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GC improvement

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This commit is contained in:
Dmitry Stogov 2018-03-01 03:17:21 +03:00
parent 4631a5e2e1
commit fd348ec43f
2 changed files with 439 additions and 349 deletions
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4
Zend/tests/gc_016.phpt
View file

@ -18,9 +18,11 @@ $a = new Foo();
$a->a = $a;
unset($a);
var_dump(gc_collect_cycles());
var_dump(gc_collect_cycles());
echo "ok\n"
?>
--EXPECT--
-> int(1)
-> int(0)
int(1)
int(1)
ok

696
Zend/zend_gc.c
View file

@ -80,56 +80,112 @@
# define ZEND_GC_DEBUG 0
#endif
#define GC_COLOR 0xc000
/* GC_TYPE */
#define GC_COLOR 0x300000
#define GC_BLACK 0x0000 /* must be zero */
#define GC_WHITE 0x8000
#define GC_GREY 0x4000
#define GC_PURPLE 0xc000
#define GC_BLACK 0x000000 /* must be zero */
#define GC_WHITE 0x100000
#define GC_GREY 0x200000
#define GC_PURPLE 0x300000
#define GC_ADDRESS(v) \
((v) & ~GC_COLOR)
#define GC_INFO_GET_COLOR(v) \
(((zend_uintptr_t)(v)) & GC_COLOR)
/* one (0) is reserved */
#define GC_ROOT_BUFFER_MAX_ENTRIES 10001
/* GC_TYPE_INFO */
#define GC_REF_SET_INFO(ref, info) \
gc_ref_set_info(ref, info)
#define GC_REF_SET_INFO_EX(ref, buffer, color) \
gc_ref_set_info_ex(ref, buffer, color)
#define GC_REF_GET_COLOR(ref) \
GC_INFO_GET_COLOR(GC_INFO(ref))
#define GC_REF_SET_COLOR(ref, c) do { \
GC_TYPE_INFO(ref) = ((c) << GC_INFO_SHIFT) | \
(GC_TYPE_INFO(ref) & (GC_TYPE_MASK | GC_FLAGS_MASK | ~(GC_COLOR << 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)
/* GC buffer size */
#define GC_INVALID 0
#define GC_FIRST_REAL_ROOT 1
#define GC_DEFAULT_THRESHOLD 10000
#define GC_DEFAULT_BUF_SIZE (16 * 1024)
#define GC_BUF_GROW_STEP (128 * 1024)
#define GC_COMPRESS_FACTOR 4096 /* shold be 0 to disable compression */
#define GC_MAX_UNCOMPRESSED ((1024 * 1024) - GC_COMPRESS_FACTOR)
#define GC_MAX_BUF_SIZE (GC_COMPRESS_FACTOR ? (0x40000000) : GC_MAX_UNCOMPRESSED)
#define GC_NEED_COMPRESSION(addr) \
((GC_COMPRESS_FACTOR > 0) && (addr >= GC_MAX_UNCOMPRESSED))
/* GC flags */
#define GC_HAS_DESTRUCTORS (1<<0)
#define GC_NUM_ADDITIONAL_ENTRIES \
((4096 - ZEND_MM_OVERHEAD - sizeof(void*) * 2) / sizeof(gc_root_buffer))
/* bit stealing tags for gc_root_buffer.ref */
#define GC_BITS 0x3
#define GC_ROOT 0x0 /* poissible 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))
/* 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;
struct _gc_root_buffer *next; /* double-linked list */
struct _gc_root_buffer *prev;
uint32_t refcount;
} gc_root_buffer;
typedef struct _gc_additional_bufer gc_additional_buffer;
struct _gc_additional_bufer {
uint32_t used;
gc_additional_buffer *next;
gc_root_buffer buf[GC_NUM_ADDITIONAL_ENTRIES];
};
typedef struct _zend_gc_globals {
zend_bool gc_enabled;
zend_bool gc_active;
zend_bool gc_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 */
gc_root_buffer roots; /* list of possible roots of cycles */
gc_root_buffer *unused; /* list of unused buffers */
gc_root_buffer *first_unused; /* pointer to first unused buffer */
gc_root_buffer *last_unused; /* pointer to last unused buffer */
