Ciao
> rue, but *all* methods executions (synchronized and not) are
> performed inside the handler, contained in the proxy instance anyway.
>
> So an user cannot use the same "lock" in order to synchronize a block
> like this:
Let's give you an example.
here is our handler implementation, and imagine that the 'lock' is not export
outside:
===
synchronized ( this.lock )
{
try
{
return method.invoke( checkedToBeSynchronized, args );
}
catch ( InvocationTargetException e )
{
throw e.getTargetException();
}
}
===
here is a possible user implementation:
- Main class create a synchronized graph instance:
MutableGraph g = CommonsGraph.synchronize( new UndirectMutableGraph.... );
- Thread 1 loops over the vertices:
synchronized(g) {
for ( BaseLabeledVertex v2 : g.getVertices() )
{
// do somethings
}
}
- Thread 2, insert a new vertex:
for ( int i = start; i < end; i++ )
{
BaseLabeledVertex v = new BaseLabeledVertex( valueOf( i ) );
g.addVertex( v );
}
in that example thread, probably you would have a
ConcurrentModificationException because:
1) Therad 1 uses a lock 'g' for the Iterator returned by g.getVertices()
2) Thread 2 uses its own lock 'this.lock' stored into Handler class.
in this situation our data structure is *not* thread safe.
The only way to synchronize the data structure is that:
-Thread 2:
for ( int i = start; i < end; i++ )
{
synchronized(g) {
BaseLabeledVertex v = new BaseLabeledVertex( valueOf( i ) );
g.addVertex( v );
}
}
but this IMHO is a wrong way to fix the problem, and moreover with this
workaround we don't need to
use CommonGraph.synchronize() method, isn't it?
> I have not clear which benefit you want to obtain with that - looks at
> Collections#synchronized* methods and see that the separation of
> concerns in clear.
you are right maybe use an external lock is not useful.
> Sure that we can, the only issue we have is that GroboUtils is not in
> the central repo, adding the external repository would make not easy
> having the component released.
unfortunately GroboUtil was the only lib that I found yesterday. Any
suggestions to some other libs?
all the best ;-)
--
Marco Speranza <[email protected]>
Google Code: http://code.google.com/u/marco.speranza79/
Il giorno 03/mar/2012, alle ore 14:34, Simone Tripodi ha scritto:
> Hola Marco,
>
>> my doubt is this: opening a synchronized block into handler implementation
>> on 'this', in my opinion is not enough, because the method
>> "CommonsGraph.synchronize()" returns a instance of the Proxy and not an
>> instance of handler.
>
> true, but *all* methods executions (synchronized and not) are
> performed inside the handler, contained in the proxy instance anyway.
>
> So an user cannot use the same "lock" in order to synchronize a block
> like this:
>
> ====
> Graph g = CommonsGraph.synchronize(g_);
> ...
> synchronized(g) {
> for ( BaseLabeledVertex v2 : g.getVertices() )
> {
> // do somethings
> }
> }
> ====
>
> I am not sure we can do much more of what we've already done, for that
> situation: the snippet below mixes the *data structure*
> synchronization with the business logic performed outside.
>
>> So my idea is to open synchronized block inside handler implementation using
>> the same Proxy instance that the method 'CommonsGraph.synchronize' will
>> return.
>> Furthermore I'd like to modify the API by adding also the possibility for
>> the user to use an your own lock, in that way
>>
>> CommonsGraph.synchronize( G graph, Object lock )
>
> I have not clear which benefit you want to obtain with that - looks at
> Collections#synchronized* methods and see that the separation of
> concerns in clear.
>
>> Finally only one question. I think that we should add some tests in order to
>> check the correct implementation of our multithrading implementation.
>> Do you think that we can use an external library in test scope?
>
> Sure that we can, the only issue we have is that GroboUtils is not in
> the central repo, adding the external repository would make not easy
> having the component released.
>
> best,
> -Simo
>
> http://people.apache.org/~simonetripodi/
> http://simonetripodi.livejournal.com/
> http://twitter.com/simonetripodi
> http://www.99soft.org/
>
>
>
> On Sat, Mar 3, 2012 at 2:13 PM, Marco Speranza <[email protected]>
> wrote:
>> Morning Simo,
>>
>> my doubt is this: opening a synchronized block into handler implementation
>> on 'this', in my opinion is not enough, because the method
>> "CommonsGraph.synchronize()" returns a instance of the Proxy and not an
>> instance of handler.
