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php-src/Zend/zend_gc.c
Dmitry Stogov 004d8951ce Merge branch 'PHP-8.2' into PHP-8.3 
* PHP-8.2:
  Fix memory leak after GC inside a foreach loop (#12572)
2023-10-30 23:36:50 +03:00

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/*
+----------------------------------------------------------------------+
| Zend Engine |
+----------------------------------------------------------------------+
| Copyright (c) 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@php.net> |
+----------------------------------------------------------------------+
*/
/**
* 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 undergoing
* 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 checks 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 possible 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"
#include "zend_fibers.h"
#include "zend_hrtime.h"
#include "zend_weakrefs.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 0x0fffffu
#define GC_COLOR 0x300000u
#define GC_BLACK 0x000000u /* must be zero */
#define GC_WHITE 0x100000u
#define GC_GREY 0x200000u
#define GC_PURPLE 0x300000u
/* Debug tracing */
#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
/* 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_TRACE_SET_COLOR(ref, c); \
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_TRACE_SET_COLOR(ref, GC_BLACK); \
GC_TYPE_INFO(ref) &= ~(GC_COLOR << GC_INFO_SHIFT); \
} while (0)
#define GC_REF_SET_PURPLE(ref) do { \
GC_TRACE_SET_COLOR(ref, GC_PURPLE); \
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_DTOR_GARBAGE 0x3 /* garbage on which only the dtor should be invoked */
#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_IS_DTOR_GARBAGE(ptr) \
((((uintptr_t)(ptr)) & GC_BITS) == GC_DTOR_GARBAGE)
#define GC_MAKE_GARBAGE(ptr) \
((void*)(((uintptr_t)(ptr)) | GC_GARBAGE))
#define GC_MAKE_DTOR_GARBAGE(ptr) \
((void*)(((uintptr_t)(ptr)) | GC_DTOR_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 (512 * 1024)
#define GC_MAX_BUF_SIZE 0x40000000
#define GC_THRESHOLD_DEFAULT (10000 + GC_FIRST_ROOT)
#define GC_THRESHOLD_STEP 10000
#define GC_THRESHOLD_MAX 1000000000
#define GC_THRESHOLD_TRIGGER 100
/* GC flags */
#define GC_HAS_DESTRUCTORS (1<<0)
/* Weak maps */
#define Z_FROM_WEAKMAP_KEY (1<<0)
#define Z_FROM_WEAKMAP (1<<1)
/* The WeakMap entry zv is reachable from roots by following the virtual
* reference from the a WeakMap key to the entry */
#define GC_FROM_WEAKMAP_KEY(zv) \
(Z_TYPE_INFO_P((zv)) & (Z_FROM_WEAKMAP_KEY << Z_TYPE_INFO_EXTRA_SHIFT))
#define GC_SET_FROM_WEAKMAP_KEY(zv) do { \
zval *_z = (zv); \
Z_TYPE_INFO_P(_z) = Z_TYPE_INFO_P(_z) | (Z_FROM_WEAKMAP_KEY << Z_TYPE_INFO_EXTRA_SHIFT); \
} while (0)
#define GC_UNSET_FROM_WEAKMAP_KEY(zv) do { \
zval *_z = (zv); \
Z_TYPE_INFO_P(_z) = Z_TYPE_INFO_P(_z) & ~(Z_FROM_WEAKMAP_KEY << Z_TYPE_INFO_EXTRA_SHIFT); \
} while (0)
/* The WeakMap entry zv is reachable from roots by following the reference from
* the WeakMap */
#define GC_FROM_WEAKMAP(zv) \
(Z_TYPE_INFO_P((zv)) & (Z_FROM_WEAKMAP << Z_TYPE_INFO_EXTRA_SHIFT))
#define GC_SET_FROM_WEAKMAP(zv) do { \
zval *_z = (zv); \
Z_TYPE_INFO_P(_z) = Z_TYPE_INFO_P(_z) | (Z_FROM_WEAKMAP << Z_TYPE_INFO_EXTRA_SHIFT); \
} while (0)
#define GC_UNSET_FROM_WEAKMAP(zv) do { \
zval *_z = (zv); \
Z_TYPE_INFO_P(_z) = Z_TYPE_INFO_P(_z) & ~(Z_FROM_WEAKMAP << Z_TYPE_INFO_EXTRA_SHIFT); \
} while (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 {
gc_root_buffer *buf; /* preallocated arrays of buffers */
bool gc_enabled;
bool gc_active; /* GC currently running, forbid nested GC */
bool gc_protected; /* GC protected, forbid root additions */
bool gc_full;
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;
zend_hrtime_t activated_at;
zend_hrtime_t collector_time;
zend_hrtime_t dtor_time;
zend_hrtime_t free_time;
#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;
static size_t gc_globals_offset;
#define GC_G(v) ZEND_TSRMG_FAST(gc_globals_offset, 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
#define GC_STACK_SEGMENT_SIZE (((4096 - ZEND_MM_OVERHEAD) / sizeof(void*)) - 2)
typedef struct _gc_stack gc_stack;
struct _gc_stack {
gc_stack *prev;
gc_stack *next;
zend_refcounted *data[GC_STACK_SEGMENT_SIZE];
};
#define GC_STACK_DCL(init) \
gc_stack *_stack = init; \
size_t _top = 0;
#define GC_STACK_PUSH(ref) \
gc_stack_push(&_stack, &_top, ref);
#define GC_STACK_POP() \
gc_stack_pop(&_stack, &_top)
static zend_never_inline gc_stack* gc_stack_next(gc_stack *stack)
{
if (UNEXPECTED(!stack->next)) {
gc_stack *segment = emalloc(sizeof(gc_stack));
segment->prev = stack;
