From: Christian Heller Date: Sun, 22 Feb 2015 10:50:03 +0000 (+0100) Subject: Server/py: Improve atomicity of record(), description of its strategy. X-Git-Tag: tce~503 X-Git-Url: https://plomlompom.com/repos/%7B%7Bprefix%7D%7D/balance?a=commitdiff_plain;h=1b641d2c660fa003e73db970cbbbc935345a495d;p=plomrogue Server/py: Improve atomicity of record(), description of its strategy. --- diff --git a/plomrogue-server.py b/plomrogue-server.py index 47390a4..c9cc20e 100755 --- a/plomrogue-server.py +++ b/plomrogue-server.py @@ -78,8 +78,10 @@ def obey(cmd, io_db, prefix): def record(cmd, io_db): - """Append cmd string plus newline to file at path_recordfile.""" - # Doesn't yet replace old record() fully. + """Append cmd string plus newline to file at path_recordfile. (Atomic.)""" + # This misses some optimizations from the original record(), namely only + # finishing the atomic write with flush() and fsync() every 15 seconds + # unless explicitely forced. Implement as needed. path_tmp = io_db["path_record"] + io_db["tmp_suffix"] if os.access(io_db["path_record"], os.F_OK): shutil.copyfile(io_db["path_record"], path_tmp) @@ -88,6 +90,8 @@ def record(cmd, io_db): file.flush() os.fsync(file.fileno()) file.close() + if os.access(io_db["path_record"], os.F_OK): + os.remove(io_db["path_record"]) os.rename(path_tmp, io_db["path_record"])