text: /*
   * metadata/gc-internals.h: Internal GC interface
   *
   * Author: Paolo Molaro <lupus@ximian.com>
   *
   * (C) 2002 Ximian, Inc.
   * Copyright 2012 Xamarin Inc (http://www.xamarin.com)
   * Licensed under the MIT license. See LICENSE file in the project root for full license information.
   */
  
  #ifndef __MONO_METADATA_GC_INTERNAL_H__
  #define __MONO_METADATA_GC_INTERNAL_H__
  
  #include <glib.h>
  #include <mono/utils/gc_wrapper.h>
  #include <mono/metadata/object-internals.h>
  #include <mono/metadata/threads-types.h>
  #include <mono/sgen/gc-internal-agnostic.h>
  #include <mono/utils/gc_wrapper.h>
  
  #define mono_domain_finalizers_lock(domain) mono_os_mutex_lock (&(domain)->finalizable_objects_hash_lock);
  #define mono_domain_finalizers_unlock(domain) mono_os_mutex_unlock (&(domain)->finalizable_objects_hash_lock);
  
  /* Register a memory area as a conservatively scanned GC root */
  #define MONO_GC_REGISTER_ROOT_PINNING(x,src,msg) mono_gc_register_root ((char*)&(x), sizeof(x), MONO_GC_DESCRIPTOR_NULL, (src), (msg))
  
  #define MONO_GC_UNREGISTER_ROOT(x) mono_gc_deregister_root ((char*)&(x))
  
  /*
   * Register a memory location as a root pointing to memory allocated using
   * mono_gc_alloc_fixed (). This includes MonoGHashTable.
   */
  /* The result of alloc_fixed () is not GC tracked memory */
  #define MONO_GC_REGISTER_ROOT_FIXED(x,src,msg) do { \
  	if (!mono_gc_is_moving ())				\
  		MONO_GC_REGISTER_ROOT_PINNING ((x),(src),(msg)); \
  	} while (0)
  
  /*
   * Return a GC descriptor for an array containing N pointers to memory allocated
   * by mono_gc_alloc_fixed ().
   */
  /* For SGEN, the result of alloc_fixed () is not GC tracked memory */
  #define MONO_GC_ROOT_DESCR_FOR_FIXED(n) (mono_gc_is_moving () ? mono_gc_make_root_descr_all_refs (0) : MONO_GC_DESCRIPTOR_NULL)
  
  /* Register a memory location holding a single object reference as a GC root */
  #define MONO_GC_REGISTER_ROOT_SINGLE(x,src,msg) do { \
  	g_assert (sizeof (x) == sizeof (MonoObject*)); \
  	mono_gc_register_root ((char*)&(x), sizeof(MonoObject*), mono_gc_make_root_descr_all_refs (1), (src), (msg)); \
  	} while (0)
  
  /*
   * This is used for fields which point to objects which are kept alive by other references
   * when using Boehm.
   */
  #define MONO_GC_REGISTER_ROOT_IF_MOVING(x,src,msg) do { \
  	if (mono_gc_is_moving ()) \
  		MONO_GC_REGISTER_ROOT_SINGLE(x,src,msg);		\
  } while (0)
  
  #define MONO_GC_UNREGISTER_ROOT_IF_MOVING(x) do { \
  	if (mono_gc_is_moving ()) \
  		MONO_GC_UNREGISTER_ROOT (x);			\
  } while (0)
  
  /* useful until we keep track of gc-references in corlib etc. */
  #define IS_GC_REFERENCE(class,t) (mono_gc_is_moving () ? FALSE : ((t)->type == MONO_TYPE_U && (class)->image == mono_defaults.corlib))
  
  void   mono_object_register_finalizer               (MonoObject  *obj);
  void   ves_icall_System_GC_InternalCollect          (int          generation);
  gint64 ves_icall_System_GC_GetTotalMemory           (MonoBoolean  forceCollection);
  void   ves_icall_System_GC_KeepAlive                (MonoObject  *obj);
  void   ves_icall_System_GC_ReRegisterForFinalize    (MonoObject  *obj);
  void   ves_icall_System_GC_SuppressFinalize         (MonoObject  *obj);
  void   ves_icall_System_GC_WaitForPendingFinalizers (void);
  