segment->next = NULL;
stack->next = segment;
}
return stack->next;
}
static zend_always_inline void gc_stack_push(gc_stack **stack, size_t *top, zend_refcounted *ref)
{
if (UNEXPECTED(*top == GC_STACK_SEGMENT_SIZE)) {
(*stack) = gc_stack_next(*stack);
(*top) = 0;
}
(*stack)->data[(*top)++] = ref;
}
static zend_always_inline zend_refcounted* gc_stack_pop(gc_stack **stack, size_t *top)
{
if (UNEXPECTED((*top) == 0)) {
if (!(*stack)->prev) {
return NULL;
} else {
(*stack) = (*stack)->prev;
(*top) = GC_STACK_SEGMENT_SIZE - 1;
return (*stack)->data[GC_STACK_SEGMENT_SIZE - 1];
}
} else {
return (*stack)->data[--(*top)];
}
}
static void gc_stack_free(gc_stack *stack)
{
gc_stack *p = stack->next;
while (p) {
stack = p->next;
efree(p);
p = stack;
}
}
static zend_always_inline uint32_t gc_compress(uint32_t idx)
{
if (EXPECTED(idx < GC_MAX_UNCOMPRESSED)) {
return idx;
}
return (idx % GC_MAX_UNCOMPRESSED) | 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)),
GC_TYPE(ref) == IS_REFERENCE
? "reference" : 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;
gc_globals->collector_time = 0;
gc_globals->dtor_time = 0;
gc_globals->free_time = 0;
gc_globals->activated_at = 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_fast_id(&gc_globals_id, &gc_globals_offset, 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;
GC_G(collector_time) = 0;
GC_G(dtor_time) = 0;
GC_G(free_time) = 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(activated_at) = zend_hrtime();
}
ZEND_API bool gc_enable(bool enable)
{
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_reset();
}
return old_enabled;
}
ZEND_API bool gc_enabled(void)
{
return GC_G(gc_enabled);
}
ZEND_API bool gc_protect(bool protect)
{
bool old_protected = GC_G(gc_protected);
GC_G(gc_protected) = protect;
return old_protected;
}
ZEND_API 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 void ZEND_FASTCALL gc_extra_root(zend_refcounted *ref)
{
uint32_t idx;
gc_root_buffer *newRoot;
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_grow_root_buffer();
if (UNEXPECTED(!GC_HAS_NEXT_UNUSED())) {
/* TODO: can this really happen? */
return;
}
idx = GC_FETCH_NEXT_UNUSED();
}
ZEND_ASSERT(GC_TYPE(ref) == IS_ARRAY || GC_TYPE(ref) == IS_OBJECT);
ZEND_ASSERT(GC_REF_ADDRESS(ref) == 0);
newRoot = GC_IDX2PTR(idx);
newRoot->ref = ref; /* GC_ROOT tag is 0 */
idx = gc_compress(idx);
GC_REF_SET_INFO(ref, idx | GC_REF_COLOR(ref));
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, gc_stack *stack)
{
HashTable *ht;
Bucket *p;
zval *zv;
uint32_t n;
GC_STACK_DCL(stack);
tail_call:
if (GC_TYPE(ref) == IS_OBJECT) {
zend_object *obj = (zend_object*)ref;
if (EXPECTED(!(OBJ_FLAGS(ref) & IS_OBJ_FREE_CALLED))) {
zval *table;
int len;
if (UNEXPECTED(GC_FLAGS(obj) & IS_OBJ_WEAKLY_REFERENCED)) {
zend_weakmap_get_object_key_entry_gc(obj, &table, &len);
n = len;
zv = table;
for (; n != 0; n-=2) {
ZEND_ASSERT(Z_TYPE_P(zv) == IS_PTR);
zval *entry = (zval*) Z_PTR_P(zv);
zval *weakmap = zv+1;
ZEND_ASSERT(Z_REFCOUNTED_P(weakmap));
if (Z_OPT_REFCOUNTED_P(entry)) {
GC_UNSET_FROM_WEAKMAP_KEY(entry);
if (GC_REF_CHECK_COLOR(Z_COUNTED_P(weakmap), GC_GREY)) {
/* Weakmap was scanned in gc_mark_roots, we must
* ensure that it's eventually scanned in
* gc_scan_roots as well. */
if (!GC_REF_ADDRESS(Z_COUNTED_P(weakmap))) {
gc_extra_root(Z_COUNTED_P(weakmap));
}
} else if (/* GC_REF_CHECK_COLOR(Z_COUNTED_P(weakmap), GC_BLACK) && */ !GC_FROM_WEAKMAP(entry)) {
/* Both the entry weakmap and key are BLACK, so we
* can mark the entry BLACK as well.
* !GC_FROM_WEAKMAP(entry) means that the weakmap
* was already scanned black (or will not be
* scanned), so it's our responsibility to mark the
* entry */
ZEND_ASSERT(GC_REF_CHECK_COLOR(Z_COUNTED_P(weakmap), GC_BLACK));
ref = Z_COUNTED_P(entry);
GC_ADDREF(ref);
if (!GC_REF_CHECK_COLOR(ref, GC_BLACK)) {
GC_REF_SET_BLACK(ref);
GC_STACK_PUSH(ref);
}
}
}
zv+=2;
}
}
if (UNEXPECTED(obj->handlers->get_gc == zend_weakmap_get_gc)) {
zend_weakmap_get_key_entry_gc(obj, &table, &len);
n = len;
zv = table;
for (; n != 0; n-=2) {
ZEND_ASSERT(Z_TYPE_P(zv+1) == IS_PTR);
zval *key = zv;
zval *entry = (zval*) Z_PTR_P(zv+1);
if (Z_OPT_REFCOUNTED_P(entry)) {
GC_UNSET_FROM_WEAKMAP(entry);
if (GC_REF_CHECK_COLOR(Z_COUNTED_P(key), GC_GREY)) {
/* Key was scanned in gc_mark_roots, we must
* ensure that it's eventually scanned in
* gc_scan_roots as well. */
if (!GC_REF_ADDRESS(Z_COUNTED_P(key))) {
gc_extra_root(Z_COUNTED_P(key));
}
} else if (/* GC_REF_CHECK_COLOR(Z_COUNTED_P(key), GC_BLACK) && */ !GC_FROM_WEAKMAP_KEY(entry)) {
/* Both the entry weakmap and key are BLACK, so we
* can mark the entry BLACK as well.
