A mutable location, that is either empty or contains a value of type 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 tryReadreturns a variable if it exists. Implemented in the successor MVar2swaptakes a value, replaces it and returns the taken value. Implemented in the successor MVar2- 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 doesn't block any threads, all waiting being
done asynchronously (via Async or Concurrent data types,
such as IO).
Given its asynchronous, non-blocking nature, it can be used on top of Javascript as well.
Inspired by Control.Concurrent.MVar from Haskell and
by scalaz.concurrent.MVar.
- Companion
- object
- Deprecated
Value members
Abstract methods
Returns true if the MVar is empty and can receive a put, or
false otherwise.
Returns true if the MVar is empty and can receive a put, or
false otherwise.
Note that due to concurrent tasks, logic built in terms of isEmpty
is problematic.
Fills the MVar if it is empty, or blocks (asynchronously)
if the MVar 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 the MVar 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
putoperation succeeds in filling theMVar, with the given value being next in line to be consumed
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
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
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