Get rid of THREAD_JOIN_IMPLEMENTED by adding thread_join() stub.

[pintos-anon] / src / threads / thread.c

diff --git a/src/threads/thread.c b/src/threads/thread.c
index 1b56f98508e16922de88d299cf02ec2f6f0a22f1..ae92e1d646dc50d50ce02d26747ca12a8bd82236 100644 (file)
--- a/src/threads/thread.c
+++ b/src/threads/thread.c
@@ -2,33 +2,37 @@
 #include <debug.h>
 #include <stddef.h>
 #include <random.h>
 #include <debug.h>
 #include <stddef.h>
 #include <random.h>

+#include <stdio.h>

 #include <string.h>
 #include <string.h>

+#include "threads/flags.h"

 #include "threads/interrupt.h"
 #include "threads/intr-stubs.h"
 #include "threads/mmu.h"
 #include "threads/palloc.h"
 #include "threads/switch.h"
 #include "threads/interrupt.h"
 #include "threads/intr-stubs.h"
 #include "threads/mmu.h"
 #include "threads/palloc.h"
 #include "threads/switch.h"

+#include "threads/synch.h"

 #ifdef USERPROG
 #ifdef USERPROG

-#include "userprog/gdt.h"
+#include "userprog/process.h"

 #endif
 
 #endif
 

-/* Value for struct thread's `magic' member.
+/* Random value for struct thread's `magic' member.

    Used to detect stack overflow.  See the big comment at the top
    of thread.h for details. */
    Used to detect stack overflow.  See the big comment at the top
    of thread.h for details. */

-#define THREAD_MAGIC 0x1234abcdu
+#define THREAD_MAGIC 0xcd6abf4b

 
 /* List of processes in THREAD_READY state, that is, processes
    that are ready to run but not actually running. */
 static struct list ready_list;
 
 /* Idle thread. */
 
 /* List of processes in THREAD_READY state, that is, processes
    that are ready to run but not actually running. */
 static struct list ready_list;
 
 /* Idle thread. */

-static struct thread *idle_thread;      /* Thread. */
-static void idle (void *aux UNUSED);    /* Thread function. */
+static struct thread *idle_thread;

 
 

-/* Initial thread.
-   This is the thread running main(). */
+/* Initial thread, the thread running init.c:main(). */

 static struct thread *initial_thread;
 
 static struct thread *initial_thread;
 

+/* Lock used by allocate_tid(). */
+static struct lock tid_lock;
+

 /* Stack frame for kernel_thread(). */
 struct kernel_thread_frame 
   {
 /* Stack frame for kernel_thread(). */
 struct kernel_thread_frame 
   {


@@ -37,23 +41,29 @@ struct kernel_thread_frame
     void *aux;                  /* Auxiliary data for function. */
   };
 
     void *aux;                  /* Auxiliary data for function. */
   };
 

+/* Statistics. */
+static long long idle_ticks;    /* # of timer ticks spent idle. */
+static long long kernel_ticks;  /* # of timer ticks in kernel threads. */
+static long long user_ticks;    /* # of timer ticks in user programs. */
+

 static void kernel_thread (thread_func *, void *aux);
 
 static void kernel_thread (thread_func *, void *aux);
 

+static void idle (void *aux UNUSED);

 static struct thread *running_thread (void);
 static struct thread *next_thread_to_run (void);
 static struct thread *running_thread (void);
 static struct thread *next_thread_to_run (void);

-static struct thread *new_thread (const char *name);
-static void init_thread (struct thread *, const char *name);
+static void init_thread (struct thread *, const char *name, int priority);

 static bool is_thread (struct thread *);
 static void *alloc_frame (struct thread *, size_t size);
 static bool is_thread (struct thread *);
 static void *alloc_frame (struct thread *, size_t size);

-static void destroy_thread (struct thread *);

 static void schedule (void);
 void schedule_tail (struct thread *prev);
 static void schedule (void);
 void schedule_tail (struct thread *prev);

+static tid_t allocate_tid (void);

 
 /* Initializes the threading system by transforming the code
 
 /* Initializes the threading system by transforming the code

-   that's currently running into a thread.  Note that this is
-   possible only because the loader was careful to put the bottom
-   of the stack at a page boundary; it won't work in general.
-   Also initializes the run queue.
+   that's currently running into a thread.  This can't work in
+   general and it is possible in this case only because loader.S
+   was careful to put the bottom of the stack at a page boundary.
+
+   Also initializes the run queue and the tid lock.

