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allow textfile to be overwritten on windows #650

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Merged
csmarchbanks merged 4 commits into from
May 11, 2021
Merged

allow textfile to be overwritten on windows #650

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0be4d06
allow textfile to be overwritten on windows
bluppfisk May 10, 2021
3688edd
lint
bluppfisk May 10, 2021
1089530
make NT the exception
bluppfisk May 10, 2021
20a31b4
forego deletion if file isn't found
bluppfisk May 11, 2021
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20 changes: 18 additions & 2 deletions prometheus_client/exposition.py
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Original file line number Diff line number Diff line change
Expand Up @@ -271,8 +271,24 @@ def write_to_textfile(path, registry):
tmppath = '%s.%s.%s' % (path, os.getpid(), threading.current_thread().ident)
with open(tmppath, 'wb') as f:
f.write(generate_latest(registry))
# rename(2) is atomic.
os.rename(tmppath, path)

# rename(2) is atomic but fails on Windows if the destination file exists
if os.name == 'nt':
if sys.version_info <= (3, 3):
# Unable to guarantee atomic rename on Windows and Python<3.3
# Remove and rename instead (risks losing the file)
try:
os.remove(path)
except FileNotFoundError:
pass

os.rename(tmppath, path)
else:
# os.replace is introduced in Python 3.3 but there is some dispute whether
# it is a truly atomic file operation: https://bugs.python.org/issue8828
os.replace(tmppath, path)
else:
os.rename(tmppath, path)


def _make_handler(url, method, timeout, headers, data, base_handler):
Expand Down