// 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_(), active_list_(NULL), free_list_(NULL) {}
  ~ThreadRegistry();

  void VisitObjectPointers(IsolateGroup* isolate_group_of_interest,
                           ObjectPointerVisitor* visitor,
                           ValidationPolicy validate_frames);

  void ReleaseStoreBuffers();
  void AcquireMarkingStacks();
  void ReleaseMarkingStacks();

#ifndef PRODUCT
  void PrintJSON(JSONStream* stream) const;
#endif

 private:
  Thread* active_list() const { return active_list_; }
  Monitor* threads_lock() const { return &threads_lock_; }

  Thread* GetFreeThreadLocked(bool is_vm_isolate);
  void ReturnThreadLocked(Thread* thread);
  void AddToActiveListLocked(Thread* thread);
  void RemoveFromActiveListLocked(Thread* thread);
  Thread* GetFromFreelistLocked(bool is_vm_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.
  mutable 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.

  friend class Isolate;
  friend class IsolateGroup;
  friend class SafepointHandler;
  friend class Scavenger;
  DISALLOW_COPY_AND_ASSIGN(ThreadRegistry);
};

}  // namespace dart

#endif  // RUNTIME_VM_THREAD_REGISTRY_H_