EC440: Threading Library

The sample code provided includes:

• ec440threads.h
• Makefile
• threads.c
• run_tests.sh

Test cases added

• test_one_thread.c: Tests the creation, execution, and cleanup of a single thread
• test_custom_schedule.c: Tests the scheduling of a few threads
• test_early_exit.c: Tests the handling of main thread exiting early
• test_many_threads.c: Tests the handling of the maximum allowed number of threads
• test_random_threads.c: Tests the handling of a few threads counting up to a random number
• test_new_threads.c: Tests the cleanup of old threads and the creation of new threads
• test_zombie_threads.c: Tests the handling of zombie threads (threads that have exited but have not been joined)
• test_wait_thread.c: Tests waiting for one busy thread to finish

threads.c

Thread control block (TCB) structure:

typedef struct thread_control_block {
  int id;
  jmp_buf registers;
  void *stack;
  enum thread_status status;
  void *ret_val;
} TCB;

Helper functions:

• void scheduler_init(): Initializes the scheduler by assigning the first thread as the main thread
• void init_handler(): Initializes the signal handler (schedule) for the timer
• TCB *get_new_thread(): Returns a new thread from the thread pool
• void thread_init(TCB *new_thread): Allocates the stack for the new thread
• void reg_init(TCB *new_thread, void *(*start_routine)(void *), void *arg): Initializes the registers for the new thread to run the start routine