gc_root_buffer to_free; /* list to free */
gc_root_buffer *next_to_free;
uint32_t buf_size; /* size of the GC buffer */
uint32_t gc_threshold; /* GC collection threshold */
uint32_t unused; /* linked list of unused buffers */
uint32_t first_unused; /* first unused buffer */
uint32_t num_roots; /* number of roots in GC buffer */
uint32_t gc_runs;
uint32_t collected;
@ -142,9 +198,6 @@ typedef struct _zend_gc_globals {
uint32_t zval_remove_from_buffer;
uint32_t zval_marked_grey;
#endif
gc_additional_buffer *additional_buffer;
} zend_gc_globals;
#ifdef ZTS
@ -184,6 +237,53 @@ static zend_gc_globals gc_globals;
# define GC_TRACE(str)
#endif
static zend_always_inline uint32_t gc_compress(uint32_t idx)
{
ZEND_ASSERT(GC_NEED_COMPRESSION(idx));
return GC_MAX_UNCOMPRESSED + ((idx - GC_MAX_UNCOMPRESSED) % GC_COMPRESS_FACTOR);
}
static zend_always_inline uint32_t gc_decompress(zend_refcounted *ref, uint32_t idx)
{
ZEND_ASSERT(GC_NEED_COMPRESSION(idx));
while (idx < GC_G(first_unused)) {
gc_root_buffer *root = GC_G(buf) + idx;
if (root->ref == ref) {
return idx;
}
idx += GC_COMPRESS_FACTOR;
}
ZEND_ASSERT(0);
}
static zend_always_inline gc_root_buffer* gc_fetch_unused(void)
{
gc_root_buffer *root;
ZEND_ASSERT(GC_HAS_UNUSED());
root = (gc_root_buffer*)((char*)GC_G(buf) + GC_G(unused));
ZEND_ASSERT(GC_IS_UNUSED(root->ref));
GC_G(unused) = (uint32_t)(uintptr_t)GC_GET_PTR(root->ref);
return root;
}
static zend_always_inline void gc_link_unused(gc_root_buffer *root)
{
root->ref = (void*)(uintptr_t)(GC_G(unused) | GC_UNUSED);
GC_G(unused) = (char*)root - (char*)GC_G(buf);
}
static zend_always_inline gc_root_buffer* gc_fetch_next_unused(void)
{
gc_root_buffer *root;
ZEND_ASSERT(GC_HAS_NEXT_UNUSED());
root = GC_G(buf) + GC_G(first_unused);
GC_G(first_unused)++;
return root;
}
static zend_always_inline void gc_ref_set_info(zend_refcounted *ref, uint32_t info)
{
GC_TYPE_INFO(ref) = (info << GC_INFO_SHIFT)
@ -192,7 +292,24 @@ static zend_always_inline void gc_ref_set_info(zend_refcounted *ref, uint32_t in
static zend_always_inline void gc_ref_set_info_ex(zend_refcounted *ref, gc_root_buffer *buffer, uint32_t color)
{
if (sizeof(gc_root_buffer) == 16) {
if (GC_COMPRESS_FACTOR) {
uint32_t addr = buffer - GC_G(buf);
if (GC_NEED_COMPRESSION(addr)) {
addr = gc_compress(addr);
}
GC_TYPE_INFO(ref) = (addr << GC_INFO_SHIFT)
| (color << GC_INFO_SHIFT)
| (GC_TYPE_INFO(ref) & (GC_TYPE_MASK | GC_FLAGS_MASK));
} else if (sizeof(gc_root_buffer) == 4) {
GC_TYPE_INFO(ref) =
(((char*)buffer + ((color) << 2) - (char*)GC_G(buf)) << (GC_INFO_SHIFT - 2))
| (GC_TYPE_INFO(ref) & (GC_TYPE_MASK | GC_FLAGS_MASK));
} else if (sizeof(gc_root_buffer) == 8) {
GC_TYPE_INFO(ref) =
(((char*)buffer + ((color) << 3) - (char*)GC_G(buf)) << (GC_INFO_SHIFT - 3))
| (GC_TYPE_INFO(ref) & (GC_TYPE_MASK | GC_FLAGS_MASK));
} else if (sizeof(gc_root_buffer) == 16) {
GC_TYPE_INFO(ref) =
(((char*)buffer + ((color) << 4) - (char*)GC_G(buf)) << (GC_INFO_SHIFT - 4))
| (GC_TYPE_INFO(ref) & (GC_TYPE_MASK | GC_FLAGS_MASK));
@ -207,25 +324,6 @@ static zend_always_inline void gc_ref_set_info_ex(zend_refcounted *ref, gc_root_