* !GC_FROM_WEAKMAP_KEY(entry) means that the key
* was already scanned black (or will not be
* scanned), so it's our responsibility to mark the
* entry */
ZEND_ASSERT(GC_REF_CHECK_COLOR(Z_COUNTED_P(key), GC_BLACK));
ref = Z_COUNTED_P(entry);
GC_ADDREF(ref);
if (!GC_REF_CHECK_COLOR(ref, GC_BLACK)) {
GC_REF_SET_BLACK(ref);
GC_STACK_PUSH(ref);
}
}
}
zv += 2;
}
goto next;
}
ht = obj->handlers->get_gc(obj, &table, &len);
n = len;
zv = table;
if (UNEXPECTED(ht)) {
GC_ADDREF(ht);
if (!GC_REF_CHECK_COLOR(ht, GC_BLACK)) {
GC_REF_SET_BLACK(ht);
for (; n != 0; n--) {
if (Z_REFCOUNTED_P(zv)) {
ref = Z_COUNTED_P(zv);
GC_ADDREF(ref);
if (!GC_REF_CHECK_COLOR(ref, GC_BLACK)) {
GC_REF_SET_BLACK(ref);
GC_STACK_PUSH(ref);
}
}
zv++;
}
goto handle_ht;
}
}
handle_zvals:
for (; n != 0; n--) {
if (Z_REFCOUNTED_P(zv)) {
ref = Z_COUNTED_P(zv);
GC_ADDREF(ref);
if (!GC_REF_CHECK_COLOR(ref, GC_BLACK)) {
GC_REF_SET_BLACK(ref);
zv++;
while (--n) {
if (Z_REFCOUNTED_P(zv)) {
zend_refcounted *ref = Z_COUNTED_P(zv);
GC_ADDREF(ref);
if (!GC_REF_CHECK_COLOR(ref, GC_BLACK)) {
GC_REF_SET_BLACK(ref);
GC_STACK_PUSH(ref);
}
}
zv++;
}
goto tail_call;
}
}
zv++;
}
}
} else if (GC_TYPE(ref) == IS_ARRAY) {
ZEND_ASSERT((zend_array*)ref != &EG(symbol_table));
ht = (zend_array*)ref;
handle_ht:
n = ht->nNumUsed;
zv = ht->arPacked;
if (HT_IS_PACKED(ht)) {
goto handle_zvals;
}
p = (Bucket*)zv;
for (; n != 0; n--) {
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_REF_SET_BLACK(ref);
p++;
while (--n) {
zv = &p->val;
if (Z_TYPE_P(zv) == IS_INDIRECT) {
zv = Z_INDIRECT_P(zv);
}
if (Z_REFCOUNTED_P(zv)) {
zend_refcounted *ref = Z_COUNTED_P(zv);
GC_ADDREF(ref);
if (!GC_REF_CHECK_COLOR(ref, GC_BLACK)) {
GC_REF_SET_BLACK(ref);
GC_STACK_PUSH(ref);
}
}
p++;
}
goto tail_call;
}
}
p++;
}
} 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)) {
GC_REF_SET_BLACK(ref);
goto tail_call;
}
}
}
next:
ref = GC_STACK_POP();
if (ref) {
goto tail_call;
}
}
static void gc_mark_grey(zend_refcounted *ref, gc_stack *stack)
{
HashTable *ht;
Bucket *p;
zval *zv;
uint32_t n;
GC_STACK_DCL(stack);
tail_call:
GC_BENCH_INC(zval_marked_grey);
if (GC_TYPE(ref) == IS_OBJECT) {
zend_object *obj = (zend_object*)ref;
if (EXPECTED(!(OBJ_FLAGS(ref) & IS_OBJ_FREE_CALLED))) {
zval *table;
int len;
if (UNEXPECTED(GC_FLAGS(obj) & IS_OBJ_WEAKLY_REFERENCED)) {
zend_weakmap_get_object_key_entry_gc(obj, &table, &len);
n = len;
zv = table;
for (; n != 0; n-=2) {
ZEND_ASSERT(Z_TYPE_P(zv) == IS_PTR);
zval *entry = (zval*) Z_PTR_P(zv);
zval *weakmap = zv+1;
ZEND_ASSERT(Z_REFCOUNTED_P(weakmap));
if (Z_REFCOUNTED_P(entry)) {
GC_SET_FROM_WEAKMAP_KEY(entry);
ref = Z_COUNTED_P(entry);
/* Only DELREF if the contribution from the weakmap has
* not been cancelled yet */
if (!GC_FROM_WEAKMAP(entry)) {
GC_DELREF(ref);
}
if (!GC_REF_CHECK_COLOR(ref, GC_GREY)) {
GC_REF_SET_COLOR(ref, GC_GREY);
GC_STACK_PUSH(ref);
}
}
zv+=2;
}
}
if (UNEXPECTED(obj->handlers->get_gc == zend_weakmap_get_gc)) {
zend_weakmap_get_entry_gc(obj, &table, &len);
n = len;
zv = table;
for (; n != 0; n--) {
ZEND_ASSERT(Z_TYPE_P(zv) == IS_PTR);
zval *entry = (zval*) Z_PTR_P(zv);
if (Z_REFCOUNTED_P(entry)) {
GC_SET_FROM_WEAKMAP(entry);
ref = Z_COUNTED_P(entry);
/* Only DELREF if the contribution from the weakmap key
* has not been cancelled yet */
if (!GC_FROM_WEAKMAP_KEY(entry)) {
GC_DELREF(ref);
}
if (!GC_REF_CHECK_COLOR(ref, GC_GREY)) {
GC_REF_SET_COLOR(ref, GC_GREY);
