root/Zend/zend_gc.c

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DEFINITIONS

This source file includes following definitions.
  1. root_buffer_dtor
  2. gc_globals_ctor_ex
  3. gc_globals_ctor
  4. gc_globals_dtor
  5. gc_reset
  6. gc_init
  7. gc_zval_possible_root
  8. gc_zobj_possible_root
  9. gc_remove_zval_from_buffer
  10. zval_scan_black
  11. zobj_scan_black
  12. zval_mark_grey
  13. zobj_mark_grey
  14. gc_mark_roots
  15. zval_scan
  16. zobj_scan
  17. gc_scan_roots
  18. zval_collect_white
  19. zobj_collect_white
  20. gc_collect_roots
  21. gc_collect_cycles

/*
   +----------------------------------------------------------------------+
   | Zend Engine                                                          |
   +----------------------------------------------------------------------+
   | Copyright (c) 1998-2013 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>                             |
   +----------------------------------------------------------------------+
*/

/* $Id$ */

#include "zend.h"
#include "zend_API.h"

#define GC_ROOT_BUFFER_MAX_ENTRIES 10000

#ifdef ZTS
ZEND_API int gc_globals_id;
#else
ZEND_API zend_gc_globals gc_globals;
#endif

static void root_buffer_dtor(zend_gc_globals *gc_globals TSRMLS_DC)
{
        if (gc_globals->buf) {
                free(gc_globals->buf);
                gc_globals->buf = NULL;
        }       
}

static void gc_globals_ctor_ex(zend_gc_globals *gc_globals TSRMLS_DC)
{
        gc_globals->gc_enabled = 0;
        gc_globals->gc_active = 0;

        gc_globals->buf = NULL;

        gc_globals->roots.next = &gc_globals->roots;
        gc_globals->roots.prev = &gc_globals->roots;
        gc_globals->unused = NULL;
        gc_globals->zval_to_free = NULL;
        gc_globals->free_list = NULL;
        gc_globals->next_to_free = NULL;

        gc_globals->gc_runs = 0;
        gc_globals->collected = 0;

#if GC_BENCH
        gc_globals->root_buf_length = 0;
        gc_globals->root_buf_peak = 0;
        gc_globals->zval_possible_root = 0;
        gc_globals->zobj_possible_root = 0;
        gc_globals->zval_buffered = 0;
        gc_globals->zobj_buffered = 0;
        gc_globals->zval_remove_from_buffer = 0;
        gc_globals->zobj_remove_from_buffer = 0;
        gc_globals->zval_marked_grey = 0;
        gc_globals->zobj_marked_grey = 0;
#endif
}

ZEND_API void gc_globals_ctor(TSRMLS_D)
{
#ifdef ZTS
        ts_allocate_id(&gc_globals_id, sizeof(zend_gc_globals), (ts_allocate_ctor) gc_globals_ctor_ex, (ts_allocate_dtor) root_buffer_dtor);
#else
        gc_globals_ctor_ex(&gc_globals);
#endif
}

ZEND_API void gc_globals_dtor(TSRMLS_D)
{
#ifndef ZTS
        root_buffer_dtor(&gc_globals TSRMLS_DC);
#endif
}

ZEND_API void gc_reset(TSRMLS_D)
{
        GC_G(gc_runs) = 0;
        GC_G(collected) = 0;

#if GC_BENCH
        GC_G(root_buf_length) = 0;
        GC_G(root_buf_peak) = 0;
        GC_G(zval_possible_root) = 0;
        GC_G(zobj_possible_root) = 0;
        GC_G(zval_buffered) = 0;
        GC_G(zobj_buffered) = 0;
        GC_G(zval_remove_from_buffer) = 0;
        GC_G(zobj_remove_from_buffer) = 0;
        GC_G(zval_marked_grey) = 0;
        GC_G(zobj_marked_grey) = 0;
#endif

        GC_G(roots).next = &GC_G(roots);
        GC_G(roots).prev = &GC_G(roots);

        if (GC_G(buf)) {
                GC_G(unused) = NULL;
                GC_G(first_unused) = GC_G(buf);

                GC_G(zval_to_free) = NULL;
        } else {
                GC_G(unused) = NULL;
                GC_G(first_unused) = NULL;
                GC_G(last_unused) = NULL;
        }
}

