/*
 * Copyright (c) 2007-2011 by Hewlett-Packard Company. All rights reserved.
 *
 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
 * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
 *
 * Permission is hereby granted to use or copy this program
 * for any purpose, provided the above notices are retained on all copies.
 * Permission to modify the code and to distribute modified code is granted,
 * provided the above notices are retained, and a notice that the code was
 * modified is included with the above copyright notice.
 */

#ifndef GC_DISCLAIM_H
#define GC_DISCLAIM_H

#include "gc.h"

#ifdef __cplusplus
extern "C" {
#endif

/*
 * This API is defined only if the library has been suitably compiled
 * (i.e. with `ENABLE_DISCLAIM` macro defined).
 */

/**
 * Prepare the object kind used by `GC_finalized_malloc`.  Call it from
 * your initialization code or, at least, at some point before using
 * finalized allocations.  The function is thread-safe.
 */
GC_API void GC_CALL GC_init_finalized_malloc(void);

/** Type of a disclaim callback.  Called with the allocator lock held. */
typedef int(GC_CALLBACK *GC_disclaim_proc)(void * /* `obj` */);

/**
 * Register `proc` to be called on each object (of given `kind`) ready
 * to be reclaimed.  If `proc()` returns a nonzero value, the
 * collector will not reclaim the object on this collection cycle
 * (`proc()` should not try to resurrect the object otherwise); objects
 * reachable from `proc()` (including the referred closure object) will
 * be protected from collection if `mark_from_all` is nonzero, but at
 * the expense that long chains of objects will take many cycles to
 * reclaim.  Any call to `GC_free()` deallocates the object (pointed by
 * the argument) without inquiring `proc()`.  Acquires the allocator lock.
 * No-op in the find-leak mode.
 */
GC_API void GC_CALL GC_register_disclaim_proc(int /* `kind` */,
                                              GC_disclaim_proc /* `proc` */,
                                              int /* `mark_from_all` */);

/** The finalizer closure used by `GC_finalized_malloc`. */
struct GC_finalizer_closure {
  GC_finalization_proc proc;
  void *cd;
};

/**
 * Allocate an object which is to be finalized by the given closure.
 * This uses a dedicated object kind with a disclaim procedure, and
 * is more efficient than `GC_register_finalizer` and friends.
 * `GC_init_finalized_malloc` must be called before using this.
 * The collector will reclaim the object during this collection cycle
 * (thus, `fc->proc()` should not try to resurrect the object).
 * The other objects reachable from `fc->proc()` (including the closure
 * object in case it is a heap-allocated one) will be protected from
 * collection.  Note that `GC_size()` (applied to such allocated object)
 * returns a value slightly bigger than the specified allocation size,
 * and that `GC_base()` result points to a "pointer-sized" word prior
 * to the start of the allocated object.
 * The disclaim procedure is not invoked in the find-leak mode.
 * There is no debugging variant of this allocation function.
 */
GC_API GC_ATTR_MALLOC GC_ATTR_ALLOC_SIZE(1) void *GC_CALL
    GC_finalized_malloc(size_t /* `size` */,
                        const struct GC_finalizer_closure * /* `fc` */)
        GC_ATTR_NONNULL(2);

#ifdef __cplusplus
} /* extern "C" */
#endif

#endif