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php-src/Zend/zend_gc.c
Xinchen Hui a6519d0514 year++
2018-01-02 12:57:58 +08:00

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/*
+----------------------------------------------------------------------+
| Zend Engine |
+----------------------------------------------------------------------+
| Copyright (c) 1998-2018 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> |
+----------------------------------------------------------------------+
*/
/* $Id$ */
/**
* zend_gc_collect_cycles
* ======================
*
* Colors and its meaning
* ----------------------
*
* BLACK (GC_BLACK) - In use or free.
* GREY (GC_GREY) - Possible member of cycle.
* WHITE (GC_WHITE) - Member of garbage cycle.
* PURPLE (GC_PURPLE) - Possible root of cycle.
*
* Colors described in the paper but not used
* ------------------------------------------
*
* GREEN - Acyclic
* RED - Candidate cycle underogin
* ORANGE - Candidate cycle awaiting epoch boundary.
*
*
* Flow
* =====
*
* The garbage collect cycle starts from 'gc_mark_roots', which traverses the
* possible roots, and calls mark_grey for roots are marked purple with
* depth-first traverse.
*
* After all possible roots are traversed and marked,
* gc_scan_roots will be called, and each root will be called with
* gc_scan(root->ref)
*
* gc_scan checkes the colors of possible members.
*
* If the node is marked as grey and the refcount > 0
* gc_scan_black will be called on that node to scan it's subgraph.
* otherwise (refcount == 0), it marks the node white.
*
* A node MAY be added to possbile roots when ZEND_UNSET_VAR happens or
* zend_assign_to_variable is called only when possible garbage node is
* produced.
* gc_possible_root() will be called to add the nodes to possible roots.
*
*
* For objects, we call their get_gc handler (by default 'zend_std_get_gc') to
* get the object properties to scan.
*
*
* @see http://researcher.watson.ibm.com/researcher/files/us-bacon/Bacon01Concurrent.pdf
*/
#include "zend.h"
#include "zend_API.h"
/* one (0) is reserved */
#define GC_ROOT_BUFFER_MAX_ENTRIES 10001
#define GC_HAS_DESTRUCTORS (1<<0)
#ifndef ZEND_GC_DEBUG
# define ZEND_GC_DEBUG 0
#endif
#ifdef ZTS
ZEND_API int gc_globals_id;
#else
ZEND_API zend_gc_globals gc_globals;
#endif
ZEND_API int (*gc_collect_cycles)(void);
#if ZEND_GC_DEBUG > 1
# define GC_TRACE(format, ...) fprintf(stderr, format "\n", ##__VA_ARGS__);
# define GC_TRACE_REF(ref, format, ...) \
do { \
gc_trace_ref((zend_refcounted *) ref); \
fprintf(stderr, format "\n", ##__VA_ARGS__); \
} while (0)
# define GC_TRACE_SET_COLOR(ref, color) \
GC_TRACE_REF(ref, "->%s", gc_color_name(color))
#else
# define GC_TRACE_REF(ref, format, ...)
# define GC_TRACE_SET_COLOR(ref, new_color)
# define GC_TRACE(str)
#endif
#define GC_REF_SET_ADDRESS(ref, a) \
GC_INFO_SET_ADDRESS(GC_INFO(ref), a)
#define GC_REF_GET_COLOR(ref) \
GC_INFO_GET_COLOR(GC_INFO(ref))
#define GC_REF_SET_COLOR(ref, c) \
do { GC_TRACE_SET_COLOR(ref, c); GC_INFO_SET_COLOR(GC_INFO(ref), c); } while (0)
#define GC_REF_SET_BLACK(ref) \
do { GC_TRACE_SET_COLOR(ref, GC_BLACK); GC_INFO_SET_BLACK(GC_INFO(ref)); } while (0)
#define GC_REF_SET_PURPLE(ref) \
