readdir() w/recursive=true needs to handle mount-cycles and large mount-graphs

[pfrazee]

Currently if you have a "mount cycle" (2 drives that mount each other) the readdir() call with {recursive: true} will enter an endless loop.

Even without a cycle, mount-graphs have the potential to become so large that recursion is not feasible. (E.g. Beaker's use of mounts for the social graph could cause a recursive readdir to iterate the "strong set.")

Ways we can solve this:

• Add a depth parameter to limit the number of recursions into subfolders
• Add a mountDepth parameter to limit the number of recursions into mounts
• Don't recurse into mounts at all (aka mountDepth is always 0)

Ways we can't solve this:

• Track mounts and break cycles. This would solve the cycle problem but large mount-graphs would still be an issue.

I personally prefer either the mountDepth option or not recursing into mounts.

[jb33k]

Is this related to https://github.com/mafintosh/hyperdrive/issues/258?

[pfrazee]

It doesn't look like it, the test case in #257 doesn't use recursive readdir