BloombergLP::bdlcc::StripedUnorderedMultiMap::visitReadOnly

Serially call the specified visitor on each element (if one exists) in this hash map having the specified key until every such element has been visited or visitor returns false. That is, for (key, value), invoke: ` bool visitor(value, key); ` Return the number of elements visited or the negation of that value if visitations stopped because visitor returned false. visitor has read‐only access to each element for duration of each invocation. The behavior is undefined if hash map manipulators are invoked from within visitor, as it may lead to a deadlock.