Add automatic methods to KeyValueDB which test for the existence of certain objects #409
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…ertain objects Motivation: We have a use case in which we care about a large object's existence, but don't care to load megabytes of data from disc. We have only a `dyn KeyValueDB` handle available; whatever we use has to be part of the trait. By adding automatic implementations for the new methods, we avoid breaking existing code which is no worse than the existing strategy. Part 2 of this fix will be tracking down the concrete type in use and implementing specializations of those methods, so that we actually do save work, but that's dependent on this PR being merged.
ordian
approved these changes
Jul 27, 2020
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Thanks for the PR!
Regarding part 2, for rocksdb it is blocked on rust-rocksdb/rust-rocksdb#439, but even then from reading the docs, it seems that this function may return false positives, this is probably not what we want.
NikVolf
approved these changes
Jul 27, 2020
dvdplm
approved these changes
Jul 28, 2020
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Also note, that this change is breaking (and also for all |
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Motivation: We have a use case in which we care about a large object's
existence, but don't care to load megabytes of data from disc. We have
only a
dyn KeyValueDBhandle available; whatever we use has to bepart of the trait.
By adding automatic implementations for the new methods, we avoid
breaking existing code. The automatic implementations are no worse than
the code which is possible with the existing API.
Part 2 of this fix will be tracking down the concrete type in use
and implementing specializations of those methods, so that we actually
do save work, but that's dependent on this PR being merged.
Compatibility: this won't change the behavior of any existing code, even if
concrete instantiators already have methods which shadow the default
implementation: playground.