ZEND_API void gc_init(TSRMLS_D)
{
        if (GC_G(buf) == NULL && GC_G(gc_enabled)) {
                GC_G(buf) = (gc_root_buffer*) malloc(sizeof(gc_root_buffer) * GC_ROOT_BUFFER_MAX_ENTRIES);
                GC_G(last_unused) = &GC_G(buf)[GC_ROOT_BUFFER_MAX_ENTRIES];
                gc_reset(TSRMLS_C);
        }
}

ZEND_API void gc_zval_possible_root(zval *zv TSRMLS_DC)
{
        if (UNEXPECTED(GC_G(free_list) != NULL &&
                       GC_ZVAL_ADDRESS(zv) != NULL &&
                           GC_ZVAL_GET_COLOR(zv) == GC_BLACK) &&
                           (GC_ZVAL_ADDRESS(zv) < GC_G(buf) ||
                            GC_ZVAL_ADDRESS(zv) >= GC_G(last_unused))) {
                /* The given zval is a garbage that is going to be deleted by
                 * currently running GC */
                return;
        }

        if (zv->type == IS_OBJECT) {
                GC_ZOBJ_CHECK_POSSIBLE_ROOT(zv);
                return;
        }

        GC_BENCH_INC(zval_possible_root);

        if (GC_ZVAL_GET_COLOR(zv) != GC_PURPLE) {
                GC_ZVAL_SET_PURPLE(zv);

                if (!GC_ZVAL_ADDRESS(zv)) {
                        gc_root_buffer *newRoot = GC_G(unused);

                        if (newRoot) {
                                GC_G(unused) = newRoot->prev;
                        } else if (GC_G(first_unused) != GC_G(last_unused)) {
                                newRoot = GC_G(first_unused);
                                GC_G(first_unused)++;
                        } else {
                                if (!GC_G(gc_enabled)) {
                                        GC_ZVAL_SET_BLACK(zv);
                                        return;
                                }
                                zv->refcount__gc++;
                                gc_collect_cycles(TSRMLS_C);
                                zv->refcount__gc--;
                                newRoot = GC_G(unused);
                                if (!newRoot) {
                                        return;
                                }
                                GC_ZVAL_SET_PURPLE(zv);
                                GC_G(unused) = newRoot->prev;
                        }

                        newRoot->next = GC_G(roots).next;
                        newRoot->prev = &GC_G(roots);
                        GC_G(roots).next->prev = newRoot;
                        GC_G(roots).next = newRoot;

                        GC_ZVAL_SET_ADDRESS(zv, newRoot);

                        newRoot->handle = 0;
                        newRoot->u.pz = zv;

                        GC_BENCH_INC(zval_buffered);
                        GC_BENCH_INC(root_buf_length);
                        GC_BENCH_PEAK(root_buf_peak, root_buf_length);
                }
        }
}

ZEND_API void gc_zobj_possible_root(zval *zv TSRMLS_DC)
{
        struct _store_object *obj;

        if (UNEXPECTED(Z_OBJ_HT_P(zv)->get_gc == NULL ||
            EG(objects_store).object_buckets == NULL)) {
                return;
        }

        GC_BENCH_INC(zobj_possible_root);

        obj = &EG(objects_store).object_buckets[Z_OBJ_HANDLE_P(zv)].bucket.obj;
        if (GC_GET_COLOR(obj->buffered) != GC_PURPLE) {
                GC_SET_PURPLE(obj->buffered);
                if (!GC_ADDRESS(obj->buffered)) {
                        gc_root_buffer *newRoot = GC_G(unused);

                        if (newRoot) {
                                GC_G(unused) = newRoot->prev;
                        } else if (GC_G(first_unused) != GC_G(last_unused)) {
                                newRoot = GC_G(first_unused);
                                GC_G(first_unused)++;
                        } else {
                                if (!GC_G(gc_enabled)) {
                                        GC_ZVAL_SET_BLACK(zv);
                                        return;
                                }
                                zv->refcount__gc++;
                                gc_collect_cycles(TSRMLS_C);
                                zv->refcount__gc--;
                                newRoot = GC_G(unused);
                                if (!newRoot) {
                                        return;
                                }
                                obj = &EG(objects_store).object_buckets[Z_OBJ_HANDLE_P(zv)].bucket.obj;
                                GC_SET_PURPLE(obj->buffered);
                                GC_G(unused) = newRoot->prev;
                        }

