我想换一个C ++类在MATLAB MEX包装用概括的方法在这里 。 基本上，我有，它返回一个C ++对象句柄初始化MEX文件：
handle = myclass_init()
然后我可以通过这个另一MEX文件（例如myclass_amethod ），其使用该句柄调用类的方法，然后最终以myclass_delete释放C ++对象：
retval = myclass_amethod(handle, parameter)
myclass_delete(handle)
我在易于使用的一类MATLAB这个包裹起来：
classdef myclass < handle
properties(SetAccess=protected)
cpp_handle_
end
methods
% class constructor
function obj = myclass()
obj.cpp_handle_ = myclass_init();
end
% class destructor
function delete(obj)
myclass_delete(obj.cpp_handle_);
end
% class method
function amethod(parameter)
myclass_amethod(obj.cpp_handle_, parameter);
end
end
end
问题：这并不在并行代码的工作
这在非并行代码工作正常。 但是，只要我把它从内parfor ：
cls = myclass();
parfor i = 1:10
cls.amethod(i)
end
我得到一个段错误，作为类的副本在由parfor循环（每个工人）但作为每个工人是一个独立的进程C ++对象实例不被复制，导致了无效的指针。
我试图最初当每个类的方法是在一个PARFOR循环中运行，以检测，并且在这些情况下重新分配C ++对象太。 但是，因为没有办法检查对象是否已经被分配给当前的工作却还是没有，这导致了多个重新分配，然后只有一个删除（当工人退出）导致内存泄漏（见附录在底部对于细节题）。
尝试的解决方案：拷贝构造函数和使用matlab.mixin.Copyable
在C ++中，的方式来处理，这将是复制构造（以使得当包装MATLAB类被复制的C ++对象只重新分配一次）。 快速搜索带来了matlab.mixin.Copyable这似乎提供所需的功能（MATLAB手柄类，即深层副本）类类型。 因此，我已经试过如下：
classdef myclass < matlab.mixin.Copyable
properties(SetAccess=protected)
cpp_handle_
end
methods
function obj = myclass(val)
if nargin < 1
% regular constructor
obj.cpp_handle_ = rand(1);
disp(['Initialized myclass with handle: ' num2str(obj.cpp_handle_)]);
else
% copy constructor
obj.cpp_handle_ = rand(1);
disp(['Copy initialized myclass with handle: ' num2str(obj.cpp_handle_)]);
end
end
% destructor
function delete(obj)
disp(['Deleted myclass with handle: ' num2str(obj.cpp_handle_)]);
end
% class method
function amethod(obj)
disp(['Class method called with handle: ' num2str(obj.cpp_handle_)]);
end
end
end
测试此类如上述，即：
cls = myclass();
parfor i = 1:10
cls.amethod(i)
end
结果在输出：
Initialized myclass with handle: 0.65548
Class method called with handle: 0.65548
Class method called with handle: 0.65548
Class method called with handle: 0.65548
Class method called with handle: 0.65548
Class method called with handle: 0.65548
Class method called with handle: 0.65548
Class method called with handle: 0.65548
Class method called with handle: 0.65548
Class method called with handle: 0.65548
Class method called with handle: 0.65548
Deleted myclass with handle: 0.65548
Deleted myclass with handle: 0.65548
Deleted myclass with handle: 0.65548
换句话说， 似乎对PARFOR产卵工人当拷贝构造函数没有被调用 。 有没有人有任何指针，以什么我做错了，或者是否有某种方式来实现时，MATLAB包装类被复制重新初始化C ++对象句柄的期望行为？
替代做法：对工人运行时检测
仅供参考，这里是我使用的工人重新分配时的另一种方法：
classdef myclass < handle
properties(SetAccess=protected)
cpp_handle_
end
methods
function obj = myclass(val)
obj.cpp_handle_ = rand(1);
disp(['Initialized myclass with handle: ' num2str(obj.cpp_handle_)]);
end
% destructor
function delete(obj)
disp(['Deleted myclass with handle: ' num2str(obj.cpp_handle_)]);
end
% class method
function amethod(obj)
obj.check_handle()
disp(['Class method called with handle: ' num2str(obj.cpp_handle_)]);
end
% reinitialize cpp handle if in a worker:
function check_handle(obj)
try
t = getCurrentTask();
% if 'getCurrentTask()' returns a task object, it means we
% are running in a worker, so reinitialize the class
if ~isempty(t)
obj.cpp_handle_ = rand(1);
disp(['cpp_handle_ reinitialized to ' num2str(obj.cpp_handle_)]);
end
catch e
% in case of getCurrentTask() being undefined, this
% probably simply means the PCT is not installed, so
% continue without throwing an error
if ~strcmp(e.identifier, 'MATLAB:UndefinedFunction')
rethrow(e);
end
end
end
end
end
和输出：
Initialized myclass with handle: 0.034446
cpp_handle_ reinitialized to 0.55625
Class method called with handle: 0.55625
cpp_handle_ reinitialized to 0.0048098
Class method called with handle: 0.0048098
cpp_handle_ reinitialized to 0.58711
Class method called with handle: 0.58711
cpp_handle_ reinitialized to 0.81725
Class method called with handle: 0.81725
cpp_handle_ reinitialized to 0.43991
cpp_handle_ reinitialized to 0.79006
cpp_handle_ reinitialized to 0.0015995
Class method called with handle: 0.0015995
cpp_handle_ reinitialized to 0.0042699
cpp_handle_ reinitialized to 0.51094
Class method called with handle: 0.51094
Class method called with handle: 0.0042699
Class method called with handle: 0.43991
cpp_handle_ reinitialized to 0.45428
Deleted myclass with handle: 0.0042699
Class method called with handle: 0.79006
Deleted myclass with handle: 0.43991
Deleted myclass with handle: 0.79006
Class method called with handle: 0.45428
从上面可以看出，在工人中运行时确实现在发生再分配。 然而， 析构函数只为每个工人调用一次，无论在C ++类是有多少时间重新分配，导致内存泄漏。
解决方案：使用loadobj
以下工作：
classdef myclass < handle
properties(SetAccess=protected, Transient=true)
cpp_handle_
end
methods(Static=true)
function obj = loadobj(a)
a.cpp_handle_ = rand(1);
disp(['Load initialized encoder with handle: ' num2str(a.cpp_handle_)]);
obj = a;
end
end
methods
function obj = myclass(val)
obj.cpp_handle_ = rand(1);
disp(['Initialized myclass with handle: ' num2str(obj.cpp_handle_)]);
end
% destructor
function delete(obj)
disp(['Deleted myclass with handle: ' num2str(obj.cpp_handle_)]);
end
% class method
function amethod(obj)
disp(['Class method called with handle: ' num2str(obj.cpp_handle_)]);
end
end
end
