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php-src/Zend/zend_gc.c
Peter Kokot 8d3f8ca12a Remove unused Git attributes ident 
The $Id$ keywords were used in Subversion where they can be substituted
with filename, last revision number change, last changed date, and last
user who changed it.

In Git this functionality is different and can be done with Git attribute
ident. These need to be defined manually for each file in the
.gitattributes file and are afterwards replaced with 40-character
hexadecimal blob object name which is based only on the particular file
contents.

This patch simplifies handling of $Id$ keywords by removing them since
they are not used anymore.
2018-07-25 00:53:25 +02:00

1461 lines
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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> |
+----------------------------------------------------------------------+
*/
/**
* 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"
#ifndef GC_BENCH
# define GC_BENCH 0
#endif
#ifndef ZEND_GC_DEBUG
# define ZEND_GC_DEBUG 0
#endif
/* GC_INFO layout */
#define GC_ADDRESS 0x0fffff
#define GC_COLOR 0x300000
#define GC_BLACK 0x000000 /* must be zero */
#define GC_WHITE 0x100000
#define GC_GREY 0x200000
#define GC_PURPLE 0x300000
/* GC_INFO access */
#define GC_REF_ADDRESS(ref) \
(((GC_TYPE_INFO(ref)) & (GC_ADDRESS << GC_INFO_SHIFT)) >> GC_INFO_SHIFT)
#define GC_REF_COLOR(ref) \
(((GC_TYPE_INFO(ref)) & (GC_COLOR << GC_INFO_SHIFT)) >> GC_INFO_SHIFT)
#define GC_REF_CHECK_COLOR(ref, color) \
((GC_TYPE_INFO(ref) & (GC_COLOR << GC_INFO_SHIFT)) == ((color) << GC_INFO_SHIFT))
#define GC_REF_SET_INFO(ref, info) do { \
GC_TYPE_INFO(ref) = \
(GC_TYPE_INFO(ref) & (GC_TYPE_MASK | GC_FLAGS_MASK)) | \
((info) << GC_INFO_SHIFT); \
} while (0)
#define GC_REF_SET_COLOR(ref, c) do { \
GC_TYPE_INFO(ref) = \
(GC_TYPE_INFO(ref) & ~(GC_COLOR << GC_INFO_SHIFT)) | \
((c) << GC_INFO_SHIFT); \
} while (0)
#define GC_REF_SET_BLACK(ref) do { \
GC_TYPE_INFO(ref) &= ~(GC_COLOR << GC_INFO_SHIFT); \
} while (0)
#define GC_REF_SET_PURPLE(ref) do { \
GC_TYPE_INFO(ref) |= (GC_COLOR << GC_INFO_SHIFT); \
} while (0)
/* bit stealing tags for gc_root_buffer.ref */
#define GC_BITS 0x3
#define GC_ROOT 0x0 /* possible root of circular garbage */
#define GC_UNUSED 0x1 /* part of linked list of unused buffers */
#define GC_GARBAGE 0x2 /* garbage to delete */
#define GC_GET_PTR(ptr) \
((void*)(((uintptr_t)(ptr)) & ~GC_BITS))
#define GC_IS_ROOT(ptr) \
((((uintptr_t)(ptr)) & GC_BITS) == GC_ROOT)
#define GC_IS_UNUSED(ptr) \
((((uintptr_t)(ptr)) & GC_BITS) == GC_UNUSED)
#define GC_IS_GARBAGE(ptr) \
((((uintptr_t)(ptr)) & GC_BITS) == GC_GARBAGE)
#define GC_MAKE_GARBAGE(ptr) \
((void*)(((uintptr_t)(ptr)) | GC_GARBAGE))
/* GC address conversion */
#define GC_IDX2PTR(idx) (GC_G(buf) + (idx))
#define GC_PTR2IDX(ptr) ((ptr) - GC_G(buf))
#define GC_IDX2LIST(idx) ((void*)(uintptr_t)(((idx) * sizeof(void*)) | GC_UNUSED))
#define GC_LIST2IDX(list) (((uint32_t)(uintptr_t)(list)) / sizeof(void*))
/* GC buffers */
#define GC_INVALID 0
#define GC_FIRST_ROOT 1
#define GC_DEFAULT_BUF_SIZE (16 * 1024)
#define GC_BUF_GROW_STEP (128 * 1024)
#define GC_MAX_UNCOMPRESSED (1024 * 1024)
#define GC_MAX_BUF_SIZE 0x40000000
#define GC_THRESHOLD_DEFAULT 10000
#define GC_THRESHOLD_STEP 10000