                        newRoot->next = GC_G(roots).next;
                        newRoot->prev = &GC_G(roots);
                        GC_G(roots).next->prev = newRoot;
                        GC_G(roots).next = newRoot;

                        GC_SET_ADDRESS(obj->buffered, newRoot);

                        newRoot->handle = Z_OBJ_HANDLE_P(zv);
                        newRoot->u.handlers = Z_OBJ_HT_P(zv);

                        GC_BENCH_INC(zobj_buffered);
                        GC_BENCH_INC(root_buf_length);
                        GC_BENCH_PEAK(root_buf_peak, root_buf_length);
                }
        }
}

ZEND_API void gc_remove_zval_from_buffer(zval *zv TSRMLS_DC)
{
        gc_root_buffer* root_buffer = GC_ADDRESS(((zval_gc_info*)zv)->u.buffered);

        if (UNEXPECTED(GC_G(free_list) != NULL &&
                           GC_ZVAL_GET_COLOR(zv) == GC_BLACK) &&
                           (GC_ZVAL_ADDRESS(zv) < GC_G(buf) ||
                            GC_ZVAL_ADDRESS(zv) >= GC_G(last_unused))) {
                /* The given zval is a garbage that is going to be deleted by
                 * currently running GC */
                if (GC_G(next_to_free) == (zval_gc_info*)zv) {
                        GC_G(next_to_free) = ((zval_gc_info*)zv)->u.next;
                }
                return;
        }
        GC_BENCH_INC(zval_remove_from_buffer);
        GC_REMOVE_FROM_BUFFER(root_buffer);
        ((zval_gc_info*)zv)->u.buffered = NULL;
}

static void zval_scan_black(zval *pz TSRMLS_DC)
{
        Bucket *p;

tail_call:
        p = NULL;
        GC_ZVAL_SET_BLACK(pz);

        if (Z_TYPE_P(pz) == IS_OBJECT && EG(objects_store).object_buckets) {
                zend_object_get_gc_t get_gc;
                struct _store_object *obj = &EG(objects_store).object_buckets[Z_OBJ_HANDLE_P(pz)].bucket.obj;

                obj->refcount++;
                if (GC_GET_COLOR(obj->buffered) != GC_BLACK) {
                        GC_SET_BLACK(obj->buffered);
                        if (EXPECTED(EG(objects_store).object_buckets[Z_OBJ_HANDLE_P(pz)].valid &&
                                     (get_gc = Z_OBJ_HANDLER_P(pz, get_gc)) != NULL)) {
                                int i, n;
                                zval **table;
                                HashTable *props = get_gc(pz, &table, &n TSRMLS_CC);

                                while (n > 0 && !table[n-1]) n--;
                                for (i = 0; i < n; i++) {
                                        if (table[i]) {
                                                pz = table[i];
                                                if (Z_TYPE_P(pz) != IS_ARRAY || Z_ARRVAL_P(pz) != &EG(symbol_table)) {
                                                        pz->refcount__gc++;
                                                }
                                                if (GC_ZVAL_GET_COLOR(pz) != GC_BLACK) {
                                                        if (!props && i == n - 1) {
                                                                goto tail_call;
                                                        } else {
                                                                zval_scan_black(pz TSRMLS_CC);
                                                        }
                                                }
                                        }
                                }
                                if (!props) {
                                        return;
                                }
                                p = props->pListHead;
                        }
                }
        } else if (Z_TYPE_P(pz) == IS_ARRAY) {
                if (Z_ARRVAL_P(pz) != &EG(symbol_table)) {
                        p = Z_ARRVAL_P(pz)->pListHead;
                }
        }
        while (p != NULL) {
                pz = *(zval**)p->pData;
                if (Z_TYPE_P(pz) != IS_ARRAY || Z_ARRVAL_P(pz) != &EG(symbol_table)) {
                        pz->refcount__gc++;
                }
                if (GC_ZVAL_GET_COLOR(pz) != GC_BLACK) {
                        if (p->pListNext == NULL) {
                                goto tail_call;
                        } else {
                                zval_scan_black(pz TSRMLS_CC);
                        }
                }
                p = p->pListNext;
        }
}

static void zobj_scan_black(struct _store_object *obj, zval *pz TSRMLS_DC)
{
        Bucket *p;
        zend_object_get_gc_t get_gc;

