digitalmars.D.learn - Memory management by interfacing C/C++
- Ferhat =?UTF-8?B?S3VydHVsbXXFnw==?= (45/45) Apr 27 2019 Hi,
- Paul Backus (5/18) Apr 27 2019 D's GC only collects memory allocated with D's `new` operator.
- Ferhat =?UTF-8?B?S3VydHVsbXXFnw==?= (4/25) Apr 28 2019 You are right. I am rewriting the things using mallocs, and will
- Paul Backus (5/9) Apr 28 2019 core.stdc.stdlib.free is (as the name suggests) the standard C
- Ferhat =?UTF-8?B?S3VydHVsbXXFnw==?= (26/36) Apr 29 2019 Thank you. It is now like:
- 9il (17/62) Apr 29 2019 Hello Ferhat,
- Ferhat =?UTF-8?B?S3VydHVsbXXFnw==?= (7/25) Apr 29 2019 An opencv d binding using ndslice substituting cv::Mat would be
Hi,
I am wrapping some C++ code for my personal project (opencvd),
and I am creating so many array pointers at cpp side and
containing them in structs. I want to learn if I am leaking
memory like crazy, although I am not facing crashes so far. Is GC
of D handling things for me? Here is an example:
```
//declaration in d
struct IntVector {
int* val;
int length;
}
// in cpp
typedef struct IntVector {
int* val;
int length;
} IntVector;
// cpp function returning a struct containing an array pointer
allocated with "new" op.
IntVector Subdiv2D_GetLeadingEdgeList(Subdiv2D sd){
std::vector<int> iv;
sd->getLeadingEdgeList(iv);
int *cintv = new int[iv.size()]; // I don't call delete
anywhere?
for(size_t i=0; i < iv.size(); i++){
cintv[i] = iv[i];
}
IntVector ret = {cintv, (int)iv.size()};
return ret;
};
// call extern c function in d:
extern (C) IntVector Subdiv2D_GetLeadingEdgeList(Subdiv2d sd);
int[] getLeadingEdgeList(){
IntVector intv = Subdiv2D_GetLeadingEdgeList(this);
int[] ret = intv.val[0..intv.length]; // just D magic. Still
no delete anywhere!
return ret;
}
```
The question is now: what will happen to "int *cintv" which is
allocated with new operator in cpp code? I have many code similar
in the project, but I have not encounter any problem so far even
in looped video processings. Is GC of D doing deallocation
automagically?
https://github.com/aferust/opencvd
Apr 27 2019
On Saturday, 27 April 2019 at 22:25:58 UTC, Ferhat Kurtulmuş wrote:Hi, I am wrapping some C++ code for my personal project (opencvd), and I am creating so many array pointers at cpp side and containing them in structs. I want to learn if I am leaking memory like crazy, although I am not facing crashes so far. Is GC of D handling things for me? Here is an example: [...] The question is now: what will happen to "int *cintv" which is allocated with new operator in cpp code? I have many code similar in the project, but I have not encounter any problem so far even in looped video processings. Is GC of D doing deallocation automagically? https://github.com/aferust/opencvdD's GC only collects memory allocated with D's `new` operator. Memory allocated by C++'s `new` operator must be freed by C++'s `delete` operator.
Apr 27 2019
On Sunday, 28 April 2019 at 03:54:17 UTC, Paul Backus wrote:On Saturday, 27 April 2019 at 22:25:58 UTC, Ferhat Kurtulmuş wrote:You are right. I am rewriting the things using mallocs, and will use core.stdc.stdlib.free on d side. I am not sure if I can use core.stdc.stdlib.free to destroy arrays allocated with new op.Hi, I am wrapping some C++ code for my personal project (opencvd), and I am creating so many array pointers at cpp side and containing them in structs. I want to learn if I am leaking memory like crazy, although I am not facing crashes so far. Is GC of D handling things for me? Here is an example: [...] The question is now: what will happen to "int *cintv" which is allocated with new operator in cpp code? I have many code similar in the project, but I have not encounter any problem so far even in looped video processings. Is GC of D doing deallocation automagically? https://github.com/aferust/opencvdD's GC only collects memory allocated with D's `new` operator. Memory allocated by C++'s `new` operator must be freed by C++'s `delete` operator.
Apr 28 2019
On Sunday, 28 April 2019 at 23:10:24 UTC, Ferhat Kurtulmuş wrote:You are right. I am rewriting the things using mallocs, and will use core.stdc.stdlib.free on d side. I am not sure if I can use core.stdc.stdlib.free to destroy arrays allocated with new op.core.stdc.stdlib.free is (as the name suggests) the standard C `free` function. As such, it can only be used to free memory allocated by the standard C functions `malloc`, `calloc`, and `realloc`. This is the same in D as it is in C and C++.
