Add threads for mach.

git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/base/trunk@9574 72102866-910b-0410-8b05-ffd578937521

Source/thr-mach.m

@@ -0,0 +1,610 @@
+/* GNU Objective C Runtime Thread Implementation
+   Copyright (C) 1996, 1997 Free Software Foundation, Inc.
+   Contributed by Galen C. Hunt (gchunt@cs.rochester.edu)
+   Modified for Mach threads by Bill Bumgarner <bbum@friday.com>
+   Condition functions added by Mircea Oancea <mircea@first.elcom.pub.ro>
+
+This file is part of GNU CC.
+
+GNU CC is free software; you can redistribute it and/or modify it under the
+terms of the GNU General Public License as published by the Free Software
+Foundation; either version 2, or (at your option) any later version.
+
+GNU CC is distributed in the hope that it will be useful, but WITHOUT ANY
+WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+details.
+
+You should have received a copy of the GNU General Public License
+along with GNU CC; see the file COPYING.  If not, write to
+the Free Software Foundation, 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA.  */
+
+/* As a special exception, if you link this library with files compiled with
+   GCC to produce an executable, this does not cause the resulting executable
+   to be covered by the GNU General Public License. This exception does not
+   however invalidate any other reasons why the executable file might be
+   covered by the GNU General Public License.  */
+
+#include <mach/mach.h>
+#include <mach/cthreads.h>
+#include <base/objc-gnu2next.h>
+#include <base/thr-mach.h>
+
+/* Global exit status. */
+int __objc_thread_exit_status = 0;
+
+/* Flag which lets us know if we ever became multi threaded */
+int __objc_is_multi_threaded = 0;
+
+/* The hook function called when the runtime becomes multi threaded */
+objc_thread_callback _objc_became_multi_threaded = NULL;
+
+/*
+  Use this to set the hook function that will be called when the 
+  runtime initially becomes multi threaded.
+  The hook function is only called once, meaning only when the 
+  2nd thread is spawned, not for each and every thread.
+
+  It returns the previous hook function or NULL if there is none.
+
+  A program outside of the runtime could set this to some function so
+  it can be informed; for example, the GNUstep Base Library sets it 
+  so it can implement the NSBecomingMultiThreaded notification.
+  */
+objc_thread_callback objc_set_thread_callback(objc_thread_callback func)
+{
+  objc_thread_callback temp = _objc_became_multi_threaded;
+  _objc_became_multi_threaded = func;
+  return temp;
+}
+
+/*
+  Private functions
+
+  These functions are utilized by the frontend, but they are not
+  considered part of the public interface.
+  */
+
+/*
+  First function called in a thread, starts everything else.
+
+  This function is passed to the backend by objc_thread_detach
+  as the starting function for a new thread.
+ */
+struct __objc_thread_start_state
+{
+  SEL selector;
+  id object;
+  id argument;
+};
+
+static volatile void
+__objc_thread_detach_function(struct __objc_thread_start_state *istate)
+{
+  /* Valid state? */
+  if (istate) {
+    id (*imp)(id,SEL,id);
+    SEL selector = istate->selector;
+    id object   = istate->object;
+    id argument = istate->argument;
+
+    /* Don't need anymore so free it */
+    objc_free(istate);
+
+    /* Clear out the thread local storage */
+    objc_thread_set_data(NULL);
+
+    /* Check to see if we just became multi threaded */
+    if (!__objc_is_multi_threaded)
+      {
+	__objc_is_multi_threaded = 1;
+
+	/* Call the hook function */
+	if (_objc_became_multi_threaded != NULL)
+	  (*_objc_became_multi_threaded)();
+      }
+
+    /* Call the method */
+    if ((imp = (id(*)(id, SEL, id))objc_msg_lookup(object, selector)))
+	(*imp)(object, selector, argument);
+    else
+      objc_error(object, OBJC_ERR_UNIMPLEMENTED,
+		 "objc_thread_detach called with bad selector.\n");
+  }
+  else
+    objc_error(nil, OBJC_ERR_BAD_STATE,
+	       "objc_thread_detach called with NULL state.\n");
+
+  /* Exit the thread */
+  objc_thread_exit();
+}
+
+/*
+  Frontend functions
+
+  These functions constitute the public interface to the Objective-C thread
+  and mutex functionality.
+  */
+
+/* Frontend thread functions */
+
+/*
+  Detach a new thread of execution and return its id.  Returns NULL if fails.