GC_STACK_PUSH(ref);
}
}
zv++;
}
goto next;
}
ht = obj->handlers->get_gc(obj, &table, &len);
n = len;
zv = table;
if (UNEXPECTED(ht)) {
GC_DELREF(ht);
if (!GC_REF_CHECK_COLOR(ht, GC_GREY)) {
GC_REF_SET_COLOR(ht, GC_GREY);
for (; n != 0; n--) {
if (Z_REFCOUNTED_P(zv)) {
ref = Z_COUNTED_P(zv);
GC_DELREF(ref);
if (!GC_REF_CHECK_COLOR(ref, GC_GREY)) {
GC_REF_SET_COLOR(ref, GC_GREY);
GC_STACK_PUSH(ref);
}
}
zv++;
}
goto handle_ht;
}
}
handle_zvals:
for (; n != 0; n--) {
if (Z_REFCOUNTED_P(zv)) {
ref = Z_COUNTED_P(zv);
GC_DELREF(ref);
if (!GC_REF_CHECK_COLOR(ref, GC_GREY)) {
GC_REF_SET_COLOR(ref, GC_GREY);
zv++;
while (--n) {
if (Z_REFCOUNTED_P(zv)) {
zend_refcounted *ref = Z_COUNTED_P(zv);
GC_DELREF(ref);
if (!GC_REF_CHECK_COLOR(ref, GC_GREY)) {
GC_REF_SET_COLOR(ref, GC_GREY);
GC_STACK_PUSH(ref);
}
}
zv++;
}
goto tail_call;
}
}
zv++;
}
}
} else if (GC_TYPE(ref) == IS_ARRAY) {
ZEND_ASSERT(((zend_array*)ref) != &EG(symbol_table));
ht = (zend_array*)ref;
handle_ht:
n = ht->nNumUsed;
if (HT_IS_PACKED(ht)) {
zv = ht->arPacked;
goto handle_zvals;
}
p = ht->arData;
for (; n != 0; n--) {
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);
if (!GC_REF_CHECK_COLOR(ref, GC_GREY)) {
GC_REF_SET_COLOR(ref, GC_GREY);
p++;
while (--n) {
zv = &p->val;
if (Z_TYPE_P(zv) == IS_INDIRECT) {
zv = Z_INDIRECT_P(zv);
}
if (Z_REFCOUNTED_P(zv)) {
zend_refcounted *ref = Z_COUNTED_P(zv);
GC_DELREF(ref);
if (!GC_REF_CHECK_COLOR(ref, GC_GREY)) {
GC_REF_SET_COLOR(ref, GC_GREY);
GC_STACK_PUSH(ref);
}
}
p++;
}
goto tail_call;
}
}
p++;
}
} else if (GC_TYPE(ref) == IS_REFERENCE) {
if (Z_REFCOUNTED(((zend_reference*)ref)->val)) {
ref = Z_COUNTED(((zend_reference*)ref)->val);
GC_DELREF(ref);
if (!GC_REF_CHECK_COLOR(ref, GC_GREY)) {
GC_REF_SET_COLOR(ref, GC_GREY);
goto tail_call;
}
}
}
next:
ref = GC_STACK_POP();
if (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(gc_stack *stack)
{
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_REF_SET_COLOR(current->ref, GC_GREY);
gc_mark_grey(current->ref, stack);
}
}
current++;
}
}
static void gc_scan(zend_refcounted *ref, gc_stack *stack)
{
HashTable *ht;
Bucket *p;
zval *zv;
uint32_t n;
GC_STACK_DCL(stack);
tail_call:
if (!GC_REF_CHECK_COLOR(ref, GC_WHITE)) {
goto next;
}
if (GC_REFCOUNT(ref) > 0) {
if (!GC_REF_CHECK_COLOR(ref, GC_BLACK)) {
GC_REF_SET_BLACK(ref);
if (UNEXPECTED(!_stack->next)) {
gc_stack_next(_stack);
}
/* Split stack and reuse the tail */
_stack->next->prev = NULL;
gc_scan_black(ref, _stack->next);
_stack->next->prev = _stack;
}
goto next;
}
if (GC_TYPE(ref) == IS_OBJECT) {
zend_object *obj = (zend_object*)ref;
if (EXPECTED(!(OBJ_FLAGS(ref) & IS_OBJ_FREE_CALLED))) {
zval *table;
int len;
if (UNEXPECTED(GC_FLAGS(obj) & IS_OBJ_WEAKLY_REFERENCED)) {
zend_weakmap_get_object_entry_gc(obj, &table, &len);
n = len;
zv = table;
for (; n != 0; n--) {
ZEND_ASSERT(Z_TYPE_P(zv) == IS_PTR);
zval *entry = (zval*) Z_PTR_P(zv);
if (Z_OPT_REFCOUNTED_P(entry)) {
ref = Z_COUNTED_P(entry);
if (GC_REF_CHECK_COLOR(ref, GC_GREY)) {
GC_REF_SET_COLOR(ref, GC_WHITE);
GC_STACK_PUSH(ref);
}
}
zv++;
}
}
ht = obj->handlers->get_gc(obj, &table, &len);
n = len;
zv = table;
if (UNEXPECTED(ht)) {
if (GC_REF_CHECK_COLOR(ht, GC_GREY)) {
GC_REF_SET_COLOR(ht, GC_WHITE);
GC_STACK_PUSH((zend_refcounted *) ht);
for (; n != 0; n--) {
if (Z_REFCOUNTED_P(zv)) {
ref = Z_COUNTED_P(zv);
if (GC_REF_CHECK_COLOR(ref, GC_GREY)) {
GC_REF_SET_COLOR(ref, GC_WHITE);