do { GC_TRACE_SET_COLOR(ref, GC_PURPLE); GC_INFO_SET_PURPLE(GC_INFO(ref)); } while (0)
#if ZEND_GC_DEBUG > 1
static const char *gc_color_name(uint32_t color) {
switch (color) {
case GC_BLACK: return "black";
case GC_WHITE: return "white";
case GC_GREY: return "grey";
case GC_PURPLE: return "purple";
default: return "unknown";
}
}
static void gc_trace_ref(zend_refcounted *ref) {
if (GC_TYPE(ref) == IS_OBJECT) {
zend_object *obj = (zend_object *) ref;
fprintf(stderr, "[%p] rc=%d addr=%d %s object(%s)#%d ",
ref, GC_REFCOUNT(ref), GC_ADDRESS(GC_INFO(ref)),
gc_color_name(GC_REF_GET_COLOR(ref)),
obj->ce->name->val, obj->handle);
} else if (GC_TYPE(ref) == IS_ARRAY) {
zend_array *arr = (zend_array *) ref;
fprintf(stderr, "[%p] rc=%d addr=%d %s array(%d) ",
ref, GC_REFCOUNT(ref), GC_ADDRESS(GC_INFO(ref)),
gc_color_name(GC_REF_GET_COLOR(ref)),
zend_hash_num_elements(arr));
} else {
fprintf(stderr, "[%p] rc=%d addr=%d %s %s ",
ref, GC_REFCOUNT(ref), GC_ADDRESS(GC_INFO(ref)),
gc_color_name(GC_REF_GET_COLOR(ref)),
zend_get_type_by_const(GC_TYPE(ref)));
}
}
#endif
static zend_always_inline void gc_remove_from_roots(gc_root_buffer *root)
{
root->next->prev = root->prev;
root->prev->next = root->next;
root->prev = GC_G(unused);
GC_G(unused) = root;
GC_BENCH_DEC(root_buf_length);
}
static zend_always_inline void gc_remove_from_additional_roots(gc_root_buffer *root)
{
root->next->prev = root->prev;
root->prev->next = root->next;
}
static void root_buffer_dtor(zend_gc_globals *gc_globals)
{
if (gc_globals->buf) {
free(gc_globals->buf);
gc_globals->buf = NULL;
}
}
static void gc_globals_ctor_ex(zend_gc_globals *gc_globals)
{
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->next_to_free = NULL;
gc_globals->to_free.next = &gc_globals->to_free;
gc_globals->to_free.prev = &gc_globals->to_free;
gc_globals->gc_runs = 0;
gc_globals->collected = 0;
gc_globals->additional_buffer = NULL;
#if GC_BENCH
gc_globals->root_buf_length = 0;
gc_globals->root_buf_peak = 0;
gc_globals->zval_possible_root = 0;
gc_globals->zval_buffered = 0;
gc_globals->zval_remove_from_buffer = 0;
gc_globals->zval_marked_grey = 0;
#endif
}
ZEND_API void gc_globals_ctor(void)
{
#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(void)
{
#ifndef ZTS
root_buffer_dtor(&gc_globals);
#endif
}
ZEND_API void gc_reset(void)
{
GC_G(gc_runs) = 0;
GC_G(collected) = 0;
GC_G(gc_full) = 0;
#if GC_BENCH
GC_G(root_buf_length) = 0;
GC_G(root_buf_peak) = 0;
GC_G(zval_possible_root) = 0;
GC_G(zval_buffered) = 0;
GC_G(zval_remove_from_buffer) = 0;
GC_G(zval_marked_grey) = 0;
#endif
GC_G(roots).next = &GC_G(roots);
GC_G(roots).prev = &GC_G(roots);
GC_G(to_free).next = &GC_G(to_free);
GC_G(to_free).prev = &GC_G(to_free);
if (GC_G(buf)) {
GC_G(unused) = NULL;
GC_G(first_unused) = GC_G(buf) + 1;
} else {
GC_G(unused) = NULL;
GC_G(first_unused) = NULL;
GC_G(last_unused) = NULL;
}
GC_G(additional_buffer) = NULL;
}
ZEND_API void gc_init(void)
{
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();
}
}
ZEND_API void ZEND_FASTCALL gc_possible_root(zend_refcounted *ref)
{
gc_root_buffer *newRoot;
if (UNEXPECTED(CG(unclean_shutdown)) || UNEXPECTED(GC_G(gc_active))) {
return;
}
