# Copyright 2018 The JAX Authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

from __future__ import annotations

from collections.abc import Hashable, Iterator
import contextlib
import functools
import itertools
import logging
import os
import sys
import threading
from typing import Any, Callable, Generic, NamedTuple, NoReturn, TypeVar, cast

from jax._src import lib
from jax._src.lib import jax_jit
from jax._src.lib import transfer_guard_lib
from jax._src.lib import xla_client
from jax._src import logging_config

logger = logging.getLogger(__name__)

_T = TypeVar('_T')


def bool_env(varname: str, default: bool) -> bool:
  """Read an environment variable and interpret it as a boolean.

  True values are (case insensitive): 'y', 'yes', 't', 'true', 'on', and '1';
  false values are 'n', 'no', 'f', 'false', 'off', and '0'.

  Args:
    varname: the name of the variable
    default: the default boolean value
  Raises: ValueError if the environment variable is anything else.
  """
  val = os.getenv(varname, str(default))
  val = val.lower()
  if val in ('y', 'yes', 't', 'true', 'on', '1'):
    return True
  elif val in ('n', 'no', 'f', 'false', 'off', '0'):
    return False
  else:
    raise ValueError(f"invalid truth value {val!r} for environment {varname!r}")

def int_env(varname: str, default: int) -> int:
  """Read an environment variable and interpret it as an integer."""
  return int(os.getenv(varname, str(default)))


UPGRADE_BOOL_HELP = (
    " This will be enabled by default in future versions of JAX, at which "
    "point all uses of the flag will be considered deprecated (following "
    "the `API compatibility policy "
    "<https://jax.readthedocs.io/en/latest/api_compatibility.html>`_).")

UPGRADE_BOOL_EXTRA_DESC = " (transient)"


class Config:
  _HAS_DYNAMIC_ATTRIBUTES = True

  def __init__(self):
    # There are two kinds of value holders: FlagHolders, which hold global
    # flags, and StateContextManagers, which hold state that can be changed
    # locally within a thread. A value holder needs a `.value` property and a
    # `._set()` method.
    self._value_holders = {}
    self.meta = {}
    self.use_absl = False
    self._contextmanager_flags = set()

  def update(self, name, val):
    if name not in self._value_holders:
      raise AttributeError(f"Unrecognized config option: {name}")
    self._value_holders[name]._set(val)

  def read(self, name):
    if name in self._contextmanager_flags:
      raise AttributeError(
          "For flags with a corresponding contextmanager, read their value "
          f"via e.g. `config.{name}` rather than `config.FLAGS.{name}`.")
    return self._read(name)

  def _read(self, name):
    try:
      return self._value_holders[name].value
    except KeyError:
      raise AttributeError(f"Unrecognized config option: {name}")

  @property
  def values(self):
    return {name: holder.value for name, holder in self._value_holders.items()}

  def add_option(self, name, holder, opt_type, meta_args, meta_kwargs):
    if name in self._value_holders:
      raise Exception(f"Config option {name} already defined")
    self._value_holders[name] = holder
    self.meta[name] = (opt_type, meta_args, meta_kwargs)

  def config_with_absl(self):
    """Registers absl flags for the JAX configs.

    E.g., for each JAX config defined using define_bool_state(), this method
    registers an absl boolean flag, with the same name.

    This is the recommended method to call if you use `app.run(main)` and you
    need JAX flags.  Example:

    ```python
    from absl import app
    import jax
    ...

    if __name__ == '__main__':
      jax.config.config_with_absl()
      app.run(main)
    ```

    """
    import absl.flags as absl_FLAGS  # noqa: F401  # pytype: disable=import-error
    from absl import app, flags as absl_flags  # pytype: disable=import-error

    self.use_absl = True
    self.absl_flags = absl_flags
    absl_defs = { bool: absl_flags.DEFINE_bool,
                  int:  absl_flags.DEFINE_integer,
                  float: absl_flags.DEFINE_float,
                  str:  absl_flags.DEFINE_string,
                  'enum': absl_flags.DEFINE_enum }

    for name, (flag_type, meta_args, meta_kwargs) in self.meta.items():
      holder = self._value_holders[name]
      absl_defs[flag_type](name, holder.value, *meta_args, **meta_kwargs)
    app.call_after_init(lambda: self.complete_absl_config(absl_flags))

  def complete_absl_config(self, absl_flags):
    # NOTE: avoid calling from outside this module. Instead, use
    # `config_with_absl()`, and (in rare cases) `parse_flags_with_absl()`.
    for name, holder in self._value_holders.items():
      try:
        flag = absl_flags.FLAGS[name]
      except KeyError:
        # This can happen if a new flag was added after config_with_absl() was
        # called, but before complete_absl_config was run. We could in principle
        # add code to DEFINE_... to register any newly added flags with ABSL
        # if config_with_absl() has already been called, but arguably the user
        # should have called config_with_absl() later.
        continue
      if flag.present:
        holder._set(flag.value)

  def parse_flags_with_absl(self):
    """Parses command-line args that start with --jax.

    This method should be used only by advanced users. Most users should use
    :meth:`config_with_absl` instead.

    This method has serious limitations: e.g., although it parses only the
    --jax* command-line args, it runs the validators of all registered absl
    flags, even non-JAX ones that have not been set yet; as such, for the
    non-JAX flags, the validators run on the default flag values, not on the
    values indicated by the command-line args.
    """
    global already_configured_with_absl
    if not already_configured_with_absl:
      # Extract just the --jax... flags (before the first --) from argv. In some
      # environments (e.g. ipython/colab) argv might be a mess of things
      # parseable by absl and other junk.
      jax_argv = itertools.takewhile(lambda a: a != '--', sys.argv)
      jax_argv = ['', *(a for a in jax_argv if a.startswith('--jax'))]

      import absl.flags  # pytype: disable=import-error
      self.config_with_absl()
      absl.flags.FLAGS(jax_argv, known_only=True)
      self.complete_absl_config(absl.flags)
      already_configured_with_absl = True


def trace_context():
  """Returns a tuple of configuration values that affect tracing.

  These values are included in the cache key for linear_util.cache.

