"""Utility functions for vector environments to share memory between processes."""
from __future__ import annotations
import multiprocessing as mp
from collections import OrderedDict
from ctypes import c_bool
from functools import singledispatch
from typing import Any
import numpy as np
from gymnasium.error import CustomSpaceError
from gymnasium.spaces import (
Box,
Dict,
Discrete,
Graph,
MultiBinary,
MultiDiscrete,
Sequence,
Space,
Text,
Tuple,
flatten,
)
__all__ = ["create_shared_memory", "read_from_shared_memory", "write_to_shared_memory"]
[docs]
@singledispatch
def create_shared_memory(
space: Space[Any], n: int = 1, ctx=mp
) -> dict[str, Any] | tuple[Any, ...] | mp.Array:
"""Create a shared memory object, to be shared across processes.
This eventually contains the observations from the vectorized environment.
Args:
space: Observation space of a single environment in the vectorized environment.
n: Number of environments in the vectorized environment (i.e. the number of processes).
ctx: The multiprocess module
Returns:
shared_memory for the shared object across processes.
Raises:
CustomSpaceError: Space is not a valid :class:`gymnasium.Space` instance
"""
if isinstance(space, Space):
raise CustomSpaceError(
f"Space of type `{type(space)}` doesn't have an registered `create_shared_memory` function. Register `{type(space)}` for `create_shared_memory` to support it."
)
else:
raise TypeError(
f"The space provided to `create_shared_memory` is not a gymnasium Space instance, type: {type(space)}, {space}"
)
@create_shared_memory.register(Box)
@create_shared_memory.register(Discrete)
@create_shared_memory.register(MultiDiscrete)
@create_shared_memory.register(MultiBinary)
def _create_base_shared_memory(
space: Box | Discrete | MultiDiscrete | MultiBinary, n: int = 1, ctx=mp
):
assert space.dtype is not None
dtype = space.dtype.char
if dtype in "?":
dtype = c_bool
return ctx.Array(dtype, n * int(np.prod(space.shape)))
@create_shared_memory.register(Tuple)
def _create_tuple_shared_memory(space: Tuple, n: int = 1, ctx=mp):
return tuple(
create_shared_memory(subspace, n=n, ctx=ctx) for subspace in space.spaces
)
@create_shared_memory.register(Dict)
def _create_dict_shared_memory(space: Dict, n: int = 1, ctx=mp):
return OrderedDict(
[
(key, create_shared_memory(subspace, n=n, ctx=ctx))
for (key, subspace) in space.spaces.items()
]
)
@create_shared_memory.register(Text)
def _create_text_shared_memory(space: Text, n: int = 1, ctx=mp):
return ctx.Array(np.dtype(np.int32).char, n * space.max_length)
@create_shared_memory.register(Graph)
@create_shared_memory.register(Sequence)
def _create_dynamic_shared_memory(space: Graph | Sequence, n: int = 1, ctx=mp):
raise TypeError(
f"As {space} has a dynamic shape then it is not possible to make a static shared memory."
)
[docs]
@singledispatch
def read_from_shared_memory(
space: Space, shared_memory: dict | tuple | mp.Array, n: int = 1
) -> dict[str, Any] | tuple[Any, ...] | np.ndarray:
"""Read the batch of observations from shared memory as a numpy array.
..notes::
The numpy array objects returned by `read_from_shared_memory` shares the
memory of `shared_memory`. Any changes to `shared_memory` are forwarded
to `observations`, and vice-versa. To avoid any side-effect, use `np.copy`.
Args:
space: Observation space of a single environment in the vectorized environment.
shared_memory: Shared object across processes. This contains the observations from the vectorized environment.
This object is created with `create_shared_memory`.
n: Number of environments in the vectorized environment (i.e. the number of processes).
Returns:
Batch of observations as a (possibly nested) numpy array.
Raises:
CustomSpaceError: Space is not a valid :class:`gymnasium.Space` instance
"""
if isinstance(space, Space):
raise CustomSpaceError(
f"Space of type `{type(space)}` doesn't have an registered `read_from_shared_memory` function. Register `{type(space)}` for `read_from_shared_memory` to support it."
