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https://issues.apache.org/jira/browse/CONFIGURATION-532?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Mike Lucas updated CONFIGURATION-532:
-------------------------------------
Description:
Currently the {{FileChangedReloadingStrategy}} only reloads when the timestamp
of the file on the filesystem is _newer_ than the timestamp it had when it was
last loaded.
This may not be the expected behaviour when, for example, an administrator
makes a backup copy of the original configuration file before making changes.
If the administrator wants to roll back to the original configuration, he may
expect that copying/renaming the backup back to the original name, would cause
the original configuration to take effect again.
Another example where the current behaviour is problematic is when using a
Deploy System (like we do at my company). We expect to be able to roll-back to
a previous configuration by simply redeploying the Config artifact, but because
the timestamps reflect when the Config artifact was _built_ (not when it was
deployed), this roll-back will not work.
The current behaviour could be kept as the default, simply adding
{{setReloadOnRollback()}} or similarly named method to change the behaviour to
reload when the timestamp is either older or newer (i.e. not equal to) the
{{lastModified}} variable. Another option would to be to create subclass
{{FileChangedOrRolledBackReloadingStrategy}} that overrides the
{{hasChanged()}} method.
In either option the actual change is to use {{!=}} instead of {{>}} in the
{{hasChanged}} method's comparison:
{code}
return file.lastModified() > lastModified;
{code}
was:
Currently the {{FileChangedReloadingStrategy}} only reloads when the timestamp
of the file on the filesystem is _newer_ than the timestamp it had when it was
last loaded.
This may not be the expected behaviour when, for example, an administrator
makes a backup copy of the original configuration file before making changes.
If the administrator wants to roll back to the original configuration, he may
expect that copying/renaming the backup back to the original name, would cause
the original configuration to take effect again.
Another example where the current behaviour is problematic is when using a
Deploy System (like we do at my company). We expect to be able to roll-back to
a previous configuration by simply redeploying the Config artifact, but because
the timestamps reflect when the Config artifact was _built_ (not when it was
deployed), this roll-back will not work.
The current behaviour could be kept as the default, simply adding
{{setReloadOnRollback()}} or similarly named method to change the behaviour to
reload when the timestamp is either older or newer (i.e. not equal to) the
{{lastModified}} variable. Another option would to be to create subclass
{{FileChangedOrRolledBackReloadingStrategy}} that overrides the
{{hasChanged()}} method.
In either the actual change is to use {{!=}} instead of {{>}} in the
{{hasChanged}} method's comparison:
{code}
return file.lastModified() > lastModified;
{code}
> FileChangedReloadingStrategy should support reloading of rolled-back (older
> timestamp) files
> --------------------------------------------------------------------------------------------
>
> Key: CONFIGURATION-532
> URL: https://issues.apache.org/jira/browse/CONFIGURATION-532
> Project: Commons Configuration
> Issue Type: Improvement
> Components: File reloading
> Affects Versions: 1.9
> Reporter: Mike Lucas
> Original Estimate: 48h
> Remaining Estimate: 48h
>
> Currently the {{FileChangedReloadingStrategy}} only reloads when the
> timestamp of the file on the filesystem is _newer_ than the timestamp it had
> when it was last loaded.
> This may not be the expected behaviour when, for example, an administrator
> makes a backup copy of the original configuration file before making changes.
> If the administrator wants to roll back to the original configuration, he may
> expect that copying/renaming the backup back to the original name, would
> cause the original configuration to take effect again.
> Another example where the current behaviour is problematic is when using a
> Deploy System (like we do at my company). We expect to be able to roll-back
> to a previous configuration by simply redeploying the Config artifact, but
> because the timestamps reflect when the Config artifact was _built_ (not when
> it was deployed), this roll-back will not work.
> The current behaviour could be kept as the default, simply adding
> {{setReloadOnRollback()}} or similarly named method to change the behaviour
> to reload when the timestamp is either older or newer (i.e. not equal to) the
> {{lastModified}} variable. Another option would to be to create subclass
> {{FileChangedOrRolledBackReloadingStrategy}} that overrides the
> {{hasChanged()}} method.
> In either option the actual change is to use {{!=}} instead of {{>}} in the
> {{hasChanged}} method's comparison:
> {code}
> return file.lastModified() > lastModified;
> {code}
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