}
}
#define GC_REF_SET_INFO(ref, info) \
gc_ref_set_info(ref, info)
#define GC_REF_SET_INFO_EX(ref, buffer, color) \
gc_ref_set_info_ex(ref, buffer, color)
#define GC_REF_GET_COLOR(ref) \
GC_INFO_GET_COLOR(GC_INFO(ref))
#define GC_REF_SET_COLOR(ref, c) do { \
GC_TYPE_INFO(ref) = ((c) << GC_INFO_SHIFT) | \
(GC_TYPE_INFO(ref) & (GC_TYPE_MASK | GC_FLAGS_MASK | ~(GC_COLOR << 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)
#if ZEND_GC_DEBUG > 1
static const char *gc_color_name(uint32_t color) {
switch (color) {
@ -260,19 +358,11 @@ static void gc_trace_ref(zend_refcounted *ref) {
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_LINK_UNUSED(root);
GC_G(num_roots)--;
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) {
@ -285,22 +375,19 @@ 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->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->buf_size = 0;
gc_globals->gc_threshold = 0;
gc_globals->unused = GC_INVALID;
gc_globals->first_unused = 0;
gc_globals->num_roots = 0;
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;
@ -329,9 +416,16 @@ ZEND_API void gc_globals_dtor(void)
ZEND_API 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_REAL_ROOT;
GC_G(num_roots) = 0;
GC_G(gc_runs) = 0;
GC_G(collected) = 0;
GC_G(gc_full) = 0;
#if GC_BENCH
GC_G(root_buf_length) = 0;
@ -341,23 +435,7 @@ ZEND_API void gc_reset(void)
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 zend_bool gc_set_enabled(zend_bool enable)
@ -365,8 +443,9 @@ ZEND_API zend_bool gc_set_enabled(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*) malloc(sizeof(gc_root_buffer) * GC_ROOT_BUFFER_MAX_ENTRIES);
GC_G(last_unused) = &GC_G(buf)[GC_ROOT_BUFFER_MAX_ENTRIES];
GC_G(buf) = (gc_root_buffer*) malloc(sizeof(gc_root_buffer) * GC_DEFAULT_BUF_SIZE);
GC_G(buf_size) = GC_DEFAULT_BUF_SIZE;
GC_G(gc_threshold) = GC_DEFAULT_THRESHOLD + GC_FIRST_REAL_ROOT;
gc_reset();
}
return old_enabled;
@ -377,6 +456,47 @@ ZEND_API zend_bool gc_enabled(void)
return GC_G(gc_enabled);
}
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_enabled) = 0;
GC_G(gc_active) = 1;
GC_G(gc_protected) = 1;
GC_G(gc_full) = 1;
CG(unclean_shutdown) = 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)
{
#if 0
/* TODO Very simple heuristic for dynamic GC buffer resizing:
* If there are "too few" collections, increase the collection threshold
* by a factor of two ??? */
if (count < 100) {
GC_G(gc_threshold) *= 2;
} else if (GC_G(gc_threshold) > GC_DEFAULT_THRESHOLD) {
GC_G(gc_threshold) /= 2;
}
#endif
}
static zend_never_inline void ZEND_FASTCALL gc_possible_root_when_full(zend_refcounted *ref)
{
gc_root_buffer *newRoot;
@ -384,39 +504,31 @@ static zend_never_inline void ZEND_FASTCALL gc_possible_root_when_full(zend_refc
ZEND_ASSERT(GC_TYPE(ref) == IS_ARRAY || GC_TYPE(ref) == IS_OBJECT);
ZEND_ASSERT(GC_INFO(ref) == 0);
if (!GC_G(gc_enabled)) {
return;
}
if (GC_G(gc_enabled) && !GC_G(gc_active)) {
GC_ADDREF(ref);
gc_collect_cycles();
GC_DELREF(ref);
if (UNEXPECTED(GC_REFCOUNT(ref)) == 0) {
gc_adjust_threshold(gc_collect_cycles());
if (UNEXPECTED(GC_DELREF(ref)) == 0) {
