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digitalmars.D.learn - Call destructor directly.

reply "Agustin" <agustin.l.alvarez hotmail.com> writes:
I'm implementing some custom memory allocator, is possible to 
call an object destructor directly?

For example

void deallocate(T)(T object)
{
   assert(object !is null);

   object.~this();
   rawDeallocate(cast(void *)object);
}
Oct 20 2013
parent reply "Adam D. Ruppe" <destructionator gmail.com> writes:
On Monday, 21 October 2013 at 02:06:02 UTC, Agustin wrote:

 I'm implementing some custom memory allocator, is possible to 
 call an object destructor directly?



destroy(object);

destroy is in the automatically imported object.dm so you don't 
have to import anything,

The source code is in dmd2/src/druntime/src/object_.d, there's a 
few overloads if you are curious how it is implemented. Short 
answer is there's a pointer to the destructor in the TypeInfo and 
destroy calls it.
Oct 20 2013
next sibling parent reply "Agustin" <agustin.l.alvarez hotmail.com> writes:
On Monday, 21 October 2013 at 02:17:54 UTC, Adam D. Ruppe wrote:

 On Monday, 21 October 2013 at 02:06:02 UTC, Agustin wrote:

 I'm implementing some custom memory allocator, is possible to 
 call an object destructor directly?



 destroy(object);

 destroy is in the automatically imported object.dm so you don't 
 have to import anything,

 The source code is in dmd2/src/druntime/src/object_.d, there's 
 a few overloads if you are curious how it is implemented. Short 
 answer is there's a pointer to the destructor in the TypeInfo 
 and destroy calls it.


Thank you :)
Oct 20 2013
parent reply "Agustin" <agustin.l.alvarez hotmail.com> writes:
On Monday, 21 October 2013 at 02:26:03 UTC, Agustin wrote:

 On Monday, 21 October 2013 at 02:17:54 UTC, Adam D. Ruppe wrote:

 On Monday, 21 October 2013 at 02:06:02 UTC, Agustin wrote:

 I'm implementing some custom memory allocator, is possible to 
 call an object destructor directly?



 destroy(object);

 destroy is in the automatically imported object.dm so you 
 don't have to import anything,

 The source code is in dmd2/src/druntime/src/object_.d, there's 
 a few overloads if you are curious how it is implemented. 
 Short answer is there's a pointer to the destructor in the 
 TypeInfo and destroy calls it.


 Thank you :)


What about constructor?. My current code is:

	T allocate(T : Object, A...)(auto ref A arguments) {
		auto pMemory = rawAllocate(__traits(classInstanceSize, T), 
T.alignof); // Return void*

		emplace!T(cast(T *)pMemory, arguments);
		return cast(T) pMemory;
	}

Doesn't seems to work, and i can't find any good documentation 
about it.
Oct 20 2013
parent reply Jonathan M Davis <jmdavisProg gmx.com> writes:
On Monday, October 21, 2013 05:07:02 Agustin wrote:

 What about constructor?. My current code is:
 
 	T allocate(T : Object, A...)(auto ref A arguments) {
 		auto pMemory = rawAllocate(__traits(classInstanceSize, T),
 T.alignof); // Return void*
 
 		emplace!T(cast(T *)pMemory, arguments);
 		return cast(T) pMemory;
 	}
 
 Doesn't seems to work, and i can't find any good documentation
 about it.


IIRC, the constructor should be name __ctor.

- Jonathan M Davis
Oct 20 2013
parent reply "Agustin" <agustin.l.alvarez hotmail.com> writes:
On Monday, 21 October 2013 at 03:46:33 UTC, Jonathan M Davis 
wrote:

 On Monday, October 21, 2013 05:07:02 Agustin wrote:

 What about constructor?. My current code is:
 
 	T allocate(T : Object, A...)(auto ref A arguments) {
 		auto pMemory = rawAllocate(__traits(classInstanceSize, T),
 T.alignof); // Return void*
 
 		emplace!T(cast(T *)pMemory, arguments);
 		return cast(T) pMemory;
 	}
 
 Doesn't seems to work, and i can't find any good documentation
 about it.


