Faster GitIgnore directory check

[fellhorn]

Why are the changes needed?

flytekit's GitIgnore performs a recursive file check to detect empty / ignored folders instead of checking the folder status directly. For folders with a lot of files (e.g. a python .venv), this can be unnecessarily slow.

An extreme example with 1M files in an ignored folder:

Old ignore folder: 5.39s
New ignore folder: 0.000158s

Code

The measurements were created using this script

import subprocess
import shutil
from pathlib import Path
import os
import logging

from flytekit.tools.ignore import (
    GitIgnore as GitIgnoreOld,
    Ignore,
)

class GitIgnoreNew(Ignore):
  # The implementation ftom this PR
  ...

import time

start = time.perf_counter()
newIgnore = GitIgnoreNew(Path.cwd())
print(f"New ignore setup: {time.perf_counter() - start}")

start = time.perf_counter()
oldIgnore = GitIgnoreOld(Path.cwd())
print(f"Old ignore setup: {time.perf_counter() - start}")

start = time.perf_counter()
assert newIgnore.is_ignored("large-file-collection")
print(f"New ignore folder: {time.perf_counter() - start}")

start = time.perf_counter()
assert newIgnore.is_ignored("large-file-collection/1.txt")
print(f"New ignore file: {time.perf_counter() - start}")

start = time.perf_counter()
assert oldIgnore.is_ignored("large-file-collection")
print(f"Old ignore folder: {time.perf_counter() - start}")


start = time.perf_counter()
assert oldIgnore.is_ignored("large-file-collection/1.txt")
print(f"Old ignore file: {time.perf_counter() - start}")

What changes were proposed in this pull request?

1. Use git ls-files to also check against the list of ignored directories

How was this patch tested?

Existing unit tests seem to already cover the changed code, performance benchmarks done manually as explained above.

Check all the applicable boxes

• I updated the documentation accordingly.
• All new and existing tests passed.
• All commits are signed-off.

[codecov]

Codecov Report

Attention: Patch coverage is 64.70588% with 6 lines in your changes missing coverage. Please review.

Project coverage is 50.91%. Comparing base (f99d50e) to head (4fa0c40).
Report is 5 commits behind head on master.

Files with missing lines	Patch %	Lines
flytekit/tools/ignore.py	64.70%	4 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3007      +/-   ##
==========================================
- Coverage   51.08%   50.91%   -0.18%     
==========================================
  Files         201      201              
  Lines       21231    21173      -58     
  Branches     2731     2728       -3     
==========================================
- Hits        10846    10780      -66     
- Misses       9787     9797      +10     
+ Partials      598      596       -2     

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