Before returning from an async function, clear the Thread's asynchronous stack trace.
- [x] After resuming an async function, load the sychronous stack trace prefix into the Thread.
- [x] Filter stack traces to remove async machinery.

Service protocol changes:

- [x] Send causal async stack trace.

Observatory changes:

- [x] Display causal async stack trace below async functions.

Fixes https://github.com/dart-lang/sdk/issues/27661

R=asiva@google.com, rmacnak@google.com

Comparisons: https://docs.google.com/a/google.com/document/d/10r6jEqr8OCiDZ4y9SYU_uOimcHiOGAZMly2ghTErALI/edit?usp=sharing
Review-Url: https://codereview.chromium.org/2646443005 .
2017-02-09 15:39:44 -08:00

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// Copyright (c) 2015, 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.
#ifndef RUNTIME_VM_THREAD_REGISTRY_H_
#define RUNTIME_VM_THREAD_REGISTRY_H_
#include "vm/globals.h"
#include "vm/growable_array.h"
#include "vm/isolate.h"
#include "vm/lockers.h"
#include "vm/stack_frame.h"
#include "vm/thread.h"
namespace dart {
#ifndef PRODUCT
class JSONStream;
class JSONArray;
#endif
// Unordered collection of threads relating to a particular isolate.
class ThreadRegistry {
public:
ThreadRegistry()
: threads_lock_(new Monitor()),
active_list_(NULL),
free_list_(NULL),
mutator_thread_(NULL) {}
~ThreadRegistry();
void VisitObjectPointers(ObjectPointerVisitor* visitor, bool validate_frames);
void PrepareForGC();
Thread* mutator_thread() const { return mutator_thread_; }
#ifndef PRODUCT
void PrintJSON(JSONStream* stream) const;
#endif
// Calculates the sum of the max memory usage in bytes of each thread.
uintptr_t ThreadHighWatermarksTotalLocked() const;
intptr_t CountZoneHandles() const;
intptr_t CountScopedHandles() const;
private:
Thread* active_list() const { return active_list_; }
Monitor* threads_lock() const { return threads_lock_; }
Thread* GetFreeThreadLocked(Isolate* isolate, bool is_mutator);
void ReturnThreadLocked(bool is_mutator, Thread* thread);
void AddToActiveListLocked(Thread* thread);
void RemoveFromActiveListLocked(Thread* thread);
Thread* GetFromFreelistLocked(Isolate* isolate);
void ReturnToFreelistLocked(Thread* thread);
// This monitor protects the threads list for an isolate, it is used whenever
// we need to iterate over threads (both active and free) in an isolate.
Monitor* threads_lock_;
Thread* active_list_; // List of active threads in the isolate.
Thread* free_list_; // Free list of Thread objects that can be reused.
// TODO(asiva): Currently we treat a mutator thread as a special thread
// and always schedule execution of Dart code on the same mutator thread
// object. The ApiLocalScope has been made thread specific but we still
// have scenarios where we do a temporary exit of an Isolate with live
// zones/handles in the API scope :
// - Dart_RunLoop()
// - IsolateSaver in Dart_NewNativePort
// - Isolate spawn (function/uri) under FLAG_i_like_slow_isolate_spawn
// Similarly, tracking async_stack_trace requires that we always reschedule
// on the same thread.
// We probably need a mechanism to return to the specific thread only
// for these specific cases. We should also determine if the embedder
// should allow exiting an isolate with live state in zones/handles in
// which case a new API for returning to the specific thread needs to be
// added.
Thread* mutator_thread_;
friend class Isolate;
friend class SafepointHandler;
DISALLOW_COPY_AND_ASSIGN(ThreadRegistry);
};
} // namespace dart
#endif // RUNTIME_VM_THREAD_REGISTRY_H_