As I stare at the code for RiakMap in the riak-java-client
(https://github.com/basho/riak-java-client/blob/develop/src/main/java/com/basho/riak/client/core/query/crdt/types/RiakMap.java),
I have the urge for a simpler implementation.
If I'm reading the code right, it looks like it handles a value of each
RiakDatatype for each key. As in, it's possible for the same key in a
map to have all of a counter, map, flag, register and set value.
If it turns out that the underlying data has only one of those, or
perhaps that I only care about one of those, it feels like
private final Map<BinaryValue, List<RiakDatatype>> entries =
new HashMap<BinaryValue, List<RiakDatatype>>();
could become
private final Map<BinaryValue, RiakDatatype> entries =
new HashMap<BinaryValue, RiakDatatype>();
What I'm getting at is that the code I'm writing to iterate over the
elements in a map is doing way more than I'd like. For a map whose
values are all registers, I've got something like:
RiakMap myMap;
for (BinaryValue key : myMap.view().keySet()) {
RiakRegister register = myMap.getRegister(key);
}
which looks clean enough, but is busy under the covers. I'm really
whining about the implementation of getRegister and friends:
public RiakRegister getRegister(BinaryValue key)
{
if (entries.containsKey(key)) {
for (RiakDatatype dt : entries.get(key)) {
if (dt.isRegister()) {
return dt.getAsRegister();
}
}
}
return null;
}
Because I'm iterating I already know the key is one of the entries, so
would you consider a patch with an unsafe* (or any other name) set of
accessors that assumes the key is present? I could of course call view
and implement my own method, but I can't see how to take out the loop
without changing the underlying data structure for entries.
If I'm iterating over lots and lots of keys (i.e. myMap.view().keySet()
contains lots and lots of elements), it might actually be enough savings
to notice. In addition though, I think it's simpler enough to be
helpful when trying to read/understand the code.
It is of course possible that the underlying data isn't what I expect,
and contains other data types too. So a full implementation might need
hints from the caller about whether to use the more general/existing
data structure, or the simplified one...and then whether to fail in the
face of data that doesn't fit in the simplified one, or silently ignore
it...or ignore it but notify the caller that it's present...and probably
other stuff I haven't considered yet.
I'd love to hear what you think about all of this.
Thanks much for your help.
-DB
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