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py/objstringio: If created from immutable object, follow copy on write policy.

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Don't create copy of immutable object's contents until .write() is called
on BytesIO.
This commit is contained in:
Paul Sokolovsky
2017-06-05 23:54:21 +03:00
parent b24ccfc639
commit 07241cd37a
5 changed files with 70 additions and 3 deletions
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30
py/objstringio.c
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@@ -68,10 +68,23 @@ STATIC mp_uint_t stringio_read(mp_obj_t o_in, void *buf, mp_uint_t size, int *er
return size;
}
STATIC void stringio_copy_on_write(mp_obj_stringio_t *o) {
const void *buf = o->vstr->buf;
o->vstr->buf = m_new(char, o->vstr->len);
memcpy(o->vstr->buf, buf, o->vstr->len);
o->vstr->fixed_buf = false;
o->ref_obj = MP_OBJ_NULL;
}
STATIC mp_uint_t stringio_write(mp_obj_t o_in, const void *buf, mp_uint_t size, int *errcode) {
(void)errcode;
mp_obj_stringio_t *o = MP_OBJ_TO_PTR(o_in);
check_stringio_is_open(o);
if (o->vstr->fixed_buf) {
stringio_copy_on_write(o);
}
mp_uint_t new_pos = o->pos + size;
if (new_pos < size) {
// Writing <size> bytes will overflow o->pos beyond limit of mp_uint_t.
@@ -155,11 +168,11 @@ STATIC mp_obj_t stringio___exit__(size_t n_args, const mp_obj_t *args) {
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(stringio___exit___obj, 4, 4, stringio___exit__);
STATIC mp_obj_stringio_t *stringio_new(const mp_obj_type_t *type, mp_uint_t alloc) {
STATIC mp_obj_stringio_t *stringio_new(const mp_obj_type_t *type) {
mp_obj_stringio_t *o = m_new_obj(mp_obj_stringio_t);
o->base.type = type;
o->vstr = vstr_new(alloc);
o->pos = 0;
o->ref_obj = MP_OBJ_NULL;
return o;
}
@@ -170,17 +183,28 @@ STATIC mp_obj_t stringio_make_new(const mp_obj_type_t *type_in, size_t n_args, s
bool initdata = false;
mp_buffer_info_t bufinfo;
mp_obj_stringio_t *o = stringio_new(type_in);
if (n_args > 0) {
if (MP_OBJ_IS_INT(args[0])) {
sz = mp_obj_get_int(args[0]);
} else {
mp_get_buffer_raise(args[0], &bufinfo, MP_BUFFER_READ);
if (MP_OBJ_IS_STR_OR_BYTES(args[0])) {
o->vstr = m_new_obj(vstr_t);
vstr_init_fixed_buf(o->vstr, bufinfo.len, bufinfo.buf);
o->vstr->len = bufinfo.len;
o->ref_obj = args[0];
return MP_OBJ_FROM_PTR(o);
}
sz = bufinfo.len;
initdata = true;
}
}
mp_obj_stringio_t *o = stringio_new(type_in, sz);
o->vstr = vstr_new(sz);
if (initdata) {
stringio_write(MP_OBJ_FROM_PTR(o), bufinfo.buf, bufinfo.len, NULL);