  Values included in this set should also most likely be included in
  the C++ JIT state, which is handled separately.
  """
  tls = jax_jit.thread_local_state()
  axis_env_state = ()
  mesh_context_manager = ()
  context: Any = tls.extra_jit_context
  if context and context.axis_env_state is not None:
    axis_env_state = context.axis_env_state
  if context and context.mesh_context_manager:
    mesh_context_manager = context.mesh_context_manager
  return (axis_env_state, mesh_context_manager, enable_x64.value,
          numpy_rank_promotion.value, default_matmul_precision.value,
          dynamic_shapes.value, numpy_dtype_promotion.value,
          default_device.value, random_seed_offset.value,
          threefry_partitionable.value,
          softmax_custom_jvp.value,
          enable_memories.value,
          disable_jit.value,
          debug_key_reuse.value,
          jax_xla_profile_version.value,
          # Technically this affects jaxpr->stablehlo lowering, not tracing.
          hlo_source_file_canonicalization_regex.value)

config = Config()

_read = config._read
update = config.update
parse_flags_with_absl = config.parse_flags_with_absl


class NoDefault: pass
no_default = NoDefault()


class _Unset: pass
unset = _Unset()

_thread_local_state = threading.local()

class _StateContextManager(Generic[_T]):
  __slots__ = (
      '_name', '_value', '_update_thread_local_hook', '_update_global_hook',
      '_validator', '_default_context_manager_value', '__doc__', '__name__',
  )

  def __init__(
      self,
      name: str,
      default: _T,
      help,
      update_global_hook: Callable[[_T], None] | None = None,
      update_thread_local_hook: Callable[[_T | None], None] | None = None,
      validator: Callable[[Any], None] | None = None,
      extra_description: str = '',
      default_context_manager_value: Any = no_default,
  ):
    self._name = name
    self.__name__ = name[4:] if name.startswith('jax_') else name
    self.__doc__ = (f"Context manager for `{name}` config option"
                    f"{extra_description}.\n\n{help}")
    self._update_global_hook = update_global_hook
    self._update_thread_local_hook = update_thread_local_hook
    self._validator = validator
    self._default_context_manager_value = default_context_manager_value
    self._set(default)

  def __bool__(self) -> NoReturn:
    raise TypeError(
        "bool() not supported for instances of type '{0}' "
        "(did you mean to use '{0}.value' instead?)".format(
            type(self).__name__))

  def _set(self, value: _T) -> None:
    self._value = value
    if self._update_global_hook:
      self._update_global_hook(value)

  @property
  def value(self) -> _T:
    val = _thread_local_state.__dict__.get(self._name, unset)
    return cast(_T, val) if val is not unset else self._value

  @contextlib.contextmanager
  def __call__(self, new_val: Any = no_default):
    if new_val is no_default:
      if self._default_context_manager_value is not no_default:
        new_val = self._default_context_manager_value  # default_context_manager_value provided to constructor
      else:
        # no default_value provided to constructor and no value provided as an
        # argument, so we raise an error
        raise TypeError(f"Context manager for {self.__name__} config option "
                        "requires an argument representing the new value for "
                        "the config option.")
    if self._validator:
      self._validator(new_val)
    prev_val = getattr(_thread_local_state, self._name, unset)
    setattr(_thread_local_state, self._name, new_val)
    if self._update_thread_local_hook:
      self._update_thread_local_hook(new_val)
    try:
      yield
    finally:
      if prev_val is unset:
        delattr(_thread_local_state, self._name)
        if self._update_thread_local_hook:
          self._update_thread_local_hook(None)
      else:
        setattr(_thread_local_state, self._name, prev_val)
        if self._update_thread_local_hook:
          self._update_thread_local_hook(cast(_T, prev_val))

  def _add_hooks(self, update_global_hook, update_thread_local_hook):
    """Private method that adds hooks to an existing context-manager.

    Used to avoid cyclic import dependencies."""
    self._update_thread_local_hook = update_thread_local_hook
    self._update_global_hook = update_global_hook
    update_global_hook(self._value)


def define_bool_state(
    name: str,
    default: bool,
    help: str,
    *,
    update_global_hook: Callable[[bool], None] | None = None,
    update_thread_local_hook: Callable[[bool | None], None] | None = None,
    upgrade: bool = False,
    extra_description: str = '',
) -> _StateContextManager[bool]:
  """Set up thread-local state and return a contextmanager for managing it.

  This function is a convenience wrapper. It defines a flag, environment
  variable, and corresponding thread-local state, which can be managed via the
  contextmanager it returns.

  The thread-local state value can be read via the ``config.<option_name>``
  attribute, where ``config`` is the singleton ``Config`` instance.

  Args:
    name: string, converted to lowercase to define the name of the config
      option (and absl flag). It is converted to uppercase to define the
      corresponding shell environment variable.
    default: boolean, a default value for the option.
    help: string, used to populate the flag help information as well as the
      docstring of the returned context manager.
    update_global_hook: a optional callback that is called with the updated
      value of the global state when it is altered or set initially.
    update_thread_local_hook: a optional callback that is called with the
      updated value of the thread-local state when it is altered or set
      initially.
    upgrade: optional indicator that this flag controls a canonical feature
      upgrade, so that it is `True` for the incoming functionality, `False`
      for the outgoing functionality to be deprecated.
    extra_description: string, optional: extra information to add to the
      summary description.

  Returns:
    A contextmanager to control the thread-local state value.

  Example:

    enable_foo = config.define_bool_state(
        name='jax_enable_foo',
        default=False,
        help='Enable foo.')

    # Now the JAX_ENABLE_FOO shell environment variable and --jax_enable_foo
    # command-line flag can be used to control the process-level value of
    # the configuration option, in addition to using e.g.
    # ``config.update("jax_enable_foo", True)`` directly. We can also use a
    # context manager:

    with enable_foo(True):
      ...

  The value of the thread-local state or flag can be accessed via
  ``config.jax_enable_foo``. Reading it via ``config.FLAGS.jax_enable_foo`` is
  an error.
  """
  if not isinstance(default, bool):
    raise TypeError(f"Default value must be of type bool, got {default}")
  default = bool_env(name.upper(), default)
  name = name.lower()
  if upgrade:
    help += ' ' + UPGRADE_BOOL_HELP
    extra_description += UPGRADE_BOOL_EXTRA_DESC
  config._contextmanager_flags.add(name)

  s = _StateContextManager[bool](
      name, default, help, update_global_hook=update_global_hook,
      update_thread_local_hook=update_thread_local_hook,
      extra_description=extra_description, default_context_manager_value=True)
  config.add_option(name, s, bool, meta_args=[], meta_kwargs={"help": help})
  setattr(Config, name, property(lambda _: s.value))
  return s


def define_enum_state(
    name: str,
    enum_values: list[str],
    default: str,
    help: str,
    *,
    update_global_hook: Callable[[str], None] | None = None,
    update_thread_local_hook: Callable[[str | None], None] | None = None,
) -> _StateContextManager[str]:
  """Set up thread-local state and return a contextmanager for managing it.

  See docstring for ``define_bool_state``.

  Args:
    name: string, converted to lowercase to define the name of the config
      option (and absl flag). It is converted to uppercase to define the
      corresponding shell environment variable.
    enum_values: list of strings representing the possible values for the
      option.
    default: string, default value.
    help: string, used to populate the flag help information as well as the
      docstring of the returned context manager.

