final class MVar[F[_], A] extends cats.effect.concurrent.MVar[F, A]
A mutable location, that is either empty or contains
a value of type A
.
It has the following fundamental atomic operations:
- put which fills the var if empty, or blocks (asynchronously) until the var is empty again
- tryPut which fills the var if empty. returns true if successful
- take which empties the var if full, returning the contained value, or blocks (asynchronously) otherwise until there is a value to pull
- tryTake empties if full, returns None if empty.
- read which reads the current value without touching it,
assuming there is one, or otherwise it waits until a value
is made available via
put
- tryRead returns
Some(a)
if full, without modifying the var, or else returnsNone
- isEmpty returns true if currently empty
The MVar
is appropriate for building synchronization
primitives and performing simple inter-thread communications.
If it helps, it's similar with a BlockingQueue(capacity = 1)
,
except that it is pure and that doesn't block any threads, all
waiting being done asynchronously.
Given its asynchronous, non-blocking nature, it can be used on top of Javascript as well.
N.B. this is a reimplementation of the interface exposed in Cats-Effect, see: cats.effect.concurrent.MVar
Inspired by Control.Concurrent.MVar from Haskell.
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def
isEmpty: F[Boolean]
Returns
true
if the var is empty,false
if full.Returns
true
if the var is empty,false
if full.- Definition Classes
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def
isInstanceOf[T0]: Boolean
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def
mapK[G[_]](f: ~>[F, G]): cats.effect.concurrent.MVar[G, A]
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ne(arg0: AnyRef): Boolean
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notify(): Unit
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def
put(a: A): F[Unit]
Fills the
MVar
if it is empty, or blocks (asynchronously) if theMVar
is full, until the given value is next in line to be consumed on take.Fills the
MVar
if it is empty, or blocks (asynchronously) if theMVar
is full, until the given value is next in line to be consumed on take.This operation is atomic.
- returns
a task that on evaluation will complete when the
put
operation succeeds in filling theMVar
, with the given value being next in line to be consumed
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- MVar → MVar
-
def
read: F[A]
Tries reading the current value, or blocks (asynchronously) until there is a value available.
Tries reading the current value, or blocks (asynchronously) until there is a value available.
This operation is atomic.
- returns
a task that on evaluation will be completed after a value has been read
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final
def
synchronized[T0](arg0: ⇒ T0): T0
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def
take: F[A]
Empties the
MVar
if full, returning the contained value, or blocks (asynchronously) until a value is available.Empties the
MVar
if full, returning the contained value, or blocks (asynchronously) until a value is available.This operation is atomic.
- returns
a task that on evaluation will be completed after a value was retrieved
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def
toString(): String
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def
tryPut(a: A): F[Boolean]
Fill the
MVar
if we can do it without blocking,Fill the
MVar
if we can do it without blocking,- returns
whether or not the put succeeded
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- MVar → MVar
-
def
tryRead: F[Option[A]]
Tries reading the current value, returning
Some(a)
if the var is full, but without modifying the var in any way.Tries reading the current value, returning
Some(a)
if the var is full, but without modifying the var in any way. OrNone
if the var is empty. -
def
tryTake: F[Option[A]]
Empty the
MVar
if fullEmpty the
MVar
if full- returns
an Option holding the current value, None means it was empty
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final
def
wait(): Unit
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def
wait(arg0: Long, arg1: Int): Unit
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