zval_dtor_func(ref);
return;
}
if (UNEXPECTED(GC_INFO(ref))) {
} else 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;
if (GC_HAS_UNUSED()) {
newRoot = GC_FETCH_UNUSED();
} else if (EXPECTED(GC_HAS_NEXT_UNUSED())) {
newRoot = GC_FETCH_NEXT_UNUSED();
} else {
gc_grow_root_buffer();
ZEND_ASSERT(GC_HAS_NEXT_UNUSED());
newRoot = GC_FETCH_NEXT_UNUSED();
}
GC_G(unused) = newRoot->prev;
GC_TRACE_SET_COLOR(ref, GC_PURPLE);
GC_REF_SET_INFO_EX(ref, newRoot, 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;
newRoot->ref = ref; /* GC_ROOT tag is 0 */
GC_G(num_roots)++;
GC_BENCH_INC(zval_buffered);
GC_BENCH_INC(root_buf_length);
@ -427,18 +539,16 @@ 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))) {
if (UNEXPECTED(GC_G(gc_protected)) || UNEXPECTED(CG(unclean_shutdown))) {
return;
}
GC_BENCH_INC(zval_possible_root);
newRoot = GC_G(unused);
if (newRoot) {
GC_G(unused) = newRoot->prev;
} else if (EXPECTED(GC_G(first_unused) != GC_G(last_unused))) {
newRoot = GC_G(first_unused);
GC_G(first_unused)++;
if (GC_HAS_UNUSED()) {
newRoot = GC_FETCH_UNUSED();
} else if (EXPECTED(GC_HAS_NEXT_UNUSED_UNDER_THRESHOLD())) {
newRoot = GC_FETCH_NEXT_UNUSED();
} else {
gc_possible_root_when_full(ref);
return;
@ -450,37 +560,13 @@ ZEND_API void ZEND_FASTCALL gc_possible_root(zend_refcounted *ref)
GC_TRACE_SET_COLOR(ref, GC_PURPLE);
GC_REF_SET_INFO_EX(ref, newRoot, 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_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_always_inline gc_root_buffer* gc_find_additional_buffer(zend_refcounted *ref, uint32_t addr)
{
gc_additional_buffer *additional_buffer = GC_G(additional_buffer);
/* We have to check each additional_buffer to find which one holds the ref */
addr -= GC_ROOT_BUFFER_MAX_ENTRIES;
while (additional_buffer) {
if (addr < additional_buffer->used) {
gc_root_buffer *root = additional_buffer->buf + addr;
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;
@ -495,18 +581,12 @@ ZEND_API void ZEND_FASTCALL gc_remove_from_buffer(zend_refcounted *ref)
}
GC_REF_SET_INFO(ref, 0);
if (EXPECTED(addr < GC_ROOT_BUFFER_MAX_ENTRIES)) {
root = GC_G(buf) + addr;
gc_remove_from_roots(root);
} else {
root = gc_find_additional_buffer(ref, addr);
gc_remove_from_additional_roots(root);
if (UNEXPECTED(GC_NEED_COMPRESSION(addr))) {
addr = gc_decompress(ref, addr);
}
/* updete next root that is going to be freed */
if (GC_G(next_to_free) == root) {
GC_G(next_to_free) = root->next;
}
root = GC_G(buf) + addr;
gc_remove_from_roots(root);
}
static void gc_scan_black(zend_refcounted *ref)
@ -718,15 +798,63 @@ tail_call:
}
}
/* Two-Finger compaction algorithm */
static void gc_compact(void)
{
if (GC_G(num_roots) + GC_FIRST_REAL_ROOT != GC_G(first_unused)) {
if (GC_G(num_roots)) {
gc_root_buffer *buf = GC_G(buf);
uint32_t free = GC_FIRST_REAL_ROOT;
uint32_t scan = GC_G(first_unused) - 1;
uint32_t addr;
zend_refcounted *p;
while (free < scan) {
while (!GC_IS_UNUSED(buf[free].ref)) {
free++;
}
while (GC_IS_UNUSED(buf[scan].ref)) {
scan--;
}
if (scan > free) {
p = buf[scan].ref;
buf[free].ref = p;
p = GC_GET_PTR(p);
addr = free;
