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reyangreyang
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Initial implementation of context (open-telemetry#57)
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‎mypy-relaxed.ini

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@@ -4,7 +4,7 @@
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disallow_any_unimported = True
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; disallow_any_expr = True
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disallow_any_decorated = True
7-
disallow_any_explicit = True
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; disallow_any_explicit = True
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disallow_any_generics = True
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disallow_subclassing_any = True
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disallow_untyped_calls = True

‎mypy.ini

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@@ -2,7 +2,7 @@
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disallow_any_unimported = True
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disallow_any_expr = True
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disallow_any_decorated = True
5-
disallow_any_explicit = True
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; disallow_any_explicit = True
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disallow_any_generics = True
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disallow_subclassing_any = True
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disallow_untyped_calls = True

‎opentelemetry-api/src/opentelemetry/context/__init__.py

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@@ -11,3 +11,144 @@
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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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"""
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The OpenTelemetry context module provides abstraction layer on top of
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thread-local storage and contextvars. The long term direction is to switch to
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contextvars provided by the Python runtime library.
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A global object ``Context`` is provided to access all the context related
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functionalities:
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>>> from opentelemetry.context import Context
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>>> Context.foo = 1
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>>> Context.foo = 2
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>>> Context.foo
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2
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When explicit thread is used, a helper function `Context.with_current_context`
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can be used to carry the context across threads:
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from threading import Thread
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from opentelemetry.context import Context
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def work(name):
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print('Entering worker:', Context)
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Context.operation_id = name
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print('Exiting worker:', Context)
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if __name__ == '__main__':
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print('Main thread:', Context)
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Context.operation_id = 'main'
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print('Main thread:', Context)
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# by default context is not propagated to worker thread
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thread = Thread(target=work, args=('foo',))
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thread.start()
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thread.join()
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print('Main thread:', Context)
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# user can propagate context explicitly
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thread = Thread(
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target=Context.with_current_context(work),
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args=('bar',),
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)
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thread.start()
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thread.join()
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print('Main thread:', Context)
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Here goes another example using thread pool:
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import time
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import threading
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from multiprocessing.dummy import Pool as ThreadPool
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from opentelemetry.context import Context
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_console_lock = threading.Lock()
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def println(msg):
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with _console_lock:
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print(msg)
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def work(name):
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println('Entering worker[{}]: {}'.format(name, Context))
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Context.operation_id = name
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time.sleep(0.01)
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println('Exiting worker[{}]: {}'.format(name, Context))
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if __name__ == "__main__":
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println('Main thread: {}'.format(Context))
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Context.operation_id = 'main'
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pool = ThreadPool(2) # create a thread pool with 2 threads
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pool.map(Context.with_current_context(work), [
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'bear',
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'cat',
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'dog',
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'horse',
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'rabbit',
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])
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pool.close()
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pool.join()
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println('Main thread: {}'.format(Context))
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Here goes a simple demo of how async could work in Python 3.7+:
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import asyncio
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from opentelemetry.context import Context
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class Span(object):
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def __init__(self, name):
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self.name = name
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self.parent = Context.current_span
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def __repr__(self):
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return ('{}(name={}, parent={})'
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.format(
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type(self).__name__,
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self.name,
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self.parent,
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))
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async def __aenter__(self):
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Context.current_span = self
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async def __aexit__(self, exc_type, exc, tb):
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Context.current_span = self.parent
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async def main():
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print(Context)
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async with Span('foo'):
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print(Context)
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await asyncio.sleep(0.1)
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async with Span('bar'):
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print(Context)
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await asyncio.sleep(0.1)
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print(Context)
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await asyncio.sleep(0.1)
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print(Context)
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if __name__ == '__main__':
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asyncio.run(main())
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"""
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import typing
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from .base_context import BaseRuntimeContext
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__all__ = ['Context']
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Context: typing.Optional[BaseRuntimeContext]
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try:
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from .async_context import AsyncRuntimeContext
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Context = AsyncRuntimeContext() # pylint:disable=invalid-name
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except ImportError:
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from .thread_local_context import ThreadLocalRuntimeContext
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Context = ThreadLocalRuntimeContext() # pylint:disable=invalid-name

‎opentelemetry-api/src/opentelemetry/context/async_context.py

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# Copyright 2019, 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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#
9+
# Unless required by applicable law or agreed to in writing, software
10+
# 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 contextvars import ContextVar
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import typing
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from . import base_context
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class AsyncRuntimeContext(base_context.BaseRuntimeContext):
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class Slot(base_context.BaseRuntimeContext.Slot):
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def __init__(self, name: str, default: 'object'):
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# pylint: disable=super-init-not-called
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self.name = name
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self.contextvar: 'ContextVar[object]' = ContextVar(name)
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self.default: typing.Callable[..., object]
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self.default = base_context.wrap_callable(default)
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def clear(self) -> None:
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self.contextvar.set(self.default())
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def get(self) -> 'object':
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try:
35+
return self.contextvar.get()
36+
except LookupError:
37+
value = self.default()
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self.set(value)
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return value
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def set(self, value: 'object') -> None:
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self.contextvar.set(value)