        GC_SET_BLACK(obj->buffered);
        if (EXPECTED(EG(objects_store).object_buckets[Z_OBJ_HANDLE_P(pz)].valid &&
                     (get_gc = Z_OBJ_HANDLER_P(pz, get_gc)) != NULL)) {
                int i, n;
                zval **table;
                HashTable *props = get_gc(pz, &table, &n TSRMLS_CC);

                for (i = 0; i < n; i++) {
                        if (table[i]) {
                                pz = table[i];
                                if (Z_TYPE_P(pz) != IS_ARRAY || Z_ARRVAL_P(pz) != &EG(symbol_table)) {
                                        pz->refcount__gc++;
                                }
                                if (GC_ZVAL_GET_COLOR(pz) != GC_BLACK) {
                                        zval_scan_black(pz TSRMLS_CC);
                                }
                        }
                }
                if (!props) {
                        return;
                }
                p = props->pListHead;
                while (p != NULL) {
                        pz = *(zval**)p->pData;
                        if (Z_TYPE_P(pz) != IS_ARRAY || Z_ARRVAL_P(pz) != &EG(symbol_table)) {
                                pz->refcount__gc++;
                        }
                        if (GC_ZVAL_GET_COLOR(pz) != GC_BLACK) {
                                zval_scan_black(pz TSRMLS_CC);
                        }
                        p = p->pListNext;
                }
        }
}

static void zval_mark_grey(zval *pz TSRMLS_DC)
{
        Bucket *p;

tail_call:
        if (GC_ZVAL_GET_COLOR(pz) != GC_GREY) {
                p = NULL;
                GC_BENCH_INC(zval_marked_grey);
                GC_ZVAL_SET_COLOR(pz, GC_GREY);

                if (Z_TYPE_P(pz) == IS_OBJECT && EG(objects_store).object_buckets) {
                        zend_object_get_gc_t get_gc;
                        struct _store_object *obj = &EG(objects_store).object_buckets[Z_OBJ_HANDLE_P(pz)].bucket.obj;

                        obj->refcount--;
                        if (GC_GET_COLOR(obj->buffered) != GC_GREY) {
                                GC_BENCH_INC(zobj_marked_grey);
                                GC_SET_COLOR(obj->buffered, GC_GREY);
                                if (EXPECTED(EG(objects_store).object_buckets[Z_OBJ_HANDLE_P(pz)].valid &&
                                             (get_gc = Z_OBJ_HANDLER_P(pz, get_gc)) != NULL)) {
                                        int i, n;
                                        zval **table;
                                        HashTable *props = get_gc(pz, &table, &n TSRMLS_CC);

                                        while (n > 0 && !table[n-1]) n--;
                                        for (i = 0; i < n; i++) {
                                                if (table[i]) {
                                                        pz = table[i];
                                                        if (Z_TYPE_P(pz) != IS_ARRAY || Z_ARRVAL_P(pz) != &EG(symbol_table)) {
                                                                pz->refcount__gc--;
                                                        }
                                                        if (!props && i == n - 1) {
                                                                goto tail_call;
                                                        } else {
                                                                zval_mark_grey(pz TSRMLS_CC);
                                                        }
                                                }
                                        }
                                        if (!props) {
                                                return;
                                        }
                                        p = props->pListHead;
                                }
                        }
                } else if (Z_TYPE_P(pz) == IS_ARRAY) {
                        if (Z_ARRVAL_P(pz) == &EG(symbol_table)) {
                                GC_ZVAL_SET_BLACK(pz);
                        } else {
                                p = Z_ARRVAL_P(pz)->pListHead;
                        }
                }
                while (p != NULL) {
                        pz = *(zval**)p->pData;
                        if (Z_TYPE_P(pz) != IS_ARRAY || Z_ARRVAL_P(pz) != &EG(symbol_table)) {
                                pz->refcount__gc--;
                        }
                        if (p->pListNext == NULL) {
                                goto tail_call;
                        } else {
                                zval_mark_grey(pz TSRMLS_CC);
                        }
                        p = p->pListNext;
                }
        }
}

