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Streamline & simplify __eq__ methods in models Dag and BaseOperator #13449

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Jan 4, 2021
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Streamline & simplify __eq__ methods in models Dag and BaseOperator #13449

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6 changes: 4 additions & 2 deletions airflow/models/baseoperator.py
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Original file line number Diff line number Diff line change
Expand Up @@ -520,8 +520,10 @@ def __init__(
)

def __eq__(self, other):
if type(self) is type(other) and self.task_id == other.task_id:
return all(self.__dict__.get(c, None) == other.__dict__.get(c, None) for c in self._comps)
if type(self) is type(other):
# Use getattr() instead of __dict__ as __dict__ doesn't return
# correct values for properties.
return all(getattr(self, c, None) == getattr(other, c, None) for c in self._comps)
return False

def __ne__(self, other):
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3 changes: 1 addition & 2 deletions airflow/models/dag.py
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Expand Up @@ -361,8 +361,7 @@ def __repr__(self):
return f"<DAG: {self.dag_id}>"

def __eq__(self, other):
if type(self) == type(other) and self.dag_id == other.dag_id:

if type(self) == type(other):
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From what I can remember, it's optimization so we can check the most common case much faster.

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@mik-laj mik-laj Jan 3, 2021 •
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See: 36e76fa and https://github.com/apache/airflow/pull/4322/files#r241802863

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That optimisation may not make sense given two reasons below:

  • all() function has the "exit fast" property, i.e., whenever there is any False element, it will return False immediately, rather than traversing all elements in the iterable. reference
  • For dag model, dag_id is the 1st element in _comps; For BaseOperator, task_id is the 1st element in _comps.

So after the change I make here, there should be zero impact on the performance (actually it improves the performance very minorly: it helps avoid comparing dag_id in dag model's __eq__for two times. Similar for BaseOperator).

Kindly let me know if it makes sense to you?

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SGTM.

# Use getattr() instead of __dict__ as __dict__ doesn't return
# correct values for properties.
return all(getattr(self, c, None) == getattr(other, c, None) for c in self._comps)
Expand Down