Re: How to destruct class instances allocated by a Region-allocator over a single GC block
On 11/04/2018 1:56 AM, Eduard Staniloiu wrote: On Monday, 9 April 2018 at 14:51:24 UTC, Per Nordlöw wrote: On Monday, 9 April 2018 at 13:51:47 UTC, Steven Schveighoffer wrote: Well, you know the type, because make returned it no? The contract is, you call obj = make!X(args), then you have to call dispose(obj), where obj is of the type X. That's how it knows. If you are thinking you want to destroy the whole block at once (typed as void[]), that's not how it works. stdx.allocator is not going to help you with GC collection, it's not geared towards that purpose. Ok, thanks! If you are using a custom allocator to allocate memory then you also have to manually dispose of the memory when it is no longer needed. You can't have a custom allocator to supply you with the memory and then have the GC track and dispose of it. I get the feeling that this is what you were looking for? As long as you can use libc's free, sure you can :)
Re: How to destruct class instances allocated by a Region-allocator over a single GC block
On Monday, 9 April 2018 at 14:51:24 UTC, Per Nordlöw wrote: On Monday, 9 April 2018 at 13:51:47 UTC, Steven Schveighoffer wrote: Well, you know the type, because make returned it no? The contract is, you call obj = make!X(args), then you have to call dispose(obj), where obj is of the type X. That's how it knows. If you are thinking you want to destroy the whole block at once (typed as void[]), that's not how it works. stdx.allocator is not going to help you with GC collection, it's not geared towards that purpose. Ok, thanks! If you are using a custom allocator to allocate memory then you also have to manually dispose of the memory when it is no longer needed. You can't have a custom allocator to supply you with the memory and then have the GC track and dispose of it. I get the feeling that this is what you were looking for?
Re: How to destruct class instances allocated by a Region-allocator over a single GC block
On Monday, 9 April 2018 at 13:51:47 UTC, Steven Schveighoffer wrote: Well, you know the type, because make returned it no? The contract is, you call obj = make!X(args), then you have to call dispose(obj), where obj is of the type X. That's how it knows. If you are thinking you want to destroy the whole block at once (typed as void[]), that's not how it works. stdx.allocator is not going to help you with GC collection, it's not geared towards that purpose. Ok, thanks!
Re: How to destruct class instances allocated by a Region-allocator over a single GC block
On 4/7/18 10:57 AM, Per Nordlöw wrote: On Saturday, 7 April 2018 at 07:50:37 UTC, Eduard Staniloiu wrote: On Friday, 6 April 2018 at 21:49:37 UTC, Per Nordlöw wrote: On Tuesday, 3 April 2018 at 09:14:28 UTC, Eduard Staniloiu wrote: So, say `reg` is your allocator, your workflow would be auto obj = reg.make!Type(args); /* do stuff */ reg.dispose(obj); // If Type has a __dtor, it will call obj.__dtor // and then reg.deallocate(obj) If I do sucessive calls to reg.make!X where X are different kinds of classes of different sizes how does reg.dispose(obj) figure out at which address(es) (where emplace filled in the data) the objects reside? It can't figure out. With custom allocators you have to manually do the memory management, so the responsibility of when and which object needs to be destroyed falls on the user of the custom allocator. IMHO, such a complexity should be wrapped in a typed allocation layer. Have Andrei spoken anything about `TypedAllocator`(s) to wrap this complexity? Well, you know the type, because make returned it no? The contract is, you call obj = make!X(args), then you have to call dispose(obj), where obj is of the type X. That's how it knows. If you are thinking you want to destroy the whole block at once (typed as void[]), that's not how it works. stdx.allocator is not going to help you with GC collection, it's not geared towards that purpose. -Steve
Re: How to destruct class instances allocated by a Region-allocator over a single GC block
On Saturday, 7 April 2018 at 07:50:37 UTC, Eduard Staniloiu wrote: On Friday, 6 April 2018 at 21:49:37 UTC, Per Nordlöw wrote: On Tuesday, 3 April 2018 at 09:14:28 UTC, Eduard Staniloiu wrote: So, say `reg` is your allocator, your workflow would be auto obj = reg.make!Type(args); /* do stuff */ reg.dispose(obj); // If Type has a __dtor, it will call obj.__dtor // and then reg.deallocate(obj) If I do sucessive calls to reg.make!X where X are different kinds of classes of different sizes how does reg.dispose(obj) figure out at which address(es) (where emplace filled in the data) the objects reside? It can't figure out. With custom allocators you have to manually do the memory management, so the responsibility of when and which object needs to be destroyed falls on the user of the custom allocator. IMHO, such a complexity should be wrapped in a typed allocation layer. Have Andrei spoken anything about `TypedAllocator`(s) to wrap this complexity?
Re: How to destruct class instances allocated by a Region-allocator over a single GC block
On Friday, 6 April 2018 at 21:49:37 UTC, Per Nordlöw wrote: On Tuesday, 3 April 2018 at 09:14:28 UTC, Eduard Staniloiu wrote: So, say `reg` is your allocator, your workflow would be auto obj = reg.make!Type(args); /* do stuff */ reg.dispose(obj); // If Type has a __dtor, it will call obj.__dtor // and then reg.deallocate(obj) If I do sucessive calls to reg.make!X where X are different kinds of classes of different sizes how does reg.dispose(obj) figure out at which address(es) (where emplace filled in the data) the objects reside? It can't figure out. With custom allocators you have to manually do the memory management, so the responsibility of when and which object needs to be destroyed falls on the user of the custom allocator.
