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use atomic ops for the expire field; passes TSAN now

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This commit is contained in:
Daan Leijen 2020-09-03 13:53:56 -07:00
parent 228b5f6e9d
commit 7058e501cb
1 changed files with 12 additions and 10 deletions
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22
src/arena.c
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@ -133,10 +133,10 @@ static bool mi_arena_alloc(mi_arena_t* arena, size_t blocks, mi_bitmap_index_t*
#define MI_CACHE_BITS_SET MI_INIT16(BITS_SET)
typedef struct mi_cache_slot_s {
void* p;
size_t memid;
mi_msecs_t expire;
bool is_committed; // TODO: use bit from p to reduce size?
void* p;
size_t memid;
_Atomic(mi_msecs_t) expire;
bool is_committed; // TODO: use bit from p to reduce size?
} mi_cache_slot_t;
static mi_cache_slot_t cache[MI_CACHE_MAX]; // = 0
@ -179,7 +179,7 @@ static void* mi_cache_pop(int numa_node, size_t size, size_t alignment, bool* co
*is_zero = false;
bool committed = slot->is_committed;
slot->p = NULL;
slot->expire = 0;
mi_atomic_store_release(&slot->expire,0);
if (*commit && !committed) {
bool commit_zero;
_mi_os_commit(p, MI_SEGMENT_SIZE, &commit_zero, tld->stats);
@ -203,15 +203,17 @@ static void mi_cache_purge(mi_os_tld_t* tld) {
for (size_t visited = 0; visited < MI_CACHE_FIELDS; visited++,idx++) { // probe just N slots
if (idx >= MI_CACHE_MAX) idx = 0; // wrap
mi_cache_slot_t* slot = &cache[idx];
if (slot->expire != 0 && now >= slot->expire) { // racy read
mi_msecs_t expire = mi_atomic_load_relaxed(&slot->expire);
if (expire != 0 && now >= expire) { // racy read
// seems expired, first claim it from available
purged++;
mi_bitmap_index_t bitidx = mi_bitmap_index_create_from_bit(idx);
if (mi_bitmap_claim(cache_available, MI_CACHE_FIELDS, 1, bitidx, NULL)) {
// was available, we claimed it
if (slot->expire != 0 && now >= slot->expire) { // safe read
expire = mi_atomic_load_acquire(&slot->expire);
if (expire != 0 && now >= expire) { // safe read
// still expired, decommit it
slot->expire = 0;
mi_atomic_store_relaxed(&slot->expire,0);
mi_assert_internal(slot->is_committed && mi_bitmap_is_claimed(cache_available_large, MI_CACHE_FIELDS, 1, bitidx));
_mi_abandoned_await_readers(); // wait until safe to decommit
_mi_os_decommit(slot->p, MI_SEGMENT_SIZE, tld->stats);
@ -252,7 +254,7 @@ static bool mi_cache_push(void* start, size_t size, size_t memid, bool is_commit
mi_cache_slot_t* slot = &cache[mi_bitmap_index_bit(bitidx)];
slot->p = start;
slot->memid = memid;
slot->expire = 0;
mi_atomic_store_relaxed(&slot->expire,0);
slot->is_committed = is_committed;
if (is_committed && !is_large) {
long delay = mi_option_get(mi_option_arena_reset_delay);
@ -262,7 +264,7 @@ static bool mi_cache_push(void* start, size_t size, size_t memid, bool is_commit
slot->is_committed = false;
}
else {
slot->expire = _mi_clock_now() + delay;
mi_atomic_store_release(&slot->expire, _mi_clock_now() + delay);
}
}