Don't fail seeing a backup refering to non-existent disk #70
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diskutil.py
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| @@ -280,6 +280,9 @@ def getDiskDeviceSize(dev): | |||
| return int(__readOneLineFile__("/sys/block/%s/device/block/size" % dev)) | |||
| elif os.path.exists("/sys/block/%s/size" % dev): | |||
| return int(__readOneLineFile__("/sys/block/%s/size" % dev)) | |||
| else: | |||
| raise Exception("%s not found as %s or %s" % (dev, "/sys/block/%s/device/block/size", | |||
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I think this will end up raising as e.g. sda not found as /sys/block/%s/device/block/size or /sys/block/%s/size, i.e. the %s characters will come out in the exception text, which doesn't seem quite what you'd expect?
If we don't need this for xs8 (i.e. we can rely on py3 functionality), could we use a format string to make it easier, at which point you'd just have e.g. raise Exception(f"{dev} not found as /sys/block/{dev}/device/block/size or /sys/block/{dev}/size")?
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We are trying to keep Python 2/3 compatibility, or at least have master and release/xs8 branches as similar as possible. Maybe a more generic and easier "Unable to get block size of %s device" % dev would be enough, also not requiring to be updated as new potential virtual files are needed to be checked.
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moving the full paths inside the format string should be good for now. At least using str.format and {0} will allow to avoid repeating dev
product.py
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| except StopIteration: | ||
| pass | ||
| except Exception as ex: | ||
| logger.log("findXenSourceBackups caught exception for partition %s: %s" % (p, ex)) |
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We probably want to use logger.logException(ex) here rather than trying to include the exception directly in the log message, as that will then give us a useful traceback etc, so e.g.:
logger.log("findXenSourceBackups caught exception for partition %s:" % (p,))
logger.logException(ex)
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BTW... got the error too this morning. Pretty boring indeed. |
Signed-off-by: Yann Dirson <[email protected]>
- it is bad practice to "catch any" - not logging anything just hides information, which can be especially important here as the reason for a try/catch is not obvious (exceptions thrown by XenServerBackup.__init__?) Signed-off-by: Yann Dirson <[email protected]>
Previous code structure was that of 2 nested if's, with nominal code path being in the positive branch of each if. Adding another condition will bring a need for logging the reason to ignore a backup, but doing that by converting inner `if` to an `elif` chain (arguably the simplest modification) would bring the nominal code path to switch to the negative/last branch of the inner `elif` chain. At the same time, the outer `if` would not seem special enough to deserve it special place (and the cyclomatic complexity). This commit leverages the existing `try:except:` block to switch to an "error out the loop" pattern, where the nominal code path is just linear. Using `StopIteration` may feel like an abuse, but: - it is the only standard `Exception` that is not a `StandardError` or a `Warning`, and defining a new one could seem overkill - the closest alternative would be a `while True` loop and breaking out in both exceptional code paths and at the end of nominal path, where the `break` statements would "stop the iteration" as well Signed-off-by: Yann Dirson <[email protected]>
…rver#66) Signed-off-by: Yann Dirson <[email protected]>
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| backups.append(backup) | ||
| except: | ||
| if not os.path.exists(os.path.join(b.mount_point, '.xen-backup-partition')): | ||
| raise StopIteration() |
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I found this raising StopIteration and catching it weird and hard to read. Why not using a try/finally doing the b.umount() in the finally and using continue here?
This fixes the various problems seen as part of #66, and then some.
This is a continuation of #67 which got closed when
xs8was destroyed and cannot be reopened (thx github).