Does P/Invoke execute the DLL and then shut it down?

If I use C# to P/Invoke a certain DLL, will the actual C++ DLL be run for the duration of the call and then be shut down, destroying all used memory? Or will .NET take charge of the memory used by the C++ DLL in an unmanaged "heap" and give pointers to those objects to the C++ DLL everytime I call a static function?

When I need a certain C++ project to have its memory persistant, should I be creating an ActiveX/COM Server to have its memory persist, and yet be able to call it from C#?

asked Mar 24 '13 at 12:47

Robinicks

43.2k115339541

add a comment |

When I need a certain C++ project to have its memory persistant, should I be creating an ActiveX/COM Server to have its memory persist, and yet be able to call it from C#?

asked Mar 24 '13 at 12:47

Robinicks

43.2k115339541

add a comment |

When I need a certain C++ project to have its memory persistant, should I be creating an ActiveX/COM Server to have its memory persist, and yet be able to call it from C#?

asked Mar 24 '13 at 12:47

Robinicks

43.2k115339541

When I need a certain C++ project to have its memory persistant, should I be creating an ActiveX/COM Server to have its memory persist, and yet be able to call it from C#?

c# c++ .net dll pinvoke

asked Mar 24 '13 at 12:47

Robinicks

43.2k115339541

asked Mar 24 '13 at 12:47

Robinicks

43.2k115339541

asked Mar 24 '13 at 12:47

Robinicks

43.2k115339541

asked Mar 24 '13 at 12:47

Robinicks

43.2k115339541

asked Mar 24 '13 at 12:47

Robinicks

43.2k115339541

add a comment |

2 Answers
2

active

oldest

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If I use C# to P/Invoke a certain DLL, will the actual C++ DLL be run for the duration of the call and then be shut down, destroying all used memory?

No. Once the DLL is loaded it will stay loaded. The DLL's lifetime is not tied to a function call. This means that variables in the DLL that have static storage persist beyond the initial p/invoke call.

edited Mar 24 '13 at 13:50

answered Mar 24 '13 at 12:50

David Heffernan

520k348221214

Where is the memory stored? Can you elaborate on that?

– Robinicks
Mar 24 '13 at 13:24

Unmanaged DLLs are loaded into the address space of the managed program's Application Domain. Note that you can dyamically load and unload Application Domains, which removes the unmanaged DLLs from memory when the app domain is unloaded.

– Matthew Watson
Mar 24 '13 at 13:41

Where is what memory stored? Be precise about the question.

– David Heffernan
Mar 24 '13 at 13:41

I meant where is the memory of the C++ DLL stored... when run by a .NET app? ... "will .NET take charge of the memory used by the C++ DLL in an unmanaged "heap" and give pointers to those objects to the C++ DLL everytime I call a static function?"

– Robinicks
Mar 24 '13 at 16:12

It's handled by the system. What you have is a native, unmanaged DLL. It's loaded with a call to LoadLibrary. Just like the .net runtime itself. .net doesn't "take charge" of anything. It just uses the standard platform mechanisms to load DLLs.

– David Heffernan
Mar 24 '13 at 16:13

add a comment |

If you are creating an object from a C++-DLL, it will actually persist until you delete it or rather dispose it. As you need to manually remove unmanaged objects, it will stay.

answered Mar 24 '13 at 12:51

bash.d

11.2k22036

So is it therefore possible to have a fully functional C++ project running as a DLL, and have simple static function P/Invoke'd from .NET with nothing breaking on the C++ side? Even if the C++ project uses objects and DirectX and complex things?

– Robinicks
Mar 24 '13 at 12:53

It depends on what you understand by fully functional? Consider for example COM, where you are creating unmanaged components which you can then use in a managed environment. SO it should be possible.

– bash.d
Mar 24 '13 at 12:54

add a comment |

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2 Answers
2

active

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2 Answers
2

active

oldest

votes

If I use C# to P/Invoke a certain DLL, will the actual C++ DLL be run for the duration of the call and then be shut down, destroying all used memory?

edited Mar 24 '13 at 13:50

answered Mar 24 '13 at 12:50

David Heffernan

520k348221214

Where is the memory stored? Can you elaborate on that?

– Robinicks
Mar 24 '13 at 13:24

Unmanaged DLLs are loaded into the address space of the managed program's Application Domain. Note that you can dyamically load and unload Application Domains, which removes the unmanaged DLLs from memory when the app domain is unloaded.

– Matthew Watson
Mar 24 '13 at 13:41

Where is what memory stored? Be precise about the question.

