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From Vladimir Ozerov <voze...@gridgain.com>
Subject Re: .Net: separate methods for async operations.
Date Tue, 13 Oct 2015 05:56:45 GMT
Dima,

I do not like JSR 107 v1.1 approach. First, it is not user friendly.
Second, it is prone to deadlock/starvation problems we are currently
discussing in another thread because these "Collectors" are continuations
essentially.

On Tue, Oct 13, 2015 at 12:42 AM, Dmitriy Setrakyan <dsetrakyan@apache.org>
wrote:

> I just took a look at JSR 107, and looks like they are taking a different
> (in my view not as elegant) route:
>
> https://github.com/jsr107/jsr107spec/blob/async/src/main/java/javax/cache/Cache.java
>
> Any thoughts on this?
>
> D.
>
> On Mon, Oct 12, 2015 at 11:11 AM, Vladimir Ozerov <vozerov@gridgain.com>
> wrote:
>
> > Well, if we asume that the most common usage will be
> > IgniteCache.async().doSomething(), then yes - backwards transformation is
> > not necessary.
> >
> > All in all this approach seems to be the most clean among other
> suggested.
> >
> > On Mon, Oct 12, 2015 at 8:38 PM, Sergi Vladykin <
> sergi.vladykin@gmail.com>
> > wrote:
> >
> > > Dmitriy,
> > >
> > > I mostly agree with your points except naming and hierarchy:
> > >
> > > 1. I don't like CacheAsync, it is ugly.
> > >
> > > 2. If IgniteCache extends AsyncCache then we can't use the same names
> for
> > > methods, we will be forced to use *blaAsync(...)* format
> > > which is ugly for me as well. Also this will pollute sync API with
> async
> > > one, while we are trying to avoid that.
> > >
> > > Sergi
> > >
> > > 2015-10-12 20:28 GMT+03:00 Dmitriy Setrakyan <dsetrakyan@apache.org>:
> > >
> > > > On Mon, Oct 12, 2015 at 10:15 AM, Vladimir Ozerov <
> > vozerov@gridgain.com>
> > > > wrote:
> > > >
> > > >
> > > > > The problem with this approach is that not all methods are async.
> > E.g.
> > > > > name(), lock(K), iterator(), etc.. So you should either mix sync
> and
> > > > async
> > > > > methods in AsyncCache still, or expose only async methods.
> > > >
> > > >
> > > > I think AsyncCache, or rather CacheAsync, should expose only async
> > > methods.
> > > > Moreover, should IgniteCache simply extend CacheAsync API?
> > > >
> > > >
> > > > > In the latter case we will require backwards
> > > > > transformation: IgniteCache AsyncCache.sync().
> > > > >
> > > >
> > > > Not sure this is needed.
> > > >
> > > >
> > > > > Consistency between platforms should have minimal priority. .Net
> and
> > > Java
> > > > > are very different. For example we cannot even have "V Get(K)"
> method
> > > in
> > > > > .Net cache. Instead we have "V TryGet(K, out bool)" because .Net
> > > supports
> > > > > structs and have full generics support and naive Java approach
> simply
> > > > > doesn't work here. Base concepts must be the same across platforms,
> > but
> > > > > methods signatures and grouping will be different.
> > > > >
> > > >
> > > > I disagree here. I think consistency matters. Moreover, based on the
> > > > previous .NET examples you have provided, I do not see much
> difference
> > > > between .NET and Java, other than different syntax. I think the same
> > > > CacheAsync design can be applied to both.
> > > >
> > > >
> > > > >
> > > > >
> > > > >
> > > > > On Mon, Oct 12, 2015 at 7:53 PM, Sergi Vladykin <
> > > > sergi.vladykin@gmail.com>
> > > > > wrote:
> > > > >
> > > > > > In my view we should not pollute sync APIs with all async
> methods,
> > > > > > definitely we have to separate them
> > > > > > for better UX.
> > > > > >
> > > > > > Currently on Java we have IgniteAsyncSupport with method
> > withAsync()
> > > > > which
> > > > > > returns the same sync API
> > > > > > but that API works in broken manner. Instead it should look
like
> > the
> > > > > > following IMO
> > > > > >
> > > > > > interface AsyncSupport<X> {
> > > > > >     X async();
> > > > > > }
> > > > > >
> > > > > > Where X will be an interface with respective async API.  For
> > example
> > > > for
> > > > > > IngneCache we will have AsyncCache
> > > > > > with all the respective async variants of all methods. Like
this
> > > > > >
> > > > > > interface IgniteCache<K,V> extends AsyncSupport<AsyncCache<K,V>>
> {
> > > > > >     V get(K key);
> > > > > > }
> > > > > >
> > > > > >
> > > > > > interface AsyncCache<K,V> {
> > > > > >     IgniteFuture<V> get(K key);
> > > > > > }
> > > > > >
> > > > > > From implementation standpoint both interfaces can be implemented
> > by
> > > > the
> > > > > > same class but for user API
> > > > > > they will be conveniently separated. Implementation of every
sync
> > > > method
> > > > > is
> > > > > > trivial if we have
> > > > > > async counterpart: just call get() on received future.
> > > > > >
> > > > > > From documentation point of view we just have to write on each
> > method