#define GC_THRESHOLD_MAX 1000000000
#define GC_THRESHOLD_TRIGGER 100
/* GC flags */
#define GC_HAS_DESTRUCTORS (1<<0)
/* unused buffers */
#define GC_HAS_UNUSED() \
(GC_G(unused) != GC_INVALID)
#define GC_FETCH_UNUSED() \
gc_fetch_unused()
#define GC_LINK_UNUSED(root) \
gc_link_unused(root)
#define GC_HAS_NEXT_UNUSED_UNDER_THRESHOLD() \
(GC_G(first_unused) < GC_G(gc_threshold))
#define GC_HAS_NEXT_UNUSED() \
(GC_G(first_unused) != GC_G(buf_size))
#define GC_FETCH_NEXT_UNUSED() \
gc_fetch_next_unused()
ZEND_API int (*gc_collect_cycles)(void);
typedef struct _gc_root_buffer {
zend_refcounted *ref;
} gc_root_buffer;
typedef struct _zend_gc_globals {
zend_bool gc_enabled;
zend_bool gc_active; /* GC currently running, forbid nested GC */
zend_bool gc_protected; /* GC protected, forbid root additions */
zend_bool gc_full;
gc_root_buffer *buf; /* preallocated arrays of buffers */
uint32_t unused; /* linked list of unused buffers */
uint32_t first_unused; /* first unused buffer */
uint32_t gc_threshold; /* GC collection threshold */
uint32_t buf_size; /* size of the GC buffer */
uint32_t num_roots; /* number of roots in GC buffer */
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
} zend_gc_globals;
#ifdef ZTS
static int gc_globals_id;
#define GC_G(v) ZEND_TSRMG(gc_globals_id, zend_gc_globals *, v)
#else
#define GC_G(v) (gc_globals.v)
static zend_gc_globals gc_globals;
#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
#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
static zend_always_inline uint32_t gc_compress(uint32_t idx)
{
return idx % GC_MAX_UNCOMPRESSED;
}
static zend_always_inline gc_root_buffer* gc_decompress(zend_refcounted *ref, uint32_t idx)
{
gc_root_buffer *root = GC_IDX2PTR(idx);
if (EXPECTED(GC_GET_PTR(root->ref) == ref)) {
return root;
}
while (1) {
idx += GC_MAX_UNCOMPRESSED;
ZEND_ASSERT(idx < GC_G(first_unused));
root = GC_IDX2PTR(idx);
if (GC_GET_PTR(root->ref) == ref) {
return root;
}
}
}
static zend_always_inline uint32_t gc_fetch_unused(void)
{
uint32_t idx;
gc_root_buffer *root;
ZEND_ASSERT(GC_HAS_UNUSED());
idx = GC_G(unused);
root = GC_IDX2PTR(idx);
ZEND_ASSERT(GC_IS_UNUSED(root->ref));
GC_G(unused) = GC_LIST2IDX(root->ref);
return idx;
}
static zend_always_inline void gc_link_unused(gc_root_buffer *root)
{
root->ref = GC_IDX2LIST(GC_G(unused));
GC_G(unused) = GC_PTR2IDX(root);
}
static zend_always_inline uint32_t gc_fetch_next_unused(void)
{
uint32_t idx;
ZEND_ASSERT(GC_HAS_NEXT_UNUSED());
idx = GC_G(first_unused);
GC_G(first_unused) = GC_G(first_unused) + 1;
return idx;
}
#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_REF_ADDRESS(ref),
gc_color_name(GC_REF_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_REF_ADDRESS(ref),
gc_color_name(GC_REF_COLOR(ref)),
zend_hash_num_elements(arr));
} else {
fprintf(stderr, "[%p] rc=%d addr=%d %s %s ",
ref, GC_REFCOUNT(ref), GC_REF_ADDRESS(ref),
gc_color_name(GC_REF_COLOR(ref)),
zend_get_type_by_const(GC_TYPE(ref)));
}
}
#endif
static zend_always_inline void gc_remove_from_roots(gc_root_buffer *root)
{
GC_LINK_UNUSED(root);
GC_G(num_roots)--;
GC_BENCH_DEC(root_buf_length);
}
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->gc_protected = 1;
gc_globals->gc_full = 0;
gc_globals->buf = NULL;
gc_globals->unused = GC_INVALID;
gc_globals->first_unused = GC_INVALID;
