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livetrax/libs/glibmm2/glib/glibmm/dispatcher.cc

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// -*- c++ -*-
/* $Id: dispatcher.cc 370 2007-01-20 10:53:28Z daniel $ */
/* Copyright 2002 The gtkmm Development Team
*
* 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <glibmm/dispatcher.h>
#include <glibmm/exceptionhandler.h>
#include <glibmm/fileutils.h>
#include <glibmm/main.h>
#include <glibmm/thread.h>
#include <cerrno>
#include <fcntl.h>
#include <glib.h>
#ifdef G_OS_WIN32
# include <windows.h>
# include <io.h>
# include <direct.h>
# include <list>
#else
# include <unistd.h>
#endif
// EINTR is not defined on Tru64. I have tried including these:
// #include <sys/types.h>
// #include <sys/statvfs.h>
// #include <signal.h>
// danielk: I think someone should just do a grep on a Tru64 box. Googling
// for "tru64 EINTR" returns lots of hits telling me that handling EINTR is
// actually a requirement on Tru64. So it must exist.
#if defined(_tru64) && !defined(EINTR)
# define EINTR 0 /* TODO: should use the real define */
#endif
namespace
{
struct DispatchNotifyData
{
Glib::Dispatcher* dispatcher;
Glib::DispatchNotifier* notifier;
DispatchNotifyData()
: dispatcher (0), notifier (0) {}
DispatchNotifyData(Glib::Dispatcher* d, Glib::DispatchNotifier* n)
: dispatcher (d), notifier (n) {}
};
static void warn_failed_pipe_io(const char* what)
{
#ifdef G_OS_WIN32
const char *const message = g_win32_error_message(GetLastError());
#else
const char *const message = g_strerror(errno);
#endif
g_critical("Error in inter-thread communication: %s() failed: %s", what, message);
}
#ifdef G_OS_WIN32
static void fd_close_and_invalidate(HANDLE& fd)
{
if(fd != 0)
{
if(!CloseHandle(fd))
warn_failed_pipe_io("CloseHandle");
fd = 0;
}
}
#else /* !G_OS_WIN32 */
/*
* Set the close-on-exec flag on the file descriptor,
* so that it won't be leaked if a new process is spawned.
*/
static void fd_set_close_on_exec(int fd)
{
const int flags = fcntl(fd, F_GETFD, 0);
if(flags < 0 || fcntl(fd, F_SETFD, unsigned(flags) | FD_CLOEXEC) < 0)
warn_failed_pipe_io("fcntl");
}
static void fd_close_and_invalidate(int& fd)
{
if(fd >= 0)
{
int result;
do
result = close(fd);
while(G_UNLIKELY(result < 0) && errno == EINTR);
if(G_UNLIKELY(result < 0))
warn_failed_pipe_io("close");
fd = -1;
}
}
#endif /* !G_OS_WIN32 */
} // anonymous namespace
namespace Glib
{
class DispatchNotifier : public sigc::trackable
{
public:
~DispatchNotifier();
static DispatchNotifier* reference_instance(const Glib::RefPtr<MainContext>& context);
static void unreference_instance(DispatchNotifier* notifier);
void send_notification(Dispatcher* dispatcher);
protected:
// Only used by reference_instance(). Should be private, but that triggers
// a silly gcc warning even though DispatchNotifier has static methods.
