RFR: 8023524: Mechanism to dump generated lambda classes / log lambda code generation

[Henry Jen]

Hi,

Please review the webrev at
http://cr.openjdk.java.net/~henryjen/ccc/8023524/0/webrev/

This webrev enable writing generated classes for lambda to disk at a
directory specified with -Djdk.internal.lambda.dumpProxyClasses.

The directory has to be an existing writable directory, otherwise, a
message will be logged. The validation is done in static block to fail
early, and is done each time when lambda capture occurs in case file
system is modified(for example, created after seeing error message).

As the code using AccessController.doPrivileged to perform file I/O, it
would be much appreciated to have extra eyes from security experts to
have a look at this.

As the directory specified should be existing writable directory, and
the generated filename is lambda class name controlled by the program,
there should be no security concerns.

Cheers,
Henry