  MonoObject *ves_icall_System_GCHandle_GetTarget (guint32 handle);
  guint32     ves_icall_System_GCHandle_GetTargetHandle (MonoObject *obj, guint32 handle, gint32 type);
  void        ves_icall_System_GCHandle_FreeHandle (guint32 handle);
  gpointer    ves_icall_System_GCHandle_GetAddrOfPinnedObject (guint32 handle);
  void        ves_icall_System_GC_register_ephemeron_array (MonoObject *array);
  MonoObject  *ves_icall_System_GC_get_ephemeron_tombstone (void);
  
  
  extern void mono_gc_init (void);
  extern void mono_gc_base_init (void);
  extern void mono_gc_cleanup (void);
  extern void mono_gc_base_cleanup (void);
  
  /*
   * Return whenever the current thread is registered with the GC (i.e. started
   * by the GC pthread wrappers on unix.
   */
  extern gboolean mono_gc_is_gc_thread (void);
  
  extern gboolean mono_gc_is_finalizer_internal_thread (MonoInternalThread *thread);
  
  extern void mono_gc_set_stack_end (void *stack_end);
  
  /* only valid after the RECLAIM_START GC event and before RECLAIM_END
   * Not exported in public headers, but can be linked to (unsupported).
   */
  gboolean mono_object_is_alive (MonoObject* obj);
  gboolean mono_gc_is_finalizer_thread (MonoThread *thread);
  gpointer mono_gc_out_of_memory (size_t size);
  void     mono_gc_enable_events (void);
  void     mono_gc_enable_alloc_events (void);
  
  void mono_gchandle_set_target (guint32 gchandle, MonoObject *obj);
  
  /*Ephemeron functionality. Sgen only*/
  gboolean    mono_gc_ephemeron_array_add (MonoObject *obj);
  
  MonoBoolean
  mono_gc_GCHandle_CheckCurrentDomain (guint32 gchandle);
  
  /* User defined marking function */
  /* It should work like this:
   * foreach (ref in GC references in the are structure pointed to by ADDR)
   *    mark_func (ref)
   */
  typedef void (*MonoGCMarkFunc)     (MonoObject **addr, void *gc_data);
  typedef void (*MonoGCRootMarkFunc) (void *addr, MonoGCMarkFunc mark_func, void *gc_data);
  
  /* Create a descriptor with a user defined marking function */
  MonoGCDescriptor mono_gc_make_root_descr_user (MonoGCRootMarkFunc marker);
  
  /* Return whenever user defined marking functions are supported */
  gboolean mono_gc_user_markers_supported (void);
  
  /* desc is the result from mono_gc_make_descr*. A NULL value means
   * all the words might contain GC pointers.
   * The memory is non-moving and it will be explicitly deallocated.
   * size bytes will be available from the returned address (ie, descr
   * must not be stored in the returned memory)
   * NOTE: Under Boehm, this returns memory allocated using GC_malloc, so the result should
   * be stored into a location registered using MONO_GC_REGISTER_ROOT_FIXED ().
   */
  void* mono_gc_alloc_fixed            (size_t size, MonoGCDescriptor descr, MonoGCRootSource source, const char *msg);
  void  mono_gc_free_fixed             (void* addr);
  
  /* make sure the gchandle was allocated for an object in domain */
  gboolean mono_gchandle_is_in_domain (guint32 gchandle, MonoDomain *domain);
  void     mono_gchandle_free_domain  (MonoDomain *domain);
  
  typedef void (*FinalizerThreadCallback) (gpointer user_data);
  
  void* mono_gc_alloc_pinned_obj (MonoVTable *vtable, size_t size);
  void* mono_gc_alloc_obj (MonoVTable *vtable, size_t size);
  void* mono_gc_alloc_vector (MonoVTable *vtable, size_t size, uintptr_t max_length);
  void* mono_gc_alloc_array (MonoVTable *vtable, size_t size, uintptr_t max_length, uintptr_t bounds_size);
  void* mono_gc_alloc_string (MonoVTable *vtable, size_t size, gint32 len);
  void* mono_gc_alloc_mature (MonoVTable *vtable, size_t size);
  MonoGCDescriptor mono_gc_make_descr_for_string (gsize *bitmap, int numbits);
  
  void  mono_gc_register_for_finalization (MonoObject *obj, void *user_data);
  void  mono_gc_add_memory_pressure (gint64 value);
  MONO_API int   mono_gc_register_root (char *start, size_t size, MonoGCDescriptor descr, MonoGCRootSource source, const char *msg);
  void  mono_gc_deregister_root (char* addr);
  void  mono_gc_finalize_domain (MonoDomain *domain);
  void  mono_gc_run_finalize (void *obj, void *data);
  void  mono_gc_clear_domain (MonoDomain * domain);
  /* Signal early termination of finalizer processing inside the gc */
  void  mono_gc_suspend_finalizers (void);
  
