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Diffstat (limited to 'src/library/scala/collection/concurrent/TrieMap.scala')
-rw-r--r-- | src/library/scala/collection/concurrent/TrieMap.scala | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/src/library/scala/collection/concurrent/TrieMap.scala b/src/library/scala/collection/concurrent/TrieMap.scala index fccc1d81b9..bcfea7a463 100644 --- a/src/library/scala/collection/concurrent/TrieMap.scala +++ b/src/library/scala/collection/concurrent/TrieMap.scala @@ -873,6 +873,44 @@ extends scala.collection.concurrent.Map[K, V] insertifhc(k, hc, v, INode.KEY_ABSENT) } + // TODO once computeIfAbsent is added to concurrent.Map, + // move the comment there and tweak the 'at most once' part + /** If the specified key is not already in the map, computes its value using + * the given thunk `op` and enters it into the map. + * + * Since concurrent maps cannot contain `null` for keys or values, + * a `NullPointerException` is thrown if the thunk `op` + * returns `null`. + * + * If the specified mapping function throws an exception, + * that exception is rethrown. + * + * Note: This method will invoke op at most once. + * However, `op` may be invoked without the result being added to the map if + * a concurrent process is also trying to add a value corresponding to the + * same key `k`. + * + * @param k the key to modify + * @param op the expression that computes the value + * @return the newly added value + */ + override def getOrElseUpdate(k: K, op: =>V): V = { + val oldv = lookup(k) + if (oldv != null) oldv.asInstanceOf[V] + else { + val v = op + if (v == null) { + throw new NullPointerException("Concurrent TrieMap values cannot be null.") + } else { + val hc = computeHash(k) + insertifhc(k, hc, v, INode.KEY_ABSENT) match { + case Some(oldv) => oldv + case None => v + } + } + } + } + def remove(k: K, v: V): Boolean = { val hc = computeHash(k) removehc(k, v, hc).nonEmpty |