Re: How to destruct class instances allocated by a Region-allocator over a single GC block
On Tuesday, 3 April 2018 at 09:14:28 UTC, Eduard Staniloiu wrote: So, say `reg` is your allocator, your workflow would be auto obj = reg.make!Type(args); /* do stuff */ reg.dispose(obj); // If Type has a __dtor, it will call obj.__dtor // and then reg.deallocate(obj) If I do sucessive calls to reg.make!X where X are different kinds of classes of different sizes how does reg.dispose(obj) figure out at which address(es) (where emplace filled in the data) the objects reside?
Re: How to destruct class instances allocated by a Region-allocator over a single GC block
On Monday, 2 April 2018 at 21:32:47 UTC, Steven Schveighoffer wrote: On 4/2/18 5:16 PM, Per Nordlöw wrote: On Monday, 2 April 2018 at 20:43:01 UTC, Alexandru Jercaianu wrote: I am not completely sure how to solve this, but maybe we can find some clues here [1]. It seems like we should use addRoot on the buffer returned by GC.instance.allocate to keep it alive. Then, we can use addRange on each node after allocation and somehow use 'TypeInfo' to trigger destructors. I'll dig into this more tomorrow and come back with a better answer. How can there not be a documented answer for this question, given that std.experimental.allocator has been in Phobos for 2 years? Has std.experimental.allocator only been used for allocating `struct`s? Is the Region allocator especially misfit for constructing classes? Since a while, the GC also calls struct destructors, so it's likely to be a problem for both. Note, addRoot and addRange will NOT call the destructors appropriately. It will just prevent those memory areas from getting collected. The memory shouldn't be collected anyway because RegionAllocator should have a reference to it. The only way it will get destroyed is removing the root/range, and then it will get collected just like any other GC block -- same as it is now. It looks like std.experimental.allocator assumes you will manually destroy items (possibly via dispose), it has no mechanism to say "here's how to destroy this memory I'm allocating if you happen to collect it". -Steve The GCAllocator from std.experimental uses the druntime core.memory.GC, and allocates with a call to GC.malloc [1] The GC doesn't know how you are using the memory chunk that he provided you with. He only keeps a track of this chunk and will collect it when there are no more references to it; you could also manually free it, if you wish so, with a call to `GCAllocator.instance.deallocate`. As Steve has said, you will have to manually destroy the items. I recommend using dispose as it checks if the destroyed object has an explicit destructor, which it calls, before deallocating the memory. So, say `reg` is your allocator, your workflow would be auto obj = reg.make!Type(args); /* do stuff */ reg.dispose(obj); // If Type has a __dtor, it will call obj.__dtor // and then reg.deallocate(obj) Hope this helps. Cheers, Edi [1] - https://dlang.org/library/core/memory/gc.malloc.html
Re: How to destruct class instances allocated by a Region-allocator over a single GC block
On 4/2/18 5:16 PM, Per Nordlöw wrote: On Monday, 2 April 2018 at 20:43:01 UTC, Alexandru Jercaianu wrote: I am not completely sure how to solve this, but maybe we can find some clues here [1]. It seems like we should use addRoot on the buffer returned by GC.instance.allocate to keep it alive. Then, we can use addRange on each node after allocation and somehow use 'TypeInfo' to trigger destructors. I'll dig into this more tomorrow and come back with a better answer. How can there not be a documented answer for this question, given that std.experimental.allocator has been in Phobos for 2 years? Has std.experimental.allocator only been used for allocating `struct`s? Is the Region allocator especially misfit for constructing classes? Since a while, the GC also calls struct destructors, so it's likely to be a problem for both. Note, addRoot and addRange will NOT call the destructors appropriately. It will just prevent those memory areas from getting collected. The memory shouldn't be collected anyway because RegionAllocator should have a reference to it. The only way it will get destroyed is removing the root/range, and then it will get collected just like any other GC block -- same as it is now. It looks like std.experimental.allocator assumes you will manually destroy items (possibly via dispose), it has no mechanism to say "here's how to destroy this memory I'm allocating if you happen to collect it". -Steve
Re: How to destruct class instances allocated by a Region-allocator over a single GC block
On Monday, 2 April 2018 at 20:43:01 UTC, Alexandru Jercaianu wrote: I am not completely sure how to solve this, but maybe we can find some clues here [1]. It seems like we should use addRoot on the buffer returned by GC.instance.allocate to keep it alive. Then, we can use addRange on each node after allocation and somehow use 'TypeInfo' to trigger destructors. I'll dig into this more tomorrow and come back with a better answer. How can there not be a documented answer for this question, given that std.experimental.allocator has been in Phobos for 2 years? Has std.experimental.allocator only been used for allocating `struct`s? Is the Region allocator especially misfit for constructing classes? Thanks, anyway.
Re: How to destruct class instances allocated by a Region-allocator over a single GC block
On Monday, 2 April 2018 at 14:52:34 UTC, Per Nordlöw wrote: As a follow-up to https://forum.dlang.org/post/jfgpngdudtprzznrc...@forum.dlang.org [...] Hi, I am not completely sure how to solve this, but maybe we can find some clues here [1]. It seems like we should use addRoot on the buffer returned by GC.instance.allocate to keep it alive. Then, we can use addRange on each node after allocation and somehow use 'TypeInfo' to trigger destructors. I'll dig into this more tomorrow and come back with a better answer. Thanks, Alex [1] - https://dlang.org/phobos/core_memory.html
