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Refactor thread local storage #894

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Refactor thread local storage #894

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56 changes: 56 additions & 0 deletions src/gc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -308,6 +308,58 @@ HL_PRIM gc_pheader *hl_gc_get_page( void *v ) {

HL_API int hl_thread_id();

HL_PRIM int hl_atomic_add32(int *a, int b);

#ifdef HL_WIN
static SRWLOCK free_list_mutex = SRWLOCK_INIT;
static inline void lock_free_list() { AcquireSRWLockExclusive(&free_list_mutex); }
static inline void unlock_free_list() { ReleaseSRWLockExclusive(&free_list_mutex); }
#else
#include <pthread.h>
static pthread_mutex_t free_list_mutex = PTHREAD_MUTEX_INITIALIZER;
static inline void lock_free_list() { pthread_mutex_lock(&free_list_mutex); }
static inline void unlock_free_list() { pthread_mutex_unlock(&free_list_mutex); }
#endif

static int tls_counter = 0;

struct tls_free_list {
int key;
struct tls_free_list *next;
};

static struct tls_free_list * free_list;

int get_tls_slot() {
lock_free_list();
if (free_list) {
struct tls_free_list *l = free_list;
int key = l->key;
free_list = l->next;
free(l);
unlock_free_list();
return key;
}
unlock_free_list();
return hl_atomic_add32(&tls_counter, 1);
}

// this function should only run in the finalizer, which is called when all threads
// are stopped
void free_tls_slot(int key) {
for (int i = 0; i < gc_threads.count; i++) {
if (key < gc_threads.threads[i]->tls_arr_size) {
gc_threads.threads[i]->tls_arr[key] = NULL;
}
}
struct tls_free_list *l = malloc(sizeof(struct tls_free_list));
l->key = key;
lock_free_list();
l->next = free_list;
free_list = l;
unlock_free_list();
}

HL_API void hl_register_thread( void *stack_top ) {
if( hl_get_thread() )
hl_fatal("Thread already registered");
Expand All @@ -324,6 +376,9 @@ HL_API void hl_register_thread( void *stack_top ) {
current_thread = t;
hl_add_root(&t->exc_value);
hl_add_root(&t->exc_handler);
hl_add_root(&t->tls_arr);
t->tls_arr_size = 0;
t->tls_arr = NULL;

gc_global_lock(true);
hl_thread_info **all = (hl_thread_info**)malloc(sizeof(void*) * (gc_threads.count + 1));
Expand All @@ -340,6 +395,7 @@ HL_API void hl_unregister_thread() {
hl_fatal("Thread not registered");
hl_remove_root(&t->exc_value);
hl_remove_root(&t->exc_handler);
hl_remove_root(&t->tls_arr);
gc_global_lock(true);
for(i=0;i<gc_threads.count;i++)
if( gc_threads.threads[i] == t ) {
Expand Down
3 changes: 2 additions & 1 deletion src/hl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -785,7 +785,6 @@ HL_API void hl_condition_free(hl_condition *cond);
HL_API hl_tls *hl_tls_alloc( bool gc_value );
HL_API void hl_tls_set( hl_tls *l, void *value );
HL_API void *hl_tls_get( hl_tls *l );
HL_API void hl_tls_free( hl_tls *l );
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@tobil4sk tobil4sk Feb 27, 2026

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This is an abi breakage, maybe it's better to deprecate it and keep a dummy implementation


// ----------------------- ALLOC --------------------------------------------------

Expand Down Expand Up @@ -984,6 +983,8 @@ typedef struct {
thread_t mach_thread_id;
pthread_t pthread_id;
#endif
int tls_arr_size;
void **tls_arr;
} hl_thread_info;

typedef struct {
Expand Down
120 changes: 28 additions & 92 deletions src/std/thread.c
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Original file line number Diff line number Diff line change
Expand Up @@ -64,13 +64,6 @@ struct _hl_condition {
CRITICAL_SECTION cs;
CONDITION_VARIABLE cond;
};

struct _hl_tls {
void (*free)( hl_tls * );
DWORD tid;
bool gc;
};

