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|
import importlib
import logging
import os
from eth_hash.abc import (
BackendAPI,
)
from eth_hash.backends import (
SUPPORTED_BACKENDS,
)
def auto_choose_backend() -> BackendAPI:
env_backend = get_backend_in_environment()
if env_backend:
return load_environment_backend(env_backend)
else:
return choose_available_backend()
def get_backend_in_environment() -> str:
return os.environ.get("ETH_HASH_BACKEND", "")
def load_backend(backend_name: str) -> BackendAPI:
import_path = f"eth_hash.backends.{backend_name}"
module = importlib.import_module(import_path)
try:
backend = module.backend
except AttributeError as e:
raise ValueError(
f"Import of {import_path} failed, because {module} does not have "
"'backend' attribute"
) from e
if isinstance(backend, BackendAPI):
return backend
else:
raise ValueError(
f"Import of {import_path} failed, because {backend} is an invalid back end"
)
def load_environment_backend(env_backend: str) -> BackendAPI:
if env_backend in SUPPORTED_BACKENDS:
try:
return load_backend(env_backend)
except ImportError as e:
raise ImportError(
f"The backend specified in ETH_HASH_BACKEND, '{env_backend}', is not "
f"installed. Install with `python -m pip install "
f'"eth-hash[{env_backend}]"`.'
) from e
else:
raise ValueError(
f"The backend specified in ETH_HASH_BACKEND, '{env_backend}', is not "
f"supported. Choose one of: {SUPPORTED_BACKENDS}"
)
def choose_available_backend() -> BackendAPI:
for backend in SUPPORTED_BACKENDS:
try:
return load_backend(backend)
except ImportError:
logging.getLogger("eth_hash").debug(
f"Failed to import {backend}", exc_info=True
)
raise ImportError(
f"None of these hashing backends are installed: {SUPPORTED_BACKENDS}.\n"
f'Install with `python -m pip install "eth-hash[{SUPPORTED_BACKENDS[0]}]"`.'
)
|