+  Thread is started by sending message with selector to object.  Message
+  takes a single argument.
+  */
+objc_thread_t
+objc_thread_detach(SEL selector, id object, id argument)
+{
+  struct __objc_thread_start_state *istate;
+  objc_thread_t        thread_id = NULL;
+
+  /* Allocate the state structure */
+  if (!(istate = (struct __objc_thread_start_state *)
+	objc_malloc(sizeof(*istate))))
+    return NULL;
+
+  /* Initialize the state structure */
+  istate->selector = selector;
+  istate->object = object;
+  istate->argument = argument;
+
+  /* lock access */
+  objc_mutex_lock(__objc_runtime_mutex);
+
+  /* Call the backend to spawn the thread */
+  if ((thread_id = __objc_thread_detach((void *)__objc_thread_detach_function,
+					istate)) == NULL)
+    {
+      /* failed! */
+      objc_mutex_unlock(__objc_runtime_mutex);
+      objc_free(istate);
+      return NULL;
+    }
+
+  /* Increment our thread counter */
+  __objc_runtime_threads_alive++;
+  objc_mutex_unlock(__objc_runtime_mutex);
+
+  return thread_id;
+}
+
+/*
+  Obtain the maximum thread priority that can set for t.  Under the
+  mach threading model, it is possible for the developer to adjust the
+  maximum priority downward only-- cannot be raised without superuser
+  privileges.  Once lowered, it cannot be raised.
+  */
+static int __mach_get_max_thread_priority(cthread_t t, int *base)
+{
+  thread_t threadP;
+  kern_return_t error;
+  struct thread_sched_info info;
+  unsigned int info_count=THREAD_SCHED_INFO_COUNT;
+    
+  if (t == NULL)
+    return -1;
+
+  threadP  = cthread_thread(t); 	/* get thread underlying */
+
+  error=thread_info(threadP, THREAD_SCHED_INFO, 
+		    (thread_info_t)&info, &info_count);
+
+  if (error != KERN_SUCCESS)
+    return -1;
+
+  if (base != NULL)
+    *base = info.base_priority;
+
+  return info.max_priority;
+}
+	
+/* Backend initialization functions */
+
+/* Initialize the threads subsystem. */
+int
+__objc_init_thread_system(void)
+{
+  return 0;
+}
+
+/* Close the threads subsystem. */
+int
+__objc_close_thread_system(void)
+{
+  return 0;
+}
+
+/* Backend thread functions */
+
+/* Create a new thread of execution. */
+objc_thread_t
+__objc_thread_detach(void (*func)(void *arg), void *arg)
+{
+  objc_thread_t thread_id;
+  cthread_t new_thread_handle;
+
+  /* create thread */
+  new_thread_handle = cthread_fork((cthread_fn_t)func, arg);
+
+  if(new_thread_handle)
+    {
+      /* this is not terribly portable */
+      thread_id = *(objc_thread_t *)&new_thread_handle; 
+      cthread_detach(new_thread_handle);
+    }
+  else
+    thread_id = NULL;
+  
+  return thread_id;
+}
+
+/* Set the current thread's priority. */
+int
+objc_thread_set_priority(int priority)
+{
+  objc_thread_t *t = objc_thread_id();
+  cthread_t cT = (cthread_t) t; 
+  int maxPriority = __mach_get_max_thread_priority(cT, NULL);
+  int sys_priority = 0;
+
+  if (maxPriority == -1)
+    return -1;
+
+  switch (priority)
+    {
+    case OBJC_THREAD_INTERACTIVE_PRIORITY:
+      sys_priority = maxPriority;
+      break;
+    case OBJC_THREAD_BACKGROUND_PRIORITY:
+      sys_priority = (maxPriority * 2) / 3;
+      break;
+    case OBJC_THREAD_LOW_PRIORITY:
+      sys_priority = maxPriority / 3;
+      break;
+    default:
+      return -1;
+    }
+
+  if (sys_priority == 0)
+    return -1;
+
+  /* Change the priority */
+  if (cthread_priority(cT, sys_priority, 0) == KERN_SUCCESS)
+    return 0;
+  else
+    return -1;
+}
+
+/* Return the current thread's priority. */
+int
+objc_thread_get_priority(void)
+{
+  objc_thread_t *t = objc_thread_id();
+  cthread_t cT = (cthread_t) t; /* see objc_thread_id() */
