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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. */
/* 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), it can be an element in a semaphore
wait list (synch.c), or it can be an element in the timer/alarm sleep
list (timer.c). It can be used these three ways only because they
are mutually exclusive: only a thread in the ready state is on
the run queue, only a thread in the blocked state is on a semaphore
wait list, whereas only a thread waiting for an timer/alarm event is on
the timer/alarm sleep 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, synch.c and timer.c. */
struct list_elem elem; /* List element. */
#ifdef USERPROG
/* Owned by userprog/process.c */
struct process* process; /* Process Structure */
struct list children; /* Threads can hold processes, but not vice versa */
uint32_t *pagedir; /* Page directory. */
#endif
/* Owned by thread.c. */
unsigned magic; /* Detects stack overflow. */
int64_t wakeup_tick; /* absolute tick when to wake up the thread */
int is_donated; /* flag if threads priority has been donated by another thread */
int saved_priority; /* saved base priority in case of priority dontation */
struct list locks; /* list of locks we currently hold */
};
/* 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;
bool thread_priority_cmp_greater (const struct list_elem *a, const struct list_elem *b,
void *aux);
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);
void thread_other_set_priority (struct thread *t, int new_priority);
void thread_donate_priority (struct thread *donator, struct thread *donee);
void thread_donation_pass_back (void);
int thread_get_nice (void);
void thread_set_nice (int);
int thread_get_recent_cpu (void);
int thread_get_load_avg (void);
#endif /* threads/thread.h */
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