ray/rllib/env/env_context.py

import copy
from typing import Optional

from ray.rllib.utils.annotations import PublicAPI
from ray.rllib.utils.typing import EnvConfigDict


@PublicAPI
class EnvContext(dict):
    """Wraps env configurations to include extra rllib metadata.

    These attributes can be used to parameterize environments per process.
    For example, one might use `worker_index` to control which data file an
    environment reads in on initialization.

    RLlib auto-sets these attributes when constructing registered envs.
    """

    def __init__(self,
                 env_config: EnvConfigDict,
                 worker_index: int,
                 vector_index: int = 0,
                 remote: bool = False,
                 num_workers: Optional[int] = None):
        """Initializes an EnvContext instance.

        Args:
            env_config: The env's configuration defined under the
                "env_config" key in the Trainer's config.
            worker_index: When there are multiple workers created, this
                uniquely identifies the worker the env is created in.
                0 for local worker, >0 for remote workers.
            num_workers: The total number of (remote) workers in the set.
                0 if only a local worker exists.
            vector_index: When there are multiple envs per worker, this
                uniquely identifies the env index within the worker.
                Starts from 0.
            remote: Whether individual sub-environments (in a vectorized
                env) should be @ray.remote actors or not.
        """
        # Store the env_config in the (super) dict.
        dict.__init__(self, env_config)

        # Set some metadata attributes.
        self.worker_index = worker_index
        self.vector_index = vector_index
        self.remote = remote
        self.num_workers = num_workers

    def copy_with_overrides(self,
                            env_config: Optional[EnvConfigDict] = None,
                            worker_index: Optional[int] = None,
                            vector_index: Optional[int] = None,
                            remote: Optional[bool] = None,
                            num_workers: Optional[int] = None) -> "EnvContext":
        """Returns a copy of this EnvContext with some attributes overridden.

        Args:
            env_config: Optional env config to use. None for not overriding
                the one from the source (self).
            worker_index: Optional worker index to use. None for not
                overriding the one from the source (self).
            vector_index: Optional vector index to use. None for not
                overriding the one from the source (self).
            remote: Optional remote setting to use. None for not overriding
                the one from the source (self).
            num_workers: Optional num_workers to use. None for not overriding
                the one from the source (self).

        Returns:
            A new EnvContext object as a copy of self plus the provided
            overrides.
        """
        return EnvContext(
            copy.deepcopy(env_config) if env_config is not None else self,
            worker_index if worker_index is not None else self.worker_index,
            vector_index if vector_index is not None else self.vector_index,
            remote if remote is not None else self.remote,
            num_workers if num_workers is not None else self.num_workers,
        )