ZEND_ASSERT(GC_TYPE(ref) == IS_ARRAY || GC_TYPE(ref) == IS_OBJECT);
ZEND_ASSERT(EXPECTED(GC_REF_GET_COLOR(ref) == GC_BLACK));
ZEND_ASSERT(!GC_ADDRESS(GC_INFO(ref)));
GC_BENCH_INC(zval_possible_root);
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)) {
return;
}
GC_ADDREF(ref);
gc_collect_cycles();
GC_DELREF(ref);
if (UNEXPECTED(GC_REFCOUNT(ref)) == 0) {
zval_dtor_func(ref);
return;
}
if (UNEXPECTED(GC_INFO(ref))) {
return;
}
newRoot = GC_G(unused);
if (!newRoot) {
#if ZEND_GC_DEBUG
if (!GC_G(gc_full)) {
fprintf(stderr, "GC: no space to record new root candidate\n");
GC_G(gc_full) = 1;
}
#endif
return;
}
GC_G(unused) = newRoot->prev;
}
GC_TRACE_SET_COLOR(ref, GC_PURPLE);
GC_INFO(ref) = (newRoot - GC_G(buf)) | GC_PURPLE;
newRoot->ref = ref;
newRoot->next = GC_G(roots).next;
newRoot->prev = &GC_G(roots);
GC_G(roots).next->prev = newRoot;
GC_G(roots).next = newRoot;
GC_BENCH_INC(zval_buffered);
GC_BENCH_INC(root_buf_length);
GC_BENCH_PEAK(root_buf_peak, root_buf_length);
}
static zend_always_inline gc_root_buffer* gc_find_additional_buffer(zend_refcounted *ref)
{
gc_additional_buffer *additional_buffer = GC_G(additional_buffer);
/* We have to check each additional_buffer to find which one holds the ref */
while (additional_buffer) {
uint32_t idx = GC_ADDRESS(GC_INFO(ref)) - GC_ROOT_BUFFER_MAX_ENTRIES;
if (idx < additional_buffer->used) {
gc_root_buffer *root = additional_buffer->buf + idx;
if (root->ref == ref) {
return root;
}
}
additional_buffer = additional_buffer->next;
}
ZEND_ASSERT(0);
return NULL;
}
ZEND_API void ZEND_FASTCALL gc_remove_from_buffer(zend_refcounted *ref)
{
gc_root_buffer *root;
ZEND_ASSERT(GC_ADDRESS(GC_INFO(ref)));
GC_BENCH_INC(zval_remove_from_buffer);
if (EXPECTED(GC_ADDRESS(GC_INFO(ref)) < GC_ROOT_BUFFER_MAX_ENTRIES)) {
root = GC_G(buf) + GC_ADDRESS(GC_INFO(ref));
gc_remove_from_roots(root);
} else {
root = gc_find_additional_buffer(ref);
gc_remove_from_additional_roots(root);
}
if (GC_REF_GET_COLOR(ref) != GC_BLACK) {
GC_TRACE_SET_COLOR(ref, GC_PURPLE);
}
GC_INFO(ref) = 0;
/* updete next root that is going to be freed */
if (GC_G(next_to_free) == root) {
GC_G(next_to_free) = root->next;
}
}
static void gc_scan_black(zend_refcounted *ref)
{
HashTable *ht;
Bucket *p, *end;
zval *zv;
tail_call:
ht = NULL;
GC_REF_SET_BLACK(ref);
if (GC_TYPE(ref) == IS_OBJECT) {
zend_object_get_gc_t get_gc;
zend_object *obj = (zend_object*)ref;
if (EXPECTED(!(GC_FLAGS(ref) & IS_OBJ_FREE_CALLED) &&
(get_gc = obj->handlers->get_gc) != NULL)) {
int n;
zval *zv, *end;
zval tmp;
ZVAL_OBJ(&tmp, obj);
ht = get_gc(&tmp, &zv, &n);
end = zv + n;
if (EXPECTED(!ht)) {
if (!n) return;
while (!Z_REFCOUNTED_P(--end)) {
if (zv == end) return;
}
}
while (zv != end) {
if (Z_REFCOUNTED_P(zv)) {
ref = Z_COUNTED_P(zv);
GC_ADDREF(ref);
if (GC_REF_GET_COLOR(ref) != GC_BLACK) {
gc_scan_black(ref);
}
}
zv++;
}
if (EXPECTED(!ht)) {
ref = Z_COUNTED_P(zv);
GC_ADDREF(ref);
if (GC_REF_GET_COLOR(ref) != GC_BLACK) {
goto tail_call;
}
return;
}
} else {
return;
}
} else if (GC_TYPE(ref) == IS_ARRAY) {
if ((zend_array*)ref != &EG(symbol_table)) {
ht = (zend_array*)ref;
} else {
return;
}
} else if (GC_TYPE(ref) == IS_REFERENCE) {
if (Z_REFCOUNTED(((zend_reference*)ref)->val)) {