if (UNEXPECTED(GC_NEED_COMPRESSION(addr))) {
addr = gc_compress(addr);
}
GC_REF_SET_INFO(p, addr | GC_REF_GET_COLOR(p));
free++;
scan--;
if (scan <= GC_G(num_roots)) {
break;
}
} else {
break;
}
}
}
GC_G(unused) = GC_INVALID;
GC_G(first_unused) = GC_G(num_roots) + GC_FIRST_REAL_ROOT;
}
}
static void gc_mark_roots(void)
{
gc_root_buffer *current = GC_G(roots).next;
gc_root_buffer *current, *last;
while (current != &GC_G(roots)) {
gc_compact();
current = GC_G(buf) + GC_FIRST_REAL_ROOT;
last = GC_G(buf) + GC_G(first_unused);
while (current != last) {
if (GC_IS_ROOT(current->ref)) {
if (GC_REF_GET_COLOR(current->ref) == GC_PURPLE) {
gc_mark_grey(current->ref);
}
current = current->next;
}
current++;
}
}
@ -829,48 +957,34 @@ tail_call:
static void gc_scan_roots(void)
{
gc_root_buffer *current = GC_G(roots).next;
gc_root_buffer *current = GC_G(buf) + GC_FIRST_REAL_ROOT;
gc_root_buffer *last = GC_G(buf) + GC_G(first_unused);
while (current != &GC_G(roots)) {
while (current != last) {
if (GC_IS_ROOT(current->ref)) {
gc_scan(current->ref);
current = current->next;
}
current++;
}
}
static void gc_add_garbage(zend_refcounted *ref)
{
gc_root_buffer *buf = GC_G(unused);
gc_root_buffer *buf;
if (buf) {
GC_G(unused) = buf->prev;
GC_REF_SET_INFO_EX(ref, buf, GC_BLACK);
} else if (GC_G(first_unused) != GC_G(last_unused)) {
buf = GC_G(first_unused);
GC_G(first_unused)++;
GC_REF_SET_INFO_EX(ref, buf, GC_BLACK);
if (GC_HAS_UNUSED()) {
buf = GC_FETCH_UNUSED();
} else if (GC_HAS_NEXT_UNUSED()) {
buf = GC_FETCH_NEXT_UNUSED();
} 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;
/* optimization: color is already GC_BLACK (0) */
GC_REF_SET_INFO(ref, GC_ROOT_BUFFER_MAX_ENTRIES + GC_G(additional_buffer)->used);
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;
gc_grow_root_buffer();
ZEND_ASSERT(GC_HAS_NEXT_UNUSED());
buf = GC_FETCH_NEXT_UNUSED();
}
GC_REF_SET_INFO_EX(ref, buf, GC_BLACK);
buf->ref = GC_MAKE_GARBAGE(ref);
GC_G(num_roots)++;
}
static int gc_collect_white(zend_refcounted *ref, uint32_t *flags)
@ -1004,50 +1118,41 @@ tail_call:
static int gc_collect_roots(uint32_t *flags)
{
uint32_t n, end;
zend_refcounted *ref;
int count = 0;
gc_root_buffer *current = GC_G(roots).next;
gc_root_buffer *current = GC_G(buf) + GC_FIRST_REAL_ROOT;
gc_root_buffer *last = GC_G(buf) + GC_G(first_unused);
/* remove non-garbage from the list */
while (current != &GC_G(roots)) {
gc_root_buffer *next = current->next;
while (current != last) {
if (GC_IS_ROOT(current->ref)) {
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_REF_SET_INFO(current->ref, 0); /* reset GC_ADDRESS() and keep GC_BLACK */
gc_remove_from_roots(current);
}
current = next;
}
current++;
}
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);
gc_compact();
/* Root buffer might be reallocated during gc_collect_white,
* make sure to reload pointers. */
n = GC_FIRST_REAL_ROOT;
end = GC_G(first_unused);
while (n != end) {
current = GC_G(buf) + n;
ref = current->ref;
if (GC_IS_ROOT(ref)) {
if (GC_REF_GET_COLOR(ref) == GC_WHITE) {
current->ref = GC_MAKE_GARBAGE(ref);
count += gc_collect_white(ref, flags);
}
current = current->next;
