On Mar 11, 2015, at 1:45 PM, Aggelos Biboudis <bibou...@gmail.com> wrote:
> Hi all, > > Please review the patch for the count terminal operator on SIZED streams. > > https://bugs.openjdk.java.net/browse/JDK-8067969 > http://cr.openjdk.java.net/~psandoz/jdk9/JDK-8067969-optimize-stream-count/webrev/ > > Thanks Paul Sandoz for sponsoring this. > This looks good. Code is nicely contained and not as much as i initially anticipated. I am pondering adding an api note to the count methods to head off any suprises as now the stream pipeline may not be executed. * @apiNote * An implementation may choose to not execute the stream pipeline (either * sequentially or in parallel) if it is capable of computing the count * directly from the stream source. In such cases no source elements will * be traversed and no intermediate operations will be evaluated. * Behavioral parameters with side-effects, which are strongly discouraged * except for harmless cases such as debugging, may be affected. For * example, consider the following stream: * <pre>{@code * List<String> l = ... * long count = l.stream().peek(System.out::println).count(); * }</pre> * The number of elements covered by the stream source, a {@code List}, is * known and the intermediate operation, {@code peek}, does not inject into * or remove elements from the stream. Thus the count is the size of the * {@code List} and there is no need to execute the pipeline and, as a * side-effect, print out the list elements. WDYT? Paul.
