RFR (S): 7130391: Add a framework for vendor-specific validation control of setting command-line switches in Hotspot

[Robert Ottenhag]

Hi,

Webrev: http://cr.openjdk.java.net/~rottenha/7130391/webrev.00

This fix adds optional validation control to the setting of command-line switches in Hotspot, and allows it to have vendor-specific extensions if necessary.

The design follows the previously added framework for vendor-specific command-line switch extensions in CR7117389.

The validation control is handled by new boolean methods Flag::is_valid_<type>(value,origin) that are called at the beginning of each call to CommandLineFlags[Ex]::<type>AtPut() to verify that the new value and origin are valid replacements for the current value and origin for this flag.

When parsing the command line options, a failed validation will typically result in an error message and exit with "Unrecognized VM option '<flag-name>'".  When used dynamically using the attach API or management API the resulting operation will fail, leaving it up to the caller to handle it as appropriate.

A simple use case for validation is a manageable flag whose current value can not be less than the previous value, while a more complex example may base the validation on multiple other flags, etc.

Thanks,

/Robert

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Oracle
Robert Ottenhag | Senior Member of Technical Staff
Oracle Oracle Java VM | ORACLE Sweden | Stockholm