>> So an user cannot use the same "lock" in order to synchronize a block like
>> this:
>>
>> ====
>> Graph g = CommonsGraph.synchronize(g_);
>> ...
>> synchronized(g) {
>> for ( BaseLabeledVertex v2 : g.getVertices() )
>> {
>> // do somethings
>> }
>> }
>> ====
>>
>> So my idea is to open synchronized block inside handler implementation using
>> the same Proxy instance that the method 'CommonsGraph.synchronize' will
>> return.
>> Furthermore I'd like to modify the API by adding also the possibility for
>> the user to use an your own lock, in that way
>>
>> CommonsGraph.synchronize( G graph, Object lock )
>>
>> WDYT?
>>
>> Finally only one question. I think that we should add some tests in order to
>> check the correct implementation of our multithrading implementation.
>> Do you think that we can use an external library in test scope?
>>
>>
>> have a nice day
>>
>>
>> --
>> Marco Speranza <[email protected]>
>> Google Code: http://code.google.com/u/marco.speranza79/
>>
>> Il giorno 03/mar/2012, alle ore 13:50, Simone Tripodi ha scritto:
>>
>>> Good morning Marco,
>>>
>>> I had the chance to have a deeper look at your yesterday's night work
>>> and think your additions are good improvements - I just wonder if we
>>> can replace the lock object with the handler itself, referencing
>>> `this` instead.
>>>
>>> Thoughts?
>>>
>>> best and have a nice WE,
>>> -Simo
>>>
>>> http://people.apache.org/~simonetripodi/
>>> http://simonetripodi.livejournal.com/
>>> http://twitter.com/simonetripodi
>>> http://www.99soft.org/
>>>
>>>
>>>
>>> On Sat, Mar 3, 2012 at 1:56 AM, Simone Tripodi <[email protected]>
>>> wrote:
>>>> I saw the commit, please read comments inline.
>>>> best,
>>>> -Simo
>>>>
>>>> http://people.apache.org/~simonetripodi/
>>>> http://simonetripodi.livejournal.com/
>>>> http://twitter.com/simonetripodi
>>>> http://www.99soft.org/
>>>>
>>>>
>>>>
>>>> On Sat, Mar 3, 2012 at 1:40 AM, Marco Speranza <[email protected]>
>>>> wrote:
>>>>> Hi I fixed the problem using proxy/handler.
>>>>>
>>>>> I put also a couple of tests. For do that I insert a test scoped
>>>>> dependency to a library net.sourceforge.groboutils.groboutils-core
>>>>>
>>>>> Ciao
>>>>>
>>>>> --
>>>>> Marco Speranza <[email protected]>
>>>>> Google Code: http://code.google.com/u/marco.speranza79/
>>>>>
>>>>> Il giorno 03/mar/2012, alle ore 01:29, Simone Tripodi ha scritto:
>>>>>
>>>>>> yes, what I didn't understand is how you would like to manage the
>>>>>> iterators issue
>>>>>>
>>>>>> sorry for the brevity but tonight I am getting crazy with at least 3
>>>>>> other projects :D
>>>>>>
>>>>>> -Simo
>>>>>>
>>>>>> http://people.apache.org/~simonetripodi/
>>>>>> http://simonetripodi.livejournal.com/
>>>>>> http://twitter.com/simonetripodi
>>>>>> http://www.99soft.org/
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Sat, Mar 3, 2012 at 1:16 AM, Marco Speranza
>>>>>> <[email protected]> wrote:
>>>>>>> I think that we have to use the same patter of java Collections: a
>>>>>>> wrapper of Graph/MutableGraph that use a synchronize block.
>>>>>>>
>>>>>>> WDYT?
>>>>>>>
>>>>>>> --
>>>>>>> Marco Speranza <[email protected]>
>>>>>>> Google Code: http://code.google.com/u/marco.speranza79/
>>>>>>>
>>>>>>> Il giorno 03/mar/2012, alle ore 01:10, Simone Tripodi ha scritto:
>>>>>>>
>>>>>>>> OK now sounds better, thanks - how would you intend to fix it?
