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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 VM_THREAD_H_
#define VM_THREAD_H_
#include "vm/base_isolate.h"
#include "vm/globals.h"
#include "vm/os_thread.h"
namespace dart {
class CHA;
class Isolate;
// A VM thread; may be executing Dart code or performing helper tasks like
// garbage collection or compilation. The Thread structure associated with
// a thread is allocated by EnsureInit before entering an isolate, and destroyed
// automatically when the underlying OS thread exits. NOTE: On Windows, CleanUp
// must currently be called manually (issue 23474).
class Thread {
// The currently executing thread, or NULL if not yet initialized.
static Thread* Current() {
return reinterpret_cast<Thread*>(OSThread::GetThreadLocal(thread_key_));
// Initializes the current thread as a VM thread, if not already done.
static void EnsureInit();
// Makes the current thread enter 'isolate'.
static void EnterIsolate(Isolate* isolate);
// Makes the current thread exit its isolate.
static void ExitIsolate();
// A VM thread other than the main mutator thread can enter an isolate as a
// "helper" to gain limited concurrent access to the isolate. One example is
// SweeperTask (which uses the class table, which is copy-on-write).
// TODO(koda): Properly synchronize heap access to expand allowed operations.
static void EnterIsolateAsHelper(Isolate* isolate);
static void ExitIsolateAsHelper();
#if defined(TARGET_OS_WINDOWS)
// Clears the state of the current thread and frees the allocation.
static void CleanUp();
// Called at VM startup.
static void InitOnce();
// The topmost zone used for allocation in this thread.
Zone* zone() {
return reinterpret_cast<BaseIsolate*>(isolate())->current_zone();
// The isolate that this thread is operating on, or NULL if none.
Isolate* isolate() const { return isolate_; }
// The (topmost) CHA for the compilation in the isolate of this thread.
// TODO(23153): Move this out of Isolate/Thread.
CHA* cha() const;
void set_cha(CHA* value);
static ThreadLocalKey thread_key_;
Isolate* isolate_;
: isolate_(NULL) {}
static void SetCurrent(Thread* current);
} // namespace dart
#endif // VM_THREAD_H_