Apr 28 2019
Ferhat =?UTF-8?B?S3VydHVsbXXFnw==?= <aferust gmail.com> On Monday, 29 April 2019 at 00:53:34 UTC, Paul Backus wrote:On Sunday, 28 April 2019 at 23:10:24 UTC, Ferhat Kurtulmuş wrote:Thank you. It is now like: /* c/cpp side */ extern (C) void deleteArr(void* arr); void deleteArr(void* arr){ delete[] arr; } struct IntVector Subdiv2D_GetLeadingEdgeList(Subdiv2D sd){ std::vector<int> iv; sd->getLeadingEdgeList(iv); int *cintv = new int[iv.size()]; for(size_t i=0; i < iv.size(); i++){ cintv[i] = iv[i]; } IntVector ret = {cintv, (int)iv.size()}; return ret; }; /* c/cpp side */ ... int[] getLeadingEdgeList(){ // d function IntVector intv = Subdiv2D_GetLeadingEdgeList(this); int[] ret = intv.val[0..intv.length].dup; deleteArr(intv.val); return ret; } ...You are right. I am rewriting the things using mallocs, and will use core.stdc.stdlib.free on d side. I am not sure if I can use core.stdc.stdlib.free to destroy arrays allocated with new op.core.stdc.stdlib.free is (as the name suggests) the standard C `free` function. As such, it can only be used to free memory allocated by the standard C functions `malloc`, `calloc`, and `realloc`. This is the same in D as it is in C and C++.
Apr 29 2019
On Saturday, 27 April 2019 at 22:25:58 UTC, Ferhat Kurtulmuş
wrote:
Hi,
I am wrapping some C++ code for my personal project (opencvd),
and I am creating so many array pointers at cpp side and
containing them in structs. I want to learn if I am leaking
memory like crazy, although I am not facing crashes so far. Is
GC of D handling things for me? Here is an example:
```
//declaration in d
struct IntVector {
int* val;
int length;
}
// in cpp
typedef struct IntVector {
int* val;
int length;
} IntVector;
// cpp function returning a struct containing an array pointer
allocated with "new" op.
IntVector Subdiv2D_GetLeadingEdgeList(Subdiv2D sd){
std::vector<int> iv;
sd->getLeadingEdgeList(iv);
int *cintv = new int[iv.size()]; // I don't call delete
anywhere?
for(size_t i=0; i < iv.size(); i++){
cintv[i] = iv[i];
}
IntVector ret = {cintv, (int)iv.size()};
return ret;
};
// call extern c function in d:
extern (C) IntVector Subdiv2D_GetLeadingEdgeList(Subdiv2d sd);
int[] getLeadingEdgeList(){
IntVector intv = Subdiv2D_GetLeadingEdgeList(this);
int[] ret = intv.val[0..intv.length]; // just D magic.
Still no delete anywhere!
return ret;
}
```
The question is now: what will happen to "int *cintv" which is
allocated with new operator in cpp code? I have many code
similar in the project, but I have not encounter any problem so
far even in looped video processings. Is GC of D doing
deallocation automagically?
https://github.com/aferust/opencvd
Hello Ferhat,
You can use RCArray!T or Slice!(RCI!T) [1, 2] as common thread
safe nogc types for D and C++ code.
See also integration C++ example [3] and C++ headers [4].
RCArray (fixed length)
[1] http://mir-algorithm.libmir.org/mir_rc_array.html
RCSlice (allows to get subslices)
[2]
http://mir-algorithm.libmir.org/mir_ndslice_allocation.html#rcslice
C++ integration example
[3]
https://github.com/libmir/mir-algorithm/tree/master/cpp_example
C++ headers
[4]
https://github.com/libmir/mir-algorithm/tree/master/include/mir
Apr 29 2019
On Monday, 29 April 2019 at 14:38:54 UTC, 9il wrote:On Saturday, 27 April 2019 at 22:25:58 UTC, Ferhat Kurtulmuş wrote:An opencv d binding using ndslice substituting cv::Mat would be useful like opencv-python using numpy. However, I started opencvd about a month ago, and I am very new to d. For now, I am the only contributor with zero mir.ndslice experience. When I gain more experience with ndslice, I would try it as substitution for cv::Mat. Thank you for links 9il. I will take a look at them.[...]Hello Ferhat, You can use RCArray!T or Slice!(RCI!T) [1, 2] as common thread safe nogc types for D and C++ code. See also integration C++ example [3] and C++ headers [4]. RCArray (fixed length) [1] http://mir-algorithm.libmir.org/mir_rc_array.html RCSlice (allows to get subslices) [2] http://mir-algorithm.libmir.org/mir_ndslice_allocation.html#rcslice C++ integration example [3] https://github.com/libmir/mir-algorithm/tree/master/cpp_example C++ headers [4] https://github.com/libmir/mir-algorithm/tree/master/include/mir
Apr 29 2019