ref = Z_COUNTED(((zend_reference*)ref)->val);
GC_ADDREF(ref);
if (GC_REF_GET_COLOR(ref) != GC_BLACK) {
goto tail_call;
}
}
return;
} else {
return;
}
if (!ht->nNumUsed) return;
p = ht->arData;
end = p + ht->nNumUsed;
while (1) {
end--;
zv = &end->val;
if (Z_TYPE_P(zv) == IS_INDIRECT) {
zv = Z_INDIRECT_P(zv);
}
if (Z_REFCOUNTED_P(zv)) {
break;
}
if (p == end) return;
}
while (p != end) {
zv = &p->val;
if (Z_TYPE_P(zv) == IS_INDIRECT) {
zv = Z_INDIRECT_P(zv);
}
if (Z_REFCOUNTED_P(zv)) {
ref = Z_COUNTED_P(zv);
GC_ADDREF(ref);
if (GC_REF_GET_COLOR(ref) != GC_BLACK) {
gc_scan_black(ref);
}
}
p++;
}
zv = &p->val;
if (Z_TYPE_P(zv) == IS_INDIRECT) {
zv = Z_INDIRECT_P(zv);
}
ref = Z_COUNTED_P(zv);
GC_ADDREF(ref);
if (GC_REF_GET_COLOR(ref) != GC_BLACK) {
goto tail_call;
}
}
static void gc_mark_grey(zend_refcounted *ref)
{
HashTable *ht;
Bucket *p, *end;
zval *zv;
tail_call:
if (GC_REF_GET_COLOR(ref) != GC_GREY) {
ht = NULL;
GC_BENCH_INC(zval_marked_grey);
GC_REF_SET_COLOR(ref, GC_GREY);
if (GC_TYPE(ref) == IS_OBJECT) {
zend_object_get_gc_t get_gc;
zend_object *obj = (zend_object*)ref;
if (EXPECTED(!(GC_FLAGS(ref) & IS_OBJ_FREE_CALLED) &&
(get_gc = obj->handlers->get_gc) != NULL)) {
int n;
zval *zv, *end;
zval tmp;
ZVAL_OBJ(&tmp, obj);
ht = get_gc(&tmp, &zv, &n);
end = zv + n;
if (EXPECTED(!ht)) {
if (!n) return;
while (!Z_REFCOUNTED_P(--end)) {
if (zv == end) return;
}
}
while (zv != end) {
if (Z_REFCOUNTED_P(zv)) {
ref = Z_COUNTED_P(zv);
GC_DELREF(ref);
gc_mark_grey(ref);
}
zv++;
}
if (EXPECTED(!ht)) {
ref = Z_COUNTED_P(zv);
GC_DELREF(ref);
goto tail_call;
}
} else {
return;
}
} else if (GC_TYPE(ref) == IS_ARRAY) {
if (((zend_array*)ref) == &EG(symbol_table)) {
GC_REF_SET_BLACK(ref);
return;
} else {
ht = (zend_array*)ref;
}
} else if (GC_TYPE(ref) == IS_REFERENCE) {
if (Z_REFCOUNTED(((zend_reference*)ref)->val)) {
ref = Z_COUNTED(((zend_reference*)ref)->val);
GC_DELREF(ref);
goto tail_call;
}
return;
} else {
return;
}
if (!ht->nNumUsed) return;
p = ht->arData;
end = p + ht->nNumUsed;
while (1) {
end--;
zv = &end->val;
if (Z_TYPE_P(zv) == IS_INDIRECT) {
zv = Z_INDIRECT_P(zv);
}
if (Z_REFCOUNTED_P(zv)) {
break;
}
if (p == end) return;
}
while (p != end) {
zv = &p->val;
if (Z_TYPE_P(zv) == IS_INDIRECT) {
zv = Z_INDIRECT_P(zv);
}
if (Z_REFCOUNTED_P(zv)) {
ref = Z_COUNTED_P(zv);
GC_DELREF(ref);
gc_mark_grey(ref);
}
p++;
}
zv = &p->val;
if (Z_TYPE_P(zv) == IS_INDIRECT) {
zv = Z_INDIRECT_P(zv);
}
ref = Z_COUNTED_P(zv);
GC_DELREF(ref);
goto tail_call;
}
}
static void gc_mark_roots(void)
{
gc_root_buffer *current = GC_G(roots).next;
while (current != &GC_G(roots)) {
if (GC_REF_GET_COLOR(current->ref) == GC_PURPLE) {
gc_mark_grey(current->ref);
}
current = current->next;
}
}
static void gc_scan(zend_refcounted *ref)
{
HashTable *ht;
Bucket *p, *end;
zval *zv;
tail_call:
if (GC_REF_GET_COLOR(ref) == GC_GREY) {
if (GC_REFCOUNT(ref) > 0) {
gc_scan_black(ref);
} else {
GC_REF_SET_COLOR(ref, GC_WHITE);
if (GC_TYPE(ref) == IS_OBJECT) {
zend_object_get_gc_t get_gc;
zend_object *obj = (zend_object*)ref;
if (EXPECTED(!(GC_FLAGS(ref) & IS_OBJ_FREE_CALLED) &&
(get_gc = obj->handlers->get_gc) != NULL)) {
int n;
zval *zv, *end;
zval tmp;
ZVAL_OBJ(&tmp, obj);
ht = get_gc(&tmp, &zv, &n);
