fix EOFError when execute targetcli commands concurrently #61
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fix issue #60 |
zoumingzhe
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1.fcntl.LOCK_UN means unlock, but save file must own the exclusive lock. So, we must use fcntl.LOCK_EX(acquire an exclusive lock) flag in here. 2.Then, fcntl.lockf is different from fcntl.flock: a)fcntl.flock always lock for the whole file b)fcntl.lockf can only lock part of the file c)see https://docs.python.org/2.7/library/fcntl.html for details I think is better to call fcntl.flock in here. 3.open file via 'wb' will truncate the file without lock protection, if load prefs.bin at the same time, maybe read empty prefs.bin and raise EOFError. 4.However the patch only avoid EOFError, prefs may be replaced with the default value if read file and truncate file at the same time. A new patch need to commit, and lock before open prefs.bin to solve the prefs consistency problem. Signed-off-by: Zou Mingzhe <[email protected]>
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…e at the same time Open prefs.bin via 'wb' will truncate file without lock protection. So read prefs.bin and truncate prefs.bin at the same time, the preferences maybe replaced with the default value. Add a prefs.lock file to guarantee the atomicity of save and load operation. The patch can not solve old value read when targetcli command concurrency. That is, if change preference at same time as execute another targetcli command, next ConfigShell will load old prefs.bin file before previous ConfigShell save it. To fix this problem, targetcli-fb:scripts\targetcli must be modified. Signed-off-by: Zou Mingzhe <[email protected]>
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fcntl.LOCK_UN means unlock, but save file must have the exclusive lock. So, we must use fcntl.LOCK_EX in here.