GC_STACK_PUSH(ref);
}
}
zv++;
}
goto handle_ht;
}
}
handle_zvals:
for (; n != 0; n--) {
if (Z_REFCOUNTED_P(zv)) {
ref = Z_COUNTED_P(zv);
if (GC_REF_CHECK_COLOR(ref, GC_GREY)) {
GC_REF_SET_COLOR(ref, GC_WHITE);
zv++;
while (--n) {
if (Z_REFCOUNTED_P(zv)) {
zend_refcounted *ref = Z_COUNTED_P(zv);
if (GC_REF_CHECK_COLOR(ref, GC_GREY)) {
GC_REF_SET_COLOR(ref, GC_WHITE);
GC_STACK_PUSH(ref);
}
}
zv++;
}
goto tail_call;
}
}
zv++;
}
}
} else if (GC_TYPE(ref) == IS_ARRAY) {
ht = (HashTable *)ref;
ZEND_ASSERT(ht != &EG(symbol_table));
handle_ht:
n = ht->nNumUsed;
if (HT_IS_PACKED(ht)) {
zv = ht->arPacked;
goto handle_zvals;
}
p = ht->arData;
for (; n != 0; n--) {
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);
if (GC_REF_CHECK_COLOR(ref, GC_GREY)) {
GC_REF_SET_COLOR(ref, GC_WHITE);
p++;
while (--n) {
zv = &p->val;
if (Z_TYPE_P(zv) == IS_INDIRECT) {
zv = Z_INDIRECT_P(zv);
}
if (Z_REFCOUNTED_P(zv)) {
zend_refcounted *ref = Z_COUNTED_P(zv);
if (GC_REF_CHECK_COLOR(ref, GC_GREY)) {
GC_REF_SET_COLOR(ref, GC_WHITE);
GC_STACK_PUSH(ref);
}
}
p++;
}
goto tail_call;
}
}
p++;
}
} else if (GC_TYPE(ref) == IS_REFERENCE) {
if (Z_REFCOUNTED(((zend_reference*)ref)->val)) {
ref = Z_COUNTED(((zend_reference*)ref)->val);
if (GC_REF_CHECK_COLOR(ref, GC_GREY)) {
GC_REF_SET_COLOR(ref, GC_WHITE);
goto tail_call;
}
}
}
next:
ref = GC_STACK_POP();
if (ref) {
goto tail_call;
}
}
static void gc_scan_roots(gc_stack *stack)
{
uint32_t idx, end;
gc_root_buffer *current;
/* Root buffer might be reallocated during gc_scan,
* make sure to reload pointers. */
idx = GC_FIRST_ROOT;
end = GC_G(first_unused);
while (idx != end) {
current = GC_IDX2PTR(idx);
if (GC_IS_ROOT(current->ref)) {
if (GC_REF_CHECK_COLOR(current->ref, GC_GREY)) {
GC_REF_SET_COLOR(current->ref, GC_WHITE);
gc_scan(current->ref, stack);
}
}
idx++;
}
/* Scan extra roots added during gc_scan */
while (idx != GC_G(first_unused)) {
current = GC_IDX2PTR(idx);
if (GC_IS_ROOT(current->ref)) {
if (GC_REF_CHECK_COLOR(current->ref, GC_GREY)) {
GC_REF_SET_COLOR(current->ref, GC_WHITE);
gc_scan(current->ref, stack);
}
}
idx++;
}
}
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, gc_stack *stack)
{
int count = 0;
HashTable *ht;
Bucket *p;
zval *zv;
uint32_t n;
GC_STACK_DCL(stack);
tail_call:
/* don't count references for compatibility ??? */
if (GC_TYPE(ref) != IS_REFERENCE) {
count++;
}
if (GC_TYPE(ref) == IS_OBJECT) {
zend_object *obj = (zend_object*)ref;
if (EXPECTED(!(OBJ_FLAGS(ref) & IS_OBJ_FREE_CALLED))) {
int len;
zval *table;
/* optimization: color is GC_BLACK (0) */
if (!GC_INFO(ref)) {
gc_add_garbage(ref);
}
if (!(OBJ_FLAGS(obj) & IS_OBJ_DESTRUCTOR_CALLED)
&& (obj->handlers->dtor_obj != zend_objects_destroy_object
|| obj->ce->destructor != NULL)) {
*flags |= GC_HAS_DESTRUCTORS;
}
if (UNEXPECTED(GC_FLAGS(obj) & IS_OBJ_WEAKLY_REFERENCED)) {
zend_weakmap_get_object_entry_gc(obj, &table, &len);
n = len;
zv = table;
for (; n != 0; n--) {
ZEND_ASSERT(Z_TYPE_P(zv) == IS_PTR);
zval *entry = (zval*) Z_PTR_P(zv);
if (Z_REFCOUNTED_P(entry) && GC_FROM_WEAKMAP_KEY(entry)) {
GC_UNSET_FROM_WEAKMAP_KEY(entry);
GC_UNSET_FROM_WEAKMAP(entry);
ref = Z_COUNTED_P(entry);
GC_ADDREF(ref);
if (GC_REF_CHECK_COLOR(ref, GC_WHITE)) {
GC_REF_SET_BLACK(ref);
GC_STACK_PUSH(ref);
}
}
zv++;
}
}
if (UNEXPECTED(obj->handlers->get_gc == zend_weakmap_get_gc)) {
zend_weakmap_get_entry_gc(obj, &table, &len);
n = len;
zv = table;