explicit DispatchNotifier(const Glib::RefPtr<MainContext>& context);
private:
static Glib::StaticPrivate<DispatchNotifier> thread_specific_instance_;
long ref_count_;
Glib::RefPtr<MainContext> context_;
#ifdef G_OS_WIN32
Glib::Mutex mutex_;
std::list<DispatchNotifyData> notify_queue_;
HANDLE fd_receiver_;
#else
int fd_receiver_;
int fd_sender_;
#endif
void create_pipe();
bool pipe_io_handler(Glib::IOCondition condition);
// noncopyable
DispatchNotifier(const DispatchNotifier&);
DispatchNotifier& operator=(const DispatchNotifier&);
};
/**** Glib::DispatchNotifier ***********************************************/
// static
Glib::StaticPrivate<DispatchNotifier>
DispatchNotifier::thread_specific_instance_ = GLIBMM_STATIC_PRIVATE_INIT;
DispatchNotifier::DispatchNotifier(const Glib::RefPtr<MainContext>& context)
:
ref_count_ (0),
context_ (context),
#ifdef G_OS_WIN32
mutex_ (),
notify_queue_ (),
fd_receiver_ (0)
#else
fd_receiver_ (-1),
fd_sender_ (-1)
#endif
{
create_pipe();
#if defined(GLIBMM_EXCEPTIONS_ENABLED)
try
#elif defined(G_OS_WIN32)
if(fd_receiver_)
#else
if(fd_receiver_ >= 0)
#endif
{
#ifdef G_OS_WIN32
const int fd = GPOINTER_TO_INT(fd_receiver_);
#else
const int fd = fd_receiver_;
#endif
context_->signal_io().connect(sigc::mem_fun(*this, &DispatchNotifier::pipe_io_handler),
fd, Glib::IO_IN);
}
#ifdef GLIBMM_EXCEPTIONS_ENABLED
catch(...)
{
# ifndef G_OS_WIN32
fd_close_and_invalidate(fd_sender_);
# endif
fd_close_and_invalidate(fd_receiver_);
throw;
}
#endif /* GLIBMM_EXCEPTIONS_ENABLED */
}
DispatchNotifier::~DispatchNotifier()
{
#ifndef G_OS_WIN32
fd_close_and_invalidate(fd_sender_);
#endif
fd_close_and_invalidate(fd_receiver_);
}
void DispatchNotifier::create_pipe()
{
#ifdef G_OS_WIN32
// On Win32, create a synchronization object instead of a pipe and store
// its handle as fd_receiver_. Use a manual-reset event object, so that
// we can closely match the behavior on Unix in pipe_io_handler().
const HANDLE event = CreateEvent(0, TRUE, FALSE, 0);
if(!event)
{
# ifdef GLIBMM_EXCEPTIONS_ENABLED
GError* const error = g_error_new(G_FILE_ERROR, G_FILE_ERROR_FAILED,
"Failed to create event for inter-thread communication: %s",
g_win32_error_message(GetLastError()));
throw Glib::FileError(error);
# else
warn_failed_pipe_io("CreateEvent"); // TODO: see below
return;
# endif
}
fd_receiver_ = event;
#else /* !G_OS_WIN32 */
int filedes[2] = { -1, -1 };
if(pipe(filedes) < 0)
{
# ifdef GLIBMM_EXCEPTIONS_ENABLED
GError* const error = g_error_new(G_FILE_ERROR, g_file_error_from_errno(errno),
"Failed to create pipe for inter-thread communication: %s",
g_strerror(errno));
throw Glib::FileError(error);
# else
// TODO: Provide an alternative to the exception. This is not trivial
// from within a constructor, though. One possibility would be to add
// a Glib::Dispatcher::valid() method which returns whether construction
// was successful.
warn_failed_pipe_io("pipe");
return;
# endif
}
fd_set_close_on_exec(filedes[0]);
fd_set_close_on_exec(filedes[1]);
fd_receiver_ = filedes[0];
fd_sender_ = filedes[1];
#endif /* !G_OS_WIN32 */
}
// static
DispatchNotifier* DispatchNotifier::reference_instance(const Glib::RefPtr<MainContext>& context)
{
DispatchNotifier* instance = thread_specific_instance_.get();
if(!instance)
{
instance = new DispatchNotifier(context);
thread_specific_instance_.set(instance);
}
else
{
// Prevent massive mess-up.
g_return_val_if_fail(instance->context_ == context, 0);
}
++instance->ref_count_; // initially 0
return instance;
}
// static
void DispatchNotifier::unreference_instance(DispatchNotifier* notifier)
{
DispatchNotifier *const instance = thread_specific_instance_.get();
// Yes, the notifier argument is only used to check for sanity.
g_return_if_fail(instance == notifier);
if(--instance->ref_count_ <= 0)
{
g_return_if_fail(instance->ref_count_ == 0); // could be < 0 if messed up
// This causes deletion of the notifier object.