‎opentelemetry-api/src/opentelemetry/context/base_context.py

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# Copyright 2019, OpenTelemetry Authors
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
4+
# 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
10+
# distributed under the License is distributed on an "AS IS" BASIS,
11+
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12+
# See the License for the specific language governing permissions and
13+
# limitations under the License.
14+
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import threading
16+
import typing
17+
18+
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def wrap_callable(target: 'object') -> typing.Callable[[], object]:
20+
if callable(target):
21+
return target
22+
return lambda: target
23+
24+
25+
class BaseRuntimeContext:
26+
class Slot:
27+
def __init__(self, name: str, default: 'object'):
28+
raise NotImplementedError
29+
30+
def clear(self) -> None:
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raise NotImplementedError
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33+
def get(self) -> 'object':
34+
raise NotImplementedError
35+
36+
def set(self, value: 'object') -> None:
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raise NotImplementedError
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_lock = threading.Lock()
40+
_slots: typing.Dict[str, Slot] = {}
41+
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@classmethod
43+
def clear(cls) -> None:
44+
"""Clear all slots to their default value."""
45+
keys = cls._slots.keys()
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for name in keys:
47+
slot = cls._slots[name]
48+
slot.clear()
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50+
@classmethod
51+
def register_slot(cls, name: str, default: 'object' = None) -> 'Slot':
52+
"""Register a context slot with an optional default value.
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:type name: str
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:param name: The name of the context slot.
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:type default: object
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:param name: The default value of the slot, can be a value or lambda.
59+
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:returns: The registered slot.
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"""
62+
with cls._lock:
63+
if name in cls._slots:
64+
raise ValueError('slot {} already registered'.format(name))
65+
slot = cls.Slot(name, default)
66+
cls._slots[name] = slot
67+
return slot
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def apply(self, snapshot: typing.Dict[str, 'object']) -> None:
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"""Set the current context from a given snapshot dictionary"""
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for name in snapshot:
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setattr(self, name, snapshot[name])
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def snapshot(self) -> typing.Dict[str, 'object']:
76+
"""Return a dictionary of current slots by reference."""
77+
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keys = self._slots.keys()
79+
return dict((n, self._slots[n].get()) for n in keys)
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def __repr__(self) -> str:
82+
return '{}({})'.format(type(self).__name__, self.snapshot())
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def __getattr__(self, name: str) -> 'object':
85+
if name not in self._slots:
86+
self.register_slot(name, None)
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slot = self._slots[name]
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return slot.get()
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def __setattr__(self, name: str, value: 'object') -> None:
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if name not in self._slots:
92+
self.register_slot(name, None)
93+
slot = self._slots[name]
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slot.set(value)
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def with_current_context(
97+
self,
98+
func: typing.Callable[..., 'object'],
99+
) -> typing.Callable[..., 'object']:
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"""Capture the current context and apply it to the provided func.
101+
"""
102+
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caller_context = self.snapshot()
104+
105+
def call_with_current_context(
106+
*args: 'object',
107+
**kwargs: 'object',
108+
) -> 'object':
109+
try:
110+
backup_context = self.snapshot()
111+
self.apply(caller_context)
112+
return func(*args, **kwargs)
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finally:
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self.apply(backup_context)
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return call_with_current_context

‎opentelemetry-api/src/opentelemetry/context/thread_local_context.py

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1+
# Copyright 2019, OpenTelemetry Authors
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#
3+
# Licensed under the Apache License, Version 2.0 (the "License");
4+
# you may not use this file except in compliance with the License.
5+
# You may obtain a copy of the License at
6+
#
7+
# http://www.apache.org/licenses/LICENSE-2.0
8+
#
9+
# Unless required by applicable law or agreed to in writing, software
10+
# distributed under the License is distributed on an "AS IS" BASIS,
11+
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12+
# See the License for the specific language governing permissions and
13+
# limitations under the License.
14+
15+
import threading
16+
import typing
17+
18+
from . import base_context
19+
20+
21+
class ThreadLocalRuntimeContext(base_context.BaseRuntimeContext):
22+
class Slot(base_context.BaseRuntimeContext.Slot):
23+
_thread_local = threading.local()
24+
25+
def __init__(self, name: str, default: 'object'):
26+
# pylint: disable=super-init-not-called
27+
self.name = name
28+
self.default: typing.Callable[..., object]
29+
self.default = base_context.wrap_callable(default)
30+
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def clear(self) -> None:
32+
setattr(self._thread_local, self.name, self.default())
33+
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def get(self) -> 'object':
35+
try:
36+
got: object = getattr(self._thread_local, self.name)
37+
return got
38+
except AttributeError:
39+
value = self.default()
40+
self.set(value)
41+
return value
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def set(self, value: 'object') -> None:
44+
setattr(self._thread_local, self.name, value)

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