  
  /* 
   * Register a root which can only be written using a write barrier.
   * Writes to the root must be done using a write barrier (MONO_ROOT_SETREF).
   * If the root uses an user defined mark routine, the writes are not required to be
   * to the area between START and START+SIZE.
   * The write barrier allows the GC to avoid scanning this root at each collection, so it
   * is more efficient.
   * FIXME: Add an API for clearing remset entries if a root with a user defined
   * mark routine is deleted.
   */
  int mono_gc_register_root_wbarrier (char *start, size_t size, MonoGCDescriptor descr, MonoGCRootSource source, const char *msg);
  
  void mono_gc_wbarrier_set_root (gpointer ptr, MonoObject *value);
  
  /* Set a field of a root registered using mono_gc_register_root_wbarrier () */
  #define MONO_ROOT_SETREF(s,fieldname,value) do {	\
  	mono_gc_wbarrier_set_root (&((s)->fieldname), (MonoObject*)value); \
  } while (0)
  
  void  mono_gc_finalize_threadpool_threads (void);
  
  /* fast allocation support */
  
  typedef enum {
  	// Regular fast path allocator.
  	MANAGED_ALLOCATOR_REGULAR,
  	// Managed allocator that just calls into the runtime. Used when allocation profiling w/ AOT.
  	MANAGED_ALLOCATOR_SLOW_PATH,
  } ManagedAllocatorVariant;
  
  int mono_gc_get_aligned_size_for_allocator (int size);
  MonoMethod* mono_gc_get_managed_allocator (MonoClass *klass, gboolean for_box, gboolean known_instance_size);
  MonoMethod* mono_gc_get_managed_array_allocator (MonoClass *klass);
  MonoMethod *mono_gc_get_managed_allocator_by_type (int atype, ManagedAllocatorVariant variant);
  
  guint32 mono_gc_get_managed_allocator_types (void);
  
  /* Return a short string identifying the GC, indented to be saved in AOT images */
  const char *mono_gc_get_gc_name (void);
  
  /* Fast write barriers */
  MonoMethod* mono_gc_get_specific_write_barrier (gboolean is_concurrent);
  MonoMethod* mono_gc_get_write_barrier (void);
  
  /* Fast valuetype copy */
  void mono_gc_wbarrier_value_copy_bitmap (gpointer dest, gpointer src, int size, unsigned bitmap);
  
  /* helper for the managed alloc support */
  MonoString *
  ves_icall_string_alloc (int length);
  
  /* 
   * Functions supplied by the runtime and called by the GC. Currently only used
   * by SGEN.
   */
  typedef struct {
  	/* 
  	 * Function called during thread startup/attach to allocate thread-local data 
  	 * needed by the other functions.
  	 */
  	gpointer (*thread_attach_func) (void);
  	/* 
  	 * Function called during thread deatch to free the data allocated by
  	 * thread_attach_func.
  	 */
  	void (*thread_detach_func) (gpointer user_data);
  	/* 
  	 * Function called from every thread when suspending for GC. It can save
  	 * data needed for marking from thread stacks. user_data is the data returned 
  	 * by attach_func. This might called with GC locks held and the word stopped,
  	 * so it shouldn't do any synchronization etc.
  	 */
  	void (*thread_suspend_func) (gpointer user_data, void *sigcontext, MonoContext *ctx);
  	/* 
  	 * Function called to mark from thread stacks. user_data is the data returned 
  	 * by attach_func. This is called twice, with the word stopped:
  	 * - in the first pass, it should mark areas of the stack using
  	 *   conservative marking by calling mono_gc_conservatively_scan_area ().
  	 * - in the second pass, it should mark the remaining areas of the stack
  	 *   using precise marking by calling mono_gc_scan_object ().
  	 */
  	void (*thread_mark_func) (gpointer user_data, guint8 *stack_start, guint8 *stack_end, gboolean precise, void *gc_data);
  	/*
  	 * Function called for debugging to get the current managed method for
  	 * tracking the provenances of objects.
  	 */
  	gpointer (*get_provenance_func) (void);
  } MonoGCCallbacks;
  