  Returns:
    A contextmanager to control the thread-local state value.
  """
  if not isinstance(default, str):
    raise TypeError(f"Default value must be of type str, got {default}")
  name = name.lower()
  default = os.getenv(name.upper(), default)
  if default not in enum_values:
    raise ValueError(f"Invalid value \"{default}\" for JAX flag {name}")
  config._contextmanager_flags.add(name)

  def validator(new_val):
    if type(new_val) is not str or new_val not in enum_values:
      raise ValueError(f"new enum value must be in {enum_values}, "
                       f"got {new_val} of type {type(new_val)}.")

  s = _StateContextManager[str](
      name,
      default,
      help,
      update_global_hook=update_global_hook,
      update_thread_local_hook=update_thread_local_hook,
      validator=validator,
  )
  config.add_option(
      name, s, 'enum',
      meta_args=[],
      meta_kwargs={"enum_values": enum_values, "help": help}
  )
  setattr(Config, name, property(lambda _: s.value))
  return s


def define_optional_enum_state(
    name: str,
    enum_values: list[str],
    default: str | None,
    help: str,
    *,
    update_global_hook: Callable[[str | None], None] | None = None,
    update_thread_local_hook: Callable[[str | None], None] | None = None,
) -> _StateContextManager[str | None]:
  """Set up thread-local state and return a contextmanager for managing it.

  See docstring for ``define_bool_state``.

  Args:
    name: string, converted to lowercase to define the name of the config
      option (and absl flag). It is converted to uppercase to define the
      corresponding shell environment variable.
    enum_values: list of strings representing the possible values for the
      option.
    default: optional string, default value.
    help: string, used to populate the flag help information as well as the
      docstring of the returned context manager.

  Returns:
    A contextmanager to control the thread-local state value.
  """
  if default is not None and not isinstance(default, str):
    raise TypeError(f"Default value must be of type str or None, got {default}")
  name = name.lower()
  default = os.getenv(name.upper(), default)
  if default is not None and default not in enum_values:
    raise ValueError(f"Invalid value \"{default}\" for JAX flag {name}")
  config._contextmanager_flags.add(name)

  def validate(new_val):
    if (new_val is not None and
      (type(new_val) is not str or new_val not in enum_values)):
      raise ValueError(f"new enum value must be None or in {enum_values}, "
                       f"got {new_val} of type {type(new_val)}.")

  s = _StateContextManager['str | None'](
      name, default, help, update_global_hook, update_thread_local_hook,
      validate
  )
  config.add_option(
      name, s, 'enum',
      meta_args=[],
      meta_kwargs={"enum_values": enum_values, "help": help}
  )
  setattr(Config, name, property(lambda _: s.value))
  return s


def define_int_state(
    name: str,
    default: int,
    help: str,
    *,
    update_global_hook: Callable[[int], None] | None = None,
    update_thread_local_hook: Callable[[int | None], None] | None = None,
) -> _StateContextManager[int]:
  """Set up thread-local state and return a contextmanager for managing it.

  See docstring for ``define_bool_state``.

  Args:
    name: string, converted to lowercase to define the name of the config
      option (and absl flag). It is converted to uppercase to define the
      corresponding shell environment variable.
    default: optional int, default value.
    help: string, used to populate the flag help information as well as the
      docstring of the returned context manager.

  Returns:
    A contextmanager to control the thread-local state value.
  """
  if not isinstance(default, int):
    raise TypeError(f"Default value must be of type int, got {default}")
  name = name.lower()
  default_env = os.getenv(name.upper())
  if default_env is not None:
    try:
      default = int(default_env)
    except ValueError:
      raise ValueError(f"Invalid value \"{default_env}\" for JAX flag {name}")
  config._contextmanager_flags.add(name)

  def validate(new_val):
    if new_val is not None and not isinstance(new_val, int):
      raise ValueError(f'new int config value must be None or of type int, '
                       f'got {new_val} of type {type(new_val)}')

  s = _StateContextManager[int](name, default, help, update_global_hook,
                                update_thread_local_hook, validate)
  config.add_option(name, s, int, meta_args=[], meta_kwargs={"help": help})
  setattr(Config, name, property(lambda _: s.value))
  return s


def define_float_state(
    name: str,
    default: float,
    help: str,
    *,
    update_global_hook: Callable[[float], None] | None = None,
    update_thread_local_hook: Callable[[float | None], None] | None = None,
) -> _StateContextManager[float]:
  """Set up thread-local state and return a contextmanager for managing it.

  See docstring for ``define_bool_state``.

  Args:
    name: string, converted to lowercase to define the name of the config
      option (and absl flag). It is converted to uppercase to define the
      corresponding shell environment variable.
    default: default value.
    help: string, used to populate the flag help information as well as the
      docstring of the returned context manager.

  Returns:
    A contextmanager to control the thread-local state value.
  """
  if not isinstance(default, float):
    raise TypeError(f"Default value must be of type float, got {default}")
  name = name.lower()
  default_env = os.getenv(name.upper())
  if default_env is not None:
    try:
      default = float(default_env)
    except ValueError:
      raise ValueError(f"Invalid value \"{default_env}\" for JAX flag {name}")
  config._contextmanager_flags.add(name)

  def validate(new_val):
    if new_val is not None and not isinstance(new_val, (float, int)):
      raise ValueError(
        f'new float config value must be None or of type float, '
        f'got {new_val} of type {type(new_val)}')

  s = _StateContextManager[float](name, default, help, update_global_hook,
                                  update_thread_local_hook, validate)
  config.add_option(name, s, float, meta_args=[], meta_kwargs={"help": help})
  setattr(Config, name, property(lambda _: s.value))
  return s


def define_string_state(
    name: str,
    default: str,
    help: str,
    *,
    update_global_hook: Callable[[str], None] | None = None,
    update_thread_local_hook: Callable[[str | None], None] | None = None,
) -> _StateContextManager[str]:
  """Set up thread-local state and return a contextmanager for managing it.

  See docstring for ``define_bool_state``.

  Args:
    name: string, converted to lowercase to define the name of the config
      option (and absl flag). It is converted to uppercase to define the
      corresponding shell environment variable.
    default: string, a default value for the option.
    help: string, used to populate the flag help information as well as the
      docstring of the returned context manager.
    update_global_hook: an optional callback that is called with the updated
      value of the global state when it is altered or set initially.
    update_thread_local_hook: an optional callback that is called with the
      updated value of the thread-local state when it is altered or set
      initially.

  Returns:
    A contextmanager to control the thread-local state value.
  """
  if not isinstance(default, str):
    raise TypeError(f"Default value must be of type str, got {default}")

  def validator(new_val):
    if not isinstance(new_val, str):
      raise ValueError('new string config value must be of type str,'
                       f' got {new_val} of type {type(new_val)}.')

  return define_string_or_object_state(
      name, default, help,
      update_global_hook=update_global_hook,
      update_thread_local_hook=update_thread_local_hook,
      validator=validator)


def define_optional_string_state(
    name: str,
    default: str | None,
    help: str,
    *,
    update_global_hook: Callable[[str], None] | None = None,
    update_thread_local_hook: Callable[[str | None], None] | None = None,
) -> _StateContextManager[str | None]:
  """Set up thread-local state and return a contextmanager for managing it.

  See docstring for ``define_bool_state``.

