+ 1 for following future contract. If we have own contract, then why do we extends Future? This only confiuses users. If he cast our future to Future, then he will expect checked exceptions and will use try-catch blocks, which will never fire because we breakes Future semantics.
Furthermore, even new development effrots in Java 8 respects this contract. E.g.: http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CompletableFuture.html They explicitly mention the following: "To simplify usage in most contexts, this class also defines methods join() <http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CompletableFuture.html#join--> and getNow(T) <http://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CompletableFuture.html#getNow-T-> that instead throw the CompletionException directly in these cases." I.e. initial contract is preserved still, but another shortcut methods are added to provide alternate semantics. So we either should remove "implements Future", or follow it's contract. On Fri, Mar 20, 2015 at 6:25 PM, Dmitriy Setrakyan <[email protected]> wrote: > Hazelcast has a future now too? I wonder where they got that idea :) > > Our future overrides the Future.get() method specifically to remove all > checked exceptions from it. This way we make it pretty clear that it will > never throw ExecutionException. I actually like our design. > > D. > > On Fri, Mar 20, 2015 at 8:12 AM, Sergey Evdokimov <[email protected] > > > wrote: > > > I've created a ticket: https://issues.apache.org/jira/browse/IGNITE-527 > > (Asynchronous cache operations must throw CacheException instead of > > IgniteException) > > > > The reason of ExecutionException is separation exception that is > > computation result and other exceptions > > like CancellationException, InterruptedException. I don't say that our > > approach is bad (throwing exception directly without wrapping into > > ExecutionException), but we must honor contract described in > > java.util.concurrent.Future > > because IgniteFuture extends java.util.concurrent.Future. Theoretically, > > user can pass our IgniteFuture to third party code as a simple > > java.util.concurrent.Future, third party code will expect > > ExecutionException > > and java.util.concurrent.TimeoutException when call "get(...)". > Hazelcast's > > future has method 'getSafely()' that throws RuntimeException directly, > but > > "get()" works according to java.util.concurrent.Future contract. > > > > > > > > > > On Fri, Mar 20, 2015 at 5:13 PM, Dmitriy Setrakyan < > [email protected]> > > wrote: > > > > > Agree that sync and async counterparts for the same operation should > > > through the same exception. Is it really not the case now? If not, we > > > should fix it. > > > > > > Disagree about ExecutionException, as the only reason it was done is to > > > support checked exceptions. We have runtime exception, so we can throw > > the > > > correct exception at all times. > > > > > > D. > > > > > > On Fri, Mar 20, 2015 at 5:32 AM, Sergey Evdokimov < > > [email protected] > > > > > > > wrote: > > > > > > > Hello, > > > > > > > > Failed cache operations throw CacheException, but failed asynchronous > > > > operations throw IgniteException. I think it's wrong. Same > synchronous > > > and > > > > asynchronous operation must throw same exception. > > > > > > > > BTW. According to contract of java.util.concurrent.Future#get() if > > result > > > > of operation is an exception Future#get() should throw > > ExecutionException > > > > that wrap result exception. We break this contract and throw result > > > > exception directly from Future#get(), this may be cause of problems, > > for > > > > example it's impossible to make out exceptions that threw during > > > > computation and other runtime exceptions. > > > > I propose to keep contract of Future#get() as described in JDK > javadocs > > > and > > > > add our method "take" that throw exception directly as implemented at > > > > Ignite currently. > > > > > > > > > >
