[utils] Make JSON file writes atomic (Fixes #3549)

pull/8/head
Philipp Hagemeister 10 years ago
parent 3b95347bb6
commit 181c8655c7

@ -24,6 +24,7 @@ import socket
import struct
import subprocess
import sys
import tempfile
import traceback
import xml.etree.ElementTree
import zlib
@ -228,16 +229,34 @@ else:
assert type(s) == type(u'')
print(s)
def write_json_file(obj, fn):
""" Encode obj as JSON and write it to fn, atomically """
# In Python 2.x, json.dump expects a bytestream.
# In Python 3.x, it writes to a character stream
if sys.version_info < (3, 0):
def write_json_file(obj, fn):
with open(fn, 'wb') as f:
json.dump(obj, f)
mode = 'wb'
encoding = None
else:
def write_json_file(obj, fn):
with open(fn, 'w', encoding='utf-8') as f:
json.dump(obj, f)
mode = 'w'
encoding = 'utf-8'
tf = tempfile.NamedTemporaryFile(
suffix='.tmp', prefix=os.path.basename(fn) + '.',
dir=os.path.dirname(fn),
delete=False)
try:
with tf:
json.dump(obj, tf)
os.rename(tf.name, fn)
except:
try:
os.remove(tf.name)
except OSError:
pass
raise
if sys.version_info >= (2, 7):
def find_xpath_attr(node, xpath, key, val):

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