for (; n != 0; n--) {
ZEND_ASSERT(Z_TYPE_P(zv) == IS_PTR);
zval *entry = (zval*) Z_PTR_P(zv);
if (Z_REFCOUNTED_P(entry) && GC_FROM_WEAKMAP(entry)) {
GC_UNSET_FROM_WEAKMAP_KEY(entry);
GC_UNSET_FROM_WEAKMAP(entry);
ref = Z_COUNTED_P(entry);
GC_ADDREF(ref);
if (GC_REF_CHECK_COLOR(ref, GC_WHITE)) {
GC_REF_SET_BLACK(ref);
GC_STACK_PUSH(ref);
}
}
zv++;
}
goto next;
}
ht = obj->handlers->get_gc(obj, &table, &len);
n = len;
zv = table;
if (UNEXPECTED(ht)) {
GC_ADDREF(ht);
if (GC_REF_CHECK_COLOR(ht, GC_WHITE)) {
GC_REF_SET_BLACK(ht);
for (; n != 0; n--) {
if (Z_REFCOUNTED_P(zv)) {
ref = Z_COUNTED_P(zv);
GC_ADDREF(ref);
if (GC_REF_CHECK_COLOR(ref, GC_WHITE)) {
GC_REF_SET_BLACK(ref);
GC_STACK_PUSH(ref);
}
}
zv++;
}
goto handle_ht;
}
}
handle_zvals:
for (; n != 0; n--) {
if (Z_REFCOUNTED_P(zv)) {
ref = Z_COUNTED_P(zv);
GC_ADDREF(ref);
if (GC_REF_CHECK_COLOR(ref, GC_WHITE)) {
GC_REF_SET_BLACK(ref);
zv++;
while (--n) {
if (Z_REFCOUNTED_P(zv)) {
zend_refcounted *ref = Z_COUNTED_P(zv);
GC_ADDREF(ref);
if (GC_REF_CHECK_COLOR(ref, GC_WHITE)) {
GC_REF_SET_BLACK(ref);
GC_STACK_PUSH(ref);
}
}
zv++;
}
goto tail_call;
}
}
zv++;
}
}
} 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;
handle_ht:
n = ht->nNumUsed;
if (HT_IS_PACKED(ht)) {
zv = ht->arPacked;
goto handle_zvals;
}
p = ht->arData;
for (; n != 0; n--) {
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_WHITE)) {
GC_REF_SET_BLACK(ref);
p++;
while (--n) {
zv = &p->val;
if (Z_TYPE_P(zv) == IS_INDIRECT) {
zv = Z_INDIRECT_P(zv);
}
if (Z_REFCOUNTED_P(zv)) {
zend_refcounted *ref = Z_COUNTED_P(zv);
GC_ADDREF(ref);
if (GC_REF_CHECK_COLOR(ref, GC_WHITE)) {
GC_REF_SET_BLACK(ref);
GC_STACK_PUSH(ref);
}
}
p++;
}
goto tail_call;
}
}
p++;
}
} 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_WHITE)) {
GC_REF_SET_BLACK(ref);
goto tail_call;
}
}
}
next:
ref = GC_STACK_POP();
if (ref) {
goto tail_call;
}
return count;
}
static int gc_collect_roots(uint32_t *flags, gc_stack *stack)
{
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)) {
GC_REF_SET_BLACK(ref);
count += gc_collect_white(ref, flags, stack);
}
idx++;
}
return count;
}
static int gc_remove_nested_data_from_buffer(zend_refcounted *ref, gc_root_buffer *root, gc_stack *stack)
{
HashTable *ht;
Bucket *p;
zval *zv;
uint32_t n;
int count = 0;
GC_STACK_DCL(stack);
tail_call:
if (root) {
root = NULL;
count++;
} else if (GC_REF_ADDRESS(ref) != 0
&& GC_REF_CHECK_COLOR(ref, GC_BLACK)) {
GC_TRACE_REF(ref, "removing from buffer");
GC_REMOVE_FROM_BUFFER(ref);
count++;
} else if (GC_TYPE(ref) == IS_REFERENCE) {
if (Z_REFCOUNTED(((zend_reference*)ref)->val)) {
ref = Z_COUNTED(((zend_reference*)ref)->val);
goto tail_call;
}
goto next;
} else {
goto next;
}
if (GC_TYPE(ref) == IS_OBJECT) {
zend_object *obj = (zend_object*)ref;
if (EXPECTED(!(OBJ_FLAGS(ref) & IS_OBJ_FREE_CALLED))) {
int len;
zval *table;
if (UNEXPECTED(GC_FLAGS(obj) & IS_OBJ_WEAKLY_REFERENCED)) {
zend_weakmap_get_object_entry_gc(obj, &table, &len);
n = len;
zv = table;
for (; n != 0; n--) {
ZEND_ASSERT(Z_TYPE_P(zv) == IS_PTR);
zval *entry = (zval*) Z_PTR_P(zv);
if (Z_OPT_REFCOUNTED_P(entry)) {
ref = Z_COUNTED_P(entry);
GC_STACK_PUSH(ref);
}
zv++;
}
}
ht = obj->handlers->get_gc(obj, &table, &len);
n = len;
zv = table;
if (UNEXPECTED(ht)) {
for (; n != 0; n--) {
if (Z_REFCOUNTED_P(zv)) {
ref = Z_COUNTED_P(zv);
GC_STACK_PUSH(ref);
}
zv++;
}
if (GC_REF_ADDRESS(ht) != 0 && GC_REF_CHECK_COLOR(ht, GC_BLACK)) {