 IIRC, the constructor should be name __ctor.

 - Jonathan M Davis


no property 'opCall' for type 'Main.MyClass' :(
Oct 20 2013
parent reply "Agustin" <agustin.l.alvarez hotmail.com> writes:
On Monday, 21 October 2013 at 03:50:24 UTC, Agustin wrote:

 On Monday, 21 October 2013 at 03:46:33 UTC, Jonathan M Davis 
 wrote:

 On Monday, October 21, 2013 05:07:02 Agustin wrote:

 What about constructor?. My current code is:
 
 	T allocate(T : Object, A...)(auto ref A arguments) {
 		auto pMemory = rawAllocate(__traits(classInstanceSize, T),
 T.alignof); // Return void*
 
 		emplace!T(cast(T *)pMemory, arguments);
 		return cast(T) pMemory;
 	}
 
 Doesn't seems to work, and i can't find any good documentation
 about it.


 IIRC, the constructor should be name __ctor.

 - Jonathan M Davis


 no property 'opCall' for type 'Main.MyClass' :(


Trait allMember return "__ctor", but seems like i cannot call it 
directly:

(cast(T)pMemory).__ctor(arguments); // Being pMemory void*
Oct 20 2013
parent reply Jonathan M Davis <jmdavisProg gmx.com> writes:
On Monday, October 21, 2013 05:53:46 Agustin wrote:

 On Monday, 21 October 2013 at 03:50:24 UTC, Agustin wrote:

 On Monday, 21 October 2013 at 03:46:33 UTC, Jonathan M Davis
 
 wrote:

 On Monday, October 21, 2013 05:07:02 Agustin wrote:

 What about constructor?. My current code is:
 	T allocate(T : Object, A...)(auto ref A arguments) {
 	
 		auto pMemory = rawAllocate(__traits(classInstanceSize, T),
 
 T.alignof); // Return void*
 
 		emplace!T(cast(T *)pMemory, arguments);
 		return cast(T) pMemory;
 	
 	}
 
 Doesn't seems to work, and i can't find any good documentation
 about it.


 
 IIRC, the constructor should be name __ctor.
 
 - Jonathan M Davis


 
 no property 'opCall' for type 'Main.MyClass' :(


 
 Trait allMember return "__ctor", but seems like i cannot call it
 directly:
 
 (cast(T)pMemory).__ctor(arguments); // Being pMemory void*


If you want to see how to use emplace, I'd advise looking at 
std.typecons.RefCounted's implementation:

https://github.com/D-Programming-Language/phobos/blob/master/std/typecons.d#L3505

emplace calls the constructor for you, so I don't know why you'd be trying to 
call it. But you can look at emplace's implementation if you want to see how 
to call __ctor.

For structs:
https://github.com/D-Programming-Language/phobos/blob/master/std/conv.d#L3976

For classes:
https://github.com/D-Programming-Language/phobos/blob/master/std/conv.d#L4716

I don't think that it'll work if the constructor is private though, so maybe 
that's your problem.

- Jonathan M Davis
Oct 20 2013
parent reply "Agustin" <agustin.l.alvarez hotmail.com> writes:
On Monday, 21 October 2013 at 05:17:01 UTC, Jonathan M Davis 
wrote:

 On Monday, October 21, 2013 05:53:46 Agustin wrote:

 On Monday, 21 October 2013 at 03:50:24 UTC, Agustin wrote:

 On Monday, 21 October 2013 at 03:46:33 UTC, Jonathan M Davis
 
 wrote:

 On Monday, October 21, 2013 05:07:02 Agustin wrote:

 What about constructor?. My current code is:
 	T allocate(T : Object, A...)(auto ref A arguments) {
 	
 		auto pMemory = rawAllocate(__traits(classInstanceSize, 
 T),
 
 T.alignof); // Return void*
 
 		emplace!T(cast(T *)pMemory, arguments);
 		return cast(T) pMemory;
 	
 	}
 
 Doesn't seems to work, and i can't find any good 
 documentation
 about it.