– David Heffernan
Mar 24 '13 at 13:41

I meant where is the memory of the C++ DLL stored... when run by a .NET app? ... "will .NET take charge of the memory used by the C++ DLL in an unmanaged "heap" and give pointers to those objects to the C++ DLL everytime I call a static function?"

– Robinicks
Mar 24 '13 at 16:12

It's handled by the system. What you have is a native, unmanaged DLL. It's loaded with a call to LoadLibrary. Just like the .net runtime itself. .net doesn't "take charge" of anything. It just uses the standard platform mechanisms to load DLLs.

– David Heffernan
Mar 24 '13 at 16:13

add a comment |

If I use C# to P/Invoke a certain DLL, will the actual C++ DLL be run for the duration of the call and then be shut down, destroying all used memory?

edited Mar 24 '13 at 13:50

answered Mar 24 '13 at 12:50

David Heffernan

520k348221214

Where is the memory stored? Can you elaborate on that?

– Robinicks
Mar 24 '13 at 13:24

Unmanaged DLLs are loaded into the address space of the managed program's Application Domain. Note that you can dyamically load and unload Application Domains, which removes the unmanaged DLLs from memory when the app domain is unloaded.

– Matthew Watson
Mar 24 '13 at 13:41

Where is what memory stored? Be precise about the question.

– David Heffernan
Mar 24 '13 at 13:41

I meant where is the memory of the C++ DLL stored... when run by a .NET app? ... "will .NET take charge of the memory used by the C++ DLL in an unmanaged "heap" and give pointers to those objects to the C++ DLL everytime I call a static function?"

– Robinicks
Mar 24 '13 at 16:12

It's handled by the system. What you have is a native, unmanaged DLL. It's loaded with a call to LoadLibrary. Just like the .net runtime itself. .net doesn't "take charge" of anything. It just uses the standard platform mechanisms to load DLLs.

– David Heffernan
Mar 24 '13 at 16:13

add a comment |

If I use C# to P/Invoke a certain DLL, will the actual C++ DLL be run for the duration of the call and then be shut down, destroying all used memory?

edited Mar 24 '13 at 13:50

answered Mar 24 '13 at 12:50

David Heffernan

520k348221214

If I use C# to P/Invoke a certain DLL, will the actual C++ DLL be run for the duration of the call and then be shut down, destroying all used memory?

edited Mar 24 '13 at 13:50

answered Mar 24 '13 at 12:50

David Heffernan

520k348221214

edited Mar 24 '13 at 13:50

answered Mar 24 '13 at 12:50

David Heffernan

520k348221214

answered Mar 24 '13 at 12:50

David Heffernan

520k348221214

answered Mar 24 '13 at 12:50

David Heffernan

520k348221214

Where is the memory stored? Can you elaborate on that?

– Robinicks
Mar 24 '13 at 13:24

Unmanaged DLLs are loaded into the address space of the managed program's Application Domain. Note that you can dyamically load and unload Application Domains, which removes the unmanaged DLLs from memory when the app domain is unloaded.

– Matthew Watson
Mar 24 '13 at 13:41

Where is what memory stored? Be precise about the question.

– David Heffernan
Mar 24 '13 at 13:41

I meant where is the memory of the C++ DLL stored... when run by a .NET app? ... "will .NET take charge of the memory used by the C++ DLL in an unmanaged "heap" and give pointers to those objects to the C++ DLL everytime I call a static function?"

– Robinicks
Mar 24 '13 at 16:12

It's handled by the system. What you have is a native, unmanaged DLL. It's loaded with a call to LoadLibrary. Just like the .net runtime itself. .net doesn't "take charge" of anything. It just uses the standard platform mechanisms to load DLLs.

– David Heffernan
Mar 24 '13 at 16:13

add a comment |

Where is the memory stored? Can you elaborate on that?

– Robinicks
Mar 24 '13 at 13:24

Unmanaged DLLs are loaded into the address space of the managed program's Application Domain. Note that you can dyamically load and unload Application Domains, which removes the unmanaged DLLs from memory when the app domain is unloaded.

– Matthew Watson
Mar 24 '13 at 13:41

Where is what memory stored? Be precise about the question.

– David Heffernan
Mar 24 '13 at 13:41

I meant where is the memory of the C++ DLL stored... when run by a .NET app? ... "will .NET take charge of the memory used by the C++ DLL in an unmanaged "heap" and give pointers to those objects to the C++ DLL everytime I call a static function?"

– Robinicks
Mar 24 '13 at 16:12

It's handled by the system. What you have is a native, unmanaged DLL. It's loaded with a call to LoadLibrary. Just like the .net runtime itself. .net doesn't "take charge" of anything. It just uses the standard platform mechanisms to load DLLs.

