177 lines
5.4 KiB
Python
177 lines
5.4 KiB
Python
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# Copyright The OpenTelemetry Authors
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from __future__ import annotations
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import logging
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import typing
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from contextvars import Token
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from os import environ
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from uuid import uuid4
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# pylint: disable=wrong-import-position
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from opentelemetry.context.context import Context, _RuntimeContext # noqa
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from opentelemetry.environment_variables import OTEL_PYTHON_CONTEXT
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from opentelemetry.util._importlib_metadata import entry_points
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logger = logging.getLogger(__name__)
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def _load_runtime_context() -> _RuntimeContext:
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"""Initialize the RuntimeContext
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Returns:
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An instance of RuntimeContext.
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"""
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# FIXME use a better implementation of a configuration manager
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# to avoid having to get configuration values straight from
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# environment variables
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default_context = "contextvars_context"
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configured_context = environ.get(OTEL_PYTHON_CONTEXT, default_context) # type: str
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try:
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return next( # type: ignore
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iter( # type: ignore
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entry_points( # type: ignore
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group="opentelemetry_context",
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name=configured_context,
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)
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)
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).load()()
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except Exception: # pylint: disable=broad-exception-caught
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logger.exception(
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"Failed to load context: %s, fallback to %s",
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configured_context,
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default_context,
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)
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return next( # type: ignore
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iter( # type: ignore
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entry_points( # type: ignore
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group="opentelemetry_context",
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name=default_context,
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)
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)
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).load()()
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_RUNTIME_CONTEXT = _load_runtime_context()
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def create_key(keyname: str) -> str:
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"""To allow cross-cutting concern to control access to their local state,
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the RuntimeContext API provides a function which takes a keyname as input,
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and returns a unique key.
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Args:
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keyname: The key name is for debugging purposes and is not required to be unique.
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Returns:
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A unique string representing the newly created key.
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"""
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return keyname + "-" + str(uuid4())
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def get_value(key: str, context: typing.Optional[Context] = None) -> "object":
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"""To access the local state of a concern, the RuntimeContext API
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provides a function which takes a context and a key as input,
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and returns a value.
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Args:
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key: The key of the value to retrieve.
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context: The context from which to retrieve the value, if None, the current context is used.
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Returns:
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The value associated with the key.
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"""
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return context.get(key) if context is not None else get_current().get(key)
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def set_value(
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key: str, value: "object", context: typing.Optional[Context] = None
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) -> Context:
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"""To record the local state of a cross-cutting concern, the
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RuntimeContext API provides a function which takes a context, a
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key, and a value as input, and returns an updated context
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which contains the new value.
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Args:
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key: The key of the entry to set.
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value: The value of the entry to set.
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context: The context to copy, if None, the current context is used.
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Returns:
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A new `Context` containing the value set.
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"""
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if context is None:
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context = get_current()
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new_values = context.copy()
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new_values[key] = value
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return Context(new_values)
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def get_current() -> Context:
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"""To access the context associated with program execution,
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the Context API provides a function which takes no arguments
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and returns a Context.
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Returns:
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The current `Context` object.
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"""
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return _RUNTIME_CONTEXT.get_current()
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def attach(context: Context) -> Token[Context]:
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"""Associates a Context with the caller's current execution unit. Returns
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a token that can be used to restore the previous Context.
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Args:
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context: The Context to set as current.
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Returns:
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A token that can be used with `detach` to reset the context.
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"""
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return _RUNTIME_CONTEXT.attach(context)
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def detach(token: Token[Context]) -> None:
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"""Resets the Context associated with the caller's current execution unit
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to the value it had before attaching a specified Context.
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Args:
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token: The Token that was returned by a previous call to attach a Context.
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"""
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try:
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_RUNTIME_CONTEXT.detach(token)
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except Exception: # pylint: disable=broad-exception-caught
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logger.exception("Failed to detach context")
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# FIXME This is a temporary location for the suppress instrumentation key.
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# Once the decision around how to suppress instrumentation is made in the
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# spec, this key should be moved accordingly.
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_SUPPRESS_INSTRUMENTATION_KEY = create_key("suppress_instrumentation")
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_SUPPRESS_HTTP_INSTRUMENTATION_KEY = create_key(
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"suppress_http_instrumentation"
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)
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__all__ = [
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"Context",
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"attach",
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"create_key",
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"detach",
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"get_current",
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"get_value",
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"set_value",
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]
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