 
 IIRC, the constructor should be name __ctor.
 
 - Jonathan M Davis


 
 no property 'opCall' for type 'Main.MyClass' :(


 
 Trait allMember return "__ctor", but seems like i cannot call 
 it
 directly:
 
 (cast(T)pMemory).__ctor(arguments); // Being pMemory void*


 If you want to see how to use emplace, I'd advise looking at
 std.typecons.RefCounted's implementation:

 https://github.com/D-Programming-Language/phobos/blob/master/std/typecons.d#L3505

 emplace calls the constructor for you, so I don't know why 
 you'd be trying to
 call it. But you can look at emplace's implementation if you 
 want to see how
 to call __ctor.

 For structs:
 https://github.com/D-Programming-Language/phobos/blob/master/std/conv.d#L3976

 For classes:
 https://github.com/D-Programming-Language/phobos/blob/master/std/conv.d#L4716

 I don't think that it'll work if the constructor is private 
 though, so maybe
 that's your problem.

 - Jonathan M Davis


I'm silly the issue was at this line

		auto pMemory = rawAllocate(__traits(classInstanceSize, T), 
T.alignof);

		emplace(pMemory, arguments);

Correct was

		auto pMemory = rawAllocate(__traits(classInstanceSize, T), 
T.alignof);

		emplace(&pMemory, arguments);

Thanks guys
Oct 20 2013
parent reply "Agustin" <agustin.l.alvarez hotmail.com> writes:
On Monday, 21 October 2013 at 05:40:13 UTC, Agustin wrote:

 On Monday, 21 October 2013 at 05:17:01 UTC, Jonathan M Davis 
 wrote:

 On Monday, October 21, 2013 05:53:46 Agustin wrote:

 On Monday, 21 October 2013 at 03:50:24 UTC, Agustin wrote:

 On Monday, 21 October 2013 at 03:46:33 UTC, Jonathan M Davis
 
 wrote:

 On Monday, October 21, 2013 05:07:02 Agustin wrote:

 What about constructor?. My current code is:
 	T allocate(T : Object, A...)(auto ref A arguments) {
 	
 		auto pMemory = rawAllocate(__traits(classInstanceSize, 
 T),
 
 T.alignof); // Return void*
 
 		emplace!T(cast(T *)pMemory, arguments);
 		return cast(T) pMemory;
 	
 	}
 
 Doesn't seems to work, and i can't find any good 
 documentation
 about it.


 
 IIRC, the constructor should be name __ctor.
 
 - Jonathan M Davis


 
 no property 'opCall' for type 'Main.MyClass' :(


 
 Trait allMember return "__ctor", but seems like i cannot call 
 it
 directly:
 
 (cast(T)pMemory).__ctor(arguments); // Being pMemory void*


 If you want to see how to use emplace, I'd advise looking at
 std.typecons.RefCounted's implementation:

 https://github.com/D-Programming-Language/phobos/blob/master/std/typecons.d#L3505

 emplace calls the constructor for you, so I don't know why 
 you'd be trying to
 call it. But you can look at emplace's implementation if you 
 want to see how
 to call __ctor.

 For structs:
 https://github.com/D-Programming-Language/phobos/blob/master/std/conv.d#L3976

 For classes:
 https://github.com/D-Programming-Language/phobos/blob/master/std/conv.d#L4716

 I don't think that it'll work if the constructor is private 
 though, so maybe
 that's your problem.