 
    After calling this function, be sure to initialize the page
    allocator before trying to create any threads with
 
    After calling this function, be sure to initialize the page
    allocator before trying to create any threads with


@@ -63,13 +73,14 @@ thread_init (void)
 {
   ASSERT (intr_get_level () == INTR_OFF);
 
 {
   ASSERT (intr_get_level () == INTR_OFF);
 

+  lock_init (&tid_lock, "tid");
+  list_init (&ready_list);
+

   /* Set up a thread structure for the running thread. */
   initial_thread = running_thread ();
   /* Set up a thread structure for the running thread. */
   initial_thread = running_thread ();

-  init_thread (initial_thread, "main");
+  init_thread (initial_thread, "main", PRI_DEFAULT);

   initial_thread->status = THREAD_RUNNING;
   initial_thread->status = THREAD_RUNNING;

-
-  /* Initialize run queue. */
-  list_init (&ready_list);
+  initial_thread->tid = allocate_tid ();

 }
 
 /* Starts preemptive thread scheduling by enabling interrupts.
 }
 
 /* Starts preemptive thread scheduling by enabling interrupts.


@@ -77,31 +88,69 @@ thread_init (void)
 void
 thread_start (void) 
 {
 void
 thread_start (void) 
 {

-  /* Create idle thread. */
-  idle_thread = thread_create ("idle", idle, NULL);
-  idle_thread->status = THREAD_BLOCKED;
-
-  /* Enable interrupts. */
+  thread_create ("idle", PRI_DEFAULT, idle, NULL);

   intr_enable ();
 }
 
   intr_enable ();
 }
 

-/* Creates a new kernel thread named NAME, which executes
-   FUNCTION passing AUX as the argument, and adds it to the ready
-   queue.  If thread_start() has been called, then the new thread
-   may be scheduled before thread_create() returns.  Use a
-   semaphore or some other form of synchronization if you need to
-   ensure ordering. */
-struct thread *
-thread_create (const char *name, thread_func *function, void *aux) 
+/* Called by the timer interrupt handler at each timer tick to
+   update statistics. */
+void
+thread_tick (void) 
+{
+  struct thread *t = thread_current ();
+  if (t == idle_thread)
+    idle_ticks++;
+#ifdef USERPROG
+  else if (t->pagedir != NULL)
+    user_ticks++;
+#endif
+  else
+    kernel_ticks++;
+}
+
+/* Prints thread statistics. */
+void
+thread_print_stats (void) 
+{
+  printf ("Thread: %lld idle ticks, %lld kernel ticks, %lld user ticks\n",
+          idle_ticks, kernel_ticks, user_ticks);
+}
+
+/* Creates a new kernel thread named NAME with the given initial
+   PRIORITY, which executes FUNCTION passing AUX as the argument,
+   and adds it to the ready queue.  Returns the thread identifier
+   for the new thread, or TID_ERROR if creation fails.
+
+   If thread_start() has been called, then the new thread may be
+   scheduled before thread_create() returns.  It could even exit
+   before thread_create() returns.  Contrariwise, the original
+   thread may run for any amount of time before the new thread is
+   scheduled.  Use a semaphore or some other form of
+   synchronization if you need to ensure ordering.
+
+   The code provided sets the new thread's `priority' member to
+   PRIORITY, but no actual priority scheduling is implemented.
+   Priority scheduling is the goal of Problem 1-3. */
+tid_t
+thread_create (const char *name, int priority,
+               thread_func *function, void *aux) 

 {
   struct thread *t;
   struct kernel_thread_frame *kf;
   struct switch_entry_frame *ef;
   struct switch_threads_frame *sf;
 {
   struct thread *t;
   struct kernel_thread_frame *kf;
   struct switch_entry_frame *ef;
   struct switch_threads_frame *sf;

+  tid_t tid;

 
   ASSERT (function != NULL);
 
 
   ASSERT (function != NULL);
 

-  t = new_thread (name);
+  /* Allocate thread. */
+  t = palloc_get_page (PAL_ZERO);
+  if (t == NULL)
+    return TID_ERROR;
+
+  /* Initialize thread. */
+  init_thread (t, name, priority);
+  tid = t->tid = allocate_tid ();

