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/* Creating and controlling threads.
Copyright (C) 2005-2016 Free Software Foundation, Inc.
This program 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 3, or (at your option)
any later version.
This program 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 this program; if not, see <http://www.gnu.org/licenses/>. */
/* Written by Bruno Haible <bruno@clisp.org>, 2005.
Based on GCC's gthr-posix.h, gthr-posix95.h, gthr-solaris.h,
gthr-win32.h. */
#include <config.h>
/* Specification. */
# define _GLTHREAD_THREAD_INLINE _GL_EXTERN_INLINE
#include "glthread/thread.h"
#include <stdlib.h>
#include "glthread/lock.h"
/* ========================================================================= */
#if USE_POSIX_THREADS
#include <pthread.h>
#ifdef PTW32_VERSION
const gl_thread_t gl_null_thread /* = { .p = NULL } */;
#endif
#endif
/* ========================================================================= */
#if USE_WINDOWS_THREADS
#include <process.h>
/* -------------------------- gl_thread_t datatype -------------------------- */
/* The Thread-Local Storage (TLS) key that allows to access each thread's
'struct gl_thread_struct *' pointer. */
static DWORD self_key = (DWORD)-1;
/* Initializes self_key. This function must only be called once. */
static void
do_init_self_key (void)
{
self_key = TlsAlloc ();
/* If this fails, we're hosed. */
if (self_key == (DWORD)-1)
abort ();
}
/* Initializes self_key. */
static void
init_self_key (void)
{
gl_once_define(static, once)
gl_once (once, do_init_self_key);
}
/* This structure contains information about a thread.
It is stored in TLS under key self_key. */
struct gl_thread_struct
{
/* Fields for managing the handle. */
HANDLE volatile handle;
CRITICAL_SECTION handle_lock;
/* Fields for managing the exit value. */
void * volatile result;
/* Fields for managing the thread start. */
void * (*func) (void *);
void *arg;
};
/* Return a real HANDLE object for the current thread. */
static HANDLE
get_current_thread_handle (void)
{
HANDLE this_handle;
/* GetCurrentThread() returns a pseudo-handle, i.e. only a symbolic
identifier, not a real handle. */
if (!DuplicateHandle (GetCurrentProcess (), GetCurrentThread (),
GetCurrentProcess (), &this_handle,
0, FALSE, DUPLICATE_SAME_ACCESS))
abort ();
return this_handle;
}
gl_thread_t
gl_thread_self_func (void)
{
gl_thread_t thread;
if (self_key == (DWORD)-1)
init_self_key ();
thread = TlsGetValue (self_key);
if (thread == NULL)
{
/* This happens only in threads that have not been created through
glthread_create(), such as the main thread. */
for (;;)
{
thread =
(struct gl_thread_struct *)
malloc (sizeof (struct gl_thread_struct));
if (thread != NULL)
break;
/* Memory allocation failed. There is not much we can do. Have to
busy-loop, waiting for the availability of memory. */
Sleep (1);
}
thread->handle = get_current_thread_handle ();
InitializeCriticalSection (&thread->handle_lock);
thread->result = NULL; /* just to be deterministic */
TlsSetValue (self_key, thread);
}
return thread;
}
/* The main function of a freshly creating thread. It's a wrapper around
the FUNC and ARG arguments passed to glthread_create_func. */
static unsigned int WINAPI
wrapper_func (void *varg)
{
struct gl_thread_struct *thread = (struct gl_thread_struct *)varg;
EnterCriticalSection (&thread->handle_lock);
/* Create a new handle for the thread only if the parent thread did not yet
fill in the handle. */
if (thread->handle == NULL)
thread->handle = get_current_thread_handle ();
LeaveCriticalSection (&thread->handle_lock);
if (self_key == (DWORD)-1)
init_self_key ();
TlsSetValue (self_key, thread);
/* Run the thread. Store the exit value if the thread was not terminated
otherwise. */
thread->result = thread->func (thread->arg);
return 0;
}
int
glthread_create_func (gl_thread_t *threadp, void * (*func) (void *), void *arg)
{
struct gl_thread_struct *thread =
(struct gl_thread_struct *) malloc (sizeof (struct gl_thread_struct));
if (thread == NULL)
return ENOMEM;
thread->handle = NULL;
InitializeCriticalSection (&thread->handle_lock);
thread->result = NULL; /* just to be deterministic */
thread->func = func;
thread->arg = arg;
{
unsigned int thread_id;
HANDLE thread_handle;
thread_handle = (HANDLE)
_beginthreadex (NULL, 100000, wrapper_func, thread, 0, &thread_id);
/* calls CreateThread with the same arguments */
if (thread_handle == NULL)
{
DeleteCriticalSection (&thread->handle_lock);
free (thread);
return EAGAIN;
}
EnterCriticalSection (&thread->handle_lock);
if (thread->handle == NULL)
thread->handle = thread_handle;
else
/* thread->handle was already set by the thread itself. */
CloseHandle (thread_handle);
LeaveCriticalSection (&thread->handle_lock);
*threadp = thread;
return 0;
}
}
int
glthread_join_func (gl_thread_t thread, void **retvalp)
{
if (thread == NULL)
return EINVAL;
if (thread == gl_thread_self ())
return EDEADLK;
if (WaitForSingleObject (thread->handle, INFINITE) == WAIT_FAILED)
return EINVAL;
if (retvalp != NULL)
*retvalp = thread->result;
DeleteCriticalSection (&thread->handle_lock);
CloseHandle (thread->handle);
free (thread);
return 0;
}
int
gl_thread_exit_func (void *retval)
{
gl_thread_t thread = gl_thread_self ();
thread->result = retval;
_endthreadex (0); /* calls ExitThread (0) */
abort ();
}
#endif
/* ========================================================================= */
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