Skip to main content

Using a File Mapping for IPC

File mapping enables a process to treat the contents of a file as if they were a block of memory in the process's address space. The process can use simple pointer operations to examine and modify the contents of the file. When two or more processes access the same file mapping, each process receives a pointer to memory in its own address space that it can use to read or modify the contents of the file. The processes must use a synchronization object, such as a semaphore, to prevent data corruption in a multitasking environment.

You can use a special case of file mapping to provide named shared memory between processes. If you specify the system swapping file when creating a file-mapping object, the file-mapping object is treated as a shared memory block. Other processes can access the same block of memory by opening the same file-mapping object.

File mapping is quite efficient and also provides operating-system–supported security attributes that can help prevent unauthorized data corruption. File mapping can be used only between processes on a local computer; it cannot be used over a network.

File mapping is an efficient way for two or more processes on the same computer to share data, but you must provide synchronization between the processes. For more information, see File Mapping and Synchronization.
Labels:

Comments

Post a Comment

Popular posts from this blog

MFC - Microsoft Foundation Classes Design Patterns

1 Introduction This paper describes the use of object-oriented software design patterns, as presented in Design Patterns: Elements of Reusable Object-Oriented Software by Gamma et al., within the Microsoft Foundation Class Library (MFC). MFC is used for implementing applications for Microsoft Windows operating systems. Because of the size of the MFC library, a complete analysis would have been beyond the scope of this assignment. Instead, we identified various possible locations for design patterns, using the class hierachy diagram of MFC, and studied the source carefully at these locations. When we did not find a pattern where we expected one, we have documented it anyway, with examples of how the particular problem could have been solved differently, perhaps more elegantly, using design patterns. We have included a brief introduction to MFC in Section 2 , as background information. The analysis has been split into three parts, with one section for each major design pattern ca...
1 comment
Read more

Explain Polymorphism and Flavors of Polymorphism...

Polymorphism is the ability of different objects to react in an individual manner to the same message. This notion was imported from natural languages. For example, the verb "to close" means different things when applied to different objects. Closing a door, closing a bank account, or closing a program's window are all different actions; their exact meaning is determined by the object on which the action is performed. Most object-oriented languages implement polymorphism only in the form of virtual functions. But C++ has two more mechanisms of static (meaning: compile-time) polymorphism: Operator overloading. Applying the += operator to integers or string objects, for example, is interpreted by each of these objects in an individual manner. Obviously, the underlying implementation of += differs in every type. Yet, intuitively, we can predict what results are. Templates. A vector of integers, for example, reacts differently from a vector of string objects when it receives ...
17 comments
Read more

• Why might you need exception handling be used in the constructor when memory allocation is involved?

Your first reaction should be: "Never use memory allocation in the constructor." Create a separate initialization function to do the job. You cannot return from the constructor and this is the reason you may have to use exception handling mechanism to process the memory allocation errors. You should clean up whatever objects and memory allocations you have made prior to throwing the exception, but throwing an exception from constructor may be tricky, because memory has already been allocated and there is no simple way to clean up the memory within the constructor.
Post a Comment
Read more