workbench/libs/thread/detachthread.c

   1 /*
   2  * thread.library - threading and synchronisation primitives
   3  *
   4  * Copyright © 2007 Robert Norris
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the same terms as AROS itself.
   8  */
   9
  10 #include "thread_intern.h"
  11
  12 #include <proto/exec.h>
  13 #include <assert.h>
  14
  15 /*****************************************************************************
  16
  17     NAME */
  18         AROS_LH1(BOOL, DetachThread,
  19
  20 /*  SYNOPSIS */
  21         AROS_LHA(uint32_t, thread_id, D0),
  22
  23 /*  LOCATION */
  24         struct ThreadBase *, ThreadBase, 8, Thread)
  25
  26 /*  FUNCTION
  27         Detaches a thread from the parent process.
  28
  29     INPUTS
  30         thread_id - ID of thread to detach.
  31
  32     RESULT
  33         TRUE if the thread was detached, FALSE if the thread was already
  34         detached or another error occured.
  35
  36     NOTES
  37         You cannot detach a thread that is already detached.
  38
  39         Once detached, the thread is no longer accessible from any other
  40         thread.
  41
  42     EXAMPLE
  43         DetachThread(id);
  44
  45     BUGS
  46         Currently this doesn't really do anything other than make it so you
  47         can't call WaitThread() on the thread. Threads can't truly be detached
  48         from the parent process since they run in the same address space, and
  49         so when the process exits the program code and all its other resources
  50         a freed.
  51
  52         thread.library protects against this by waiting for all threads to
  53         complete (detached or not) before allowing the main process to exit.
  54
  55         Detached threads can't be truly implemented until a thread task and its
  56         allocated resources can exist independently of the process that created
  57         it.
  58
  59     SEE ALSO
  60         CreateThread(), CurrentThread(), WaitThread(), WaitAllThreads()
  61
  62     INTERNALS
  63
  64 *****************************************************************************/
  65 {
  66     AROS_LIBFUNC_INIT
  67
  68     assert(thread_id);
  69
  70     /* get thread data */
  71     struct _Thread *thread = _getthreadbyid(thread_id, ThreadBase);
  72     if (thread == NULL)
  73         return FALSE;
  74
  75     /* mark it detached */
  76     ObtainSemaphore(&thread->lock);
  77     thread->detached = TRUE;
  78     ReleaseSemaphore(&thread->lock);
  79
  80     return TRUE;
  81
  82     AROS_LIBFUNC_EXIT
  83 } /* DetachThread */