end = zv + n;
if (EXPECTED(!ht)) {
if (!n) return;
while (!Z_REFCOUNTED_P(--end)) {
if (zv == end) return;
}
}
while (zv != end) {
if (Z_REFCOUNTED_P(zv)) {
ref = Z_COUNTED_P(zv);
gc_scan(ref);
}
zv++;
}
if (EXPECTED(!ht)) {
ref = Z_COUNTED_P(zv);
goto tail_call;
}
} else {
return;
}
} else if (GC_TYPE(ref) == IS_ARRAY) {
if ((zend_array*)ref == &EG(symbol_table)) {
GC_REF_SET_BLACK(ref);
return;
} else {
ht = (zend_array*)ref;
}
} else if (GC_TYPE(ref) == IS_REFERENCE) {
if (Z_REFCOUNTED(((zend_reference*)ref)->val)) {
ref = Z_COUNTED(((zend_reference*)ref)->val);
goto tail_call;
}
return;
} else {
return;
}
if (!ht->nNumUsed) return;
p = ht->arData;
end = p + ht->nNumUsed;
while (1) {
end--;
zv = &end->val;
if (Z_TYPE_P(zv) == IS_INDIRECT) {
zv = Z_INDIRECT_P(zv);
}
if (Z_REFCOUNTED_P(zv)) {
break;
}
if (p == end) return;
}
while (p != end) {
zv = &p->val;
if (Z_TYPE_P(zv) == IS_INDIRECT) {
zv = Z_INDIRECT_P(zv);
}
if (Z_REFCOUNTED_P(zv)) {
ref = Z_COUNTED_P(zv);
gc_scan(ref);
}
p++;
}
zv = &p->val;
if (Z_TYPE_P(zv) == IS_INDIRECT) {
zv = Z_INDIRECT_P(zv);
}
ref = Z_COUNTED_P(zv);
goto tail_call;
}
}
}
static void gc_scan_roots(void)
{
gc_root_buffer *current = GC_G(roots).next;
while (current != &GC_G(roots)) {
gc_scan(current->ref);
current = current->next;
}
}
static void gc_add_garbage(zend_refcounted *ref)
{
gc_root_buffer *buf = GC_G(unused);
if (buf) {
GC_G(unused) = buf->prev;
#if 1
/* optimization: color is already GC_BLACK (0) */
GC_INFO(ref) = buf - GC_G(buf);
#else
GC_REF_SET_ADDRESS(ref, buf - GC_G(buf));
#endif
} else if (GC_G(first_unused) != GC_G(last_unused)) {
buf = GC_G(first_unused);
GC_G(first_unused)++;
#if 1
/* optimization: color is already GC_BLACK (0) */
GC_INFO(ref) = buf - GC_G(buf);
#else
GC_REF_SET_ADDRESS(ref, buf - GC_G(buf));
#endif
} else {
/* If we don't have free slots in the buffer, allocate a new one and
* set it's address above GC_ROOT_BUFFER_MAX_ENTRIES that have special
* meaning.
*/
if (!GC_G(additional_buffer) || GC_G(additional_buffer)->used == GC_NUM_ADDITIONAL_ENTRIES) {
gc_additional_buffer *new_buffer = emalloc(sizeof(gc_additional_buffer));
new_buffer->used = 0;
new_buffer->next = GC_G(additional_buffer);
GC_G(additional_buffer) = new_buffer;
}
buf = GC_G(additional_buffer)->buf + GC_G(additional_buffer)->used;
#if 1
/* optimization: color is already GC_BLACK (0) */
GC_INFO(ref) = GC_ROOT_BUFFER_MAX_ENTRIES + GC_G(additional_buffer)->used;
#else
GC_REF_SET_ADDRESS(ref, GC_ROOT_BUFFER_MAX_ENTRIES) + GC_G(additional_buffer)->used;
#endif
GC_G(additional_buffer)->used++;
}
if (buf) {
buf->ref = ref;
buf->next = GC_G(roots).next;
buf->prev = &GC_G(roots);
GC_G(roots).next->prev = buf;
GC_G(roots).next = buf;
}
}
static int gc_collect_white(zend_refcounted *ref, uint32_t *flags)
{
int count = 0;
HashTable *ht;
Bucket *p, *end;
zval *zv;
tail_call:
if (GC_REF_GET_COLOR(ref) == GC_WHITE) {
ht = NULL;
GC_REF_SET_BLACK(ref);
/* don't count references for compatibility ??? */
if (GC_TYPE(ref) != IS_REFERENCE) {
count++;
}
if (GC_TYPE(ref) == IS_OBJECT) {
zend_object_get_gc_t get_gc;
zend_object *obj = (zend_object*)ref;
if (EXPECTED(!(GC_FLAGS(ref) & IS_OBJ_FREE_CALLED) &&