>>>>>>>> TIA,
>>>>>>>> -Simo
>>>>>>>>
>>>>>>>> http://people.apache.org/~simonetripodi/
>>>>>>>> http://simonetripodi.livejournal.com/
>>>>>>>> http://twitter.com/simonetripodi
>>>>>>>> http://www.99soft.org/
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Sat, Mar 3, 2012 at 1:01 AM, Marco Speranza
>>>>>>>> <[email protected]> wrote:
>>>>>>>>>>>
>>>>>>>>>>> furthermore there is another problem: with handler is not possible
>>>>>>>>>>> to use correctly synchronization block like this
>>>>>>>>>>>
>>>>>>>>>>> ====
>>>>>>>>>>> Graph g = CommonsGraph.synchronize(g_);
>>>>>>>>>>> ...
>>>>>>>>>>> synchronized(g) {
>>>>>>>>>>> for ( BaseLabeledVertex v2 : g.getVertices() )
>>>>>>>>>>> {
>>>>>>>>>>> // do somethings
>>>>>>>>>>> }
>>>>>>>>>>> }
>>>>>>>>>>> ====
>>>>>>>>>>
>>>>>>>>>> sorry I don't understand what you meant/intend to do
>>>>>>>>>
>>>>>>>>> I'm trying to explain better. the method getVertices return an
>>>>>>>>> Iterator. In a multi-thread environment you have to ensure that
>>>>>>>>> during the 'for' execution the [graph] data structure remains
>>>>>>>>> consistent.
>>>>>>>>> Also for java collection is the same
>>>>>>>>> [http://docs.oracle.com/javase/6/docs/api/java/util/Collections.html#synchronizedCollection(java.util.Collection)]
>>>>>>>>>
>>>>>>>>> So if we use a proxy/handler there is no way to "export" the
>>>>>>>>> mutex/lock variable used into handler class.
>>>>>>>>>
>>>>>>>>> In our CommonsGraph the variable this.lock is private and is non
>>>>>>>>> possible to export out of the method, so the user can not utilize the
>>>>>>>>> lock to synchronize his block.
>>>>>>>>>
>>>>>>>>> ===
>>>>>>>>> public Object invoke( Object proxy, Method method, Object[]
>>>>>>>>> args )
>>>>>>>>> throws Throwable
>>>>>>>>> {
>>>>>>>>> if ( synchronizedMethods.contains( method ) )
>>>>>>>>> {
>>>>>>>>> try
>>>>>>>>> {
>>>>>>>>> synchronized ( this.lock )
>>>>>>>>> {
>>>>>>>>> return method.invoke( synchronizedMethods,
>>>>>>>>> args );
>>>>>>>>> }
>>>>>>>>> }
>>>>>>>>> catch ( InvocationTargetException e )
>>>>>>>>> {
>>>>>>>>> throw e.getTargetException();
>>>>>>>>> }
>>>>>>>>> }
>>>>>>>>> return method.invoke( synchronizedMethods, args );
>>>>>>>>> }
>>>>>>>>> ===
>>>>>>>>>
>>>>>>>>> ciao
>>>>>>>>>
>>>>>>>>> --
>>>>>>>>> Marco Speranza <[email protected]>
>>>>>>>>> Google Code: http://code.google.com/u/marco.speranza79/
>>>>>>>>>
>>>>>>>>> Il giorno 03/mar/2012, alle ore 00:45, Simone Tripodi ha scritto:
>>>>>>>>>
>>>>>>>>>>> furthermore there is another problem: with handler is not possible
>>>>>>>>>>> to use correctly synchronization block like this
>>>>>>>>>>>
>>>>>>>>>>> ====
>>>>>>>>>>> Graph g = CommonsGraph.synchronize(g_);
>>>>>>>>>>> ...
>>>>>>>>>>> synchronized(g) {
>>>>>>>>>>> for ( BaseLabeledVertex v2 : g.getVertices() )
>>>>>>>>>>> {
>>>>>>>>>>> // do somethings
>>>>>>>>>>> }
>>>>>>>>>>> }
>>>>>>>>>>> ====
>>>>>>>>>>
>>>>>>>>>> sorry I don't understand what you meant/intend to do
>>>>>>>>>>
>>>>>>>>>>> I really think that a synchronized wrapper it's the best solution.
>>>>>>>>>>>
>>>>>>>>>>> WDYT?
>>>>>>>>>>
>>>>>>>>>> they sucks because we have to keep them updated while , but if there
>>>>>>>>>> are not alternatives...
>>>>>>>>>> -Simo
>>>>>>>>>>
>>>>>>>>>> http://people.apache.org/~simonetripodi/
>>>>>>>>>> http://simonetripodi.livejournal.com/
>>>>>>>>>> http://twitter.com/simonetripodi
>>>>>>>>>> http://www.99soft.org/
>>>>>>>>>>
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