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Make accumulator for get-range configurable #31

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19 changes: 10 additions & 9 deletions src/me/vedang/clj_fdb/core.clj
Original file line number Diff line number Diff line change
Expand Up @@ -112,7 +112,6 @@
(fsub/range s t))
(range arg2))))


(defn get-range
"Takes the following:
- TransactionContext `tc`
Expand All @@ -123,6 +122,8 @@
The `opts` map takes the following option at the moment:
- `keyfn` :
- `valfn` : Functions to transform the key/value to the correct format.
- `coll` : A collection of the type into which the result should be
accumulated.

Note that the byte-arrays are always sent through the `fimpl/decode`
function first. (So if you have stored a Tuple in FDB, the `valfn`
Expand All @@ -146,16 +147,16 @@
(partial fimpl/decode (or s k))
fimpl/decode)
keyfn (comp (:keyfn opts identity) key-decoder)
valfn (comp (:valfn opts identity) fimpl/decode)]
valfn (comp (:valfn opts identity) fimpl/decode)
empty-coll (or (empty (:coll opts)) {})]
(ftr/read tc
(fn [^Transaction tr]
(reduce (fn [acc ^KeyValue kv]
(assoc acc
(keyfn (.getKey kv))
(valfn (.getValue kv))))
{}
(ftr/get-range tr rg)))))))

(persistent!
(reduce (fn [acc ^KeyValue kv]
(conj! acc [(keyfn (.getKey kv))
(valfn (.getValue kv))]))
(transient empty-coll)
(ftr/get-range tr rg))))))))

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The persistent / transient is a simple enough change (though I find the use of the -> to be overkill here)

Re: The collection option, let me think about how I want to return an ordered range.

A map makes sense to me since the value cannot and should not be separated from the key. But this does break ordering which is an important property to maintain. I still think that ordered-map is the right way to go here.

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@FiV0 FiV0 Dec 16, 2022

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Personally I would always consume (transform or use otherwise in my app) everything that is returned by get-range so I find the building up of a hash-map or other map unnecessary. Something like '([k1 v1] [k2 v2] ...)seems sufficient and if somebody needs a hash-map they can always (into {} res). Especially if you want to write performant code this is just overhead.

I will look at your other comments some time this weekend.

(defn clear-range
"Takes the following:
Expand Down
18 changes: 18 additions & 0 deletions test/me/vedang/clj_fdb/core_test.clj
Original file line number Diff line number Diff line change
Expand Up @@ -61,6 +61,24 @@
(is (= expected-map
(fc/get-range db rg {:keyfn second :valfn bs/to-string})))))))

(deftest get-range-accumulator-test
(testing "Test the best-case path for `fc/get-range`. End is exclusive."
(let [input-keys ["bar" "car" "foo" "gum"]
begin (ftup/pack (ftup/from u/*test-prefix* "b"))
end (ftup/pack (ftup/from u/*test-prefix* "g"))
rg (frange/range begin end)
v "1"
expected-vec [["bar" v] ["car" v] ["foo" v]]]
(with-open [^Database db (cfdb/open fdb)]
(ftr/run db
(fn [^Transaction tr]
(doseq [k input-keys]
(let [k (ftup/from u/*test-prefix* k)]
(fc/set tr k (bs/to-byte-array v))))))

(is (= expected-vec
(fc/get-range db rg {:keyfn second :valfn bs/to-string :coll []})))))))


(deftest clear-range-tests
(testing "Test the best-case path for `fc/clear-range`. End is exclusive."
Expand Down