gc_globals->gc_threshold = GC_INVALID;
gc_globals->buf_size = GC_INVALID;
gc_globals->num_roots = 0;
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->zval_buffered = 0;
gc_globals->zval_remove_from_buffer = 0;
gc_globals->zval_marked_grey = 0;
#endif
}
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
}
void gc_globals_dtor(void)
{
#ifndef ZTS
root_buffer_dtor(&gc_globals);
#endif
}
void gc_reset(void)
{
if (GC_G(buf)) {
GC_G(gc_active) = 0;
GC_G(gc_protected) = 0;
GC_G(gc_full) = 0;
GC_G(unused) = GC_INVALID;
GC_G(first_unused) = GC_FIRST_ROOT;
GC_G(num_roots) = 0;
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(zval_buffered) = 0;
GC_G(zval_remove_from_buffer) = 0;
GC_G(zval_marked_grey) = 0;
#endif
}
}
ZEND_API zend_bool gc_enable(zend_bool enable)
{
zend_bool old_enabled = GC_G(gc_enabled);
GC_G(gc_enabled) = enable;
if (enable && !old_enabled && GC_G(buf) == NULL) {
GC_G(buf) = (gc_root_buffer*) pemalloc(sizeof(gc_root_buffer) * GC_DEFAULT_BUF_SIZE, 1);
GC_G(buf)[0].ref = NULL;
GC_G(buf_size) = GC_DEFAULT_BUF_SIZE;
GC_G(gc_threshold) = GC_THRESHOLD_DEFAULT + GC_FIRST_ROOT;
gc_reset();
}
return old_enabled;
}
ZEND_API zend_bool gc_enabled(void)
{
return GC_G(gc_enabled);
}
ZEND_API zend_bool gc_protect(zend_bool protect)
{
zend_bool old_protected = GC_G(gc_protected);
GC_G(gc_protected) = protect;
return old_protected;
}
ZEND_API zend_bool gc_protected(void)
{
return GC_G(gc_protected);
}
static void gc_grow_root_buffer(void)
{
size_t new_size;
if (GC_G(buf_size) >= GC_MAX_BUF_SIZE) {
if (!GC_G(gc_full)) {
zend_error(E_WARNING, "GC buffer overflow (GC disabled)\n");
GC_G(gc_active) = 1;
GC_G(gc_protected) = 1;
GC_G(gc_full) = 1;
return;
}
}
if (GC_G(buf_size) < GC_BUF_GROW_STEP) {
new_size = GC_G(buf_size) * 2;
} else {
new_size = GC_G(buf_size) + GC_BUF_GROW_STEP;
}
if (new_size > GC_MAX_BUF_SIZE) {
new_size = GC_MAX_BUF_SIZE;
}
GC_G(buf) = perealloc(GC_G(buf), sizeof(gc_root_buffer) * new_size, 1);
GC_G(buf_size) = new_size;
}
static void gc_adjust_threshold(int count)
{
uint32_t new_threshold;
/* TODO Very simple heuristic for dynamic GC buffer resizing:
* If there are "too few" collections, increase the collection threshold
* by a fixed step */
if (count < GC_THRESHOLD_TRIGGER) {
/* increase */
if (GC_G(gc_threshold) < GC_THRESHOLD_MAX) {
new_threshold = GC_G(gc_threshold) + GC_THRESHOLD_STEP;
if (new_threshold > GC_THRESHOLD_MAX) {
new_threshold = GC_THRESHOLD_MAX;
}
if (new_threshold > GC_G(buf_size)) {
gc_grow_root_buffer();
}
if (new_threshold <= GC_G(buf_size)) {
GC_G(gc_threshold) = new_threshold;
}
}
} else if (GC_G(gc_threshold) > GC_THRESHOLD_DEFAULT) {
new_threshold = GC_G(gc_threshold) - GC_THRESHOLD_STEP;
if (new_threshold < GC_THRESHOLD_DEFAULT) {
new_threshold = GC_THRESHOLD_DEFAULT;
}
GC_G(gc_threshold) = new_threshold;
}
}
static zend_never_inline void ZEND_FASTCALL gc_possible_root_when_full(zend_refcounted *ref)
{
uint32_t idx;
gc_root_buffer *newRoot;
ZEND_ASSERT(GC_TYPE(ref) == IS_ARRAY || GC_TYPE(ref) == IS_OBJECT);
ZEND_ASSERT(GC_INFO(ref) == 0);
if (GC_G(gc_enabled) && !GC_G(gc_active)) {
GC_ADDREF(ref);
gc_adjust_threshold(gc_collect_cycles());
if (UNEXPECTED(GC_DELREF(ref)) == 0) {
rc_dtor_func(ref);
return;
} else if (UNEXPECTED(GC_INFO(ref))) {
return;
}
}
if (GC_HAS_UNUSED()) {
idx = GC_FETCH_UNUSED();
