4600-project-1

Project 1 for CSCE4600, for Team G4

Build

Build with make

Run with make run

Clean with make clean

Explanation of Solution

Counting Semaphores:

This project uses four counting semaphores:

• sem_freelist tracks the number of blocks on the freelist.

  • This prevents any thread from trying to read a nonexistent (nullptr) block from the freelist.

• sem_freelist_minus_1 tracks the number of blocks on the freelist minus 1:

  • This is used to circumvent a deadlock situation where Thread-1 (the producer) will eat the last block on the freelist and put it on list1, where Thread-2 (the transformer) will never be able to consume it, since it's blocked on the empty freelist.
  • Without this, you'd need to check that sem_freelist > 1, and the project specifications only allow the use of P() and V(), A.K.A. wait() and signal().

• sem_list1 tracks the number of blocks on list1.

  • This prevents any thread from trying to read a nonexistent (nullptr) block from list1.

• sem_list2 tracks the number of blocks on list2.

  • This prevents any thread from trying to read a nonexistent (nullptr) block from list2.

All counting semaphores were used for thread synchronization.

Binary Semaphores:

This project uses three binary semaphores:

• sem_freelist guarantees mutual exclusion when accessing the freelist.

  • This prevents memory corruption, as list accesses are thread-unsafe.

• sem_list1 guarantees mutual exclusion when accessing list1.

  • This prevents memory corruption, as list accesses are thread-unsafe.

• sem_list2 guarantees mutual exclusion when accessing list2.

  • This prevents memory corruption, as list accesses are thread-unsafe.

All binary semaphores were used for mutual exclusion.