 
   /* Stack frame for kernel_thread(). */
   kf = alloc_frame (t, sizeof *kf);
 
   /* Stack frame for kernel_thread(). */
   kf = alloc_frame (t, sizeof *kf);


@@ -120,60 +169,28 @@ thread_create (const char *name, thread_func *function, void *aux)
   /* Add to run queue. */
   thread_unblock (t);
 
   /* Add to run queue. */
   thread_unblock (t);
 

-  return t;
+  return tid;

 }
 
 }
 

-#ifdef USERPROG
-/* Starts a new thread running a user program loaded from
-   FILENAME, and adds it to the ready queue.  If thread_start()
-   has been called, then new thread may be scheduled before
-   thread_execute() returns.*/
-bool
-thread_execute (const char *filename) 
-{
-  struct thread *t;
-  struct intr_frame *if_;
-  struct switch_entry_frame *ef;
-  struct switch_threads_frame *sf;
-  void (*start) (void);
-
-  ASSERT (filename != NULL);
-
-  t = new_thread (filename);
-  if (t == NULL)
-    return false;
-  
-  if (!addrspace_load (t, filename, &start)) 
-    PANIC ("%s: program load failed", filename);
-
-  /* Interrupt frame. */
-  if_ = alloc_frame (t, sizeof *if_);
-  if_->es = SEL_UDSEG;
-  if_->ds = SEL_UDSEG;
-  if_->eip = start;
-  if_->cs = SEL_UCSEG;
-  if_->eflags = FLAG_IF | FLAG_MBS;
-  if_->esp = PHYS_BASE;
-  if_->ss = SEL_UDSEG;
-
-  /* Stack frame for switch_entry(). */
-  ef = alloc_frame (t, sizeof *ef);
-  ef->eip = intr_exit;
-
-  /* Stack frame for switch_threads(). */
-  sf = alloc_frame (t, sizeof *sf);
-  sf->eip = switch_entry;
+/* Puts the current thread to sleep.  It will not be scheduled
+   again until awoken by thread_unblock().

 
 

-  /* Add to run queue. */
-  thread_unblock (t);
+   This function must be called with interrupts turned off.  It
+   is usually a better idea to use one of the synchronization
+   primitives in synch.h. */
+void
+thread_block (void) 
+{
+  ASSERT (!intr_context ());
+  ASSERT (intr_get_level () == INTR_OFF);

 
 

-  return true;
+  thread_current ()->status = THREAD_BLOCKED;
+  schedule ();

 }
 }

-#endif

 
 

-/* Transitions a blocked thread T from its current state to the
-   ready-to-run state.  If T is not blocked, there is no effect.
-   (Use thread_yield() to make the running thread ready.) */
+/* Transitions a blocked thread T to the ready-to-run state.
+   This is an error if T is not blocked.  (Use thread_yield() to
+   make the running thread ready.) */

 void
 thread_unblock (struct thread *t) 
 {
 void
 thread_unblock (struct thread *t) 
 {


@@ -182,20 +199,17 @@ thread_unblock (struct thread *t)
   ASSERT (is_thread (t));
 
   old_level = intr_disable ();
   ASSERT (is_thread (t));
 
   old_level = intr_disable ();

-  if (t->status == THREAD_BLOCKED) 
-    {
-      list_push_back (&ready_list, &t->elem);
-      t->status = THREAD_READY;
-    }
+  ASSERT (t->status == THREAD_BLOCKED);
+  list_push_back (&ready_list, &t->elem);
+  t->status = THREAD_READY;

   intr_set_level (old_level);
 }
 
   intr_set_level (old_level);
 }
 

-/* Returns the name of thread T. */
+/* Returns the name of the running thread. */

 const char *
 const char *

-thread_name (struct thread *t) 
+thread_name (void) 

 {
 {

-  ASSERT (is_thread (t));
-  return t->name;
+  return thread_current ()->name;

 }
 
 /* Returns the running thread.
 }
 
 /* Returns the running thread.


