Enhance WrapperHandler
- docstrings - add try_call_all method - update tests
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@@ -6,7 +6,24 @@ W = TypeVar("W")
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T = TypeVar("T")
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class WrapperHandler(Generic[W]):
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"""
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A handler for managing multiple wrappers with retry logic.
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It attempts to call a function on the current wrapper, and if it fails,
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it retries a specified number of times before switching to the next wrapper.
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If all wrappers fail, it raises an exception.
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Note: use `build_wrappers` to create an instance of this class for better error handling.
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"""
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def __init__(self, wrappers: list[W], try_per_wrapper: int = 3, retry_delay: int = 2):
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"""
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Initializes the WrapperHandler with a list of wrappers and retry settings.\n
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Use `build_wrappers` to create an instance of this class for better error handling.
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Args:
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wrappers (list[W]): A list of wrapper instances to manage.
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try_per_wrapper (int): Number of retries per wrapper before switching to the next.
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retry_delay (int): Delay in seconds between retries.
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"""
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self.wrappers = wrappers
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self.retry_per_wrapper = try_per_wrapper
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self.retry_delay = retry_delay
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@@ -14,9 +31,19 @@ class WrapperHandler(Generic[W]):
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self.retry_count = 0
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def try_call(self, func: Callable[[W], T]) -> T:
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"""
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Attempts to call the provided function on the current wrapper.
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If it fails, it retries a specified number of times before switching to the next wrapper.
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If all wrappers fail, it raises an exception.
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Args:
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func (Callable[[W], T]): A function that takes a wrapper and returns a result.
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Returns:
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T: The result of the function call.
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Raises:
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Exception: If all wrappers fail after retries.
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"""
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iterations = 0
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while iterations < len(self.wrappers):
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print(f"Trying wrapper {self.index}")
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try:
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wrapper = self.wrappers[self.index]
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result = func(wrapper)
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@@ -24,7 +51,6 @@ class WrapperHandler(Generic[W]):
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return result
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except Exception as e:
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self.retry_count += 1
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print(f"Error occurred {self.retry_count}/{self.retry_per_wrapper}: {e}")
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if self.retry_count >= self.retry_per_wrapper:
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self.index = (self.index + 1) % len(self.wrappers)
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self.retry_count = 0
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@@ -35,8 +61,44 @@ class WrapperHandler(Generic[W]):
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raise Exception(f"All wrappers failed after retries")
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def try_call_all(self, func: Callable[[W], T]) -> list[T]:
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"""
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Calls the provided function on all wrappers, collecting results.
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If a wrapper fails, it logs a warning and continues with the next.
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If all wrappers fail, it raises an exception.
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Args:
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func (Callable[[W], T]): A function that takes a wrapper and returns a result.
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Returns:
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list[T]: A list of results from the function calls.
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Raises:
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Exception: If all wrappers fail.
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"""
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results = []
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for wrapper in self.wrappers:
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try:
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result = func(wrapper)
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results.append(result)
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except Exception as e:
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log_warning(f"{wrapper} failed: {e}")
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if not results:
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raise Exception("All wrappers failed")
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return results
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@staticmethod
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def build_wrappers(constructors: Iterable[Type[W]], try_per_wrapper: int = 3, retry_delay: int = 2) -> 'WrapperHandler[W]':
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"""
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Builds a WrapperHandler instance with the given wrapper constructors.
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It attempts to initialize each wrapper and logs a warning if any cannot be initialized.
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Only successfully initialized wrappers are included in the handler.
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Args:
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constructors (Iterable[Type[W]]): An iterable of wrapper classes to instantiate. e.g. [WrapperA, WrapperB]
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try_per_wrapper (int): Number of retries per wrapper before switching to the next.
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retry_delay (int): Delay in seconds between retries.
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Returns:
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WrapperHandler[W]: An instance of WrapperHandler with the initialized wrappers.
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Raises:
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Exception: If no wrappers could be initialized.
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"""
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result = []
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for wrapper_class in constructors:
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try:
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@@ -58,3 +58,22 @@ class TestWrapperHandler:
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assert result == "Success"
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assert handler.index == 1 # Should return to the second wrapper after failure
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assert handler.retry_count == 0
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def test_try_call_all(self):
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wrappers = [FailingWrapper, MockWrapper, FailingWrapper]
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handler: WrapperHandler[MockWrapper] = WrapperHandler.build_wrappers(wrappers, try_per_wrapper=1, retry_delay=0)
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results = handler.try_call_all(lambda w: w.do_something())
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assert results == ["Success"] # Only the second wrapper should succeed
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wrappers = [FailingWrapper, MockWrapper, FailingWrapper, MockWrapper]
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handler: WrapperHandler[MockWrapper] = WrapperHandler.build_wrappers(wrappers, try_per_wrapper=1, retry_delay=0)
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results = handler.try_call_all(lambda w: w.do_something())
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assert results == ["Success", "Success"] # Only the second and fourth wrappers should succeed
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# Test when all wrappers fail
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handler_all_fail: WrapperHandler[MockWrapper] = WrapperHandler.build_wrappers([FailingWrapper, FailingWrapper], try_per_wrapper=1, retry_delay=0)
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with pytest.raises(Exception) as exc_info:
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handler_all_fail.try_call_all(lambda w: w.do_something())
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assert "All wrappers failed" in str(exc_info.value)
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