[jira] [Created] (CONFIGURATION-532) FileChangedReloadingStrategy should support reloading of rolled-back (older timestamp) files

["Mike Lucas (JIRA)" <ji...@apache.org>]

Mike Lucas created CONFIGURATION-532:
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             Summary: 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


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}

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