GC_TRACE_REF(ht, "removing from buffer");
GC_REMOVE_FROM_BUFFER(ht);
}
goto handle_ht;
}
handle_zvals:
for (; n != 0; n--) {
if (Z_REFCOUNTED_P(zv)) {
ref = Z_COUNTED_P(zv);
zv++;
while (--n) {
if (Z_REFCOUNTED_P(zv)) {
zend_refcounted *ref = Z_COUNTED_P(zv);
GC_STACK_PUSH(ref);
}
zv++;
}
goto tail_call;
}
zv++;
}
}
} else if (GC_TYPE(ref) == IS_ARRAY) {
ht = (zend_array*)ref;
handle_ht:
n = ht->nNumUsed;
if (HT_IS_PACKED(ht)) {
zv = ht->arPacked;
goto handle_zvals;
}
p = ht->arData;
for (; n != 0; n--) {
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);
p++;
while (--n) {
zv = &p->val;
if (Z_TYPE_P(zv) == IS_INDIRECT) {
zv = Z_INDIRECT_P(zv);
}
if (Z_REFCOUNTED_P(zv)) {
zend_refcounted *ref = Z_COUNTED_P(zv);
GC_STACK_PUSH(ref);
}
p++;
}
goto tail_call;
}
p++;
}
}
next:
ref = GC_STACK_POP();
if (ref) {
goto tail_call;
}
return count;
}
static void zend_get_gc_buffer_release(void);
static void zend_gc_root_tmpvars(void);
ZEND_API int zend_gc_collect_cycles(void)
{
int total_count = 0;
bool should_rerun_gc = 0;
bool did_rerun_gc = 0;
zend_hrtime_t start_time = zend_hrtime();
rerun_gc:
if (GC_G(num_roots)) {
int count;
gc_root_buffer *current, *last;
zend_refcounted *p;
uint32_t gc_flags = 0;
uint32_t idx, end;
gc_stack stack;
stack.prev = NULL;
stack.next = NULL;
if (GC_G(gc_active)) {
GC_G(collector_time) += zend_hrtime() - start_time;
return 0;
}
GC_TRACE("Collecting cycles");
GC_G(gc_runs)++;
GC_G(gc_active) = 1;
GC_TRACE("Marking roots");
gc_mark_roots(&stack);
GC_TRACE("Scanning roots");
gc_scan_roots(&stack);
GC_TRACE("Collecting roots");
count = gc_collect_roots(&gc_flags, &stack);
if (!GC_G(num_roots)) {
/* nothing to free */
GC_TRACE("Nothing to free");
gc_stack_free(&stack);
GC_G(gc_active) = 0;
goto finish;
}
zend_fiber_switch_block();
end = GC_G(first_unused);
if (gc_flags & GC_HAS_DESTRUCTORS) {
GC_TRACE("Calling destructors");
/* During a destructor call, new externally visible references to nested data may
* be introduced. These references can be introduced in a way that does not
* modify any refcounts, so we have no real way to detect this situation
* short of rerunning full GC tracing. What we do instead is to only run
* destructors at this point and automatically re-run GC afterwards. */
should_rerun_gc = 1;
/* Mark all roots for which a dtor will be invoked as DTOR_GARBAGE. Additionally
* color them purple. This serves a double purpose: First, they should be
* considered new potential roots for the next GC run. Second, it will prevent
* their removal from the root buffer by nested data removal. */
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_TYPE(p) == IS_OBJECT && !(OBJ_FLAGS(p) & IS_OBJ_DESTRUCTOR_CALLED)) {
zend_object *obj = (zend_object *) p;
if (obj->handlers->dtor_obj != zend_objects_destroy_object
|| obj->ce->destructor) {
current->ref = GC_MAKE_DTOR_GARBAGE(obj);
GC_REF_SET_COLOR(obj, GC_PURPLE);
} else {
GC_ADD_FLAGS(obj, IS_OBJ_DESTRUCTOR_CALLED);
}
}
}
current++;
idx++;
}
/* Remove nested data for objects on which a destructor will be called.
* This will not remove the objects themselves, as they have been colored
* purple. */
idx = GC_FIRST_ROOT;
current = GC_IDX2PTR(GC_FIRST_ROOT);
while (idx != end) {
if (GC_IS_DTOR_GARBAGE(current->ref)) {
p = GC_GET_PTR(current->ref);
count -= gc_remove_nested_data_from_buffer(p, current, &stack);
}
current++;
idx++;
}
/* Actually call destructors.