– David Heffernan
Mar 24 '13 at 16:13

Where is the memory stored? Can you elaborate on that?

– Robinicks
Mar 24 '13 at 13:24

Unmanaged DLLs are loaded into the address space of the managed program's Application Domain. Note that you can dyamically load and unload Application Domains, which removes the unmanaged DLLs from memory when the app domain is unloaded.

– Matthew Watson
Mar 24 '13 at 13:41

Where is what memory stored? Be precise about the question.

– David Heffernan
Mar 24 '13 at 13:41

I meant where is the memory of the C++ DLL stored... when run by a .NET app? ... "will .NET take charge of the memory used by the C++ DLL in an unmanaged "heap" and give pointers to those objects to the C++ DLL everytime I call a static function?"

– Robinicks
Mar 24 '13 at 16:12

It's handled by the system. What you have is a native, unmanaged DLL. It's loaded with a call to LoadLibrary. Just like the .net runtime itself. .net doesn't "take charge" of anything. It just uses the standard platform mechanisms to load DLLs.

– David Heffernan
Mar 24 '13 at 16:13

add a comment |

If you are creating an object from a C++-DLL, it will actually persist until you delete it or rather dispose it. As you need to manually remove unmanaged objects, it will stay.

answered Mar 24 '13 at 12:51

bash.d

11.2k22036

So is it therefore possible to have a fully functional C++ project running as a DLL, and have simple static function P/Invoke'd from .NET with nothing breaking on the C++ side? Even if the C++ project uses objects and DirectX and complex things?

– Robinicks
Mar 24 '13 at 12:53

It depends on what you understand by fully functional? Consider for example COM, where you are creating unmanaged components which you can then use in a managed environment. SO it should be possible.

– bash.d
Mar 24 '13 at 12:54

add a comment |

If you are creating an object from a C++-DLL, it will actually persist until you delete it or rather dispose it. As you need to manually remove unmanaged objects, it will stay.

answered Mar 24 '13 at 12:51

bash.d

11.2k22036

So is it therefore possible to have a fully functional C++ project running as a DLL, and have simple static function P/Invoke'd from .NET with nothing breaking on the C++ side? Even if the C++ project uses objects and DirectX and complex things?

– Robinicks
Mar 24 '13 at 12:53

It depends on what you understand by fully functional? Consider for example COM, where you are creating unmanaged components which you can then use in a managed environment. SO it should be possible.

– bash.d
Mar 24 '13 at 12:54

add a comment |

If you are creating an object from a C++-DLL, it will actually persist until you delete it or rather dispose it. As you need to manually remove unmanaged objects, it will stay.

answered Mar 24 '13 at 12:51

bash.d

11.2k22036

If you are creating an object from a C++-DLL, it will actually persist until you delete it or rather dispose it. As you need to manually remove unmanaged objects, it will stay.

answered Mar 24 '13 at 12:51

bash.d

11.2k22036

answered Mar 24 '13 at 12:51

bash.d

11.2k22036

answered Mar 24 '13 at 12:51

bash.d

11.2k22036

answered Mar 24 '13 at 12:51

bash.d

11.2k22036

So is it therefore possible to have a fully functional C++ project running as a DLL, and have simple static function P/Invoke'd from .NET with nothing breaking on the C++ side? Even if the C++ project uses objects and DirectX and complex things?

– Robinicks
Mar 24 '13 at 12:53

It depends on what you understand by fully functional? Consider for example COM, where you are creating unmanaged components which you can then use in a managed environment. SO it should be possible.

– bash.d
Mar 24 '13 at 12:54

add a comment |

So is it therefore possible to have a fully functional C++ project running as a DLL, and have simple static function P/Invoke'd from .NET with nothing breaking on the C++ side? Even if the C++ project uses objects and DirectX and complex things?

– Robinicks
Mar 24 '13 at 12:53

It depends on what you understand by fully functional? Consider for example COM, where you are creating unmanaged components which you can then use in a managed environment. SO it should be possible.

– bash.d
Mar 24 '13 at 12:54

So is it therefore possible to have a fully functional C++ project running as a DLL, and have simple static function P/Invoke'd from .NET with nothing breaking on the C++ side? Even if the C++ project uses objects and DirectX and complex things?

– Robinicks
Mar 24 '13 at 12:53

It depends on what you understand by fully functional? Consider for example COM, where you are creating unmanaged components which you can then use in a managed environment. SO it should be possible.

– bash.d
Mar 24 '13 at 12:54

add a comment |

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