  Args:
    name: string, converted to lowercase to define the name of the config
      option (and absl flag). It is converted to uppercase to define the
      corresponding shell environment variable.
    default: optional string, a default value for the option.
    help: string, used to populate the flag help information as well as the
      docstring of the returned context manager.
    update_global_hook: an optional callback that is called with the updated
      value of the global state when it is altered or set initially.
    update_thread_local_hook: an optional callback that is called with the
      updated value of the thread-local state when it is altered or set
      initially.

  Returns:
    A contextmanager to control the thread-local state value.
  """
  if default is not None and not isinstance(default, str):
    raise TypeError(f"Default value must be of type str or None, got {default}")

  def validator(new_val):
    if new_val is not None and not isinstance(new_val, str):
      raise ValueError('new string config value must be None or of type str,'
                       f' got {new_val} of type {type(new_val)}.')

  return define_string_or_object_state(
      name, default, help,
      update_global_hook=update_global_hook,
      update_thread_local_hook=update_thread_local_hook,
      validator=validator)

def define_string_or_object_state(
    name: str,
    default: Any,
    help: str,
    *,
    update_global_hook: Callable[[Any], None] | None = None,
    update_thread_local_hook: Callable[[Any], None] | None = None,
    validator: Callable[[Any], None] | None = None,
) -> _StateContextManager[Any]:
  """Set up thread-local state and return a contextmanager for managing it.

  Similar to ``define_string_state``, except the context manager will accept
  any object, not just a string. Any value passed via commandline flag or
  environment variable will be treated as a string.

  Args:
    name: string, converted to lowercase to define the name of the config
      option (and absl flag). It is converted to uppercase to define the
      corresponding shell environment variable.
    default: string, a default value for the option.
    help: string, used to populate the flag help information as well as the
      docstring of the returned context manager.
    update_global_hook: an optional callback that is called with the updated
      value of the global state when it is altered or set initially.
    update_thread_local_hook: an optional callback that is called with the
      updated value of the thread-local state when it is altered or set
      initially.
    validator: an optional callback that is called with the new
      value on any update, and should raise an error if the new value is
      invalid.

  Returns:
    A contextmanager to control the thread-local state value.
  """
  name = name.lower()
  default = os.getenv(name.upper(), default)
  config._contextmanager_flags.add(name)

  s = _StateContextManager[Any](
      name, default, help, update_global_hook, update_thread_local_hook,
      validator)
  setattr(Config, name, property(lambda _: s.value))
  config.add_option(name, s, str, meta_args=[], meta_kwargs={"help": help})
  return s


class FlagHolder(Generic[_T]):
  __slots__ = ("_name", "value", "_update_hook")

  _name: str
  value: _T
  _update_hook: Callable[[Any], None] | None

  def __init__(self, name: str, default: _T,
               update_hook: Callable[[Any], None] | None = None):
    self._name = name
    self._update_hook = update_hook
    self._set(default)

  def __bool__(self) -> NoReturn:
    raise TypeError(
        "bool() not supported for instances of type '{0}' "
        "(did you mean to use '{0}.value' instead?)".format(
            type(self).__name__))

  def _set(self, value: _T) -> None:
    self.value = value
    if self._update_hook is not None:
      self._update_hook(value)


def check_exists(name):
  if name not in config._value_holders:
    raise AttributeError(f"Unrecognized config option: {name}")


def DEFINE_bool(name, default, *args, **kwargs) -> FlagHolder[bool]:
  update_hook = kwargs.pop("update_hook", None)
  holder = FlagHolder(name, default, update_hook)
  config.add_option(name, holder, bool, args, kwargs)
  return holder


def DEFINE_integer(name, default, *args, **kwargs) -> FlagHolder[int]:
  update_hook = kwargs.pop("update_hook", None)
  holder = FlagHolder(name, default, update_hook)
  config.add_option(name, holder, int, args, kwargs)
  return holder


def DEFINE_float(name, default, *args, **kwargs) -> FlagHolder[float]:
  update_hook = kwargs.pop("update_hook", None)
  holder = FlagHolder(name, default, update_hook)
  config.add_option(name, holder, float, args, kwargs)
  return holder


def DEFINE_string(name, default, *args, **kwargs) -> FlagHolder[str]:
  update_hook = kwargs.pop("update_hook", None)
  holder = FlagHolder(name, default, update_hook)
  config.add_option(name, holder, str, args, kwargs)
  return holder


def DEFINE_enum(name, default, *args, **kwargs) -> FlagHolder[str]:
  update_hook = kwargs.pop("update_hook", None)
  holder = FlagHolder(name, default, update_hook)
  config.add_option(name, holder, 'enum', args, kwargs)
  return holder


already_configured_with_absl = False


# The C++ JIT maintains its own copy of several configuration items as
# a global/thread-local state. These methods allow updates to part of the
# state when a configuration value changes.
class _GlobalExtraJitContext(NamedTuple):
  numpy_rank_promotion: str | None = None
  numpy_dtype_promotion: str | None = None
  default_matmul_precision: Any | None = None
  dynamic_shapes: bool = False
  random_seed_offset: int = 0
  threefry_partitionable: bool = False
  softmax_custom_jvp: bool = False
  xla_profile_version: int = 0


def _update_global_jit_state(**kw):
  gs = jax_jit.global_state()
  context = gs.extra_jit_context or _GlobalExtraJitContext()
  gs.extra_jit_context = context._replace(**kw)


class _ThreadLocalExtraJitContext(NamedTuple):
  """A namedtuple containing states to add to the cache key.

  Just in time compilation (for jit, pmap, etc) behavior is configurable through
  global and thread-local options, used in the cache key.

  The initialization, which uses both config.py and core.py is done using
  `_update_thread_local_jit_state` in core.py to prevent circular imports.
  """
  dynamic_trace_state: Any | None = None
  axis_env_state: Hashable = ()
  mesh_context_manager: Hashable = ()

  # Values set by _StateContextManager context managers.
  # CAUTION: these must be initialized to `None`! The state context manager
  # restores these to None on exit. If the object default is not `None`, the
  # context manager is not a no-op, which leads to problems with stale state
  # (e.g. spurious cache misses in tests).
  numpy_rank_promotion: str | None = None
  numpy_dtype_promotion: str | None = None
  default_matmul_precision: Any | None = None
  dynamic_shapes: bool | None = None
  random_seed_offset: int | None = None
  threefry_partitionable: bool | None = None
  softmax_custom_jvp: bool | None = None
  xla_profile_version: int | None = None


class _ThreadLocalStateCache(threading.local):
  """"A thread local cache for _ThreadLocalExtraJitContext

  The extra_jit_context in jax_jit.thread_local_state() may get updated and thus
  incurring dispatch overhead for comparing this python object during jit calls.
  We want to duduplicate the objects that have the same hash/equality to also
  have the same object ID, since the equality check is much faster if the object
  IDs match.
  """
  def __init__(self):
    self.canonicalize = functools.lru_cache(128)(lambda x: x)


