source: CIVL/text/include/pthread.cvl@ 67577e8

//Mutex types
enum{
PTHREAD_MUTEX_NORMAL,
PTHREAD_MUTEX_RECURSIVE,
PTHREAD_MUTEX_ERRORCHECK
};

enum{
PTHREAD_MUTEX_STALLED,
PTHREAD_MUTEX_ROBUST
};

enum{
PTHREAD_CREATE_DETACHED,
PTHREAD_CREATE_JOINABLE
};

enum{
PTHREAD_SCOPE_SYSTEM,
PTHREAD_SCOPE_PROCESS
};

enum{
PTHREAD_INHERIT_SCHED,
PTHREAD_EXPLICIT_SCHED
};

//Mutex initializer
#define __LOCK_INITIALIZER      0
#define PTHREAD_MUTEX_INITIALIZER       {0,0,0,PTHREAD_MUTEX_NORMAL,__LOCK_INITIALIZER}
#define PTHREAD_COND_INITIALIZER        {__LOCK_INITIALIZER,0}

//Error definitions
enum{
EINVAL,      //Designates an invalid value
ENOTSUP,
EOWNERDEAD,  //Designates the termination of the owning thread
EBUSY,        //Mutex is already locked
EDEADLK,      //If mutex type is errorcheck and already owns the mutex
EPERM        //If mutex is robust or errorcheck and does not own the mutex
};

/* Struct definitions */

/* pthread_attr_t struct definition
  Description: This struct corresponds to the pthread_attr_t which is the attribute of a pthread_t. It's fields
  define the way the pthread_t is able to interact (join/detach), (memory capacity), (scope) etc.
  
  Fields: void * stackaddr: The address of the attr's stack in memory
  size_t stacksize: The memory capacity for the attr's stack
  size_t guardsize: The guardsize attribute controls the size of the guard area for the created thread' stack. The
                    guardsize attribute provides protection against overflow of the stack pointer.
  int detachstate: Defines a threads ability to join with two values: PTHREAD_CREATE_DETACHED and PTHREAD_CREATE_JOINABLE
  int inheritsched: The inheritance scheduling policy of the thread
  int contentionscope: Defines the contention scope of the thread
  int schedpolicy: Determines the scheduling policy of the thread
  
*/

typedef struct {
  void *stackaddr;
  size_t stacksize;
  size_t guardsize;
  int detachstate;
  int inheritsched;
  int contentionscope;
  int schedpolicy;
} pthread_attr_t;

/* pthread_mutexattr_t struct definition
  Description: The pthread_mutexattr_t defines multiple attributes of a mutex and controls its interactions with threads 
  Fields: robust: defines the robustness of the mutex; if robust and the owning thread terminates, it will notify the 
          next thread of this to prevent deadlocks and other errors
          pshared: defines the process shared element of the thread and which processes can interact with the mutex
          protocol: defines the priority protocol of the mutex and which threads may interact first
          type: defines the type of the mutex as either PTHREAD_MUTEX_DEFAULT/NORMAL, PTHREAD_MUTEX_ERRORCHECK, or 
          PTHREAD_MUTEX_RECURSIVE, each explained in pthread_mutex_lock below
          prioceiling: defines the lowest priority the mutex's critical section can be at
*/

typedef struct {
  int robust;
  int pshared;
  int protocol;
  int type;
  int prioceiling;
}pthread_mutexattr_t;

/* pthread_mutex_t struct definition
  Description: The pthread_mutex_t is a locking mechanism for threads to interact with in order to control the scheduling
  of the threads. It can be locked, which allows for blocking of other threads waiting on the mutex and unlocked, allowing
  access. It has a pthread_mutexattr_t which defines its behavior.
  Fields: count - used for recursive mutex, incremented when locked, decremented when unlocked, mutex released when count is 0
  owner - current process owner of the mutex
  lock - int of 0 or 1, respectively 0 if unlocked, 1 if locked
  prioceiling - allows locking without adherence to the priority ceiling
  attr - see above
*/

typedef struct {
  int count;
  $proc owner;
  int lock;
  int prioceiling;
  pthread_mutexattr_t *attr;
} pthread_mutex_t;

//Unimplemented
/*
typedef struct {
  int pshared;
  clockid_t clock_id;
}pthread_condattr_t;
*/

/* pthread_cond_t struct definition
  Description: The pthread_cond_t is another locking mechanism which interacts with the mutex variable. When
  the mutex is locked, the condition can be accessed, leading the accessing thread to unlock it, and sleep
  until the signal is given
  Fields: proccount - specifies the number of processes/threads still waiting on this condition variable
  signal - Boolean value stating whether the condition is satisfied (indicated by 1) or not (0)
*/

typedef struct {
  int proccount;
  _Bool signal;
} pthread_cond_t;

/* pthread_t struct definition
  Description: The pthread_t is a struct containing a $proc variable as well as a thread attribute which defines
  its interactions with other threads. It encapsulates the $proc and allows attributes to apply to it.
  Fields: thr: the $proc variable that is the heart of the thread
  attr: see above
*/

typedef struct {
  $proc thr;
  const pthread_attr_t *attr;
} pthread_t;

typedef struct __pthread_pool_t {
  pthread_t** threads;
  int len;
} __pthread_pool_t;