static void zobj_mark_grey(struct _store_object *obj, zval *pz TSRMLS_DC)
{
        Bucket *p;
        zend_object_get_gc_t get_gc;

        if (GC_GET_COLOR(obj->buffered) != GC_GREY) {
                GC_BENCH_INC(zobj_marked_grey);
                GC_SET_COLOR(obj->buffered, GC_GREY);
                if (EXPECTED(EG(objects_store).object_buckets[Z_OBJ_HANDLE_P(pz)].valid &&
                             (get_gc = Z_OBJ_HANDLER_P(pz, get_gc)) != NULL)) {
                        int i, n;
                        zval **table;
                        HashTable *props = get_gc(pz, &table, &n TSRMLS_CC);

                        for (i = 0; i < n; i++) {
                                if (table[i]) {
                                        pz = table[i];
                                        if (Z_TYPE_P(pz) != IS_ARRAY || Z_ARRVAL_P(pz) != &EG(symbol_table)) {
                                                pz->refcount__gc--;
                                        }
                                        zval_mark_grey(pz TSRMLS_CC);
                                }
                        }
                        if (!props) {
                                return;
                        }
                        p = props->pListHead;
                        while (p != NULL) {
                                pz = *(zval**)p->pData;
                                if (Z_TYPE_P(pz) != IS_ARRAY || Z_ARRVAL_P(pz) != &EG(symbol_table)) {
                                        pz->refcount__gc--;
                                }
                                zval_mark_grey(pz TSRMLS_CC);
                                p = p->pListNext;
                        }
                }
        }
}

static void gc_mark_roots(TSRMLS_D)
{
        gc_root_buffer *current = GC_G(roots).next;

        while (current != &GC_G(roots)) {
                if (current->handle) {
                        if (EG(objects_store).object_buckets) {
                                struct _store_object *obj = &EG(objects_store).object_buckets[current->handle].bucket.obj;

                                if (GC_GET_COLOR(obj->buffered) == GC_PURPLE) {
                                        zval z;

                                        INIT_PZVAL(&z);
                                        Z_OBJ_HANDLE(z) = current->handle;
                                        Z_OBJ_HT(z) = current->u.handlers;
                                        zobj_mark_grey(obj, &z TSRMLS_CC);
                                } else {
                                        GC_SET_ADDRESS(obj->buffered, NULL);
                                        GC_REMOVE_FROM_BUFFER(current);
                                }
                        }
                } else {
                        if (GC_ZVAL_GET_COLOR(current->u.pz) == GC_PURPLE) {
                                zval_mark_grey(current->u.pz TSRMLS_CC);
                        } else {
                                GC_ZVAL_SET_ADDRESS(current->u.pz, NULL);
                                GC_REMOVE_FROM_BUFFER(current);
                        }
                }
                current = current->next;
        }
}

static void zval_scan(zval *pz TSRMLS_DC)
{
        Bucket *p;

tail_call:      
        if (GC_ZVAL_GET_COLOR(pz) == GC_GREY) {
                p = NULL;
                if (pz->refcount__gc > 0) {
                        zval_scan_black(pz TSRMLS_CC);
                } else {
                        GC_ZVAL_SET_COLOR(pz, GC_WHITE);
                        if (Z_TYPE_P(pz) == IS_OBJECT && EG(objects_store).object_buckets) {
                                zend_object_get_gc_t get_gc;
                                struct _store_object *obj = &EG(objects_store).object_buckets[Z_OBJ_HANDLE_P(pz)].bucket.obj;

                                if (GC_GET_COLOR(obj->buffered) == GC_GREY) {
                                        if (obj->refcount > 0) {
                                                zobj_scan_black(obj, pz TSRMLS_CC);
                                        } else {
                                                GC_SET_COLOR(obj->buffered, GC_WHITE);
                                                if (EXPECTED(EG(objects_store).object_buckets[Z_OBJ_HANDLE_P(pz)].valid &&
                                                             (get_gc = Z_OBJ_HANDLER_P(pz, get_gc)) != NULL)) {
                                                        int i, n;
                                                        zval **table;
                                                        HashTable *props = get_gc(pz, &table, &n TSRMLS_CC);