 - Jonathan M Davis


 I'm silly the issue was at this line

 		auto pMemory = rawAllocate(__traits(classInstanceSize, T), 
 T.alignof);

 		emplace(pMemory, arguments);

 Correct was

 		auto pMemory = rawAllocate(__traits(classInstanceSize, T), 
 T.alignof);

 		emplace(&pMemory, arguments);

 Thanks guys


That didn't work, but after reading how emplace works, i had to 
make some changes.

	public T allocate(T : Object, A...)(auto ref A arguments) {
		auto pMemory = rawAllocate(__traits(classInstanceSize, T), 
T.alignof);
		assert(pMemory !is null, "Not enought memory on the allocator");

		byte[] * pByteMemory = cast(byte[] *) pMemory;
		*pByteMemory = typeid(T).init[];

		auto pObject = cast(T) pMemory;
		static if (is(typeof(pObject.__ctor(arguments))))
		{
			pObject.__ctor(arguments);
		}
		return pObject;
	}

That would work.
Oct 20 2013
parent reply =?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:
On 10/20/2013 10:59 PM, Agustin wrote:


 That didn't work, but after reading how emplace works, i had to make
 some changes.

      public T allocate(T : Object, A...)(auto ref A arguments) {
          auto pMemory = rawAllocate(__traits(classInstanceSize, T),
 T.alignof);


Does rawAllocate still return void*? For classes, emplace requires (or 
at least "also accepts" a slice).

Your code will be simpler if rawAllocate returned a slice:

import std.conv;

void[] rawAllocate(size_t, size_t)
{
     static ubyte[1000] buffer;
     return buffer;
}

T allocate(T : Object, A...)(auto ref A arguments) {
     auto pMemory = rawAllocate(__traits(classInstanceSize, T), T.alignof);

     return emplace!T(pMemory, arguments);
}

class C
{
     this(int i, double d)
     {}
}

void main()
{
     auto c = allocate!C(42, 1.5);
}

If it has to return void*, you can make a slice from a plain pointer 
with the following syntax:

void * rawAllocate(size_t, size_t)
{
     static ubyte[1000] buffer;
     return buffer.ptr;
}

import std.stdio;

void main()
{
     enum requiredLength = 42;
     auto rawPtr = rawAllocate(requiredLength, 16);
     auto slice = rawPtr[0..requiredLength];  // <-- slice from plain 
pointer
     writeln(slice);
}

Ali
Oct 21 2013
parent "Agustin" <agustin.l.alvarez hotmail.com> writes:
On Monday, 21 October 2013 at 07:31:30 UTC, Ali Çehreli wrote:

 On 10/20/2013 10:59 PM, Agustin wrote:


 That didn't work, but after reading how emplace works, i had


 to make

 some changes.

      public T allocate(T : Object, A...)(auto ref A


 arguments) {

          auto pMemory =


 rawAllocate(__traits(classInstanceSize, T),

 T.alignof);


 Does rawAllocate still return void*? For classes, emplace 
 requires (or at least "also accepts" a slice).

 Your code will be simpler if rawAllocate returned a slice:

 import std.conv;

 void[] rawAllocate(size_t, size_t)
 {
     static ubyte[1000] buffer;
     return buffer;
 }

 T allocate(T : Object, A...)(auto ref A arguments) {
     auto pMemory = rawAllocate(__traits(classInstanceSize, T), 
 T.alignof);

     return emplace!T(pMemory, arguments);
 }

 class C
 {
     this(int i, double d)
     {}
 }

 void main()
 {
     auto c = allocate!C(42, 1.5);
 }

 If it has to return void*, you can make a slice from a plain 
 pointer with the following syntax:

 void * rawAllocate(size_t, size_t)
 {
     static ubyte[1000] buffer;
     return buffer.ptr;
 }

 import std.stdio;

 void main()
 {
     enum requiredLength = 42;
     auto rawPtr = rawAllocate(requiredLength, 16);
     auto slice = rawPtr[0..requiredLength];  // <-- slice from 
 plain pointer
     writeln(slice);
 }

 Ali


Thanks!, i didn't knew i could do that, void[] sounds like an 
array of nothing :P.

On Monday, 21 October 2013 at 11:48:11 UTC, Benjamin Thaut wrote:

 Am 21.10.2013 04:17, schrieb Adam D. Ruppe:

 On Monday, 21 October 2013 at 02:06:02 UTC, Agustin wrote:

 I'm implementing some custom memory allocator, is possible to 
 call an
 object destructor directly?



 destroy(object);

 destroy is in the automatically imported object.dm so you 
 don't have to
 import anything,

 The source code is in dmd2/src/druntime/src/object_.d, there's 
 a few
 overloads if you are curious how it is implemented. Short 
 answer is
 there's a pointer to the destructor in the TypeInfo and 
 destroy calls it.