} else if (EXPECTED(GC_HAS_NEXT_UNUSED())) {
idx = GC_FETCH_NEXT_UNUSED();
} else {
gc_grow_root_buffer();
if (UNEXPECTED(!GC_HAS_NEXT_UNUSED())) {
return;
}
idx = GC_FETCH_NEXT_UNUSED();
}
newRoot = GC_IDX2PTR(idx);
newRoot->ref = ref; /* GC_ROOT tag is 0 */
GC_TRACE_SET_COLOR(ref, GC_PURPLE);
idx = gc_compress(idx);
GC_REF_SET_INFO(ref, idx | GC_PURPLE);
GC_G(num_roots)++;
GC_BENCH_INC(zval_buffered);
GC_BENCH_INC(root_buf_length);
GC_BENCH_PEAK(root_buf_peak, root_buf_length);
}
ZEND_API void ZEND_FASTCALL gc_possible_root(zend_refcounted *ref)
{
uint32_t idx;
gc_root_buffer *newRoot;
if (UNEXPECTED(GC_G(gc_protected))) {
return;
}
GC_BENCH_INC(zval_possible_root);
if (EXPECTED(GC_HAS_UNUSED())) {
idx = GC_FETCH_UNUSED();
} else if (EXPECTED(GC_HAS_NEXT_UNUSED_UNDER_THRESHOLD())) {
idx = GC_FETCH_NEXT_UNUSED();
} else {
gc_possible_root_when_full(ref);
return;
}
ZEND_ASSERT(GC_TYPE(ref) == IS_ARRAY || GC_TYPE(ref) == IS_OBJECT);
ZEND_ASSERT(GC_INFO(ref) == 0);
newRoot = GC_IDX2PTR(idx);
newRoot->ref = ref; /* GC_ROOT tag is 0 */
GC_TRACE_SET_COLOR(ref, GC_PURPLE);
idx = gc_compress(idx);
GC_REF_SET_INFO(ref, idx | GC_PURPLE);
GC_G(num_roots)++;
GC_BENCH_INC(zval_buffered);
GC_BENCH_INC(root_buf_length);
GC_BENCH_PEAK(root_buf_peak, root_buf_length);
}
static zend_never_inline void ZEND_FASTCALL gc_remove_compressed(zend_refcounted *ref, uint32_t idx)
{
gc_root_buffer *root = gc_decompress(ref, idx);
gc_remove_from_roots(root);
}
ZEND_API void ZEND_FASTCALL gc_remove_from_buffer(zend_refcounted *ref)
{
gc_root_buffer *root;
uint32_t idx = GC_REF_ADDRESS(ref);
GC_BENCH_INC(zval_remove_from_buffer);
if (!GC_REF_CHECK_COLOR(ref, GC_BLACK)) {
GC_TRACE_SET_COLOR(ref, GC_BLACK);
}
GC_REF_SET_INFO(ref, 0);
/* Perform decompression only in case of large buffers */
if (UNEXPECTED(GC_G(first_unused) >= GC_MAX_UNCOMPRESSED)) {
gc_remove_compressed(ref, idx);
return;
}
ZEND_ASSERT(idx);
root = GC_IDX2PTR(idx);
gc_remove_from_roots(root);
}
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(!(OBJ_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_CHECK_COLOR(ref, GC_BLACK)) {
gc_scan_black(ref);
}
}
zv++;
}
if (EXPECTED(!ht)) {
ref = Z_COUNTED_P(zv);
GC_ADDREF(ref);
if (!GC_REF_CHECK_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_CHECK_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_CHECK_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_CHECK_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_CHECK_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(!(OBJ_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;
}
}
/* Two-Finger compaction algorithm */
static void gc_compact(void)
{
if (GC_G(num_roots) + GC_FIRST_ROOT != GC_G(first_unused)) {
if (GC_G(num_roots)) {
gc_root_buffer *free = GC_IDX2PTR(GC_FIRST_ROOT);
gc_root_buffer *scan = GC_IDX2PTR(GC_G(first_unused) - 1);
gc_root_buffer *end = GC_IDX2PTR(GC_G(num_roots));
uint32_t idx;
zend_refcounted *p;
while (free < scan) {
while (!GC_IS_UNUSED(free->ref)) {
free++;
}
while (GC_IS_UNUSED(scan->ref)) {
scan--;
}
if (scan > free) {
p = scan->ref;
free->ref = p;
p = GC_GET_PTR(p);
idx = gc_compress(GC_PTR2IDX(free));
GC_REF_SET_INFO(p, idx | GC_REF_COLOR(p));
free++;
scan--;
if (scan <= end) {
break;
}
}
}
}
GC_G(unused) = GC_INVALID;
GC_G(first_unused) = GC_G(num_roots) + GC_FIRST_ROOT;