                                                        while (n > 0 && !table[n-1]) n--;
                                                        for (i = 0; i < n; i++) {
                                                                if (table[i]) {
                                                                        pz = table[i];
                                                                        if (!props && i == n - 1) {
                                                                                goto tail_call;
                                                                        } else {
                                                                                zval_scan(pz TSRMLS_CC);
                                                                        }
                                                                }
                                                        }
                                                        if (!props) {
                                                                return;
                                                        }
                                                        p = props->pListHead;
                                                }
                                        }
                                }
                        } else if (Z_TYPE_P(pz) == IS_ARRAY) {
                                if (Z_ARRVAL_P(pz) == &EG(symbol_table)) {
                                        GC_ZVAL_SET_BLACK(pz);
                                } else {
                                        p = Z_ARRVAL_P(pz)->pListHead;
                                }
                        }
                }
                while (p != NULL) {
                        if (p->pListNext == NULL) {
                                pz = *(zval**)p->pData;
                                goto tail_call;
                        } else {
                                zval_scan(*(zval**)p->pData TSRMLS_CC);
                        }
                        p = p->pListNext;
                }
        }
}

static void zobj_scan(zval *pz TSRMLS_DC)
{
        Bucket *p;
        zend_object_get_gc_t get_gc;

        if (EG(objects_store).object_buckets) {
                struct _store_object *obj = &EG(objects_store).object_buckets[Z_OBJ_HANDLE_P(pz)].bucket.obj;

                if (GC_GET_COLOR(obj->buffered) == GC_GREY) {
                        if (obj->refcount > 0) {
                                zobj_scan_black(obj, pz TSRMLS_CC);
                        } else {
                                GC_SET_COLOR(obj->buffered, GC_WHITE);
                                if (EXPECTED(EG(objects_store).object_buckets[Z_OBJ_HANDLE_P(pz)].valid &&
                                             (get_gc = Z_OBJ_HANDLER_P(pz, get_gc)) != NULL)) {
                                        int i, n;
                                        zval **table;
                                        HashTable *props = get_gc(pz, &table, &n TSRMLS_CC);

                                        for (i = 0; i < n; i++) {
                                                if (table[i]) {
                                                        pz = table[i];
                                                        zval_scan(pz TSRMLS_CC);
                        }
                                        }
                                        if (!props) {
                                                return;
                                        }
                                        p = props->pListHead;
                                        while (p != NULL) {
                                                zval_scan(*(zval**)p->pData TSRMLS_CC);
                                                p = p->pListNext;
                                        }
                                }
                        }
                }
        }
}

static void gc_scan_roots(TSRMLS_D)
{
        gc_root_buffer *current = GC_G(roots).next;

        while (current != &GC_G(roots)) {
                if (current->handle) {
                        zval z;

                        INIT_PZVAL(&z);
                        Z_OBJ_HANDLE(z) = current->handle;
                        Z_OBJ_HT(z) = current->u.handlers;
                        zobj_scan(&z TSRMLS_CC);
                } else {
                        zval_scan(current->u.pz TSRMLS_CC);
                }
                current = current->next;
        }
}

static void zval_collect_white(zval *pz TSRMLS_DC)
{
        Bucket *p;

tail_call:
        if (((zval_gc_info*)(pz))->u.buffered == (gc_root_buffer*)GC_WHITE) {
                p = NULL;
                GC_ZVAL_SET_BLACK(pz);

                if (Z_TYPE_P(pz) == IS_OBJECT && EG(objects_store).object_buckets) {
                        zend_object_get_gc_t get_gc;
                        struct _store_object *obj = &EG(objects_store).object_buckets[Z_OBJ_HANDLE_P(pz)].bucket.obj;

                        if (obj->buffered == (gc_root_buffer*)GC_WHITE) {
                                /* PURPLE instead of BLACK to prevent buffering in nested gc calls */
                                GC_SET_PURPLE(obj->buffered);

                                if (EXPECTED(EG(objects_store).object_buckets[Z_OBJ_HANDLE_P(pz)].valid &&
                                             (get_gc = Z_OBJ_HANDLER_P(pz, get_gc)) != NULL)) {
                                        int i, n;
                                        zval **table, *zv;
                                        HashTable *props = get_gc(pz, &table, &n TSRMLS_CC);

                                        if (!props) {
                                                /* restore refcount and put into list to free */
                                                pz->refcount__gc++;
                                                ((zval_gc_info*)pz)->u.next = GC_G(zval_to_free);
                                                GC_G(zval_to_free) = (zval_gc_info*)pz;
                                        }