thread_specific_instance_.set(0);
}
}
void DispatchNotifier::send_notification(Dispatcher* dispatcher)
{
#ifdef G_OS_WIN32
{
const Mutex::Lock lock (mutex_);
const bool was_empty = notify_queue_.empty();
notify_queue_.push_back(DispatchNotifyData(dispatcher, this));
if(was_empty)
{
// The event will stay in signaled state until it is reset
// in pipe_io_handler() after processing the last queued event.
if(!SetEvent(fd_receiver_))
warn_failed_pipe_io("SetEvent");
}
}
#else /* !G_OS_WIN32 */
DispatchNotifyData data (dispatcher, this);
gssize n_written;
do
n_written = write(fd_sender_, &data, sizeof(data));
while(G_UNLIKELY(n_written < 0) && errno == EINTR);
// All data must be written in a single call to write(), otherwise we cannot
// guarantee reentrancy since another thread might be scheduled between two
// write() calls. From the glibc manual:
//
// "Reading or writing pipe data is atomic if the size of data written is not
// greater than PIPE_BUF. This means that the data transfer seems to be an
// instantaneous unit, in that nothing else in the system can observe a state
// in which it is partially complete. Atomic I/O may not begin right away (it
// may need to wait for buffer space or for data), but once it does begin it
// finishes immediately."
//
// The minimum value allowed by POSIX for PIPE_BUF is 512, so we are on safe
// grounds here.
if(G_UNLIKELY(n_written != sizeof(data)))
warn_failed_pipe_io("write");
#endif /* !G_OS_WIN32 */
}
bool DispatchNotifier::pipe_io_handler(Glib::IOCondition)
{
DispatchNotifyData data;
#ifdef G_OS_WIN32
{
const Mutex::Lock lock (mutex_);
// Should never be empty at this point, but let's allow for bogus
// notifications with no data available anyway; just to be safe.
if(notify_queue_.empty())
{
if(!ResetEvent(fd_receiver_))
warn_failed_pipe_io("ResetEvent");
return true;
}
data = notify_queue_.front();
notify_queue_.pop_front();
// Handle only a single event with each invocation of the I/O handler,
// and reset to nonsignaled state only after the last event in the queue
// has been processed. This matches the behavior on Unix.
if(notify_queue_.empty())
{
if(!ResetEvent(fd_receiver_))
warn_failed_pipe_io("ResetEvent");
}
}
#else /* !G_OS_WIN32 */
gssize n_read;
do
n_read = read(fd_receiver_, &data, sizeof(data));
while(G_UNLIKELY(n_read < 0) && errno == EINTR);
// Pipe I/O of a block size not greater than PIPE_BUF should be atomic.
// See the comment on atomicity in send_notification() for details.
if(G_UNLIKELY(n_read != sizeof(data)))
{
// Should probably never be zero, but for safety let's allow for bogus
// notifications when no data is actually available. Although in fact
// the read() should block in that case.
if(n_read != 0)
warn_failed_pipe_io("read");
return true;
}
#endif /* !G_OS_WIN32 */
g_return_val_if_fail(data.notifier == this, true);
#ifdef GLIBMM_EXCEPTIONS_ENABLED
// Actually, we wouldn't need the try/catch block because the Glib::Source
// C callback already does it for us. However, we do it anyway because the
// default return value is 'false', which is not what we want.
try
#endif
{
data.dispatcher->signal_(); // emit
}
#ifdef GLIBMM_EXCEPTIONS_ENABLED
catch(...)
{
Glib::exception_handlers_invoke();
}
#endif
return true;
}
/**** Glib::Dispatcher *****************************************************/
Dispatcher::Dispatcher()
:
signal_ (),
notifier_ (DispatchNotifier::reference_instance(MainContext::get_default()))
{}
Dispatcher::Dispatcher(const Glib::RefPtr<MainContext>& context)
:
signal_ (),
notifier_ (DispatchNotifier::reference_instance(context))
{}
Dispatcher::~Dispatcher()
{
DispatchNotifier::unreference_instance(notifier_);
}
void Dispatcher::emit()
{
notifier_->send_notification(this);
}
void Dispatcher::operator()()
{
notifier_->send_notification(this);
}
sigc::connection Dispatcher::connect(const sigc::slot<void>& slot)
{
return signal_.connect(slot);
}
} // namespace Glib