The resource resolver in DevTools can cause performance degradation
during application restarts in large projects. Key methods like
isDeleted() and getAdditionalResources() rely on nested loops, leading
to O(n*m) complexity.
This commit refactors ClassLoaderFiles to use a pre-computed, flattened
map. This provides O(1) complexity for direct lookups and allows for
efficient single-loop iteration.
The ClassLoaderFilesResourcePatternResolver is updated to leverage this
new, efficient structure:
- getFile() and size() are improved from O(n) to O(1).
- isDeleted() and getAdditionalResources() are improved from O(n*m) to
O(m) by eliminating nested loops.
- Data consistency is maintained across all operations.
This optimization significantly improves restart performance with a
minimal memory footprint, while preserving the existing API and
exception handling behavior.
See gh-46289
Signed-off-by: DongHoon Lee <dhl1924@naver.com>
Moritz Halbritter
DongHoon Lee
Andy Wilkinson
Stéphane Nicoll
Phillip Webb