_thread_local_state_cache = _ThreadLocalStateCache()


def update_thread_local_jit_state(**kw):
  tls = jax_jit.thread_local_state()
  # After xla_client._version >= 70, the thread_local object will necessarily
  # be initialized when accessed. The following line can be removed when the
  # minimum  jaxlib version is past version 70
  context = tls.extra_jit_context or _ThreadLocalExtraJitContext()
  tmp = context._replace(**kw)
  tls.extra_jit_context = _thread_local_state_cache.canonicalize(tmp)


# TODO(b/214340779): remove flag when XLA:CPU is improved.
jax2tf_associative_scan_reductions = define_bool_state(
    name='jax2tf_associative_scan_reductions',
    default=False,
    help=(
        'JAX has two separate lowering rules for the cumulative reduction '
        'primitives (cumsum, cumprod, cummax, cummin). On CPUs and GPUs it uses '
        'a lax.associative_scan, while for TPUs it uses the HLO ReduceWindow. '
        'The latter has a slow implementation on CPUs and GPUs. '
        'By default, jax2tf uses the TPU lowering. Set this flag to True to '
        'use the associative scan lowering usage, and only if it makes a difference '
        'for your application. '
        'See the jax2tf README.md for more details.'
    )
)

jax2tf_default_native_serialization = define_bool_state(
    name='jax2tf_default_native_serialization',
    default=bool_env('JAX2TF_DEFAULT_NATIVE_SERIALIZATION', True),
    help=(
        'Sets the default value of the native_serialization parameter to '
        'jax2tf.convert. Prefer using the parameter instead of the flag, '
        'the flag may be removed in the future.'
    )
)

jax_serialization_version = define_int_state(
    name='jax_serialization_version',
    # Note: bump the default serialization version at least one month after
    # we update XlaCallModule to support the new version, so that serialized
    # modules are forward compatible with deployed versions of XlaCallModule.
    # Version 9 of XlaCallModule is supported since October 27th, 2023.
    default=int_env('JAX_SERIALIZATION_VERSION', 9),
    help=(
        'The version number to use for native serialization. This must be '
        'within the range of versions supported by the tf.XlaCallModule '
        'used in your deployment environment. '
        'See https://github.com/google/jax/blob/main/jax/experimental/jax2tf/README.md#native-serialization-versions.'
    )
)

jax_platforms = define_optional_string_state(
    name='jax_platforms',
    default=None,
    help=(
        'Comma-separated list of platform names specifying which platforms jax '
        'should initialize. If any of the platforms in this list are not successfully '
        'initialized, an exception will be raised and the program will be aborted. '
        'The first platform in the list will be the default platform. '
        'For example, config.jax_platforms=cpu,tpu means that CPU and TPU backends '
        'will be initialized, and the CPU backend will be used unless otherwise '
        'specified. If TPU initialization fails, it will raise an exception. '
        'By default, jax will try to initialize all available '
        'platforms and will default to GPU or TPU if available, and fallback to CPU '
        'otherwise.'
        ))

enable_checks = define_bool_state(
    name='jax_enable_checks',
    default=False,
    help='Turn on invariant checking for JAX internals. Makes things slower.')

debug_key_reuse = define_bool_state(
    name='jax_debug_key_reuse',
    default=False,
    help=('Turn on experimental key reuse checking. With this configuration enabled,'
          ' typed PRNG keys (i.e. keys created with jax.random.key()) will have their'
          ' usage tracked, and incorrect reuse of a previously-used key will lead to'
          ' an error. Currently enabling this leads to a small Python overhead on'
          ' every call to a JIT-compiled function with keys as inputs or outputs.'))

check_tracer_leaks = define_bool_state(
    name='jax_check_tracer_leaks',
    default=False,
    help=('Turn on checking for leaked tracers as soon as a trace completes. '
          'Enabling leak checking may have performance impacts: some caching '
          'is disabled, and other overheads may be added. Additionally, be aware '
          'that some Python debuggers can cause false positives, so it is recommended '
          'to disable any debuggers while leak checking is enabled.'))
checking_leaks = functools.partial(check_tracer_leaks, True)

debug_nans = define_bool_state(
    name='jax_debug_nans',
    default=False,
    help=('Add nan checks to every operation. When a nan is detected on the '
          'output of a jit-compiled computation, call into the un-compiled '
          'version in an attempt to more precisely identify the operation '
          'which produced the nan.'))

debug_infs = define_bool_state(
    name='jax_debug_infs',
    default=False,
    help=('Add inf checks to every operation. When an inf is detected on the '
          'output of a jit-compiled computation, call into the un-compiled '
          'version in an attempt to more precisely identify the operation '
          'which produced the inf.'))

log_compiles = define_bool_state(
    name='jax_log_compiles',
    default=False,
    help=('Log a message each time every time `jit` or `pmap` compiles an XLA '
          'computation. Logging is performed with `logging`. When this '
          'option is set, the log level is WARNING; otherwise the level is '
          'DEBUG.'))

explain_cache_misses = define_bool_state(
    name='jax_explain_cache_misses',
    default=False,
    help=('Each time there is a miss on one of the main caches (e.g. the '
          'tracing cache), log an explanation.. Logging is performed with '
          '`logging`. When this option is set, the log level is WARNING; '
          'otherwise the level is DEBUG.'))

log_checkpoint_residuals = define_bool_state(
    name='jax_log_checkpoint_residuals',
    default=False,
    help=('Log a message every time jax.checkpoint (aka jax.remat) is '
          'partially evaluated (e.g. for autodiff), printing what residuals '
          'are saved.'))

pmap_shmap_merge = define_bool_state(
    name='jax_pmap_shmap_merge',
    default=False,
    upgrade=True,
    help='If True, pmap and shard_map API will be merged.')

def _update_jax_memories_global(val):
  lib.jax_jit.global_state().enable_memories = val

def _update_jax_memories_thread_local(val):
  lib.jax_jit.thread_local_state().enable_memories = val

enable_memories = define_bool_state(
    'jax_enable_memories',
    default=False,
    upgrade=True,
    update_global_hook=_update_jax_memories_global,
    update_thread_local_hook=_update_jax_memories_thread_local,
    help=("If True, will allow fetching memory kinds available on executable "
          "and annotate Shardings with it."))

spmd_mode = define_enum_state(
    name='jax_spmd_mode',
    enum_values=['allow_all', 'allow_jit'],
    default='allow_jit',
    help=("Decides whether Math on `jax.Array`'s that are not fully addressable "
          "(i.e. spans across multiple processes) is allowed. The options are: "
          "* allow_jit: Default, `pjit` and `jax.jit` computations are allowed "
          "    to execute on non-fully addressable `jax.Array`s\n"
          "* allow_all: `jnp`, normal math (like `a + b`, etc), `pjit`, "
          "    `jax.jit` and all other operations are allowed to "
          "    execute on non-fully addressable `jax.Array`s."))


distributed_debug = define_bool_state(
    name='jax_distributed_debug',
    default=False,
    help=('Enable logging useful for debugging multi-process distributed '
          'computations. Logging is performed with `logging` at WARNING '
          'level.'))

