Use a deallocate_config future to release self.settings when
it is no longer needed. It's necessary to manage concurrency
since commit c95fc64 because mutation of self.settings
is no longer limited to the EbuildMetadataPhase _start method,
where exclusive access was guaranteed within the main thread.

Add support to the isAlive() method to detect when the
EbuildMetadataPhase has started but the pid is not yet
available (due to async_check_locale usage from commit
c95fc64). This can be used to check if an
EbuildMetadataPhase instance has been successfully started
so that it can be relied upon to set the result of the
deallocate_config future.

Bug: https://bugs.gentoo.org/924319
Signed-off-by: Zac Medico <zmedico@gentoo.org>

For EbuildMetadataPhase consumers like MetadataRegen and
depgraph, store a pool of config instances in a config_pool
list, and return instaces to the list when the deallocate_config
future is done.

Bug: https://bugs.gentoo.org/924319
Fixes: c95fc64 ("EbuildPhase: async_check_locale")
Signed-off-by: Zac Medico <zmedico@gentoo.org>

Make the ResolverPlayground _create_ebuild_manifests method
call egencache --jobs, which reliably triggers the KeyError
from bug 924319 for multiple tests:

lib/portage/tests/bin/test_doins.py::DoIns::testDoInsFallback Exception in callback EbuildMetadataPhase._async_start_done(<Task finishe...Error('EAPI')>)
handle: <Handle EbuildMetadataPhase._async_start_done(<Task finishe...Error('EAPI')>)>
Traceback (most recent call last):
  File "/usr/lib/python3.12/asyncio/events.py", line 88, in _run
    self._context.run(self._callback, *self._args)
  File "lib/_emerge/EbuildMetadataPhase.py", line 154, in _async_start_done
    future.cancelled() or future.result()
                          ^^^^^^^^^^^^^^^
  File "lib/_emerge/EbuildMetadataPhase.py", line 130, in _async_start
    retval = portage.doebuild(
             ^^^^^^^^^^^^^^^^^
  File "lib/portage/package/ebuild/doebuild.py", line 1030, in doebuild
    doebuild_environment(
  File "lib/portage/package/ebuild/doebuild.py", line 519, in doebuild_environment
    eapi = mysettings.configdict["pkg"]["EAPI"]
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^
  File "lib/portage/util/__init__.py", line 1684, in __getitem__
    return UserDict.__getitem__(self, item_key)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "lib/portage/cache/mappings.py", line 175, in __getitem__
    return self.data[key]
           ~~~~~~~~~^^^^^
KeyError: 'EAPI'

Bug: https://bugs.gentoo.org/924319
Signed-off-by: Zac Medico <zmedico@gentoo.org>

Wrap asyncio.Lock for compatibility with python 3.9 where the
deprecated loop parameter is required in order to avoid "got
Future <Future pending> attached to a different loop" errors.

The pordbapi async_aux_get method can use asyncio.Lock to
serialize access to its doebuild_settings attribute in order
to prevent issues like bug 924319.

Bug: https://bugs.gentoo.org/924319
Signed-off-by: Zac Medico <zmedico@gentoo.org>

For the portdbapi async_aux_get method, there is not a very
good place to store a config pool, so instead use asyncio.Lock
to manage access to the portdbapi doebuild_settings attribute
when using the main event loop in the main thread. For other
threads, clone a config instance since we do not have a
thread-safe config pool. This cloning is expensive, but since
portage internals do not trigger this case, it suffices for now
(an AssertionError ensures that internals do not trigger it).
For the main event loop running in the main thread, performance
with the asyncio.Lock should not be significantly different to
performance prior to commit c95fc64, since check_locale
results are typically cached and before there was only a single
shared doebuild_settings instance with access serialized via
the EbuildMetadataPhase _start method.

Update async_aux_get callers to use asyncio.ensure_future on
the returned coroutine when needed, since it used to return
a future instead of a coroutine, and sometimes a future is
needed for add_done_callback usage.

In the portdbapi async_fetch_map method, fix a broken reference
to "future" which should have been "aux_get_future", an error
discovered while testing this patch.

Bug: https://bugs.gentoo.org/924319
Fixes: c95fc64 ("EbuildPhase: async_check_locale")
Signed-off-by: Zac Medico <zmedico@gentoo.org>

Bug: https://bugs.gentoo.org/923841
Signed-off-by: Zac Medico <zmedico@gentoo.org>

Change config.environ() check_locale calls to async_check_locale
calls in the EbuildPhase _async_start method in order to eliminate
synchronous waiting for child processes in the main event loop
thread.

Bug: https://bugs.gentoo.org/923841
Signed-off-by: Zac Medico <zmedico@gentoo.org>