@@ -217,6 +231,13 @@ thread_current (void)
   return t;
 }
 
   return t;
 }
 

+/* Returns the running thread's tid. */
+tid_t
+thread_tid (void) 
+{
+  return thread_current ()->tid;
+}
+

 /* Deschedules the current thread and destroys it.  Never
    returns to the caller. */
 void
 /* Deschedules the current thread and destroys it.  Never
    returns to the caller. */
 void


@@ -224,6 +245,10 @@ thread_exit (void)
 {
   ASSERT (!intr_context ());
 
 {
   ASSERT (!intr_context ());
 

+#ifdef USERPROG
+  process_exit ();
+#endif
+

   /* Just set our status to dying and schedule another process.
      We will be destroyed during the call to schedule_tail(). */
   intr_disable ();
   /* Just set our status to dying and schedule another process.
      We will be destroyed during the call to schedule_tail(). */
   intr_disable ();


@@ -249,36 +274,47 @@ thread_yield (void)
   intr_set_level (old_level);
 }
 
   intr_set_level (old_level);
 }
 

-/* Puts the current thread to sleep.  It will not be scheduled
-   again until awoken by thread_unblock().
+/* Waits for the thread with the specified TID to terminate.  If
+   TID has already terminated or TID does not refer to an
+   immediate child of the current thread, returns immediately.

 
 

-   This function must be called with interrupts turned off.  It
-   is usually a better idea to use one of the synchronization
-   primitives in synch.h. */
+   This function will be implemented in problem 1-2.  For now, it
+   does nothing. */

 void
 void

-thread_block (void) 
+thread_join (tid_t child_tid UNUSED) 

 {
 {

-  ASSERT (!intr_context ());
-  ASSERT (intr_get_level () == INTR_OFF);
+}

 
 

-  thread_current ()->status = THREAD_BLOCKED;
-  schedule ();
+/* Sets the current thread's priority to NEW_PRIORITY. */
+void
+thread_set_priority (int new_priority) 
+{
+  thread_current ()->priority = new_priority;
+}
+
+/* Returns the current thread's priority. */
+int
+thread_get_priority (void) 
+{
+  return thread_current ()->priority;

 }
 \f
 /* Idle thread.  Executes when no other thread is ready to run. */
 static void
 idle (void *aux UNUSED) 
 {
 }
 \f
 /* Idle thread.  Executes when no other thread is ready to run. */
 static void
 idle (void *aux UNUSED) 
 {

+  idle_thread = thread_current ();
+

   for (;;) 
     {
   for (;;) 
     {

-      /* Wait for an interrupt. */
-      DEBUG (idle, "idle");
-      asm ("hlt");
-

       /* Let someone else run. */
       intr_disable ();
       thread_block ();
       intr_enable ();
       /* Let someone else run. */
       intr_disable ();
       thread_block ();
       intr_enable ();

+
+      /* Use CPU `hlt' instruction to wait for interrupt.
+         See [IA32-v2a] "HLT" and [IA32-v3] 7.7. */
+      asm ("hlt");

     }
 }
 
     }
 }
 


@@ -303,7 +339,7 @@ running_thread (void)
      down to the start of a page.  Because `struct thread' is
      always at the beginning of a page and the stack pointer is
      somewhere in the middle, this locates the curent thread. */
      down to the start of a page.  Because `struct thread' is
      always at the beginning of a page and the stack pointer is
      somewhere in the middle, this locates the curent thread. */

-  asm ("movl %%esp, %0\n" : "=g" (esp));
+  asm ("mov %0, %%esp" : "=g" (esp));

   return pg_round_down (esp);
 }
 
   return pg_round_down (esp);
 }
 


@@ -314,31 +350,20 @@ is_thread (struct thread *t)
   return t != NULL && t->magic == THREAD_MAGIC;
 }
 
   return t != NULL && t->magic == THREAD_MAGIC;
 }
 

-/* Creates a new thread named NAME and initializes its fields.
-   Returns the new thread if successful or a null pointer on
-   failure. */
-static struct thread *
-new_thread (const char *name) 
+/* Does basic initialization of T as a blocked thread named
+   NAME. */
+static void
+init_thread (struct thread *t, const char *name, int priority)

 {
 {

-  struct thread *t;
-
+  ASSERT (t != NULL);
+  ASSERT (PRI_MIN <= priority && priority <= PRI_MAX);

   ASSERT (name != NULL);
   ASSERT (name != NULL);

-  
-  t = palloc_get (PAL_ZERO);
-  if (t != NULL)
-    init_thread (t, name);
-
-  return t;
-}

