vine: a couple of memory leaks

[btovar]

I saw these leaks only with recovery tasks.

Merge Checklist

The following items must be completed before PRs can be merged.
Check these off to verify you have completed all steps.

• make test Run local tests prior to pushing.
• make format Format source code to comply with lint policies. Note that some lint errors can only be resolved manually (e.g., Python)
• make lint Run lint on source code prior to pushing.
• Manual Update: Update the manual to reflect user-visible changes.
• Type Labels: Select a github label for the type: bugfix, enhancement, etc.
• Product Labels: Select a github label for the product: TaskVine, Makeflow, etc.
• PR RTM: Mark your PR as ready to merge.

[dthain]

Oh good catch! But it seems to me that an insert of a duplicate key is a bigger problem than the leak of the table entry, it is also possibly the leak of the contained object too.

Do we need a notice() here to indicate the implied loss of an object at that key? Or maybe check to see if it is the same object and key?

[btovar]

That would be a good idea! As it is right now there is the memleak of the actual object value as the caller assumes it is always inserted.

[dthain]

Or perhaps hash_table_insert should return the prior value (or null) at that key?

No point in returning zero on memory allocation failure -- those should be calling xxmalloc instead.