Re: Cannot take the .keys of shared AA. Is this a regression in 2.087 or a feature?
On Friday, August 16, 2019 2:16:31 AM MDT Piotr Mitana via Digitalmars-d-
learn wrote:
> On Thursday, 15 August 2019 at 19:51:30 UTC, Jonathan M Davis
>
> wrote:
> > Not being able to implicitly convert to const is a bit odd, but
> > arguably, nothing should ever be called on a shared AA anyway.
> > If an operation isn't thread-safe, then it shouldn't work with
> > shared. To use a shared object safely, you have to protect
> > access to it with a mutex or some other synchronization
> > mechanism, after which you would normally cast away shared to
> > operate on the object as thread-local while the lock is in
> > place and then release the lock when you're done (also making
> > sure that no thread-local references exist when the lock is
> > released). Because keys is not at all thread-safe, I'd strongly
> > argue that it should not work on a shared AA, and if it does,
> > that's a bug.
>
> OK, I get the point. So I should go with something similar to
> this, right?
>
> import core.sync.mutex;
> import std;
>
> shared(string[string]) dict;
> shared(Mutex) mtx;
>
> shared static this()
> {
> mtx = new shared Mutex;
> }
>
> void main()
> {
> mtx.lock;
> (cast(string[string]) dict).keys;
> mtx.unlock;
> }
>
> Or I could use synchronized, if dict was inside a class. Thank
> you!
Yes. Or you can use synchronized blocks. e.g.
synchronized(mtx)
{
(cast(string[string]) dict).keys;
}
- Jonathan M Davis
Re: Cannot take the .keys of shared AA. Is this a regression in 2.087 or a feature?
On Thursday, 15 August 2019 at 19:51:30 UTC, Jonathan M Davis
wrote:
Not being able to implicitly convert to const is a bit odd, but
arguably, nothing should ever be called on a shared AA anyway.
If an operation isn't thread-safe, then it shouldn't work with
shared. To use a shared object safely, you have to protect
access to it with a mutex or some other synchronization
mechanism, after which you would normally cast away shared to
operate on the object as thread-local while the lock is in
place and then release the lock when you're done (also making
sure that no thread-local references exist when the lock is
released). Because keys is not at all thread-safe, I'd strongly
argue that it should not work on a shared AA, and if it does,
that's a bug.
OK, I get the point. So I should go with something similar to
this, right?
import core.sync.mutex;
import std;
shared(string[string]) dict;
shared(Mutex) mtx;
shared static this()
{
mtx = new shared Mutex;
}
void main()
{
mtx.lock;
(cast(string[string]) dict).keys;
mtx.unlock;
}
Or I could use synchronized, if dict was inside a class. Thank
you!
Re: Cannot take the .keys of shared AA. Is this a regression in 2.087 or a feature?
On Thursday, 15 August 2019 at 19:51:30 UTC, Jonathan M Davis
wrote:
n Thursday, August 15, 2019 11:33:06 AM MDT Piotr Mitana via
Digitalmars-d- learn wrote:
Code:
import std;
shared(string[string]) dict;
void main()
{
dict.keys;
}
Error:
/dlang/dmd/linux/bin64/../../src/druntime/import/object.d(3417):
Error: cannot implicitly convert expression aa of type
shared(string[string]) to const(shared(string)[string])
onlineapp.d(7): Error: template instance
`object.keys!(shared(string[string]), shared(string), string)`
error instantiating
Before D 2.087 it compiled - is this a regression?
Not being able to implicitly convert to const is a bit odd, but
arguably, nothing should ever be called on a shared AA anyway.
If an operation isn't thread-safe, then it shouldn't work with
shared. To use a shared object safely, you have to protect
access to it with a mutex or some other synchronization
mechanism, after which you would normally cast away shared to
operate on the object as thread-local while the lock is in
place and then release the lock when you're done (also making
sure that no thread-local references exist when the lock is
released). Because keys is not at all thread-safe, I'd strongly
argue that it should not work on a shared AA, and if it does,
that's a bug.
- Jonathan M Davis
D really needs some official thread-safe implementations of
containers, hashmaps etc.
Re: Cannot take the .keys of shared AA. Is this a regression in 2.087 or a feature?
n Thursday, August 15, 2019 11:33:06 AM MDT Piotr Mitana via Digitalmars-d-
learn wrote:
> Code:
>
> import std;
>
> shared(string[string]) dict;
>
> void main()
> {
> dict.keys;
> }
>
> Error:
>
> /dlang/dmd/linux/bin64/../../src/druntime/import/object.d(3417):
> Error: cannot implicitly convert expression aa of type
> shared(string[string]) to const(shared(string)[string])
> onlineapp.d(7): Error: template instance
> `object.keys!(shared(string[string]), shared(string), string)`
> error instantiating
>
> Before D 2.087 it compiled - is this a regression?
Not being able to implicitly convert to const is a bit odd, but arguably,
nothing should ever be called on a shared AA anyway. If an operation isn't
thread-safe, then it shouldn't work with shared. To use a shared object
safely, you have to protect access to it with a mutex or some other
synchronization mechanism, after which you would normally cast away shared
to operate on the object as thread-local while the lock is in place and then
release the lock when you're done (also making sure that no thread-local
references exist when the lock is released). Because keys is not at all
thread-safe, I'd strongly argue that it should not work on a shared AA, and
if it does, that's a bug.
- Jonathan M Davis
Cannot take the .keys of shared AA. Is this a regression in 2.087 or a feature?
Code:
import std;
shared(string[string]) dict;
void main()
{
dict.keys;
}
Error:
/dlang/dmd/linux/bin64/../../src/druntime/import/object.d(3417):
Error: cannot implicitly convert expression aa of type
shared(string[string]) to const(shared(string)[string])
onlineapp.d(7): Error: template instance
`object.keys!(shared(string[string]), shared(string), string)`
error instantiating
Before D 2.087 it compiled - is this a regression?