)
else:
raise TypeError(
f"The space provided to `read_from_shared_memory` is not a gymnasium Space instance, type: {type(space)}, {space}"
)
@read_from_shared_memory.register(Box)
@read_from_shared_memory.register(Discrete)
@read_from_shared_memory.register(MultiDiscrete)
@read_from_shared_memory.register(MultiBinary)
def _read_base_from_shared_memory(
space: Box | Discrete | MultiDiscrete | MultiBinary, shared_memory, n: int = 1
):
return np.frombuffer(shared_memory.get_obj(), dtype=space.dtype).reshape(
(n,) + space.shape
)
@read_from_shared_memory.register(Tuple)
def _read_tuple_from_shared_memory(space: Tuple, shared_memory, n: int = 1):
return tuple(
read_from_shared_memory(subspace, memory, n=n)
for (memory, subspace) in zip(shared_memory, space.spaces)
)
@read_from_shared_memory.register(Dict)
def _read_dict_from_shared_memory(space: Dict, shared_memory, n: int = 1):
return OrderedDict(
[
(key, read_from_shared_memory(subspace, shared_memory[key], n=n))
for (key, subspace) in space.spaces.items()
]
)
@read_from_shared_memory.register(Text)
def _read_text_from_shared_memory(space: Text, shared_memory, n: int = 1) -> tuple[str]:
data = np.frombuffer(shared_memory.get_obj(), dtype=np.int32).reshape(
(n, space.max_length)
)
return tuple(
"".join(
[
space.character_list[val]
for val in values
if val < len(space.character_set)
]
)
for values in data
)
[docs]
@singledispatch
def write_to_shared_memory(
space: Space,
index: int,
value: np.ndarray,
shared_memory: dict[str, Any] | tuple[Any, ...] | mp.Array,
):
"""Write the observation of a single environment into shared memory.
Args:
space: Observation space of a single environment in the vectorized environment.
index: Index of the environment (must be in `[0, num_envs)`).
value: Observation of the single environment to write to shared memory.
shared_memory: Shared object across processes. This contains the observations from the vectorized environment.
This object is created with `create_shared_memory`.
Raises:
CustomSpaceError: Space is not a valid :class:`gymnasium.Space` instance
"""
if isinstance(space, Space):
raise CustomSpaceError(
f"Space of type `{type(space)}` doesn't have an registered `write_to_shared_memory` function. Register `{type(space)}` for `write_to_shared_memory` to support it."
)
else:
raise TypeError(
f"The space provided to `write_to_shared_memory` is not a gymnasium Space instance, type: {type(space)}, {space}"
)
@write_to_shared_memory.register(Box)
@write_to_shared_memory.register(Discrete)
@write_to_shared_memory.register(MultiDiscrete)
@write_to_shared_memory.register(MultiBinary)
def _write_base_to_shared_memory(
space: Box | Discrete | MultiDiscrete | MultiBinary,
index: int,
value,
shared_memory,
):
size = int(np.prod(space.shape))
destination = np.frombuffer(shared_memory.get_obj(), dtype=space.dtype)
np.copyto(
destination[index * size : (index + 1) * size],
np.asarray(value, dtype=space.dtype).flatten(),
)
@write_to_shared_memory.register(Tuple)
def _write_tuple_to_shared_memory(
space: Tuple, index: int, values: tuple[Any, ...], shared_memory
):
for value, memory, subspace in zip(values, shared_memory, space.spaces):
write_to_shared_memory(subspace, index, value, memory)
@write_to_shared_memory.register(Dict)
def _write_dict_to_shared_memory(
space: Dict, index: int, values: dict[str, Any], shared_memory
):
for key, subspace in space.spaces.items():
write_to_shared_memory(subspace, index, values[key], shared_memory[key])
@write_to_shared_memory.register(Text)
def _write_text_to_shared_memory(space: Text, index: int, values: str, shared_memory):
size = space.max_length
destination = np.frombuffer(shared_memory.get_obj(), dtype=np.int32)
np.copyto(
destination[index * size : (index + 1) * size],
flatten(space, values),
)
