php-src/Zend/zend_gc.h

/*
   +----------------------------------------------------------------------+
   | Zend Engine                                                          |
   +----------------------------------------------------------------------+
   | Copyright (c) 1998-2017 Zend Technologies Ltd. (http://www.zend.com) |
   +----------------------------------------------------------------------+
   | This source file is subject to version 2.00 of the Zend license,     |
   | that is bundled with this package in the file LICENSE, and is        |
   | available through the world-wide-web at the following url:           |
   | http://www.zend.com/license/2_00.txt.                                |
   | If you did not receive a copy of the Zend license and are unable to  |
   | obtain it through the world-wide-web, please send a note to          |
   | license@zend.com so we can mail you a copy immediately.              |
   +----------------------------------------------------------------------+
   | Authors: David Wang <planetbeing@gmail.com>                          |
   |          Dmitry Stogov <dmitry@zend.com>                             |
   +----------------------------------------------------------------------+
*/

/* $Id$ */

#ifndef ZEND_GC_H
#define ZEND_GC_H

#ifndef GC_BENCH
# define GC_BENCH 0
#endif

#if GC_BENCH
# define GC_BENCH_INC(counter) GC_G(counter)++
# define GC_BENCH_DEC(counter) GC_G(counter)--
# define GC_BENCH_PEAK(peak, counter) do {		\
		if (GC_G(counter) > GC_G(peak)) {		\
			GC_G(peak) = GC_G(counter);			\
		}										\
	} while (0)
#else
# define GC_BENCH_INC(counter)
# define GC_BENCH_DEC(counter)
# define GC_BENCH_PEAK(peak, counter)
#endif

#define GC_COLOR  0xc000

#define GC_BLACK  0x0000
#define GC_WHITE  0x8000
#define GC_GREY   0x4000
#define GC_PURPLE 0xc000

#define GC_ADDRESS(v) \
	((v) & ~GC_COLOR)
#define GC_INFO_GET_COLOR(v) \
	(((zend_uintptr_t)(v)) & GC_COLOR)
#define GC_INFO_SET_ADDRESS(v, a) \
	do {(v) = ((v) & GC_COLOR) | (a);} while (0)
#define GC_INFO_SET_COLOR(v, c) \
	do {(v) = ((v) & ~GC_COLOR) | (c);} while (0)
#define GC_INFO_SET_BLACK(v) \
	do {(v) = (v) & ~GC_COLOR;} while (0)
#define GC_INFO_SET_PURPLE(v) \
	do {(v) = (v) | GC_COLOR;} while (0)

typedef struct _gc_root_buffer {
	zend_refcounted          *ref;
	struct _gc_root_buffer   *next;     /* double-linked list               */
	struct _gc_root_buffer   *prev;
	uint32_t                 refcount;
} gc_root_buffer;

#define GC_NUM_ADDITIONAL_ENTRIES \
	((4096 - ZEND_MM_OVERHEAD - sizeof(void*) * 2) / sizeof(gc_root_buffer))

typedef struct _gc_additional_bufer gc_additional_buffer;

struct _gc_additional_bufer {
	uint32_t              used;
	gc_additional_buffer *next;
	gc_root_buffer        buf[GC_NUM_ADDITIONAL_ENTRIES];
};

typedef struct _zend_gc_globals {
	zend_bool         gc_enabled;
	zend_bool         gc_active;
	zend_bool         gc_full;

	gc_root_buffer   *buf;				/* preallocated arrays of buffers   */
	gc_root_buffer    roots;			/* list of possible roots of cycles */
	gc_root_buffer   *unused;			/* list of unused buffers           */
	gc_root_buffer   *first_unused;		/* pointer to first unused buffer   */
	gc_root_buffer   *last_unused;		/* pointer to last unused buffer    */

	gc_root_buffer    to_free;			/* list to free                     */
	gc_root_buffer   *next_to_free;

	uint32_t gc_runs;
	uint32_t collected;

#if GC_BENCH
	uint32_t root_buf_length;
	uint32_t root_buf_peak;
	uint32_t zval_possible_root;
	uint32_t zval_buffered;
	uint32_t zval_remove_from_buffer;
	uint32_t zval_marked_grey;
#endif

	gc_additional_buffer *additional_buffer;

} zend_gc_globals;

#ifdef ZTS
BEGIN_EXTERN_C()
ZEND_API extern int gc_globals_id;
END_EXTERN_C()
#define GC_G(v) ZEND_TSRMG(gc_globals_id, zend_gc_globals *, v)
#else
#define GC_G(v) (gc_globals.v)
extern ZEND_API zend_gc_globals gc_globals;
#endif

BEGIN_EXTERN_C()
ZEND_API extern int (*gc_collect_cycles)(void);

ZEND_API void ZEND_FASTCALL gc_possible_root(zend_refcounted *ref);
ZEND_API void ZEND_FASTCALL gc_remove_from_buffer(zend_refcounted *ref);
ZEND_API void gc_globals_ctor(void);
ZEND_API void gc_globals_dtor(void);
ZEND_API void gc_init(void);
ZEND_API void gc_reset(void);

/* The default implementation of the gc_collect_cycles callback. */
ZEND_API int  zend_gc_collect_cycles(void);
END_EXTERN_C()

#define GC_REMOVE_FROM_BUFFER(p) do { \
		zend_refcounted *_p = (zend_refcounted*)(p); \
		if (GC_ADDRESS(GC_INFO(_p))) { \
			gc_remove_from_buffer(_p); \
		} \
	} while (0)

#define GC_MAY_LEAK(ref) \
	((GC_TYPE_INFO(ref) & \
		(GC_INFO_MASK | (GC_COLLECTABLE << GC_FLAGS_SHIFT))) == \
	(GC_COLLECTABLE << GC_FLAGS_SHIFT))

static zend_always_inline void gc_check_possible_root(zend_refcounted *ref)
{
	if (GC_TYPE(ref) == IS_REFERENCE) {
		zval *zv = &((zend_reference*)ref)->val;

		if (!Z_REFCOUNTED_P(zv)) {
			return;
		}
		ref = Z_COUNTED_P(zv);
	}
	if (UNEXPECTED(GC_MAY_LEAK(ref))) {
		gc_possible_root(ref);
	}
}

#endif /* ZEND_GC_H */

/*
 * Local variables:
 * tab-width: 4
 * c-basic-offset: 4
 * indent-tabs-mode: t
 * End:
 * vim600: sw=4 ts=4 fdm=marker
 * vim<600: sw=4 ts=4
 */