(get_gc = obj->handlers->get_gc) != NULL)) {
int n;
zval *zv, *end;
zval tmp;
#if 1
/* optimization: color is GC_BLACK (0) */
if (!GC_INFO(ref)) {
#else
if (!GC_ADDRESS(GC_INFO(ref))) {
#endif
gc_add_garbage(ref);
}
if (obj->handlers->dtor_obj &&
((obj->handlers->dtor_obj != zend_objects_destroy_object) ||
(obj->ce->destructor != NULL))) {
*flags |= GC_HAS_DESTRUCTORS;
}
ZVAL_OBJ(&tmp, obj);
ht = get_gc(&tmp, &zv, &n);
end = zv + n;
if (EXPECTED(!ht)) {
if (!n) return count;
while (!Z_REFCOUNTED_P(--end)) {
/* count non-refcounted for compatibility ??? */
if (Z_TYPE_P(zv) != IS_UNDEF) {
count++;
}
if (zv == end) return count;
}
}
while (zv != end) {
if (Z_REFCOUNTED_P(zv)) {
ref = Z_COUNTED_P(zv);
GC_ADDREF(ref);
count += gc_collect_white(ref, flags);
/* count non-refcounted for compatibility ??? */
} else if (Z_TYPE_P(zv) != IS_UNDEF) {
count++;
}
zv++;
}
if (EXPECTED(!ht)) {
ref = Z_COUNTED_P(zv);
GC_ADDREF(ref);
goto tail_call;
}
} else {
return count;
}
} else if (GC_TYPE(ref) == IS_ARRAY) {
#if 1
/* optimization: color is GC_BLACK (0) */
if (!GC_INFO(ref)) {
#else
if (!GC_ADDRESS(GC_INFO(ref))) {
#endif
gc_add_garbage(ref);
}
ht = (zend_array*)ref;
} else if (GC_TYPE(ref) == IS_REFERENCE) {
if (Z_REFCOUNTED(((zend_reference*)ref)->val)) {
ref = Z_COUNTED(((zend_reference*)ref)->val);
GC_ADDREF(ref);
goto tail_call;
}
return count;
} else {
return count;
}
if (!ht->nNumUsed) return count;
p = ht->arData;
end = p + ht->nNumUsed;
while (1) {
end--;
zv = &end->val;
if (Z_TYPE_P(zv) == IS_INDIRECT) {
zv = Z_INDIRECT_P(zv);
}
if (Z_REFCOUNTED_P(zv)) {
break;
}
/* count non-refcounted for compatibility ??? */
if (Z_TYPE_P(zv) != IS_UNDEF) {
count++;
}
if (p == end) return count;
}
while (p != end) {
zv = &p->val;
if (Z_TYPE_P(zv) == IS_INDIRECT) {
zv = Z_INDIRECT_P(zv);
}
if (Z_REFCOUNTED_P(zv)) {
ref = Z_COUNTED_P(zv);
GC_ADDREF(ref);
count += gc_collect_white(ref, flags);
/* count non-refcounted for compatibility ??? */
} else if (Z_TYPE_P(zv) != IS_UNDEF) {
count++;
}
p++;
}
zv = &p->val;
if (Z_TYPE_P(zv) == IS_INDIRECT) {
zv = Z_INDIRECT_P(zv);
}
ref = Z_COUNTED_P(zv);
GC_ADDREF(ref);
goto tail_call;
}
return count;
}
static int gc_collect_roots(uint32_t *flags)
{
int count = 0;
gc_root_buffer *current = GC_G(roots).next;
/* remove non-garbage from the list */
while (current != &GC_G(roots)) {
gc_root_buffer *next = current->next;
if (GC_REF_GET_COLOR(current->ref) == GC_BLACK) {
if (EXPECTED(GC_ADDRESS(GC_INFO(current->ref)) < GC_ROOT_BUFFER_MAX_ENTRIES)) {
gc_remove_from_roots(current);
} else {
gc_remove_from_additional_roots(current);
}
GC_INFO(current->ref) = 0; /* reset GC_ADDRESS() and keep GC_BLACK */
}
current = next;
}
current = GC_G(roots).next;
while (current != &GC_G(roots)) {
if (GC_REF_GET_COLOR(current->ref) == GC_WHITE) {
count += gc_collect_white(current->ref, flags);
}
current = current->next;
}
/* relink remaining roots into list to free */
if (GC_G(roots).next != &GC_G(roots)) {
if (GC_G(to_free).next == &GC_G(to_free)) {
/* move roots into list to free */
GC_G(to_free).next = GC_G(roots).next;
GC_G(to_free).prev = GC_G(roots).prev;
GC_G(to_free).next->prev = &GC_G(to_free);
GC_G(to_free).prev->next = &GC_G(to_free);