*
* The root buffer might be reallocated during destructors calls,
* make sure to reload pointers as necessary. */
zend_hrtime_t dtor_start_time = zend_hrtime();
idx = GC_FIRST_ROOT;
while (idx != end) {
current = GC_IDX2PTR(idx);
if (GC_IS_DTOR_GARBAGE(current->ref)) {
p = GC_GET_PTR(current->ref);
/* Mark this is as a normal root for the next GC run,
* it's no longer garbage for this run. */
current->ref = p;
/* Double check that the destructor hasn't been called yet. It could have
* already been invoked indirectly by some other destructor. */
if (!(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);
GC_ADDREF(obj);
obj->handlers->dtor_obj(obj);
GC_DELREF(obj);
}
}
idx++;
}
GC_G(dtor_time) += zend_hrtime() - dtor_start_time;
if (GC_G(gc_protected)) {
/* something went wrong */
zend_get_gc_buffer_release();
zend_fiber_switch_unblock();
GC_G(collector_time) += zend_hrtime() - start_time;
return 0;
}
}
gc_stack_free(&stack);
/* Destroy zvals. The root buffer may be reallocated. */
GC_TRACE("Destroying zvals");
zend_hrtime_t free_start_time = zend_hrtime();
idx = GC_FIRST_ROOT;
while (idx != end) {
current = GC_IDX2PTR(idx);
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) = GC_NULL |
(GC_TYPE_INFO(obj) & ~GC_TYPE_MASK);
/* Modify current before calling free_obj (bug #78811: free_obj() can cause the root buffer (with current) to be reallocated.) */
current->ref = GC_MAKE_GARBAGE(((char*)obj) - obj->handlers->offset);
if (!(OBJ_FLAGS(obj) & IS_OBJ_FREE_CALLED)) {
GC_ADD_FLAGS(obj, IS_OBJ_FREE_CALLED);
GC_ADDREF(obj);
obj->handlers->free_obj(obj);
GC_DELREF(obj);
}
ZEND_OBJECTS_STORE_ADD_TO_FREE_LIST(obj->handle);
} else if (GC_TYPE(p) == IS_ARRAY) {
zend_array *arr = (zend_array*)p;
GC_TYPE_INFO(arr) = GC_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);
}
}
idx++;
}
/* Free objects */
current = GC_IDX2PTR(GC_FIRST_ROOT);
last = GC_IDX2PTR(end);
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_G(free_time) += zend_hrtime() - free_start_time;
zend_fiber_switch_unblock();
GC_TRACE("Collection finished");
GC_G(collected) += count;
total_count += count;
GC_G(gc_active) = 0;
}
gc_compact();
/* Objects with destructors were removed from this GC run. Rerun GC right away to clean them
* up. We do this only once: If we encounter more destructors on the second run, we'll not
* run GC another time. */
if (should_rerun_gc && !did_rerun_gc) {
did_rerun_gc = 1;
goto rerun_gc;
}
finish:
zend_get_gc_buffer_release();
zend_gc_root_tmpvars();
GC_G(collector_time) += zend_hrtime() - start_time;
return total_count;
}
ZEND_API void zend_gc_get_status(zend_gc_status *status)
{
status->active = GC_G(gc_active);
status->gc_protected = GC_G(gc_protected);
status->full = GC_G(gc_full);
status->runs = GC_G(gc_runs);
status->collected = GC_G(collected);
status->threshold = GC_G(gc_threshold);
status->buf_size = GC_G(buf_size);
status->num_roots = GC_G(num_roots);
status->application_time = zend_hrtime() - GC_G(activated_at);
status->collector_time = GC_G(collector_time);
status->dtor_time = GC_G(dtor_time);
status->free_time = GC_G(free_time);
}
ZEND_API zend_get_gc_buffer *zend_get_gc_buffer_create(void) {
/* There can only be one get_gc() call active at a time,
* so there only needs to be one buffer. */
zend_get_gc_buffer *gc_buffer = &EG(get_gc_buffer);
gc_buffer->cur = gc_buffer->start;
return gc_buffer;
}
ZEND_API void zend_get_gc_buffer_grow(zend_get_gc_buffer *gc_buffer) {
size_t old_capacity = gc_buffer->end - gc_buffer->start;
size_t new_capacity = old_capacity == 0 ? 64 : old_capacity * 2;
gc_buffer->start = erealloc(gc_buffer->start, new_capacity * sizeof(zval));
gc_buffer->end = gc_buffer->start + new_capacity;
gc_buffer->cur = gc_buffer->start + old_capacity;
}
static void zend_get_gc_buffer_release(void) {
zend_get_gc_buffer *gc_buffer = &EG(get_gc_buffer);
efree(gc_buffer->start);
gc_buffer->start = gc_buffer->end = gc_buffer->cur = NULL;
}
/* TMPVAR operands are destroyed using zval_ptr_dtor_nogc(), because they usually cannot contain
* cycles. However, there are some rare exceptions where this is possible, in which case we rely
* on the producing code to root the value. If a GC run occurs between the rooting and consumption
* of the value, we would end up leaking it. To avoid this, root all live TMPVAR values here. */
static void zend_gc_root_tmpvars(void) {
zend_execute_data *ex = EG(current_execute_data);
for (; ex; ex = ex->prev_execute_data) {
zend_function *func = ex->func;
if (!func || !ZEND_USER_CODE(func->type)) {
continue;
}
uint32_t op_num = ex->opline - ex->func->op_array.opcodes;
for (uint32_t i = 0; i < func->op_array.last_live_range; i++) {
const zend_live_range *range = &func->op_array.live_range[i];
if (range->start > op_num) {
break;
}
if (range->end <= op_num) {
continue;
}
uint32_t kind = range->var & ZEND_LIVE_MASK;
if (kind == ZEND_LIVE_TMPVAR || kind == ZEND_LIVE_LOOP) {
uint32_t var_num = range->var & ~ZEND_LIVE_MASK;
zval *var = ZEND_CALL_VAR(ex, var_num);
if (Z_REFCOUNTED_P(var)) {
gc_check_possible_root(Z_COUNTED_P(var));
}
}
}
}
}
#if GC_BENCH
void gc_bench_print(void)
{
fprintf(stderr, "GC Statistics\n");
fprintf(stderr, "-------------\n");
fprintf(stderr, "Runs: %d\n", GC_G(gc_runs));
fprintf(stderr, "Collected: %d\n", GC_G(collected));
fprintf(stderr, "Root buffer length: %d\n", GC_G(root_buf_length));
fprintf(stderr, "Root buffer peak: %d\n\n", GC_G(root_buf_peak));
fprintf(stderr, " Possible Remove from Marked\n");
fprintf(stderr, " Root Buffered buffer grey\n");
fprintf(stderr, " -------- -------- ----------- ------\n");
fprintf(stderr, "ZVAL %8d %8d %9d %8d\n", GC_G(zval_possible_root), GC_G(zval_buffered), GC_G(zval_remove_from_buffer), GC_G(zval_marked_grey));
}
#endif
#ifdef ZTS
size_t zend_gc_globals_size(void)
{
return sizeof(zend_gc_globals);
}
#endif
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