Meeting 19: InterProcess Communication using Shared Memory

Today we are going to see how processes can communicate using shared memory

• Stack, Heap, and mapped memory segment
• POSIX Shared Memory API
• Windows Shared Memory API
• Cross-platform shared memory using QSharedMemory
• Boost interprocess library
• Exercise

Links:

• Slides
• Example Code

Exercise 19: QSharedMemory

GitHub Invitation URL: exercise19

Steps:

1. Clone the assignment for today after accepting the GitHub invitation at the link above. The repository contains five files:

• shared_ring_buffer.h and shared_ring_buffer.tpp implement a shared deque between threads.
• qt_shared_deque_1.cpp a simple process that dequeues from the buffer
• qt_shared_deque_2.cpp a simple process that enqueues a constant to the buffer
• CMakeLists.txt is the build configuration for the exercise. It builds two applications that are meant to be run at the same time.

2. Build and run the applications in separate shells. Verify they communicate properly.

3. Modify qt_shared_deque_2.cpp so that it prompts the user via standard input for an integer to enqueue as long as there is space in the buffer.

4. Recompile your applications. Start qt_shared_deque_2 first and enter in several numbers at the prompt. Then in a separate shell start qt_shared_deque_1. What happens?

5. Now, use git to commit the source files changed to the local repository.

6. Finally, use git push to synchronize the repository with that on GitHub.

You have completed the Exercise.