-
Notifications
You must be signed in to change notification settings - Fork 509
/
Blocker.scala
67 lines (58 loc) · 2.22 KB
/
Blocker.scala
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
/*
* Copyright (c) 2017-2022 The Typelevel Cats-effect Project Developers
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package cats
package effect
import scala.concurrent.ExecutionContext
import cats.effect.internals.BlockerPlatform
/**
* An execution context that is safe to use for blocking operations.
*
* Used in conjunction with [[ContextShift]], this type allows us to write functions
* that require a special `ExecutionContext` for evaluation, while discouraging the
* use of a shared, general purpose pool (e.g. the global context).
*
* Instances of this class should *NOT* be passed implicitly because they hold state
* and in some cases your application may need different instances of [[Blocker]].
*/
final class Blocker private (val blockingContext: ExecutionContext) extends AnyVal {
/**
* Like `Sync#delay` but the supplied thunk is evaluated on the blocking
* execution context.
*/
def delay[F[_], A](thunk: => A)(implicit F: Sync[F], cs: ContextShift[F]): F[A] =
blockOn(F.delay(thunk))
/**
* Evaluates the supplied task on the blocking execution context via `blockOn`.
*/
def blockOn[F[_], A](fa: F[A])(implicit cs: ContextShift[F]): F[A] =
cs.blockOn(this)(fa)
/**
* `blockOn` as a natural transformation.
*/
def blockOnK[F[_]](implicit cs: ContextShift[F]): F ~> F =
new (F ~> F) {
def apply[A](fa: F[A]): F[A] = blockOn(fa)
}
}
object Blocker extends BlockerPlatform {
/**
* Creates a blocker that delegates to the supplied execution context.
*
* This must not be used with general purpose contexts like
* `scala.concurrent.ExecutionContext.Implicits.global`.
*/
def liftExecutionContext(ec: ExecutionContext): Blocker = new Blocker(ec)
}