random_seed_offset = define_int_state(
    name='jax_random_seed_offset',
    default=0,
    help=('Offset to all random seeds (e.g. argument to jax.random.key()).'),
    update_global_hook=lambda val: _update_global_jit_state(
        random_seed_offset=val),
    update_thread_local_hook=lambda val: update_thread_local_jit_state(
        random_seed_offset=val)
)

legacy_prng_key = define_enum_state(
    name='jax_legacy_prng_key',
    enum_values=['allow', 'warn', 'error'],
    default='allow',
    help=('Specify the behavior when raw PRNG keys are passed to '
          'jax.random APIs.')
)

enable_custom_prng = define_bool_state(
    name='jax_enable_custom_prng',
    default=False,
    upgrade=True,
    help=('Enables an internal upgrade that allows one to define custom '
          'pseudo-random number generator implementations.'))

default_prng_impl = define_enum_state(
    name='jax_default_prng_impl',
    enum_values=['threefry2x32', 'rbg', 'unsafe_rbg'],
    default='threefry2x32',
    help=('Select the default PRNG implementation, used when one is not '
          'explicitly provided at seeding time.'))

threefry_partitionable = define_bool_state(
    name='jax_threefry_partitionable',
    default=False,
    upgrade=True,
    help=('Enables internal threefry PRNG implementation changes that '
          'render it automatically partitionable in some cases. Without this '
          'flag, using the standard jax.random pseudo-random number generation '
          'may result in extraneous communication and/or redundant distributed '
          'computation. With this flag, the communication overheads disappear '
          'in some cases.'),
    update_global_hook=lambda val: _update_global_jit_state(
        threefry_partitionable=val),
    update_thread_local_hook=lambda val: update_thread_local_jit_state(
        threefry_partitionable=val))


softmax_custom_jvp = define_bool_state(
    name='jax_softmax_custom_jvp',
    default=False,
    upgrade=True,
    help=('Use a new custom_jvp rule for jax.nn.softmax. The new rule should '
          'improve memory usage and stability. Set True to use new '
          'behavior. See https://github.com/google/jax/pull/15677'),
    update_global_hook=lambda val: _update_global_jit_state(
        softmax_custom_jvp=val),
    update_thread_local_hook=lambda val: update_thread_local_jit_state(
        softmax_custom_jvp=val))


enable_custom_vjp_by_custom_transpose = define_bool_state(
    name='jax_enable_custom_vjp_by_custom_transpose',
    default=False,
    upgrade=True,
    help=('Enables an internal upgrade that implements `jax.custom_vjp` by '
          'reduction to `jax.custom_jvp` and `jax.custom_transpose`.'))

raise_persistent_cache_errors = define_bool_state(
    name='jax_raise_persistent_cache_errors',
    default=False,
    help=('If true, exceptions raised when reading or writing to the '
          'persistent compilation cache will be allowed through, halting '
          'program execution if not manually caught. If false, exceptions are '
          'caught and raised as warnings, allowing program execution to '
          'continue. Defaults to false so cache bugs or intermittent issues '
          'are non-fatal.'))

persistent_cache_min_compile_time_secs = define_float_state(
    name='jax_persistent_cache_min_compile_time_secs',
    default=1.,
    help=('The minimum compile time of a computation to be written to the '
          'persistent compilation cache. This threshold can be raised to '
          'decrease the number of entries written to the cache.'))

persistent_cache_min_entry_size_bytes = define_int_state(
    name='jax_persistent_cache_min_entry_size_bytes',
    default=0,
    help=('The minimum size (in bytes) of an entry that will be cached in the '
          'persistent compilation cache: '
          '* -1: disable the size restriction and prevent overrides. '
          '* Leave at default (0) to allow for overrides. The override will '
          '  typically ensure that the minimum size is optimal for the '
          '  filesystem being used for the cache. '
          '* > 0: the actual minimum size desired; no overrides.'))

compilation_cache_include_metadata_in_key = define_bool_state(
    name='jax_compilation_cache_include_metadata_in_key',
    default=False,
    help=(
        'Include metadata, such as file names and line numbers, in the'
        ' compilation cache key. If false, the cache will still get hits even'
        ' if functions or files are moved, etc. However, it means that'
        ' executables loaded from the cache may have stale metadata, which'
        ' may show up in, e.g., profiles.'
    ),
)

hlo_source_file_canonicalization_regex = define_optional_string_state(
    name='jax_hlo_source_file_canonicalization_regex',
    default=None,
    help=('Used to canonicalize the source_path metadata of HLO instructions '
          'by removing the given regex. If set, re.sub() is called on each '
          'source_file with the given regex, and all matches are removed. '
          'This can be used to avoid spurious cache misses when using the '
          'persistent compilation cache, which includes HLO metadata in the '
          'cache key.'))

include_full_tracebacks_in_locations = define_bool_state(
    name='jax_include_full_tracebacks_in_locations',
    default=True,
    help=(
        'Include Python tracebacks in MLIR locations in IR emitted by JAX.'
    ),
)

traceback_in_locations_limit = define_int_state(
    name='jax_traceback_in_locations_limit',
    default=10,
    help=(
        'Limit the number of frames at the Python traceback frames included in '
        'MLIR locations. If set to the negative value, traceback will not be '
        'limited.'
    ),
)

share_autotune_config_between_hosts = define_bool_state(
    name='jax_share_autotune_config_between_hosts',
    default=False,
    help=(
        'If set to True, the coordinator process will share autotune configs '
        'other participants. This will increase overall compilation time, but '
        'will lead to equal compiled modules in each process. '
        'If both jax_share_binary_between_hosts and '
        'jax_share_autotune_config_between_hosts are set, compiled HLO will be '
        "shared when it's possible and autotune config sharing will be used "
        'as a fallback.'
    ),
)

share_binary_between_hosts = define_bool_state(
    name='jax_share_binary_between_hosts',
    default=False,
    help=(
        'If set to True, the compiled module will be shared between hosts '
        'directly.'
    ),
)

share_binary_between_hosts_timeout_ms = define_int_state(
    name='jax_share_binary_between_hosts_timeout_ms',
    default=20 * 60 * 1000,
    help='Timeout for the compiled module share.',
)

enable_compilation_cache = define_bool_state(
    name='jax_enable_compilation_cache',
    default=True,
    help=('If set to False, the compilation cache will be disabled regardless '
          'of whether set_cache_dir() was called. If set to True, the '
          'path could be set to a default value or via a call to '
          'set_cache_dir().'),
)

compilation_cache_dir = define_optional_string_state(
    name='jax_compilation_cache_dir',
    default=None,
    help=('Path for the cache. '
          'Precedence: '
          '1. A call to compilation_cache.set_cache_dir(). '
          '2. The value of this flag set in the command line or by default.'),
)

default_dtype_bits = define_enum_state(
    name='jax_default_dtype_bits',
    enum_values=['32', '64'],
    default='64',
    help=('Specify bit width of default dtypes, either 32-bit or 64-bit. '
          'This is a temporary flag that will be used during the process '
          'of deprecating the ``jax_enable_x64`` flag.'))