} else {
/* add roots into list to free */
GC_G(to_free).prev->next = GC_G(roots).next;
GC_G(roots).next->prev = GC_G(to_free).prev;
GC_G(roots).prev->next = &GC_G(to_free);
GC_G(to_free).prev = GC_G(roots).prev;
}
GC_G(roots).next = &GC_G(roots);
GC_G(roots).prev = &GC_G(roots);
}
return count;
}
static void gc_remove_nested_data_from_buffer(zend_refcounted *ref, gc_root_buffer *root)
{
HashTable *ht = NULL;
Bucket *p, *end;
zval *zv;
tail_call:
if (root ||
(GC_ADDRESS(GC_INFO(ref)) != 0 &&
GC_REF_GET_COLOR(ref) == GC_BLACK)) {
GC_TRACE_REF(ref, "removing from buffer");
if (root) {
if (EXPECTED(GC_ADDRESS(GC_INFO(root->ref)) < GC_ROOT_BUFFER_MAX_ENTRIES)) {
gc_remove_from_roots(root);
} else {
gc_remove_from_additional_roots(root);
}
GC_INFO(ref) = 0;
root = NULL;
} else {
GC_REMOVE_FROM_BUFFER(ref);
}
if (GC_TYPE(ref) == IS_OBJECT) {
zend_object_get_gc_t get_gc;
zend_object *obj = (zend_object*)ref;
if (EXPECTED(!(GC_FLAGS(ref) & IS_OBJ_FREE_CALLED) &&
(get_gc = obj->handlers->get_gc) != NULL)) {
int n;
zval *zv, *end;
zval tmp;
ZVAL_OBJ(&tmp, obj);
ht = get_gc(&tmp, &zv, &n);
end = zv + n;
if (EXPECTED(!ht)) {
if (!n) return;
while (!Z_REFCOUNTED_P(--end)) {
if (zv == end) return;
}
}
while (zv != end) {
if (Z_REFCOUNTED_P(zv)) {
ref = Z_COUNTED_P(zv);
gc_remove_nested_data_from_buffer(ref, NULL);
}
zv++;
}
if (EXPECTED(!ht)) {
ref = Z_COUNTED_P(zv);
goto tail_call;
}
} else {
return;
}
} else if (GC_TYPE(ref) == IS_ARRAY) {
ht = (zend_array*)ref;
} else if (GC_TYPE(ref) == IS_REFERENCE) {
if (Z_REFCOUNTED(((zend_reference*)ref)->val)) {
ref = Z_COUNTED(((zend_reference*)ref)->val);
goto tail_call;
}
return;
} else {
return;
}
if (!ht->nNumUsed) return;
p = ht->arData;
end = p + ht->nNumUsed;
while (1) {
end--;
zv = &end->val;
if (Z_TYPE_P(zv) == IS_INDIRECT) {
zv = Z_INDIRECT_P(zv);
}
if (Z_REFCOUNTED_P(zv)) {
break;
}
if (p == end) return;
}
while (p != end) {
zv = &p->val;
if (Z_TYPE_P(zv) == IS_INDIRECT) {
zv = Z_INDIRECT_P(zv);
}
if (Z_REFCOUNTED_P(zv)) {
ref = Z_COUNTED_P(zv);
gc_remove_nested_data_from_buffer(ref, NULL);
}
p++;
}
zv = &p->val;
if (Z_TYPE_P(zv) == IS_INDIRECT) {
zv = Z_INDIRECT_P(zv);
}
ref = Z_COUNTED_P(zv);
goto tail_call;
}
}
ZEND_API int zend_gc_collect_cycles(void)
{
int count = 0;
if (GC_G(roots).next != &GC_G(roots)) {
gc_root_buffer *current, *next, *orig_next_to_free;
zend_refcounted *p;
gc_root_buffer to_free;
uint32_t gc_flags = 0;
gc_additional_buffer *additional_buffer_snapshot;
#if ZEND_GC_DEBUG
zend_bool orig_gc_full;
#endif
if (GC_G(gc_active)) {
return 0;
}
GC_TRACE("Collecting cycles");
GC_G(gc_runs)++;
GC_G(gc_active) = 1;
GC_TRACE("Marking roots");
gc_mark_roots();
GC_TRACE("Scanning roots");
gc_scan_roots();
#if ZEND_GC_DEBUG
orig_gc_full = GC_G(gc_full);
GC_G(gc_full) = 0;
#endif
GC_TRACE("Collecting roots");
additional_buffer_snapshot = GC_G(additional_buffer);
count = gc_collect_roots(&gc_flags);
#if ZEND_GC_DEBUG
GC_G(gc_full) = orig_gc_full;
#endif
GC_G(gc_active) = 0;
if (GC_G(to_free).next == &GC_G(to_free)) {
/* nothing to free */
GC_TRACE("Nothing to free");
return 0;
}
/* Copy global to_free list into local list */
to_free.next = GC_G(to_free).next;
to_free.prev = GC_G(to_free).prev;
