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prevent segfault after mmap failure #707
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Fixes #706.
This PR causes the db to revert to
mmap(db, db.datasz)if the call tommap(db, minsz)fails. The original error is still returned, so callers will see"mmap failure"returned fromdb.Update. I also wrapped this error in a new type, so that callers can check for it explicitly. This is good to have, since I imagine applications will want to panic instead of continuing to attempt moredb.Updatecalls. Another option would be to add aPanicOnFailedMmapflag so that bolt will automatically panic under these conditions.I'm not 100% sure that this code is safe, but I've confirmed that it resolves the segfault bug, and it appears that calls to
db.Viewwill succeed even after mmap failure.