                                        while (n > 0 && !table[n-1]) n--;
                                        for (i = 0; i < n; i++) {
                                                if (table[i]) {
                                                        zv = table[i];
                                                        if (Z_TYPE_P(zv) != IS_ARRAY || Z_ARRVAL_P(zv) != &EG(symbol_table)) {
                                                                zv->refcount__gc++;
                                                        }
                                                        if (!props && i == n - 1) {
                                                                pz = zv;
                                                                goto tail_call;
                                                        } else {
                                                                zval_collect_white(zv TSRMLS_CC);
                                                        }
                                                }
                                        }
                                        if (!props) {
                                                return;
                                        }
                                        p = props->pListHead;
                                }
                        }
                } else {
                        if (Z_TYPE_P(pz) == IS_ARRAY) {
                                p = Z_ARRVAL_P(pz)->pListHead;
                        }
                }

                /* restore refcount and put into list to free */
                pz->refcount__gc++;
                ((zval_gc_info*)pz)->u.next = GC_G(zval_to_free);
                GC_G(zval_to_free) = (zval_gc_info*)pz;

                while (p != NULL) {
                        pz = *(zval**)p->pData;
                        if (Z_TYPE_P(pz) != IS_ARRAY || Z_ARRVAL_P(pz) != &EG(symbol_table)) {
                                pz->refcount__gc++;
                        }
                        if (p->pListNext == NULL) {
                                goto tail_call;
                        } else {
                                zval_collect_white(pz TSRMLS_CC);
                        }
                        p = p->pListNext;
                }
        }
}

static void zobj_collect_white(zval *pz TSRMLS_DC)
{
        Bucket *p;

        if (EG(objects_store).object_buckets) {
                zend_object_get_gc_t get_gc;
                struct _store_object *obj = &EG(objects_store).object_buckets[Z_OBJ_HANDLE_P(pz)].bucket.obj;

                if (obj->buffered == (gc_root_buffer*)GC_WHITE) {
                        /* PURPLE instead of BLACK to prevent buffering in nested gc calls */
                        GC_SET_PURPLE(obj->buffered);

                        if (EXPECTED(EG(objects_store).object_buckets[Z_OBJ_HANDLE_P(pz)].valid &&
                                     (get_gc = Z_OBJ_HANDLER_P(pz, get_gc)) != NULL)) {
                                int i, n;
                                zval **table;
                                HashTable *props = get_gc(pz, &table, &n TSRMLS_CC);

                                for (i = 0; i < n; i++) {
                                        if (table[i]) {
                                                pz = table[i];
                                                if (Z_TYPE_P(pz) != IS_ARRAY || Z_ARRVAL_P(pz) != &EG(symbol_table)) {
                                                        pz->refcount__gc++;
                                                }
                                                zval_collect_white(pz TSRMLS_CC);
                                        }
                                }
                                if (!props) {
                                        return;
                                }
                                p = props->pListHead;
                                while (p != NULL) {
                                        pz = *(zval**)p->pData;
                                        if (Z_TYPE_P(pz) != IS_ARRAY || Z_ARRVAL_P(pz) != &EG(symbol_table)) {
                                                pz->refcount__gc++;
                                        }
                                        zval_collect_white(pz TSRMLS_CC);
                                        p = p->pListNext;
                                }
                        }
                }
        }
}

static void gc_collect_roots(TSRMLS_D)
{
        gc_root_buffer *current = GC_G(roots).next;

        while (current != &GC_G(roots)) {
                if (current->handle) {
                        if (EG(objects_store).object_buckets) {
                                struct _store_object *obj = &EG(objects_store).object_buckets[current->handle].bucket.obj;
                                zval z;

                                GC_SET_ADDRESS(obj->buffered, NULL);
                                INIT_PZVAL(&z);
                                Z_OBJ_HANDLE(z) = current->handle;
                                Z_OBJ_HT(z) = current->u.handlers;
                                zobj_collect_white(&z TSRMLS_CC);
                        }
                } else {
                        GC_ZVAL_SET_ADDRESS(current->u.pz, NULL);
                        zval_collect_white(current->u.pz TSRMLS_CC);
                }