+  int basePriority;
+  int maxPriority;
+  int sys_priority = 0;
+
+  int interactiveT, backgroundT, lowT; /* thresholds */
+
+  maxPriority = __mach_get_max_thread_priority(cT, &basePriority);
+
+  if(maxPriority == -1)
+    return -1;
+
+  if (basePriority > ( (maxPriority * 2) / 3))
+    return OBJC_THREAD_INTERACTIVE_PRIORITY;
+
+  if (basePriority > ( maxPriority / 3))
+    return OBJC_THREAD_BACKGROUND_PRIORITY;
+
+  return OBJC_THREAD_LOW_PRIORITY;
+}
+
+/* Yield our process time to another thread. */
+void
+objc_thread_yield(void)
+{
+  cthread_yield();
+}
+
+/* Terminate the current thread. */
+int
+objc_thread_exit(void)
+{
+  /* Decrement our counter of the number of threads alive */
+  objc_mutex_lock(__objc_runtime_mutex);
+  __objc_runtime_threads_alive--;
+  objc_mutex_unlock(__objc_runtime_mutex);
+
+  /* exit the thread */
+  cthread_exit(&__objc_thread_exit_status);
+
+  /* Failed if we reached here */
+  return -1;
+}
+
+/* Returns an integer value which uniquely describes a thread. */
+objc_thread_t
+objc_thread_id(void)
+{
+  cthread_t self = cthread_self();
+
+  return *(objc_thread_t *)&self;
+}
+
+/* Sets the thread's local storage pointer. */
+int
+objc_thread_set_data(void *value)
+{
+  cthread_set_data(cthread_self(), (any_t) value);
+  return 0;
+}
+
+/* Returns the thread's local storage pointer. */
+void *
+objc_thread_get_data(void)
+{
+  return (void *) cthread_data(cthread_self());
+}
+
+/* Backend mutex functions */
+
+/* Allocate a mutex. */
+objc_mutex_t
+objc_mutex_allocate(objc_mutex_t mutex)
+{
+  int err = 0;
+  objc_mutex_t mutex;
+
+  /* Allocate the mutex structure */
+  if (!(mutex = (objc_mutex_t)objc_malloc(sizeof(struct objc_mutex))))
+    return NULL;
+
+  mutex->backend = objc_malloc(sizeof(struct mutex));
+
+  err = mutex_init((mutex_t)(mutex->backend));
+
+  if (err != 0)
+    {
+      objc_free(mutex->backend);
+      objc_free(mutex);
+      return NULL;
+    }
+
+  /* Initialize mutex */
+  mutex->owner = NULL;
+  mutex->depth = 0;
+  return mutex;
+}
+
+/* Deallocate a mutex. */
+int
+objc_mutex_deallocate(objc_mutex_t mutex)
+{
+  int depth;
+
+  /* Valid mutex? */
+  if (!mutex)
+    return -1;
+
+  /* Acquire lock on mutex */
+  depth = objc_mutex_lock(mutex);
+
+  mutex_clear((mutex_t)(mutex->backend));
+
+  objc_free(mutex->backend);
+  mutex->backend = NULL;
+
+  /* Free the mutex structure */
+  objc_free(mutex);
+
+  /* Return last depth */
+  return depth;
+}
+
+/* Grab a lock on a mutex. */
+int
+objc_mutex_lock(objc_mutex_t mutex)
+{
+  objc_thread_t thread_id;
+
+  /* Valid mutex? */
+  if (!mutex)
+    return -1;
+
+  /* If we already own the lock then increment depth */
+  thread_id = objc_thread_id();
+  if (mutex->owner == thread_id)
+    return ++mutex->depth;
+
+  mutex_lock((mutex_t)(mutex->backend));
+
+  /* Successfully locked the thread */
+  mutex->owner = thread_id;
+  return mutex->depth = 1;
+}
+
+/* Try to grab a lock on a mutex. */
+int
+objc_mutex_trylock(objc_mutex_t mutex)
+{
+  objc_thread_t thread_id;
+  int status;
+
+  /* Valid mutex? */
+  if (!mutex)
+    return -1;
+
+  /* If we already own the lock then increment depth */ 
+  thread_id = objc_thread_id();
+  if (mutex->owner == thread_id)
+    return ++mutex->depth;
+    
+  if (mutex_try_lock((mutex_t)(mutex->backend)) == 0)
+    status = -1;
+  else
+    status = 0;
+
+  /* Failed? */
+  if (status)
+    return status;
+
+  /* Successfully locked the thread */
+  mutex->owner = thread_id;
+  return mutex->depth = 1;
+}
+
+/* Unlock the mutex */
+int
+objc_mutex_unlock(objc_mutex_t mutex)
+{
+  objc_thread_t thread_id;