  /* Set the callback functions callable by the GC */
  void mono_gc_set_gc_callbacks (MonoGCCallbacks *callbacks);
  MonoGCCallbacks *mono_gc_get_gc_callbacks (void);
  
  /* Functions callable from the thread mark func */
  
  /* Scan the memory area between START and END conservatively */
  void mono_gc_conservatively_scan_area (void *start, void *end);
  
  /* Scan OBJ, returning its new address */
  void *mono_gc_scan_object (void *obj, void *gc_data);
  
  /* Return the suspend signal number used by the GC to suspend threads,
     or -1 if not applicable. */
  int mono_gc_get_suspend_signal (void);
  
  /* Return the suspend signal number used by the GC to suspend threads,
     or -1 if not applicable. */
  int mono_gc_get_restart_signal (void);
  
  /*
   * Return a human readable description of the GC in malloc-ed memory.
   */
  char* mono_gc_get_description (void);
  
  /*
   * Configure the GC to desktop mode
   */
  void mono_gc_set_desktop_mode (void);
  
  /*
   * Return whenever this GC can move objects
   */
  gboolean mono_gc_is_moving (void);
  
  typedef void* (*MonoGCLockedCallbackFunc) (void *data);
  
  void* mono_gc_invoke_with_gc_lock (MonoGCLockedCallbackFunc func, void *data);
  
  int mono_gc_get_los_limit (void);
  
  guint8* mono_gc_get_card_table (int *shift_bits, gpointer *card_mask);
  gboolean mono_gc_card_table_nursery_check (void);
  
  void* mono_gc_get_nursery (int *shift_bits, size_t *size);
  
  void mono_gc_set_current_thread_appdomain (MonoDomain *domain);
  
  void mono_gc_set_skip_thread (gboolean skip);
  
  #ifndef HOST_WIN32
  int mono_gc_pthread_create (pthread_t *new_thread, const pthread_attr_t *attr, void *(*start_routine)(void *), void *arg);
  #endif
  
  /*
   * Return whenever GC is disabled
   */
  gboolean mono_gc_is_disabled (void);
  
  /*
   * Return whenever this is the null GC
   */
  gboolean mono_gc_is_null (void);
  
  void mono_gc_set_string_length (MonoString *str, gint32 new_length);
  
  #if defined(__MACH__)
  void mono_gc_register_mach_exception_thread (pthread_t thread);
  pthread_t mono_gc_get_mach_exception_thread (void);
  #endif
  
  gboolean mono_gc_precise_stack_mark_enabled (void);
  
  typedef struct _RefQueueEntry RefQueueEntry;
  
  struct _RefQueueEntry {
  	void *dis_link;
  	guint32 gchandle;
  	MonoDomain *domain;
  	void *user_data;
  	RefQueueEntry *next;
  };
  
  struct _MonoReferenceQueue {
  	RefQueueEntry *queue;
  	mono_reference_queue_callback callback;
  	MonoReferenceQueue *next;
  	gboolean should_be_deleted;
  };
  
  enum {
  	MONO_GC_FINALIZER_EXTENSION_VERSION = 1,
  };
  
  typedef struct {
  	int version;
  	gboolean (*is_class_finalization_aware) (MonoClass *klass);
  	void (*object_queued_for_finalization) (MonoObject *object);
  } MonoGCFinalizerCallbacks;
  
  MONO_API void mono_gc_register_finalizer_callbacks (MonoGCFinalizerCallbacks *callbacks);
  
  
  #ifdef HOST_WIN32
  BOOL APIENTRY mono_gc_dllmain (HMODULE module_handle, DWORD reason, LPVOID reserved);
  #endif
  
  guint mono_gc_get_vtable_bits (MonoClass *klass);
  
  void mono_gc_register_altstack (gpointer stack, gint32 stack_size, gpointer altstack, gint32 altstack_size);
  
  /* If set, print debugging messages around finalizers. */
  extern gboolean log_finalizers;
  
  /* If set, do not run finalizers. */
  extern gboolean mono_do_not_finalize;
  /* List of names of classes not to finalize. */
  extern gchar **mono_do_not_finalize_class_names;
  
  #endif /* __MONO_METADATA_GC_INTERNAL_H__ */
  
  