#else

# include <pthread.h>
Expand Down Expand Up @@ -104,13 +97,6 @@ struct _hl_condition {
pthread_mutex_t mutex;
pthread_cond_t cond;
};

struct _hl_tls {
void (*free)( hl_tls * );
pthread_key_t key;
bool gc;
};

#endif

// ----------------- ALLOC
Expand Down Expand Up @@ -463,95 +449,45 @@ DEFINE_PRIM(_VOID, condition_broadcast, _CONDITION)

// ----------------- THREAD LOCAL

#if defined(HL_THREADS)
static void **_tls_get( hl_tls *t ) {
# ifdef HL_WIN
return (void**)TlsGetValue(t->tid);
# else
return (void**)pthread_getspecific(t->key);
# endif
}
static void _tls_set( hl_tls *t, void *store ) {
# ifdef HL_WIN
TlsSetValue(t->tid, store);
# else
pthread_setspecific(t->key, store);
# endif
}
#endif
int get_tls_slot();
void free_tls_slot(int id);

struct _hl_tls {
void (*free)( hl_tls * );
int key;
bool gc;
};

static void tls_free(hl_tls *l) { free_tls_slot(l->key); }

HL_PRIM hl_tls *hl_tls_alloc( bool gc_value ) {
# if !defined(HL_THREADS)
hl_tls *l = (hl_tls*)hl_gc_alloc_finalizer(sizeof(hl_tls));
l->free = hl_tls_free;
l->value = NULL;
return l;
# elif defined(HL_WIN)
hl_tls *l = (hl_tls*)hl_gc_alloc_finalizer(sizeof(hl_tls));
l->free = hl_tls_free;
l->tid = TlsAlloc();
l->gc = gc_value;
TlsSetValue(l->tid,NULL);
return l;
# else
hl_tls *l = (hl_tls*)hl_gc_alloc_finalizer(sizeof(hl_tls));
l->free = hl_tls_free;
l->free = tls_free;
l->gc = gc_value;
pthread_key_create(&l->key,NULL);
l->key = get_tls_slot();
return l;
# endif
}

HL_PRIM void hl_tls_free( hl_tls *l ) {
# if !defined(HL_THREADS)
free(l);
# elif defined(HL_WIN)
if( l->free ) {
TlsFree(l->tid);
l->free = NULL;
}
# else
if( l->free ) {
pthread_key_delete(l->key);
l->free = NULL;
}
# endif
}

HL_PRIM void hl_tls_set( hl_tls *l, void *v ) {
# if !defined(HL_THREADS)
l->value = v;
# else
if( l->gc ) {
void **store = _tls_get(l);
if( !store) {
if( !v )
return;
store = (void**)malloc(sizeof(void*));
hl_add_root(store);
_tls_set(l, store);
} else {
if( !v ) {
free(store);
hl_remove_root(store);
_tls_set(l, NULL);
return;
}
}
*store = v;
} else
_tls_set(l, v);
# endif
hl_thread_info *info = hl_get_thread();
if (l->key >= info->tls_arr_size) {
int new_max = info->tls_arr_size > 0 ? info->tls_arr_size * 2 : 16;
new_max = l->key > new_max ? l->key : new_max;
void **new_arr = hl_gc_alloc_raw(sizeof(void*) * new_max);
memcpy(new_arr, info->tls_arr, info->tls_arr_size * sizeof(void*));
info->tls_arr = new_arr;
info->tls_arr_size = new_max;
}
info->tls_arr[l->key] = v;
}

HL_PRIM void *hl_tls_get( hl_tls *l ) {
# if !defined(HL_THREADS)
return l->value;
# else
void **store = _tls_get(l);
if( !l->gc ) return store;
return store ? *store : NULL;
# endif
hl_thread_info *info = hl_get_thread();
if (l->key < info->tls_arr_size) {
return info->tls_arr[l->key];
} else {
return NULL;
}
}

#define _TLS _ABSTRACT(hl_tls)
Expand Down
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