+
+  /* Valid mutex? */
+  if (!mutex)
+    return -1;
+
+  /* If another thread owns the lock then abort */
+  thread_id = objc_thread_id();
+  if (mutex->owner != thread_id)
+    return -1;
+
+  /* Decrement depth and return */
+  if (mutex->depth > 1)
+    return --mutex->depth;
+
+  /* Depth down to zero so we are no longer the owner */
+  mutex->depth = 0;
+  mutex->owner = NULL;
+
+  mutex_unlock((mutex_t)(mutex->backend));
+
+  return 0;
+}
+
+/* Backend condition mutex functions */
+
+/* Allocate a condition. */
+objc_condition_t 
+objc_condition_allocate(void)
+{
+  objc_condition_t condition;
+    
+  /* Allocate the condition mutex structure */
+  if (!(condition = 
+	(objc_condition_t)objc_malloc(sizeof(struct objc_condition))))
+    return NULL;
+
+  condition->backend = objc_malloc(sizeof(struct condition));
+  condition_init((condition_t)(condition->backend));
+
+  return condition;
+}
+
+/* Deallocate a condition. */
+int
+objc_condition_deallocate(objc_condition_t condition)
+{
+  /* Broadcast the condition */
+  if (objc_condition_broadcast(condition))
+    return -1;
+
+  condition_clear((condition_t)(condition->backend));
+  objc_free(condition->backend);
+  condition->backend = NULL;
+
+  /* Free the condition mutex structure */
+  objc_free(condition);
+  return 0;
+}
+
+/* Wait on the condition */
+int
+objc_condition_wait(objc_condition_t condition, objc_mutex_t mutex)
+{
+  objc_thread_t thread_id;
+
+  /* Valid arguments? */
+  if (!mutex || !condition)
+    return -1;
+
+  /* Make sure we are owner of mutex */
+  thread_id = objc_thread_id();
+  if (mutex->owner != thread_id)
+    return -1;
+
+  /* Cannot be locked more than once */
+  if (mutex->depth > 1)
+    return -1;
+
+  /* Virtually unlock the mutex */
+  mutex->depth = 0;
+  mutex->owner = (objc_thread_t)NULL;
+
+  condition_wait((condition_t)(condition->backend),
+		 (mutex_t)(mutex->backend));
+
+  /* Make ourselves owner of the mutex */
+  mutex->owner = thread_id;
+  mutex->depth = 1;
+
+  return 0;
+}
+
+/* Wake up all threads waiting on this condition. */
+int
+objc_condition_broadcast(objc_condition_t condition)
+{
+  /* Valid condition mutex? */
+  if (!condition)
+    return -1;
+
+  condition_broadcast((condition_t)(condition->backend));
+  return 0;
+}
+
+/* Wake up one thread waiting on this condition. */
+int
+objc_condition_signal(objc_condition_t condition)
+{
+  /* Valid condition mutex? */
+  if (!condition)
+    return -1;
+
+  condition_signal((condition_t)(condition->backend));
+  return 0;
+}
+
+/* Make the objc thread system aware that a thread which is managed
+   (started, stopped) by external code could access objc facilities
+   from now on.  This is used when you are interfacing with some
+   external non-objc-based environment/system - you must call
+   objc_thread_add() before an alien thread makes any calls to
+   Objective-C.  Do not cause the _objc_became_multi_threaded hook to
+   be executed. */
+void 
+objc_thread_add(void)
+{
+  objc_mutex_lock(__objc_runtime_mutex);
+  __objc_is_multi_threaded = 1;
+  __objc_runtime_threads_alive++;
+  objc_mutex_unlock(__objc_runtime_mutex);  
+}
+
+/* Make the objc thread system aware that a thread managed (started,
+   stopped) by some external code will no longer access objc and thus
+   can be forgotten by the objc thread system.  Call
+   objc_thread_remove() when your alien thread is done with making
+   calls to Objective-C. */
+void
+objc_thread_remove(void)
+{
+  objc_mutex_lock(__objc_runtime_mutex);
+  __objc_runtime_threads_alive--;
+  objc_mutex_unlock(__objc_runtime_mutex);  
+}
+
+/* End of File */