}
}
static void gc_mark_roots(void)
{
gc_root_buffer *current, *last;
gc_compact();
current = GC_IDX2PTR(GC_FIRST_ROOT);
last = GC_IDX2PTR(GC_G(first_unused));
while (current != last) {
if (GC_IS_ROOT(current->ref)) {
if (GC_REF_CHECK_COLOR(current->ref, GC_PURPLE)) {
gc_mark_grey(current->ref);
}
}
current++;
}
}
static void gc_scan(zend_refcounted *ref)
{
HashTable *ht;
Bucket *p, *end;
zval *zv;
tail_call:
if (GC_REF_CHECK_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(!(OBJ_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_IDX2PTR(GC_FIRST_ROOT);
gc_root_buffer *last = GC_IDX2PTR(GC_G(first_unused));
while (current != last) {
if (GC_IS_ROOT(current->ref)) {
gc_scan(current->ref);
}
current++;
}
}
static void gc_add_garbage(zend_refcounted *ref)
{
uint32_t idx;
gc_root_buffer *buf;
if (GC_HAS_UNUSED()) {
idx = GC_FETCH_UNUSED();
} else if (GC_HAS_NEXT_UNUSED()) {
idx = GC_FETCH_NEXT_UNUSED();
} else {
gc_grow_root_buffer();
if (UNEXPECTED(!GC_HAS_NEXT_UNUSED())) {
return;
}
idx = GC_FETCH_NEXT_UNUSED();
}
buf = GC_IDX2PTR(idx);
buf->ref = GC_MAKE_GARBAGE(ref);
idx = gc_compress(idx);
GC_REF_SET_INFO(ref, idx | GC_BLACK);
GC_G(num_roots)++;
}
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_CHECK_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(!(OBJ_FLAGS(ref) & IS_OBJ_FREE_CALLED) &&
(get_gc = obj->handlers->get_gc) != NULL)) {
int n;
zval *zv, *end;
zval tmp;
/* optimization: color is GC_BLACK (0) */
if (!GC_INFO(ref)) {
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) {
/* optimization: color is GC_BLACK (0) */
if (!GC_INFO(ref)) {
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)
{
uint32_t idx, end;
zend_refcounted *ref;
int count = 0;
gc_root_buffer *current = GC_IDX2PTR(GC_FIRST_ROOT);
gc_root_buffer *last = GC_IDX2PTR(GC_G(first_unused));
/* remove non-garbage from the list */
while (current != last) {
if (GC_IS_ROOT(current->ref)) {
if (GC_REF_CHECK_COLOR(current->ref, GC_BLACK)) {
GC_REF_SET_INFO(current->ref, 0); /* reset GC_ADDRESS() and keep GC_BLACK */
gc_remove_from_roots(current);
}
}
current++;
}
gc_compact();
/* Root buffer might be reallocated during gc_collect_white,
* make sure to reload pointers. */
idx = GC_FIRST_ROOT;
end = GC_G(first_unused);
while (idx != end) {
current = GC_IDX2PTR(idx);
ref = current->ref;
ZEND_ASSERT(GC_IS_ROOT(ref));
current->ref = GC_MAKE_GARBAGE(ref);
if (GC_REF_CHECK_COLOR(ref, GC_WHITE)) {
count += gc_collect_white(ref, flags);
}
idx++;
}
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_REF_ADDRESS(ref) != 0 &&
GC_REF_CHECK_COLOR(ref, GC_BLACK))) {
GC_TRACE_REF(ref, "removing from buffer");
if (root) {
gc_remove_from_roots(root);
GC_REF_SET_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(!(OBJ_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(num_roots)) {
gc_root_buffer *current, *last;
zend_refcounted *p;
uint32_t gc_flags = 0;
uint32_t idx, end;
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();
GC_TRACE("Collecting roots");
count = gc_collect_roots(&gc_flags);
if (!GC_G(num_roots)) {
/* nothing to free */
GC_TRACE("Nothing to free");
GC_G(gc_active) = 0;
return 0;
}
end = GC_G(first_unused);
if (gc_flags & GC_HAS_DESTRUCTORS) {
uint32_t *refcounts;
GC_TRACE("Calling destructors");
// TODO: may be use emalloc() ???