to_free.next->prev = &to_free;
to_free.prev->next = &to_free;
/* Free global list */
GC_G(to_free).next = &GC_G(to_free);
GC_G(to_free).prev = &GC_G(to_free);
orig_next_to_free = GC_G(next_to_free);
#if ZEND_GC_DEBUG
orig_gc_full = GC_G(gc_full);
GC_G(gc_full) = 0;
#endif
if (gc_flags & GC_HAS_DESTRUCTORS) {
GC_TRACE("Calling destructors");
/* Remember reference counters before calling destructors */
current = to_free.next;
while (current != &to_free) {
current->refcount = GC_REFCOUNT(current->ref);
current = current->next;
}
/* Call destructors */
current = to_free.next;
while (current != &to_free) {
p = current->ref;
GC_G(next_to_free) = current->next;
if (GC_TYPE(p) == IS_OBJECT) {
zend_object *obj = (zend_object*)p;
if (!(GC_FLAGS(obj) & IS_OBJ_DESTRUCTOR_CALLED)) {
GC_TRACE_REF(obj, "calling destructor");
GC_FLAGS(obj) |= IS_OBJ_DESTRUCTOR_CALLED;
if (obj->handlers->dtor_obj
&& (obj->handlers->dtor_obj != zend_objects_destroy_object
|| obj->ce->destructor)) {
GC_ADDREF(obj);
obj->handlers->dtor_obj(obj);
GC_DELREF(obj);
}
}
}
current = GC_G(next_to_free);
}
/* Remove values captured in destructors */
current = to_free.next;
while (current != &to_free) {
GC_G(next_to_free) = current->next;
if (GC_REFCOUNT(current->ref) > current->refcount) {
gc_remove_nested_data_from_buffer(current->ref, current);
}
current = GC_G(next_to_free);
}
}
/* Destroy zvals */
GC_TRACE("Destroying zvals");
GC_G(gc_active) = 1;
current = to_free.next;
while (current != &to_free) {
p = current->ref;
GC_G(next_to_free) = current->next;
GC_TRACE_REF(p, "destroying");
if (GC_TYPE(p) == IS_OBJECT) {
zend_object *obj = (zend_object*)p;
EG(objects_store).object_buckets[obj->handle] = SET_OBJ_INVALID(obj);
GC_TYPE(obj) = IS_NULL;
if (!(GC_FLAGS(obj) & IS_OBJ_FREE_CALLED)) {
GC_FLAGS(obj) |= IS_OBJ_FREE_CALLED;
if (obj->handlers->free_obj) {
GC_ADDREF(obj);
obj->handlers->free_obj(obj);
GC_DELREF(obj);
}
}
SET_OBJ_BUCKET_NUMBER(EG(objects_store).object_buckets[obj->handle], EG(objects_store).free_list_head);
EG(objects_store).free_list_head = obj->handle;
p = current->ref = (zend_refcounted*)(((char*)obj) - obj->handlers->offset);
} else if (GC_TYPE(p) == IS_ARRAY) {
zend_array *arr = (zend_array*)p;
GC_TYPE(arr) = IS_NULL;
/* GC may destroy arrays with rc>1. This is valid and safe. */
HT_ALLOW_COW_VIOLATION(arr);
zend_hash_destroy(arr);
}
current = GC_G(next_to_free);
}
/* Free objects */
current = to_free.next;
while (current != &to_free) {
next = current->next;
p = current->ref;
if (EXPECTED(current >= GC_G(buf) && current < GC_G(buf) + GC_ROOT_BUFFER_MAX_ENTRIES)) {
current->prev = GC_G(unused);
GC_G(unused) = current;
}
efree(p);
current = next;
}
while (GC_G(additional_buffer) != additional_buffer_snapshot) {
gc_additional_buffer *next = GC_G(additional_buffer)->next;
efree(GC_G(additional_buffer));
GC_G(additional_buffer) = next;
}
GC_TRACE("Collection finished");
GC_G(collected) += count;
GC_G(next_to_free) = orig_next_to_free;
#if ZEND_GC_DEBUG
GC_G(gc_full) = orig_gc_full;
#endif
GC_G(gc_active) = 0;
}
return count;
}
/*
* 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
*
* vim:noexpandtab:
*/
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