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perf: defer snapshot writes until end of session #606

Merged
merged 1 commit into from
Jun 2, 2022
Merged

perf: defer snapshot writes until end of session #606

merged 1 commit into from
Jun 2, 2022

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noahnu
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@noahnu noahnu commented May 28, 2022

Description

Defers snapshot writes until the end of the session. Previously we wrote the snapshots while evaluating the assertion in each individual test case.

Related Issues

Comment on lines 74 to 85
def write_file(cls, snapshot_fossil: "SnapshotFossil", merge: bool = False) -> None:
"""
Writes the snapshot data into the snapshot file that be read later.
Writes the snapshot data into the snapshot file that can be read later.
"""
filepath = snapshot_fossil.location
if merge:
base_snapshot = cls._read_file(filepath)
base_snapshot.merge(snapshot_fossil)
snapshot_fossil = base_snapshot

with open(filepath, "w", encoding=TEXT_ENCODING, newline=None) as f:
for snapshot in sorted(snapshot_fossil, key=lambda s: s.name):
snapshot_data = str(snapshot.data)
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Maybe we grab a lock for the file by filepath here.

@@ -86,13 +91,7 @@ def write_file(cls, snapshot_fossil: "SnapshotFossil") -> None:
f.write(f"\n{cls._marker_divider}\n")

@classmethod
@functools.lru_cache()
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We need to ensure the data we read is fresh during the batch reads.

@@ -79,6 +104,7 @@ def finish(self) -> int:
assertions=self._assertions,
options=self.pytest_session.config.option,
)
self.flush_snapshot_write_queue()
if self.report.num_unused:
if self.update_snapshots:
self.remove_unused_snapshots(
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Unused snapshot removal will also need to be updated.

@noahnu noahnu linked an issue May 28, 2022 that may be closed by this pull request
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codecov bot commented May 29, 2022

Codecov Report

Merging #606 (d8a4ff7) into next (83f7968) will decrease coverage by 0.06%.
The diff coverage is 97.95%.

@@            Coverage Diff             @@
##             next     #606      +/-   ##
==========================================
- Coverage   99.69%   99.62%   -0.07%     
==========================================
  Files          20       20              
  Lines        1292     1318      +26     
==========================================
+ Hits         1288     1313      +25     
- Misses          4        5       +1     

@noahnu noahnu changed the title wip: defer snapshot writing perf: defer snapshot writes until end of session Jun 2, 2022
@noahnu noahnu marked this pull request as ready for review June 2, 2022 17:33
@noahnu noahnu merged commit 9b3a19d into next Jun 2, 2022
@noahnu noahnu deleted the xdist branch June 2, 2022 17:34
tophat-opensource-bot pushed a commit that referenced this pull request Feb 2, 2023
# [4.0.0](v3.0.6...v4.0.0) (2023-02-02)

### Bug Fixes

* defer snapshot writes until end of session ([#606](#606)) ([68f1d5f](68f1d5f))
* ensure all pytest options are serializable ([#667](#667)) ([e8ed9f2](e8ed9f2))
* improve pytest-xdist compatibility ([9b9090f](9b9090f))
* lru_cache on snapshot reads ([#629](#629)) ([c1a675f](c1a675f))
* remove legacy path usage to support no:legacypath, closes [#677](#677) ([#684](#684)) ([6385979](6385979))

### Code Refactoring

* simplify data serializer for ambr ([#676](#676)) ([3d296e1](3d296e1))
* write performance improvements, api clarity ([#645](#645)) ([2c31c39](2c31c39))

### Features

* **json:** serialize None as null, close [#622](#622) ([c330680](c330680))
* numerically sort snapshots if possible, close [#657](#657) ([4ca0716](4ca0716))
* **serializer:** preserve key ordering of OrderedDict ([0a2289a](0a2289a))
* support overriding the amber serializer class ([#683](#683)) ([662c93f](662c93f))
* update python version, pytest version ([#658](#658)) ([c360b95](c360b95))

### BREAKING CHANGES

* Serializers may now throw a TaintedSnapshotError which will tell the user to regenerate the snapshot even if the underlying data has not changed. This is to support rolling out more subtle changes to the serializers, such as the introduction of serializer metadata.
* Renamed DataSerializer to AmberDataSerializer.
* **serializer:** Key order is now preserved if using OrderedDict in both the Amber serializer and JSON serializer.
* **json:** The JSONSnapshotExtension now serializes Python's None as "null" rather than "None".
* Raise minimum python version to 3.8.1 and min. pytest version to v7.
* PyTestLocation.filename has been renamed to .basename

* refactor: add test_location kwarg to get_snapshot_name

* refactor: get_snapshot_name is now static as a classmethod

* refactor: remove pre and post read/write hooks
* Pre and post read/write hooks have been removed without replacement to make internal refactor simpler. Please open a GitHub issue if you have a use case for these hooks.

* refactor: rename Fossil to Collection
* The term 'fossil' has been replaced by the clearer term 'collection'.

* refactor: pass test_location to read_snapshot

* refactor: remove singular write_snapshot method

* refactor: dirname property to method

* refactor: pass test_location to discover_snapshots

* refactor: remove usage of self.test_location

* refactor: make write_snapshot a classmethod

* refactor: do not instantiate extension with test_location
* Numerous instance methods have been refactored as classmethods.
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