numpy_dtype_promotion = define_enum_state(
    name='jax_numpy_dtype_promotion',
    enum_values=['standard', 'strict'],
    default='standard',
    help=('Specify the rules used for implicit type promotion in operations '
          'between arrays. Options are "standard" or "strict"; in strict-mode, '
          'binary operations between arrays of differing strongly-specified '
          'dtypes will result in an error.'),
    update_global_hook=lambda val: \
      _update_global_jit_state(numpy_dtype_promotion=val),
    update_thread_local_hook=lambda val: \
      update_thread_local_jit_state(numpy_dtype_promotion=val))

def _update_x64_global(val):
  lib.jax_jit.global_state().enable_x64 = val

def _update_x64_thread_local(val):
  lib.jax_jit.thread_local_state().enable_x64 = val

enable_x64 = define_bool_state(
    name='jax_enable_x64',
    default=False,
    help='Enable 64-bit types to be used',
    update_global_hook=_update_x64_global,
    update_thread_local_hook=_update_x64_thread_local)

# TODO(phawkins): remove after fixing users of FLAGS.x64_enabled.
config._contextmanager_flags.remove('jax_enable_x64')

setattr(Config, "x64_enabled", property(lambda _: enable_x64.value))

def _update_default_device_global(val):
  lib.jax_jit.global_state().default_device = val


def _update_default_device_thread_local(val):
  lib.jax_jit.thread_local_state().default_device = val


def _validate_default_device(val):
  if val is not None and not isinstance(val, xla_client.Device):
    # TODO(skyewm): this is a workaround for non-PJRT Device types. Remove when
    # all JAX backends use a single C++ device interface.
    if 'Device' in str(type(val)):
      logger.info(
          'Allowing non-`xla_client.Device` default device: %s, type: %s',
          repr(val), type(val))
      return
    raise ValueError('jax.default_device must be passed a Device object (e.g. '
                     f"`jax.devices('cpu')[0]`), got: {val!r}")


# TODO(skye): default_device only accepts devices for now. Make it work with
# platform names as well (e.g. "cpu" to mean the same as jax.devices("cpu")[0]).
default_device = define_string_or_object_state(
    name='jax_default_device',
    default=None,
    help=(
        'Configure the default device for JAX operations. Set to a Device '
        'object (e.g. ``jax.devices("cpu")[0]``) to use that Device as the '
        'default device for JAX operations and jit\'d function calls (there is '
        'no effect on multi-device computations, e.g. pmapped function calls). '
        'Set to None to use the system default device. See '
        ':ref:`faq-data-placement` for more information on device placement.'),
    update_global_hook=_update_default_device_global,
    update_thread_local_hook=_update_default_device_thread_local,
    validator=_validate_default_device)

def _update_disable_jit_global(val):
  lib.jax_jit.global_state().disable_jit = val

def _update_disable_jit_thread_local(val):
  lib.jax_jit.thread_local_state().disable_jit = val

disable_jit = define_bool_state(
    name='jax_disable_jit',
    default=False,
    help=('Disable JIT compilation and just call original Python.'),
    update_global_hook=_update_disable_jit_global,
    update_thread_local_hook=_update_disable_jit_thread_local)


numpy_rank_promotion = define_enum_state(
    name='jax_numpy_rank_promotion',
    enum_values=['allow', 'warn', 'raise'],
    default='allow',
    help=('Control NumPy-style automatic rank promotion broadcasting '
          '("allow", "warn", or "raise").'),
    update_global_hook=lambda val: \
      _update_global_jit_state(numpy_rank_promotion=val),
    update_thread_local_hook=lambda val: \
      update_thread_local_jit_state(numpy_rank_promotion=val))

default_matmul_precision = define_optional_enum_state(
    name='jax_default_matmul_precision',
    enum_values=['bfloat16', 'tensorfloat32', 'float32'],
    default=None,
    help=('Control the default matmul and conv precision for 32bit inputs.\n\n'

          'Some platforms, like TPU, offer configurable precision levels for '
          'matrix multiplication and convolution computations, trading off '
          'accuracy for speed. The precision can be controlled for each '
          'operation; for example, see the :func:`jax.lax.conv_general_dilated` '
          'and :func:`jax.lax.dot` docstrings. But it can be useful to control '
          'the default behavior obtained when an operation is not given a '
          'specific precision.\n\n'

          'This option can be used to control the default precision '
          'level for computations involved in matrix multiplication and '
          'convolution on 32bit inputs. The levels roughly describe the '
          "precision at which scalar products are computed. The 'bfloat16' "
          "option is the fastest and least precise; 'float32' is similar to "
          "full float32 precision; 'tensorfloat32' is intermediate.\n\n"),
    update_global_hook=lambda val: \
      _update_global_jit_state(default_matmul_precision=val),
    update_thread_local_hook=lambda val: \
      update_thread_local_jit_state(default_matmul_precision=val))

traceback_filtering = define_enum_state(
    name = 'jax_traceback_filtering',
    enum_values=["off", "tracebackhide", "remove_frames", "quiet_remove_frames",
                 "auto"],
    default="auto",
    help="Controls how JAX filters internal frames out of tracebacks.\n\n"
         "Valid values are:\n"
         " * \"off\": disables traceback filtering.\n"
         " * \"auto\": use \"tracebackhide\" if running under a sufficiently"
         " new IPython, or \"remove_frames\" otherwise.\n"
         " * \"tracebackhide\": adds \"__tracebackhide__\" annotations to"
         " hidden stack frames, which some traceback printers support.\n"
         " * \"remove_frames\": removes hidden frames from tracebacks, and adds"
         " the unfiltered traceback as a __cause__ of the exception.\n"
         " * \"quiet_remove_frames\": removes hidden frames from tracebacks, and adds"
         " a brief message (to the __cause__ of the exception) describing that this has"
         " happened.\n")

# This flag is for internal use.
# TODO(tianjianlu): Removes once we always enable cusparse lowering.
# TODO(b/262050896): Set to true after bug is fixed
bcoo_cusparse_lowering = define_bool_state(
    name='jax_bcoo_cusparse_lowering',
    default=False,
    help=('Enables lowering BCOO ops to cuSparse.'))

# TODO(mattjj): remove this flag when we ensure we only succeed at trace-staging
# if the intended backend can handle lowering the result
dynamic_shapes = define_bool_state(
    name='jax_dynamic_shapes',
    default=bool(os.getenv('JAX_DYNAMIC_SHAPES', '')),
    help=('Enables experimental features for staging out computations with '
          'dynamic shapes.'),
    update_global_hook=lambda val: \
      _update_global_jit_state(dynamic_shapes=val),
    update_thread_local_hook=lambda val: \
      update_thread_local_jit_state(dynamic_shapes=val))

# This flag is temporary during rollout of the remat barrier.
# TODO(parkers): Remove if there are no complaints.
remat_opt_barrier = define_bool_state(
    name='jax_remat_opt_barrier',
    default=True,
    help=('Enables using optimization-barrier op for lowering remat.'))

