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Updates to PEP 539 draft (#291)

This commit is contained in:
Erik Bray 2017-07-12 20:58:09 +02:00 committed by Brett Cannon
parent ed36ec04ac
commit 3433417193
1 changed files with 24 additions and 15 deletions
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39
pep-0539.txt
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@ -52,12 +52,12 @@ These would be superseded by a new set of analogous functions::
PyAPI_FUNC(int) PyThread_tss_create(Py_tss_t *key)
PyAPI_FUNC(void) PyThread_tss_delete(Py_tss_t *key)
PyAPI_FUNC(int) PyThread_tss_set(Py_tss_t key, void *value)
PyAPI_FUNC(void *) PyThread_tss_get(Py_tss_t key)
PyAPI_FUNC(void) PyThread_tss_delete_value(Py_tss_t key)
PyAPI_FUNC(int) PyThread_tss_set(Py_tss_t *key, void *value)
PyAPI_FUNC(void *) PyThread_tss_get(Py_tss_t *key)
PyAPI_FUNC(void) PyThread_tss_delete_value(Py_tss_t *key)
PyAPI_FUNC(void) PyThread_ReInitTSS(void)
The specification also adds three new features:
The specification also adds a few new features:
* A new type ``Py_tss_t``--an opaque type the definition of which may
depend on the underlying TLS implementation. It is defined::
@ -73,12 +73,18 @@ The specification also adds three new features:
* A constant default value for ``Py_tss_t`` variables,
``Py_tss_NEEDS_INIT``.
* A new inline function::
* Three new functions::
static inline bool PyThread_tss_is_created(Py_tss_t key)
PyAPI_FUNC(Py_tss_t *) PyThread_tss_alloc(void)
PyAPI_FUNC(void) PyThread_tss_free(Py_tss_t *key)
PyAPI_FUNC(bool) PyThread_tss_is_created(Py_tss_t *key)
which returns ``true`` if the given ``Py_tss_t`` has been initialized
(i.e. by ``PyThread_tss_create``).
The first two are needed for dynamic (de-)allocation of a `Py_tss_t`,
particularly in extension modules built with `Py_LIMITED_API`, where
static allocation of this type is not possible due to its implementation
being opaque at build time. ``PyThread_tss_is_created`` returns ``true``
if the given ``Py_tss_t`` has been initialized (i.e. by
``PyThread_tss_create``).
The new ``PyThread_tss_`` functions are almost exactly analogous to their
original counterparts with a minor difference: Whereas
@ -90,8 +96,11 @@ by ``Py_tss_NEEDS_INIT``. The returned status status code is zero on success
and non-zero on failure. The meanings of non-zero status codes are not
otherwise defined by this specification.
Similarly ``PyThread_tss_delete`` is passed a ``Py_tss_t*`` whereas
previouly the key was passed to ``PyThread_delete_key`` by value.
Similarly the other ``PyThread_tss_`` functions are passed a ``Py_tss_t*``
whereas previously the key was passed by value. This change is necessary, as
being an opaque type, the ``Py_tss_t`` type could hypothetically be almost
any size. This is especially necessary for extension modules built with
``Py_LIMITED_API``, where the size of the type is not known.
The old ``PyThread_*_key*`` functions will be marked as deprecated in the
documentation, but will not generate runtime deprecation warnings.
@ -112,18 +121,18 @@ With the proposed changes, a TSS key is initialized like::
The initialization state of the key can then be checked like::
assert(PyThread_tss_is_created(tss_key));
assert(PyThread_tss_is_created(&tss_key));
The rest of the API is used analogously to the old API::
int the_value = 1;
if (PyThread_tss_get(tss_key) == NULL) {
PyThread_tss_set(tss_key, (void *)&the_value);
assert(PyThread_tss_get(tss_key) != NULL);
if (PyThread_tss_get(&tss_key) == NULL) {
PyThread_tss_set(&tss_key, (void *)&the_value);
assert(PyThread_tss_get(&tss_key) != NULL);
}
/* ... once done with the key ... */
PyThread_tss_delete(&tss_key);
assert(!PyThread_tss_is_created(tss_key));
assert(!PyThread_tss_is_created(&tss_key));
Motivation