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thread.h
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thread.h
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#ifndef THREADS_THREAD_H
#define THREADS_THREAD_H
#include <debug.h>
#include <list.h>
#include <stdint.h>
#include "threads/synch.h"
/* States in a thread's life cycle. */
enum thread_status
{
THREAD_RUNNING, /* Running thread. */
THREAD_READY, /* Not running but ready to run. */
THREAD_BLOCKED, /* Waiting for an event to trigger. */
THREAD_DYING /* About to be destroyed. */
};
/* Thread identifier type.
You can redefine this to whatever type you like. */
typedef int tid_t;
#define TID_ERROR ((tid_t) -1) /* Error value for tid_t. */
/* Thread priorities. */
#define PRI_MIN 0 /* Lowest priority. */
#define PRI_DEFAULT 31 /* Default priority. */
#define PRI_MAX 63 /* Highest priority. */
#define STILL_ALIVE 2 /* thread still alive */
#define WAS_KILLED 0 /* thread was killed */
#define HAD_EXITED 1 /* thread had exited */
#define INIT_STATUS -100 /* initial current status*/
/* A kernel thread or user process.
Each thread structure is stored in its own 4 kB page. The
thread structure itself sits at the very bottom of the page
(at offset 0). The rest of the page is reserved for the
thread's kernel stack, which grows downward from the top of
the page (at offset 4 kB). Here's an illustration:
4 kB +---------------------------------+
| kernel stack |
| | |
| | |
| V |
| grows downward |
| |
| |
| |
| |
| |
| |
| |
| |
+---------------------------------+
| magic |
| : |
| : |
| name |
| status |
0 kB +---------------------------------+
The upshot of this is twofold:
1. First, `struct thread' must not be allowed to grow too
big. If it does, then there will not be enough room for
the kernel stack. Our base `struct thread' is only a
few bytes in size. It probably should stay well under 1
kB.
2. Second, kernel stacks must not be allowed to grow too
large. If a stack overflows, it will corrupt the thread
state. Thus, kernel functions should not allocate large
structures or arrays as non-static local variables. Use
dynamic allocation with malloc() or palloc_get_page()
instead.
The first symptom of either of these problems will probably be
an assertion failure in thread_current(), which checks that
the `magic' member of the running thread's `struct thread' is
set to THREAD_MAGIC. Stack overflow will normally change this
value, triggering the assertion. */
/* The `elem' member has a dual purpose. It can be an element in
the run queue (thread.c), or it can be an element in a
semaphore wait list (synch.c). It can be used these two ways
only because they are mutually exclusive: only a thread in the
ready state is on the run queue, whereas only a thread in the
blocked state is on a semaphore wait list. */
struct thread
{
/* Owned by thread.c. */
tid_t tid; /* Thread identifier. */
enum thread_status status; /* Thread state. */
char name[16]; /* Name (for debugging purposes). */
uint8_t *stack; /* Saved stack pointer. */
int priority; /* Priority. */
struct list_elem allelem; /* List element for all threads list. */
/* Shared between thread.c and synch.c. */
struct list_elem elem; /* List element. */
/*File descriptors list */
struct list fd_list;
/*Size of the file descriptors */
int fd_size;
/*Executed file held by this thread */
struct file *exec_file;
/*Semaphore to wait for child to load */
struct semaphore sema_exec;
/*Semaphore to wait for child PID to exit */
struct semaphore sema_wait;
/*List of children this thread has */
struct list child_list;
/*Pointer to this thread's parent */
struct thread * parent;
#ifdef USERPROG
/* Owned by userprog/process.c. */
uint32_t *pagedir; /* Page directory. */
#endif
/* Owned by thread.c. */
unsigned magic; /* Detects stack overflow. */
};
/*New child element structure added */
struct child_element{
/*List element used to add in child list */
struct list_elem child_elem;
/*Pointer to the real child thread */
struct thread * real_child;
/*The status the child thread exits with */
int exit_status;
/*The child thread's current status */
int cur_status;
/*PID of this child */
int child_pid;
/*Flag to check if wait() is called before */
bool first_time;
/*Flag to check if load was successful */
bool loaded_success;
};
/* If false (default), use round-robin scheduler.
If true, use multi-level feedback queue scheduler.
Controlled by kernel command-line option "-o mlfqs". */
extern bool thread_mlfqs;
void thread_init (void);
void thread_start (void);
void thread_tick (void);
void thread_print_stats (void);
typedef void thread_func (void *aux);
tid_t thread_create (const char *name, int priority, thread_func *, void *);
void thread_block (void);
void thread_unblock (struct thread *);
struct thread *thread_current (void);
tid_t thread_tid (void);
const char *thread_name (void);
void thread_exit (void) NO_RETURN;
void thread_yield (void);
/* Performs some operation on thread t, given auxiliary data AUX. */
typedef void thread_action_func (struct thread *t, void *aux);
void thread_foreach (thread_action_func *, void *);
int thread_get_priority (void);
void thread_set_priority (int);
int thread_get_nice (void);
void thread_set_nice (int);
int thread_get_recent_cpu (void);
int thread_get_load_avg (void);
struct thread *thread_get (tid_t tid);
#endif /* threads/thread.h */