thread_state.h

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// Copyright (c) 2019, 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_STATE_H_
#define RUNTIME_VM_THREAD_STATE_H_
 
#include "include/dart_api.h"
#include "vm/os_thread.h"
 
namespace dart {
 
class HandleScope;
class LongJumpScope;
class Zone;
 
// ThreadState is a container for auxiliary thread-local state: e.g. it
// owns a stack of Zones for allocation and a stack of StackResources
// for stack unwinding.
//
// Important: this class is shared between compiler and runtime and
// as such it should not expose any runtime internals due to layering
// restrictions.
class ThreadState : public BaseThread {
 public:
  // The currently executing thread, or nullptr if not yet initialized.
  static ThreadState* Current() { return OSThread::CurrentVMThread(); }
 
  explicit ThreadState(bool is_os_thread);
  virtual ~ThreadState();
 
  // OSThread corresponding to this thread.
  OSThread* os_thread() const { return os_thread_; }
  void set_os_thread(OSThread* os_thread) { os_thread_ = os_thread; }
 
  // The topmost zone used for allocation in this thread.
  Zone* zone() const { return zone_; }
 
  bool ZoneIsOwnedByThread(Zone* zone) const;
 
  StackResource* top_resource() const { return top_resource_; }
  void set_top_resource(StackResource* value) { top_resource_ = value; }
  static intptr_t top_resource_offset() {
    return OFFSET_OF(ThreadState, top_resource_);
  }
 
  LongJumpScope* long_jump_base() const { return long_jump_base_; }
  void set_long_jump_base(LongJumpScope* value) { long_jump_base_ = value; }
 
  bool IsValidZoneHandle(Dart_Handle object) const;
  intptr_t CountZoneHandles() const;
  bool IsValidScopedHandle(Dart_Handle object) const;
  intptr_t CountScopedHandles() const;
 
  virtual bool MayAllocateHandles() = 0;
 
  HandleScope* top_handle_scope() const {
#if defined(DEBUG)
    return top_handle_scope_;
#else
    return 0;
#endif
  }
 
  void set_top_handle_scope(HandleScope* handle_scope) {
#if defined(DEBUG)
    top_handle_scope_ = handle_scope;
#endif
  }
 
 private:
  void set_zone(Zone* zone) { zone_ = zone; }
 
  OSThread* os_thread_ = nullptr;
  Zone* zone_ = nullptr;
  StackResource* top_resource_ = nullptr;
  LongJumpScope* long_jump_base_ = nullptr;
 
  // This field is only used in the DEBUG builds, but we don't exclude it
  // because it would cause RELEASE and DEBUG builds to have different
  // offsets for various Thread fields that are used from generated code.
  HandleScope* top_handle_scope_ = nullptr;
 
  friend class ApiZone;
  friend class StackZone;
};
 
}  // namespace dart
 
#endif  // RUNTIME_VM_THREAD_STATE_H_