                GC_REMOVE_FROM_BUFFER(current);
                current = current->next;
        }
}

#define FREE_LIST_END ((zval_gc_info*)(~(zend_uintptr_t)GC_COLOR))

ZEND_API int gc_collect_cycles(TSRMLS_D)
{
        int count = 0;

        if (GC_G(roots).next != &GC_G(roots)) {
                zval_gc_info *p, *q, *orig_free_list, *orig_next_to_free;

                if (GC_G(gc_active)) {
                        return 0;
                }
                GC_G(gc_runs)++;
                GC_G(zval_to_free) = FREE_LIST_END;
                GC_G(gc_active) = 1;
                gc_mark_roots(TSRMLS_C);
                gc_scan_roots(TSRMLS_C);
                gc_collect_roots(TSRMLS_C);

                orig_free_list = GC_G(free_list);
                orig_next_to_free = GC_G(next_to_free);
                p = GC_G(free_list) = GC_G(zval_to_free);
                GC_G(zval_to_free) = NULL;
                GC_G(gc_active) = 0;

                /* First call destructors */
                while (p != FREE_LIST_END) {
                        if (Z_TYPE(p->z) == IS_OBJECT) {
                                if (EG(objects_store).object_buckets &&
                                        EG(objects_store).object_buckets[Z_OBJ_HANDLE(p->z)].valid &&
                                        EG(objects_store).object_buckets[Z_OBJ_HANDLE(p->z)].bucket.obj.refcount <= 0 &&
                                        EG(objects_store).object_buckets[Z_OBJ_HANDLE(p->z)].bucket.obj.dtor &&
                                        !EG(objects_store).object_buckets[Z_OBJ_HANDLE(p->z)].destructor_called) {

                                        EG(objects_store).object_buckets[Z_OBJ_HANDLE(p->z)].destructor_called = 1;
                                        EG(objects_store).object_buckets[Z_OBJ_HANDLE(p->z)].bucket.obj.refcount++;
                                        EG(objects_store).object_buckets[Z_OBJ_HANDLE(p->z)].bucket.obj.dtor(EG(objects_store).object_buckets[Z_OBJ_HANDLE(p->z)].bucket.obj.object, Z_OBJ_HANDLE(p->z) TSRMLS_CC);
                                        EG(objects_store).object_buckets[Z_OBJ_HANDLE(p->z)].bucket.obj.refcount--;
                                }
                        }
                        count++;
                        p = p->u.next;
                }

                /* Destroy zvals */
                p = GC_G(free_list);
                while (p != FREE_LIST_END) {
                        GC_G(next_to_free) = p->u.next;
                        if (Z_TYPE(p->z) == IS_OBJECT) {
                                if (EG(objects_store).object_buckets &&
                                        EG(objects_store).object_buckets[Z_OBJ_HANDLE(p->z)].valid &&
                                        EG(objects_store).object_buckets[Z_OBJ_HANDLE(p->z)].bucket.obj.refcount <= 0) {
                                        EG(objects_store).object_buckets[Z_OBJ_HANDLE(p->z)].bucket.obj.refcount = 1;
                                        Z_TYPE(p->z) = IS_NULL;
                                        zend_objects_store_del_ref_by_handle_ex(Z_OBJ_HANDLE(p->z), Z_OBJ_HT(p->z) TSRMLS_CC);
                                }
                        } else if (Z_TYPE(p->z) == IS_ARRAY) {
                                Z_TYPE(p->z) = IS_NULL;
                                zend_hash_destroy(Z_ARRVAL(p->z));
                                FREE_HASHTABLE(Z_ARRVAL(p->z));
                        } else {
                                zval_dtor(&p->z);
                                Z_TYPE(p->z) = IS_NULL;
                        }
                        p = GC_G(next_to_free);
                }

                /* Free zvals */
                p = GC_G(free_list);
                while (p != FREE_LIST_END) {
                        q = p->u.next;
                        FREE_ZVAL_EX(&p->z);
                        p = q;
                }
                GC_G(collected) += count;
                GC_G(free_list) = orig_free_list;
                GC_G(next_to_free) = orig_next_to_free;
        }

        return count;
}

/*
 * Local variables:
 * tab-width: 4
 * c-basic-offset: 4
 * indent-tabs-mode: t
 * End:
 */

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