# TODO(sharadmv,mattjj): set default to True, then remove
eager_pmap = define_bool_state(
    name='jax_eager_pmap',
    default=True,
    upgrade=True,
    help='Enable eager-mode pmap when jax_disable_jit is activated.')

xla_runtime_errors = define_bool_state(
    name='jax_experimental_unsafe_xla_runtime_errors',
    default=False,
    help=('Enable XLA runtime errors for jax.experimental.checkify.checks '
          'on CPU and GPU. These errors are async, might get lost and are not '
          'very readable. But, they crash the computation and enable you '
          'to write jittable checks without needing to checkify. Does not '
          'work under pmap/pjit.')
)

jax_xla_profile_version = define_int_state(
    name='jax_xla_profile_version',
    default=0,
    help=(
        'Optional profile version for XLA compilation. This is meaningful '
        'only when XLA is configured to support the remote compilation '
        'profile feature.'),
    update_global_hook=lambda val: _update_global_jit_state(
        xla_profile_version=val),
    update_thread_local_hook=lambda val: update_thread_local_jit_state(
        xla_profile_version=val),
)

@contextlib.contextmanager
def explicit_device_put_scope() -> Iterator[None]:
  """Indicates that the current context is an explicit device_put*() call."""
  state = transfer_guard_lib.thread_local_state()
  prev = state.explicit_device_put
  state.explicit_device_put = True
  try:
    yield
  finally:
    state.explicit_device_put = prev

@contextlib.contextmanager
def explicit_device_get_scope() -> Iterator[None]:
  """Indicates that the current context is an explicit device_get() call."""
  state = transfer_guard_lib.thread_local_state()
  prev = state.explicit_device_get
  state.explicit_device_get = True
  try:
    yield
  finally:
    state.explicit_device_get = prev

def _update_transfer_guard(state, key, val):
  """Applies the transfer guard level within transfer_guard_lib."""
  if val is None:
    setattr(state, key, None)
  elif val == 'allow':
    setattr(state, key, transfer_guard_lib.TransferGuardLevel.ALLOW)
  elif val == 'log':
    setattr(state, key, transfer_guard_lib.TransferGuardLevel.LOG)
  elif val == 'disallow':
    setattr(state, key, transfer_guard_lib.TransferGuardLevel.DISALLOW)
  elif val == 'log_explicit':
    setattr(state, key, transfer_guard_lib.TransferGuardLevel.LOG_EXPLICIT)
  elif val == 'disallow_explicit':
    setattr(state, key, transfer_guard_lib.TransferGuardLevel.DISALLOW_EXPLICIT)
  else:
    assert False, f'Invalid transfer guard level {val}'

transfer_guard_host_to_device = define_optional_enum_state(
    name='jax_transfer_guard_host_to_device',
    enum_values=[
        'allow', 'log', 'disallow', 'log_explicit', 'disallow_explicit'
    ],
    # The default is applied by transfer_guard_lib. Use None here to avoid
    # accidentally overriding --jax_transfer_guard.
    default=None,
    help=('Select the transfer guard level for host-to-device transfers. '
          'Default is "allow".'),
    update_global_hook=lambda val: _update_transfer_guard(
        transfer_guard_lib.global_state(), 'host_to_device', val),
    update_thread_local_hook=lambda val: _update_transfer_guard(
        transfer_guard_lib.thread_local_state(), 'host_to_device', val))

transfer_guard_device_to_device = define_optional_enum_state(
    name='jax_transfer_guard_device_to_device',
    enum_values=[
        'allow', 'log', 'disallow', 'log_explicit', 'disallow_explicit'
    ],
    # The default is applied by transfer_guard_lib. Use None here to avoid
    # accidentally overriding --jax_transfer_guard.
    default=None,
    help=('Select the transfer guard level for device-to-device transfers. '
          'Default is "allow".'),
    update_global_hook=lambda val: _update_transfer_guard(
        transfer_guard_lib.global_state(), 'device_to_device', val),
    update_thread_local_hook=lambda val: _update_transfer_guard(
        transfer_guard_lib.thread_local_state(), 'device_to_device', val))

transfer_guard_device_to_host = define_optional_enum_state(
    name='jax_transfer_guard_device_to_host',
    enum_values=[
        'allow', 'log', 'disallow', 'log_explicit', 'disallow_explicit'
    ],
    # The default is applied by transfer_guard_lib. Use None here to avoid
    # accidentally overriding --jax_transfer_guard.
    default=None,
    help=('Select the transfer guard level for device-to-host transfers. '
          'Default is "allow".'),
    update_global_hook=lambda val: _update_transfer_guard(
        transfer_guard_lib.global_state(), 'device_to_host', val),
    update_thread_local_hook=lambda val: _update_transfer_guard(
        transfer_guard_lib.thread_local_state(), 'device_to_host', val))

def _update_all_transfer_guard_global(val):
  for name in ('jax_transfer_guard_host_to_device',
               'jax_transfer_guard_device_to_device',
               'jax_transfer_guard_device_to_host'):
    config.update(name, val)

_transfer_guard = define_optional_enum_state(
    name='jax_transfer_guard',
    enum_values=[
        'allow', 'log', 'disallow', 'log_explicit', 'disallow_explicit'
    ],
    # The default is applied by transfer_guard_lib. Use None here to avoid
    # accidentally overriding --jax_transfer_guard_*.
    default=None,
    help=('Select the transfer guard level for all transfers. This option is '
          'set-only; the transfer guard level for a specific direction should '
          'be read using the per-transfer direction option. '
          'Default is "allow".'),
    update_global_hook=_update_all_transfer_guard_global)

@contextlib.contextmanager
def transfer_guard(new_val: str) -> Iterator[None]:
  """A contextmanager to control the transfer guard level for all transfers.

  For more information, see
  https://jax.readthedocs.io/en/latest/transfer_guard.html

  Args:
    new_val: The new thread-local transfer guard level for all transfers.

  Yields:
    None.
  """
  with contextlib.ExitStack() as stack:
    stack.enter_context(transfer_guard_host_to_device(new_val))
    stack.enter_context(transfer_guard_device_to_device(new_val))
    stack.enter_context(transfer_guard_device_to_host(new_val))
    stack.enter_context(_transfer_guard(new_val))
    yield


def _update_debug_log_modules(module_names_str: str | None):
  logging_config.disable_all_debug_logging()
  if not module_names_str:
    return
  module_names = module_names_str.split(',')
  for module_name in module_names:
    logging_config.enable_debug_logging(module_name)

# Don't define a context manager since this isn't threadsafe.
define_string_state(
    name='jax_debug_log_modules',
    default='',
    help=('Comma-separated list of module names (e.g. "jax" or '
          '"jax._src.xla_bridge,jax._src.dispatch") to enable debug logging '
          'for.'),
    update_global_hook=_update_debug_log_modules)

pmap_no_rank_reduction = define_bool_state(
    name='jax_pmap_no_rank_reduction',
    default=False,
    help=(
        "If True, pmap shards have a the same rank as their enclosing array."
    )
)
