Performs a transactional read and checks that it is consistent with all
reads already made by txn.
Performs a transactional read and checks that it is consistent with all
reads already made by txn. Equivalent to apply(), which is more
concise in many situations.
an active transaction.
the value of the Ref as observed by txn.
Returns f(get), possibly reevaluating f to avoid rollback if a
conflicting change is made but the old and new values are equal after
application of f.
Returns f(get), possibly reevaluating f to avoid rollback if a
conflicting change is made but the old and new values are equal after
application of f. Requires that f(x) == f(y) if x == y.
getWith(f) is equivalent to f(relaxedGet({ f(_) == f(_) })), although
perhaps more efficient.
an idempotent function.
the result of applying f to the value contained in this Ref.
Returns the same value as get, but allows the caller to determine
whether txn should be rolled back if another thread changes the value
of this Ref before txn is committed.
Returns the same value as get, but allows the caller to determine
whether txn should be rolled back if another thread changes the value
of this Ref before txn is committed. If ref.relaxedGet(equiv)
returns v0 in txn, another context changes ref to v1, and
equiv(v0, v1) == true, then txn won't be required to roll back (at
least not due to this read). If additional changes are made to ref
additional calls to the equivalence function will be made, always with
v0 as the first parameter.
equiv will always be invoked on the current thread. Extreme care
should be taken if the equivalence function accesses any Refs.
As an example, to perform a read that will not be validated during commit you can use the maximally permissive equivalence function:
val unvalidatedValue = ref.relaxedGet({ (_, _) => true })
To check view serializability rather than conflict serializability for a read:
val viewSerializableValue = ref.relaxedGet({ _ == _ })
The getWith method provides related functionality.
an equivalence function that returns true if a transaction that observed the first argument will still complete correctly, where the second argument is the actual value that should have been observed.
a value of the Ref, not necessary consistent with the rest of
the reads performed by txn.
Performs a transactional read and checks that it is consistent with all
reads already made by txn.
Performs a transactional read and checks that it is consistent with all
reads already made by txn. Equivalent to get.
Example:
val x = Ref(0)
atomic { implicit t =>
...
val v = x() // perform a read inside a transaction
...
}
an active transaction.
the value of the Ref as observed by txn.
Provides all of the operations of a
Source[A], without the ability to get aSource.View.