fltk/src/Fl_lock.cxx
engelsman 4e059441bd added extra text for Fl::awake() and Fl::flush()
also converted some old html tags to doxygen in Fl.cxx and Fl_lock.cxx



git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@6787 ea41ed52-d2ee-0310-a9c1-e6b18d33e121
2009-05-14 20:16:09 +00:00

400 lines
10 KiB
C++

//
// "$Id$"
//
// Multi-threading support code for the Fast Light Tool Kit (FLTK).
//
// Copyright 1998-2009 by Bill Spitzak and others.
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Library General Public
// License as published by the Free Software Foundation; either
// version 2 of the License, or (at your option) any later version.
//
// This library 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
// Library General Public License for more details.
//
// You should have received a copy of the GNU Library General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
// USA.
//
// Please report all bugs and problems on the following page:
//
// http://www.fltk.org/str.php
//
#include <FL/Fl.H>
#include <config.h>
#include <stdlib.h>
/*
From Bill:
I would prefer that FLTK contain the minimal amount of extra
stuff for doing threads. There are other portable thread
wrapper libraries out there and FLTK should not be providing
another. This file is an attempt to make minimal additions
and make them self-contained in this source file.
From Mike:
Starting with 1.1.8, we now have a callback so that you can
process awake() messages as they come in.
The API:
Fl::lock() - recursive lock. You must call this before the
first call to Fl::wait()/run() to initialize the thread
system. The lock is locked all the time except when
Fl::wait() is waiting for events.
Fl::unlock() - release the recursive lock.
Fl::awake(void*) - Causes Fl::wait() to return (with the lock
locked) even if there are no events ready.
Fl::awake(void (*cb)(void *), void*) - Call a function
in the main thread from within another thread of execution.
Fl::thread_message() - returns an argument sent to an
Fl::awake() call, or returns NULL if none. WARNING: the
current implementation only has a one-entry queue and only
returns the most recent value!
*/
#ifndef FL_DOXYGEN
Fl_Awake_Handler *Fl::awake_ring_;
void **Fl::awake_data_;
int Fl::awake_ring_size_;
int Fl::awake_ring_head_;
int Fl::awake_ring_tail_;
#endif
static const int AWAKE_RING_SIZE = 1024;
static void lock_ring();
static void unlock_ring();
/** Adds an awake handler for use in awake(). */
int Fl::add_awake_handler_(Fl_Awake_Handler func, void *data)
{
int ret = 0;
lock_ring();
if (!awake_ring_) {
awake_ring_size_ = AWAKE_RING_SIZE;
awake_ring_ = (Fl_Awake_Handler*)malloc(awake_ring_size_*sizeof(Fl_Awake_Handler));
awake_data_ = (void**)malloc(awake_ring_size_*sizeof(void*));
}
if (awake_ring_head_==awake_ring_tail_-1 || awake_ring_head_+1==awake_ring_tail_) {
// ring is full. Return -1 as an error indicator.
ret = -1;
} else {
awake_ring_[awake_ring_head_] = func;
awake_data_[awake_ring_head_] = data;
++awake_ring_head_;
if (awake_ring_head_ == awake_ring_size_)
awake_ring_head_ = 0;
}
unlock_ring();
return ret;
}
/** Gets the last stored awake handler for use in awake(). */
int Fl::get_awake_handler_(Fl_Awake_Handler &func, void *&data)
{
int ret = 0;
lock_ring();
if (!awake_ring_ || awake_ring_head_ == awake_ring_tail_) {
ret = -1;
} else {
func = awake_ring_[awake_ring_tail_];
data = awake_data_[awake_ring_tail_];
++awake_ring_tail_;
if (awake_ring_tail_ == awake_ring_size_)
awake_ring_tail_ = 0;
}
unlock_ring();
return ret;
}
//
/**
Let the main thread know an update is pending
and have it call a specific function
See void awake(void* message=0).
*/
int Fl::awake(Fl_Awake_Handler func, void *data) {
int ret = add_awake_handler_(func, data);
Fl::awake();
return ret;
}
////////////////////////////////////////////////////////////////
// Windows threading...
/** \fn void Fl::lock()
The lock() method blocks the current thread until it
can safely access FLTK widgets and data. Child threads should
call this method prior to updating any widgets or accessing
data. The main thread must call lock() to initialize
the threading support in FLTK.
Child threads must call unlock() when they are done
accessing FLTK.
When the wait() method is waiting
for input or timeouts, child threads are given access to FLTK.
Similarly, when the main thread needs to do processing, it will
wait until all child threads have called unlock() before processing
additional data.
See also: \ref advanced_multithreading
*/
/** \fn void Fl::unlock()
The unlock() method releases the lock that was set
using the lock() method. Child
threads should call this method as soon as they are finished
accessing FLTK.
See also: \ref advanced_multithreading
*/
/** \fn void Fl::awake(void* msg)
The awake() method sends a message pointer to the main thread,
causing any pending Fl::wait() call to
terminate so that the main thread can retrieve the message and any pending
redraws can be processed.
Multiple calls to Fl::awake() will queue multiple pointers