 
 

-/* Initializes T as a new, blocked thread named NAME. */
-static void
-init_thread (struct thread *t, const char *name)
-{

   memset (t, 0, sizeof *t);
   memset (t, 0, sizeof *t);

+  t->status = THREAD_BLOCKED;

   strlcpy (t->name, name, sizeof t->name);
   t->stack = (uint8_t *) t + PGSIZE;
   strlcpy (t->name, name, sizeof t->name);
   t->stack = (uint8_t *) t + PGSIZE;

-  t->status = THREAD_BLOCKED;
+  t->priority = priority;

   t->magic = THREAD_MAGIC;
 }
 
   t->magic = THREAD_MAGIC;
 }
 


@@ -369,22 +394,6 @@ next_thread_to_run (void)
     return list_entry (list_pop_front (&ready_list), struct thread, elem);
 }
 
     return list_entry (list_pop_front (&ready_list), struct thread, elem);
 }
 

-/* Destroys T, which must be in the dying state and must not be
-   the running thread. */
-static void
-destroy_thread (struct thread *t) 
-{
-  ASSERT (is_thread (t));
-  ASSERT (t->status == THREAD_DYING);
-  ASSERT (t != thread_current ());
-
-#ifdef USERPROG
-  addrspace_destroy (t);
-#endif
-  if (t != initial_thread)
-    palloc_free (t);
-}
-

 /* Completes a thread switch by activating the new thread's page
    tables, and, if the previous thread is dying, destroying it.
 
 /* Completes a thread switch by activating the new thread's page
    tables, and, if the previous thread is dying, destroying it.
 


@@ -395,6 +404,10 @@ destroy_thread (struct thread *t)
    the first time a thread is scheduled it is called by
    switch_entry() (see switch.S).
 
    the first time a thread is scheduled it is called by
    switch_entry() (see switch.S).
 

+   It's not safe to call printf() until the thread switch is
+   complete.  In practice that means that printf()s should be
+   added at the end of the function.
+

    After this function and its caller returns, the thread switch
    is complete. */
 void
    After this function and its caller returns, the thread switch
    is complete. */
 void


@@ -409,20 +422,27 @@ schedule_tail (struct thread *prev)
 
 #ifdef USERPROG
   /* Activate the new address space. */
 
 #ifdef USERPROG
   /* Activate the new address space. */

-  addrspace_activate (cur);
+  process_activate ();

 #endif
 
 #endif
 

-  /* If the thread we switched from is dying, destroy it.
-     This must happen late because it's not a good idea to
-     e.g. destroy the page table you're currently using. */
+  /* If the thread we switched from is dying, destroy its struct
+     thread.  This must happen late so that thread_exit() doesn't
+     pull out the rug under itself. */

   if (prev != NULL && prev->status == THREAD_DYING) 
   if (prev != NULL && prev->status == THREAD_DYING) 

-    destroy_thread (prev);
+    {
+      ASSERT (prev != cur);
+      if (prev != initial_thread)
+        palloc_free_page (prev);
+    }

 }
 
 /* Schedules a new process.  At entry, interrupts must be off and
    the running process's state must have been changed from
    running to some other state.  This function finds another
 }
 
 /* Schedules a new process.  At entry, interrupts must be off and
    the running process's state must have been changed from
    running to some other state.  This function finds another

-   thread to run and switches to it. */
+   thread to run and switches to it.
+
+   It's not safe to call printf() until schedule_tail() has
+   completed. */

 static void
 schedule (void) 
 {
 static void
 schedule (void) 
 {


@@ -438,6 +458,20 @@ schedule (void)
     prev = switch_threads (cur, next);
   schedule_tail (prev); 
 }
     prev = switch_threads (cur, next);
   schedule_tail (prev); 
 }

+
+/* Returns a tid to use for a new thread. */
+static tid_t
+allocate_tid (void) 
+{
+  static tid_t next_tid = 1;
+  tid_t tid;
+
+  lock_acquire (&tid_lock);
+  tid = next_tid++;
+  lock_release (&tid_lock);
+
+  return tid;
+}

 \f
 /* Offset of `stack' member within `struct thread'.
    Used by switch.S, which can't figure it out on its own. */
 \f
 /* Offset of `stack' member within `struct thread'.
    Used by switch.S, which can't figure it out on its own. */