 Using destroy will zero the entire memory block after 
 destroying the object. If you are freeing the memory right 
 after destroying this is going to cost you performance.

 To avoid this declare:

 extern (C) void rt_finalize2(void* p, bool det = true, bool 
 resetMemory = true);

 and then call

 rt_finalize(cast(void*)object, false, false);

 Also if you want to give a nice error message in case you are 
 calling a construcor that does not exist you should take a look 
 at my AllocatorNew function:

 https://github.com/Ingrater/druntime/blob/merge64/src/core/allocator.d#L616

 Doing it the way emplace does will just result in a error 
 message

 "Dont know how to initialize a object of type YourObject"

 With some meta programming you can get error messages like:

 "Dont know how to initialize a object of type YourObject
 Available constructors:
 this(int, int)
 this(float)
 this(void*)"

 Kind Regards
 Benjamin Thaut


I just need to call the destructor of the class since the memory 
of the allocators is released at the end of the application.

         // Pre allocate 1GB.
         auto pMemory = GC.malloc(1_048_576 * 1000, 
GC.BlkAttr.NONE);

         // Allocate a linear allocator of 10MB.
         auto pLinearAllocator = new LinearAllocator(1_048_576 * 
10, pMemory);

         // Allocates a pool allocator of 50MB.
         auto pMemoryBlock = pMemory + 1_048_576 * 10;
         auto pPoolAllocator = new 
PoolAllocator!MyComponent(1_048_576 * 50, pMemory + 1_048_576 * 
10);

         // Game loop, etc.
         // ..... (When a object is called to release, it won't 
release its memory rather than cache the entry and call the 
object destructor. Releasing the object from GC

         // end of game
         exit() // Allocators are released here, because GC will 
not find any reference to it, and will call any object destructor 
left.
Oct 21 2013
prev sibling parent reply Benjamin Thaut <code benjamin-thaut.de> writes:
Am 21.10.2013 04:17, schrieb Adam D. Ruppe:

 On Monday, 21 October 2013 at 02:06:02 UTC, Agustin wrote:

 I'm implementing some custom memory allocator, is possible to call an
 object destructor directly?



 destroy(object);

 destroy is in the automatically imported object.dm so you don't have to
 import anything,

 The source code is in dmd2/src/druntime/src/object_.d, there's a few
 overloads if you are curious how it is implemented. Short answer is
 there's a pointer to the destructor in the TypeInfo and destroy calls it.


Using destroy will zero the entire memory block after destroying the 
object. If you are freeing the memory right after destroying this is 
going to cost you performance.

To avoid this declare:

extern (C) void rt_finalize2(void* p, bool det = true, bool resetMemory 
= true);

and then call

rt_finalize(cast(void*)object, false, false);

Also if you want to give a nice error message in case you are calling a 
construcor that does not exist you should take a look at my AllocatorNew 
function:

https://github.com/Ingrater/druntime/blob/merge64/src/core/allocator.d#L616

Doing it the way emplace does will just result in a error message

"Dont know how to initialize a object of type YourObject"

With some meta programming you can get error messages like:

"Dont know how to initialize a object of type YourObject
Available constructors:
this(int, int)
this(float)
this(void*)"

Kind Regards
Benjamin Thaut
Oct 21 2013
parent "Dicebot" <public dicebot.lv> writes:
On Monday, 21 October 2013 at 11:48:11 UTC, Benjamin Thaut wrote:

 Using destroy will zero the entire memory block after 
 destroying the object. If you are freeing the memory right 
 after destroying this is going to cost you performance.

 To avoid this declare:

 extern (C) void rt_finalize2(void* p, bool det = true, bool 
 resetMemory = true);


It is probably a good idea to use malloc/free for deterministic 
allocators anyway as GC is not really supposed to be used that 
way by design.
Oct 21 2013