refcounts = pemalloc(sizeof(uint32_t) * end, 1);
/* Remember reference counters before calling destructors */
idx = GC_FIRST_ROOT;
current = GC_IDX2PTR(GC_FIRST_ROOT);
while (idx != end) {
if (GC_IS_GARBAGE(current->ref)) {
p = GC_GET_PTR(current->ref);
refcounts[idx] = GC_REFCOUNT(p);
}
current++;
idx++;
}
/* Call destructors
*
* The root buffer might be reallocated during destructors calls,
* make sure to reload pointers as necessary. */
idx = GC_FIRST_ROOT;
while (idx != end) {
current = GC_IDX2PTR(idx);
if (GC_IS_GARBAGE(current->ref)) {
p = GC_GET_PTR(current->ref);
if (GC_TYPE(p) == IS_OBJECT
&& !(OBJ_FLAGS(p) & IS_OBJ_DESTRUCTOR_CALLED)) {
zend_object *obj = (zend_object*)p;
GC_TRACE_REF(obj, "calling destructor");
GC_ADD_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);
}
}
}
idx++;
}
/* Remove values captured in destructors */
idx = GC_FIRST_ROOT;
current = GC_IDX2PTR(GC_FIRST_ROOT);
while (idx != end) {
if (GC_IS_GARBAGE(current->ref)) {
p = GC_GET_PTR(current->ref);
if (GC_REFCOUNT(p) > refcounts[idx]) {
gc_remove_nested_data_from_buffer(p, current);
}
}
current++;
idx++;
}
pefree(refcounts, 1);
if (GC_G(gc_protected)) {
/* something went wrong */
return 0;
}
}
/* Destroy zvals */
GC_TRACE("Destroying zvals");
GC_G(gc_protected) = 1;
current = GC_IDX2PTR(GC_FIRST_ROOT);
last = GC_IDX2PTR(GC_G(first_unused));
while (current != last) {
if (GC_IS_GARBAGE(current->ref)) {
p = GC_GET_PTR(current->ref);
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_INFO(obj) = IS_NULL |
(GC_TYPE_INFO(obj) & ~GC_TYPE_MASK);
if (!(OBJ_FLAGS(obj) & IS_OBJ_FREE_CALLED)) {
GC_ADD_FLAGS(obj, IS_OBJ_FREE_CALLED);
if (obj->handlers->free_obj) {
GC_ADDREF(obj);
obj->handlers->free_obj(obj);
GC_DELREF(obj);
}
}
ZEND_OBJECTS_STORE_ADD_TO_FREE_LIST(obj->handle);
current->ref = GC_MAKE_GARBAGE(((char*)obj) - obj->handlers->offset);
} else if (GC_TYPE(p) == IS_ARRAY) {
zend_array *arr = (zend_array*)p;
GC_TYPE_INFO(arr) = IS_NULL |
(GC_TYPE_INFO(arr) & ~GC_TYPE_MASK);
/* GC may destroy arrays with rc>1. This is valid and safe. */
HT_ALLOW_COW_VIOLATION(arr);
zend_hash_destroy(arr);
}
}
current++;
}
/* Free objects */
current = GC_IDX2PTR(GC_FIRST_ROOT);
while (current != last) {
if (GC_IS_GARBAGE(current->ref)) {
p = GC_GET_PTR(current->ref);
GC_LINK_UNUSED(current);
GC_G(num_roots)--;
efree(p);
}
current++;
}
GC_TRACE("Collection finished");
GC_G(collected) += count;
GC_G(gc_protected) = 0;
GC_G(gc_active) = 0;
}
gc_compact();
return count;
}
ZEND_API void zend_gc_get_status(zend_gc_status *status)
{
status->runs = GC_G(gc_runs);
status->collected = GC_G(collected);
status->threshold = GC_G(gc_threshold);
status->num_roots = GC_G(num_roots);
}
/*
* 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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