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Add exists command support #152

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merged 2 commits into from
Oct 6, 2019
Merged

Add exists command support #152

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4271343
Add exists command support
alirezameskin Oct 5, 2019
bb6e9f5
Change the return type to Boolean
alirezameskin Oct 6, 2019
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1 change: 1 addition & 0 deletions modules/effects/src/main/scala/dev/profunktor/redis4cats/algebra/strings.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -26,6 +26,7 @@ trait StringCommands[F[_], K, V]
with Increment[F, K, V]
with Bits[F, K, V] {
def del(key: K*): F[Unit]
def exists(key: K*): F[Long]
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I think it would be better if we return F[Boolean] since Redis would return either 1 if the key exists or 0 if it doesn't, and that can be easily matched to true and false.

On the other hand, I don't really like what Redis does with accepting multiple keys as input. It'll just return the sum of the partial results. For example:

redis> SET key1 "Hello"
"OK"
redis> EXISTS key1
(integer) 1
redis> EXISTS nosuchkey
(integer) 0
redis> SET key2 "World"
"OK"
redis> EXISTS key1 key2 nosuchkey
(integer) 2

I think we could do better and return true if ALL the keys exist and false if at least one key doesn't exist. Similar to what the Monoid[All] instance would do.

What do you think?

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makes sense

def expire(k: K, seconds: FiniteDuration): F[Unit]
}

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5 changes: 5 additions & 0 deletions modules/effects/src/main/scala/dev/profunktor/redis4cats/interpreter/Redis.scala
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Expand Up @@ -137,6 +137,11 @@ private[redis4cats] class BaseRedis[F[_]: ContextShift, K, V](
async.flatMap(c => F.delay(c.del(key: _*)))
}.void

def exists(key: K*): F[Long] =
JRFuture {
async.flatMap(c => F.delay(c.exists(key: _*)))
}.map(x => Long.box(x))

def expire(key: K, expiresIn: FiniteDuration): F[Unit] =
JRFuture {
async.flatMap(c => F.delay(c.expire(key, expiresIn.toSeconds)))
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8 changes: 8 additions & 0 deletions modules/tests/src/test/scala/dev/profunktor/redis4cats/Fs2TestScenarios.scala
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Expand Up @@ -134,8 +134,12 @@ trait Fs2TestScenarios {
for {
x <- cmd.get(key)
_ <- IO { assert(x.isEmpty) }
exist1 <- cmd.exists(key)
_ <- IO { assert(exist1 == 0L) }
isSet1 <- cmd.setNx(key, "some value")
_ <- IO { assert(isSet1) }
exist2 <- cmd.exists(key)
_ <- IO { assert(exist2 == 1L) }
y <- cmd.get(key)
_ <- IO { assert(y.contains("some value")) }
isSet2 <- cmd.setNx(key, "should not happen")
Expand All @@ -150,11 +154,15 @@ trait Fs2TestScenarios {
_ <- IO { assert(val3.isEmpty) }
isSet5 <- cmd.mSetNx(Map("multikey1" -> "someVal1", "multikey2" -> "someVal2"))
_ <- IO { assert(!isSet5) }
exist3 <- cmd.exists(key, "multikey1", "_not_existing_key_")
_ <- IO { assert(exist3 == 2L) }
w <- cmd.get(key)
_ <- IO { assert(w.contains("some value")) }
_ <- cmd.del(key)
z <- cmd.get(key)
_ <- IO { assert(z.isEmpty) }
exist4 <- cmd.exists(key)
_ <- IO { assert(exist4 == 0L) }
} yield ()
}

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