for the main thread to process, up to a system-defined (typically several
thousand) depth. The default message handler saves the last message which
can be accessed using the
Fl::thread_message() function.
The second form of awake() registers a function that will be
called by the main thread during the next message handling cycle.
awake() will return 0 if the callback function was registered,
and -1 if registration failed. Over a thousand awake callbacks can be
registered simultaneously.
In the context of a threaded application, a call to Fl::awake() with no
argument will trigger event loop handling in the main thread. Since
it is not possible to call Fl::flush() from a subsidiary thread,
Fl::awake() is the best (and only, really) substitute.
See also: \ref advanced_multithreading
*/
#ifdef WIN32
# include <windows.h>
# include <process.h>
# include <FL/x.H>
// These pointers are in Fl_win32.cxx:
extern void (*fl_lock_function)();
extern void (*fl_unlock_function)();
// The main thread's ID
static DWORD main_thread;
// Microsoft's version of a MUTEX...
CRITICAL_SECTION cs;
CRITICAL_SECTION *cs_ring;
void unlock_ring() {
LeaveCriticalSection(cs_ring);
}
void lock_ring() {
if (!cs_ring) {
cs_ring = (CRITICAL_SECTION*)malloc(sizeof(CRITICAL_SECTION));
InitializeCriticalSection(cs_ring);
}
EnterCriticalSection(cs_ring);
}
//
// 'unlock_function()' - Release the lock.
//
static void unlock_function() {
LeaveCriticalSection(&cs);
}
//
// 'lock_function()' - Get the lock.
//
static void lock_function() {
EnterCriticalSection(&cs);
}
void Fl::lock() {
if (!main_thread) InitializeCriticalSection(&cs);
lock_function();
if (!main_thread) {
fl_lock_function = lock_function;
fl_unlock_function = unlock_function;
main_thread = GetCurrentThreadId();
}
}
void Fl::unlock() {
unlock_function();
}
void Fl::awake(void* msg) {
PostThreadMessage( main_thread, fl_wake_msg, (WPARAM)msg, 0);
}
////////////////////////////////////////////////////////////////
// POSIX threading...
#elif HAVE_PTHREAD
# include <unistd.h>
# include <fcntl.h>
# include <pthread.h>
// Pipe for thread messaging via Fl::awake()...
static int thread_filedes[2];
// Mutex and state information for Fl::lock() and Fl::unlock()...
static pthread_mutex_t fltk_mutex;
static pthread_t owner;
static int counter;
static void lock_function_init_std() {
pthread_mutex_init(&fltk_mutex, NULL);
}
static void lock_function_std() {
if (!counter || owner != pthread_self()) {
pthread_mutex_lock(&fltk_mutex);
owner = pthread_self();
}
counter++;
}
static void unlock_function_std() {
if (!--counter) pthread_mutex_unlock(&fltk_mutex);
}
# ifdef PTHREAD_MUTEX_RECURSIVE
static bool lock_function_init_rec() {
pthread_mutexattr_t attrib;
pthread_mutexattr_init(&attrib);
if (pthread_mutexattr_settype(&attrib, PTHREAD_MUTEX_RECURSIVE)) {
pthread_mutexattr_destroy(&attrib);
return true;
}
pthread_mutex_init(&fltk_mutex, &attrib);
return false;
}
static void lock_function_rec() {
pthread_mutex_lock(&fltk_mutex);
}
static void unlock_function_rec() {
pthread_mutex_unlock(&fltk_mutex);
}
# endif // PTHREAD_MUTEX_RECURSIVE
void Fl::awake(void* msg) {
write(thread_filedes[1], &msg, sizeof(void*));
}
static void* thread_message_;
void* Fl::thread_message() {
void* r = thread_message_;
thread_message_ = 0;
return r;
}
static void thread_awake_cb(int fd, void*) {
read(fd, &thread_message_, sizeof(void*));
Fl_Awake_Handler func;
void *data;
while (Fl::get_awake_handler_(func, data)==0) {
(*func)(data);
}
}
// These pointers are in Fl_x.cxx:
extern void (*fl_lock_function)();
extern void (*fl_unlock_function)();
void Fl::lock() {
if (!thread_filedes[1]) {
// Initialize thread communication pipe to let threads awake FLTK
// from Fl::wait()
pipe(thread_filedes);
// Make the write side of the pipe non-blocking to avoid deadlock
// conditions (STR #1537)
fcntl(thread_filedes[1], F_SETFL,
fcntl(thread_filedes[1], F_GETFL) | O_NONBLOCK);
// Monitor the read side of the pipe so that messages sent via
// Fl::awake() from a thread will "wake up" the main thread in
// Fl::wait().
Fl::add_fd(thread_filedes[0], FL_READ, thread_awake_cb);
// Set lock/unlock functions for this system, using a system-supplied
// recursive mutex if supported...
# ifdef PTHREAD_MUTEX_RECURSIVE
if (!lock_function_init_rec()) {
fl_lock_function = lock_function_rec;
fl_unlock_function = unlock_function_rec;
} else {
# endif // PTHREAD_MUTEX_RECURSIVE
lock_function_init_std();
fl_lock_function = lock_function_std;
fl_unlock_function = unlock_function_std;
# ifdef PTHREAD_MUTEX_RECURSIVE
}
# endif // PTHREAD_MUTEX_RECURSIVE
}
fl_lock_function();
}
void Fl::unlock() {
fl_unlock_function();
}
// Mutex code for the awake ring buffer
static pthread_mutex_t *ring_mutex;
void unlock_ring() {
pthread_mutex_unlock(ring_mutex);
}
void lock_ring() {
if (!ring_mutex) {
ring_mutex = (pthread_mutex_t*)malloc(sizeof(pthread_mutex_t));
pthread_mutex_init(ring_mutex, NULL);
}
pthread_mutex_lock(ring_mutex);
}
#else
void unlock_ring() {
}
void lock_ring() {
}
void Fl::awake(void*) {
}
#endif // WIN32
//
// End of "$Id$".
//