mtarraylist.c
// This file is a part of Julia. License is MIT: https://julialang.org/license
#include "julia.h"
#include "julia_internal.h"
#include "julia_assert.h"
#ifdef __cplusplus
extern "C" {
#endif
// this file provides some alternate API functions for small_arraylist (push and add)
// which can be safely observed from other threads concurrently
// there is only permitted to be a single writer thread (or a mutex)
// but there can be any number of observers
typedef struct {
_Atomic(uint32_t) len;
uint32_t max;
_Atomic(_Atomic(void*)*) items;
_Atomic(void*) _space[SMALL_AL_N_INLINE];
} small_mtarraylist_t;
// change capacity to at least newlen
static void mtarraylist_resizeto(small_mtarraylist_t *a, size_t len, size_t newlen) JL_NOTSAFEPOINT
{
size_t max = a->max;
if (newlen > max) {
size_t nm = max * 2;
if (nm == 0)
nm = 1;
while (newlen > nm)
nm *= 2;
void *olditems = (void*)jl_atomic_load_relaxed(&a->items);
void *p = calloc_s(nm * sizeof(void*));
memcpy(p, olditems, len * sizeof(void*));
jl_atomic_store_release(&a->items, (_Atomic(void*)*)p);
a->max = nm;
if (olditems != (void*)&a->_space[0]) {
jl_task_t *ct = jl_current_task;
jl_gc_add_quiescent(ct->ptls, (void**)olditems, free);
}
}
}
// single-threaded
void mtarraylist_push(small_arraylist_t *_a, void *elt)
{
small_mtarraylist_t *a = (small_mtarraylist_t*)_a;
size_t len = jl_atomic_load_relaxed(&a->len);
mtarraylist_resizeto(a, len, len + 1);
jl_atomic_store_release(&jl_atomic_load_relaxed(&a->items)[len], elt);
jl_atomic_store_release(&a->len, len + 1);
}
// single-threaded
void mtarraylist_add(small_arraylist_t *_a, void *elt, size_t idx)
{
small_mtarraylist_t *a = (small_mtarraylist_t*)_a;
size_t len = jl_atomic_load_relaxed(&a->len);
mtarraylist_resizeto(a, len, idx + 1);
jl_atomic_store_release(&jl_atomic_load_relaxed(&a->items)[idx], elt);
if (jl_atomic_load_relaxed(&a->len) < idx + 1)
jl_atomic_store_release(&a->len, idx + 1);
}
// concurrent-safe
size_t mtarraylist_length(small_arraylist_t *_a)
{
small_mtarraylist_t *a = (small_mtarraylist_t*)_a;
return jl_atomic_load_relaxed(&a->len);
}
// concurrent-safe
void *mtarraylist_get(small_arraylist_t *_a, size_t idx)
{
small_mtarraylist_t *a = (small_mtarraylist_t*)_a;
size_t len = jl_atomic_load_acquire(&a->len);
if (idx >= len)
return NULL;
return jl_atomic_load_relaxed(&jl_atomic_load_relaxed(&a->items)[idx]);
}