}
n++;
}
/* 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;
}
@ -1063,11 +1168,7 @@ tail_call:
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_REF_SET_INFO(ref, 0);
root = NULL;
} else {
@ -1157,15 +1258,11 @@ 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;
if (GC_G(num_roots)) {
gc_root_buffer *current, *last;
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
uint32_t n, end;
if (GC_G(gc_active)) {
return 0;
@ -1180,61 +1277,51 @@ ZEND_API int zend_gc_collect_cycles(void)
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)) {
if (!GC_G(num_roots)) {
/* nothing to free */
GC_TRACE("Nothing to free");
GC_G(gc_active) = 0;
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
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) * GC_G(first_unused), 1);
/* Remember reference counters before calling destructors */
current = to_free.next;
while (current != &to_free) {
current->refcount = GC_REFCOUNT(current->ref);
current = current->next;
n = GC_FIRST_REAL_ROOT;
current = GC_G(buf) + GC_FIRST_REAL_ROOT;
while (n != end) {
if (GC_IS_GARBAGE(current->ref)) {
p = GC_GET_PTR(current->ref);
refcounts[n] = GC_REFCOUNT(p);
}
current++;
n++;
}
/* 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) {
/* Call destructors
*
* The root buffer might be reallocated during destructors calls,
* make sure to reload pointers as necessary. */
n = GC_FIRST_REAL_ROOT;
while (n != end) {
current = GC_G(buf) + n;
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_FLAGS(obj) & IS_OBJ_DESTRUCTOR_CALLED)) {
GC_TRACE_REF(obj, "calling destructor");
GC_ADD_FLAGS(obj, IS_OBJ_DESTRUCTOR_CALLED);
if (obj->handlers->dtor_obj
@ -1246,27 +1333,35 @@ ZEND_API int zend_gc_collect_cycles(void)
}
}
}
current = GC_G(next_to_free);
n++;
}
/* 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);
n = GC_FIRST_REAL_ROOT;
current = GC_G(buf) + GC_FIRST_REAL_ROOT;
last = GC_G(buf) + GC_G(first_unused);
while (n != end) {
if (GC_IS_GARBAGE(current->ref)) {
p = GC_GET_PTR(current->ref);
if (GC_REFCOUNT(p) > refcounts[n]) {
gc_remove_nested_data_from_buffer(p, current);
}
current = GC_G(next_to_free);
}
current++;
n++;
}
pefree(refcounts, 1);
}
/* 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_G(gc_protected) = 1;
current = GC_G(buf) + GC_FIRST_REAL_ROOT;
last = GC_G(buf) + 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;
@ -1284,7 +1379,7 @@ ZEND_API int zend_gc_collect_cycles(void)
}
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);
current->ref = GC_MAKE_GARBAGE(((char*)obj) - obj->handlers->offset);
} else if (GC_TYPE(p) == IS_ARRAY) {
zend_array *arr = (zend_array*)p;
@ -1296,37 +1391,30 @@ ZEND_API int zend_gc_collect_cycles(void)
zend_hash_destroy(arr);
}
current = GC_G(next_to_free);
}
current++;
}
/* 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;
}
current = GC_G(buf) + GC_FIRST_REAL_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 = 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;
current++;
}
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_protected) = 0;
GC_G(gc_active) = 0;
}
gc_compact();
return count;
}