> > > > > that
> > > > > > it is a async variant of some
> > > > > > method on main API like following:
> > > > > >
> > > > > >    /**
> > > > > >      * Asynchronous variant of method {@link
> > > IgniteCache#get(Object)}.
> > > > > >      */
> > > > > >
> > > > > > This way we will not need to maintain the same docs for all
sync
> > and
> > > > > async
> > > > > > methods.
> > > > > >
> > > > > > Sorry, I'm not an expert in .Net but I believe this approach
will
> > fit
> > > > > .Net
> > > > > > as well, so it can be consistent across platforms.
> > > > > >
> > > > > > Sergi
> > > > > >
> > > > > >
> > > > > >
> > > > > > 2015-10-12 19:10 GMT+03:00 Dmitriy Setrakyan <
> > dsetrakyan@apache.org
> > > >:
> > > > > >
> > > > > > > Do I understand correctly that you are suggesting adding
> > > "Async(..)"
> > > > > > > counterparts for all the synchronous methods?
> > > > > > >
> > > > > > > Are there any objections about this? If we do it in .NET,
then
> we
> > > > might
> > > > > > as
> > > > > > > well do it in Java, because in my view the same reasoning
can
> be
> > > made
> > > > > for
> > > > > > > Java. This will cause significant proliferation of Async
> methods.
> > > For
> > > > > > > example just on IgniteCache API, we will have to add about
40
> > > Async()
> > > > > > > methods.
> > > > > > >
> > > > > > > D.
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > On Mon, Oct 12, 2015 at 3:45 AM, Vladimir Ozerov <
> > > > vozerov@gridgain.com
> > > > > >
> > > > > > > wrote:
> > > > > > >
> > > > > > > > No. "await" is actually return from the method immediately.
> Let
> > > me
> > > > > show
> > > > > > > it
> > > > > > > > again:
> > > > > > > >
> > > > > > > > async Task<int> GetAndMultiply() {
> > > > > > > >     Task<int> res =  cache.GetAsync(1);
> > > > > > > >
> > > > > > > >     await res;
> > > > > > > >
> > > > > > > >     return res.Result * res.Result;
> > > > > > > > }
> > > > > > > >
> > > > > > > > maps to the following pseudo-code in Java:
> > > > > > > >
> > > > > > > > Future<Integer> getAndMultiply() {
> > > > > > > >     Future<Integer> res =  cache.getAsync(1);
> > > > > > > >
> > > > > > > >     return res.chain((f) => {
> > > > > > > >         return f.get() * f.get();
> > > > > > > >     });
> > > > > > > > }
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > > On Mon, Oct 12, 2015 at 1:36 PM, Yakov Zhdanov <
> > > > yzhdanov@apache.org>
> > > > > > > > wrote:
> > > > > > > >
> > > > > > > > > Is current thread blocked until "await" instruction
is
> > > completed
> > > > in
> > > > > > > > > parallel thread?
> > > > > > > > >
> > > > > > > > > --Yakov
> > > > > > > > >
> > > > > > > > > 2015-10-12 10:41 GMT+03:00 Vladimir Ozerov <
> > > vozerov@gridgain.com
> > > > >:
> > > > > > > > >
> > > > > > > > > > Example with Get() operation:
> > > > > > > > > >
> > > > > > > > > > async Task<int> GetAndMultiply() {
> > > > > > > > > >     // This line is executed in current
thread.
> > > > > > > > > >     Task<int> res = cache.GetAsync(1);
> > > > > > > > > >
> > > > > > > > > >     await res;
> > > > > > > > > >
> > > > > > > > > >     // This code is executed in another
thread when res
> is
> > > > ready.
> > > > > > > > > >     int mul = res.Result * res.Result;
> > > > > > > > > >
> > > > > > > > > >     return mul;
> > > > > > > > > > }
> > > > > > > > > >
> > > > > > > > > > On Mon, Oct 12, 2015 at 10:12 AM, Dmitriy
Setrakyan <
> > > > > > > > > dsetrakyan@apache.org
> > > > > > > > > > >
> > > > > > > > > > wrote:
> > > > > > > > > >
> > > > > > > > > > > On Sun, Oct 11, 2015 at 3:42 AM, Vladimir
Ozerov <
> > > > > > > > vozerov@gridgain.com
> > > > > > > > > >
> > > > > > > > > > > wrote:
> > > > > > > > > > >
> > > > > > > > > > > > Guys, let's try keeping this topic
focused on .Net
> > > please,
> > > > > > > because
> > > > > > > > > the
> > > > > > > > > > > > product is not released yet and
we can create any API
> > we
> > > > > like.
> > > > > > > > > > > >
> > > > > > > > > > > > Dima, answering your question
about async/await -
> this
> > is
> > > > > > > actually
> > > > > > > > > > native
> > > > > > > > > > > > continuation support in .Net.
Consider the following
> > .Net
> > > > > > method:
> > > > > > > > > > > >
> > > > > > > > > > > > async void PutAndPrint() {
> > > > > > > > > > > >     await cache.PutAsync(1, 1);
> > > > > > > > > > > >
> > > > > > > > > > > >     Console.WriteLine("Put value
to cache.");
> > > > > > > > > > > > }
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > And what if the method putAsync would
return a value.
> How
> > > > would
> > > > > > > this
> > > > > > > > > code
> > > > > > > > > > > change?
> > > > > > > > > > >
> > > > > > > > > >
> > > > > > > > >
> > > > > > > >
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>

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