synchronized (this[.classinfo]) in druntime and phobos

[Andrew Wiley]

On Sun, Jun 3, 2012 at 4:39 PM, deadalnix <deadalnix at gmail.com> wrote:

> Le 03/06/2012 21:40, Andrew Wiley a écrit :
>
>> On Sun, Jun 3, 2012 at 12:29 PM, deadalnix <deadalnix at gmail.com
>> <mailto:deadalnix at gmail.com>> wrote:
>>
>>    Le 01/06/2012 22:55, Sean Kelly a écrit :
>>
>>        On Jun 1, 2012, at 5:26 AM, deadalnix wrote:
>>
>>
>>            The main drawback is the same as opApply : return (and
>>            break/continue but it is less relevant for opSynchronized).
>>            Solution to this problem have been proposed in the past
>>            using compiler and stack magic.
>>
>>            It open door for stuff like :
>>            ReadWriteLock rw;
>>            synchronized(rw.read) {
>>
>>            }
>>
>>            synchronized(rw.write) {
>>
>>            }
>>
>>
>>        Opens the door?  This works today exactly as outlined above.  Or
>>        am I missing a part of your argument?
>>
>>            And many types of lock : spin lock, interprocesses locks,
>>            semaphores, . . . And all can be used with the synchronized
>>            syntax, and without exposing locking and unlocking primitives.
>>
>>
>>        All works today.
>>
>>
>>    Unless you do some monitor magic, it doesn't.
>>
>> Yes, it does.
>> -----
>> class Something {
>>     private:
>>         ReadWriteLock _rw;
>>     public:
>>         this() {
>>             _rw = new ReadWriteLock();
>>         }
>>         void doSomething() shared {
>>             synchronized(_rw.read) {
>>                 // do things
>>             }
>>         }
>> }
>> -----
>> I've used this pattern in code. There might be some casting required
>> because the core synchronization primitives haven't been updated to use
>> shared yet.
>>
>
> And where is that ReadWriteLock ?
>

On the GC heap, just like the Monitor object pointed to by __monitor if you
mark a method or class as synchronized.
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