1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544
|
/* 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 Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
#include <glibmm/dispatcher.h>
#include <glibmm/exceptionhandler.h>
#include <glibmm/fileutils.h>
#include <glibmm/main.h>
#include <cerrno>
#include <fcntl.h>
#include <glib.h>
#include <forward_list>
#include <memory>
#include <utility> // For std::move()
#ifdef G_OS_WIN32
#include <windows.h>
#include <io.h>
#include <direct.h>
#include <list>
#include <mutex>
#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 Glib
{
class DispatchNotifier;
}
namespace
{
struct DispatchNotifyData
{
Glib::Dispatcher::Impl* dispatcher_impl;
Glib::DispatchNotifier* notifier;
DispatchNotifyData()
: dispatcher_impl(nullptr), notifier(nullptr)
{}
DispatchNotifyData(Glib::Dispatcher::Impl* d, Glib::DispatchNotifier* n)
: dispatcher_impl(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
{
// The most important reason for having the dispatcher implementation in a separate
// class is that its deletion can be delayed until it's safe to delete it.
// Deletion is safe when the pipe does not contain any message to the dispatcher
// to delete. When the pipe is empty, it's surely safe.
struct Dispatcher::Impl
{
public:
sigc::signal<void()> signal_;
DispatchNotifier* notifier_;
explicit Impl(const Glib::RefPtr<MainContext>& context);
// noncopyable
Impl(const Impl&) = delete;
Impl& operator=(const Impl&) = delete;
};
class DispatchNotifier : public sigc::trackable
{
public:
~DispatchNotifier() noexcept;
// noncopyable
DispatchNotifier(const DispatchNotifier&) = delete;
DispatchNotifier& operator=(const DispatchNotifier&) = delete;
static DispatchNotifier* reference_instance(const Glib::RefPtr<MainContext>& context);
static void unreference_instance(DispatchNotifier* notifier, Dispatcher::Impl* dispatcher_impl);
void send_notification(Dispatcher::Impl* dispatcher_impl);
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 thread_local DispatchNotifier* thread_specific_instance_;
using UniqueImplPtr = std::unique_ptr<Dispatcher::Impl>;
std::forward_list<UniqueImplPtr> orphaned_dispatcher_impl_;
long ref_count_;
Glib::RefPtr<MainContext> context_;
#ifdef G_OS_WIN32
std::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);
bool pipe_is_empty();
};
/**** Glib::DispatchNotifier ***********************************************/
thread_local DispatchNotifier* DispatchNotifier::thread_specific_instance_ = nullptr;
DispatchNotifier::DispatchNotifier(const Glib::RefPtr<MainContext>& context)
: orphaned_dispatcher_impl_(),
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();
try
{
// PollFD::fd_t is the type of GPollFD::fd.
// In Windows, it has the same size as HANDLE, but it's not guaranteed to be the same type.
// In Unix, a file descriptor is an int.
const auto fd = (PollFD::fd_t)fd_receiver_;
// The following code is equivalent to
// context_->signal_io().connect(
// sigc::mem_fun(*this, &DispatchNotifier::pipe_io_handler), fd, Glib::IOCondition::IO_IN);
// except for source->set_can_recurse(true).
const auto source = IOSource::create(fd, Glib::IOCondition::IO_IN);
// If the signal emission in pipe_io_handler() starts a new main loop,
// the event source shall not be blocked while that loop runs. (E.g. while
// a connected slot function shows a modal dialog box.)
source->set_can_recurse(true);
source->connect(sigc::mem_fun(*this, &DispatchNotifier::pipe_io_handler));
g_source_attach(source->gobj(), context_->gobj());
}
catch (...)
{
#ifndef G_OS_WIN32
fd_close_and_invalidate(fd_sender_);
#endif
fd_close_and_invalidate(fd_receiver_);
throw;
}
}
DispatchNotifier::~DispatchNotifier() noexcept
{
#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)
{
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);
}
fd_receiver_ = event;
#else /* !G_OS_WIN32 */
int filedes[2] = { -1, -1 };
if (pipe(filedes) < 0)
{
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);
}
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_;
if (!instance)
{
instance = new DispatchNotifier(context);
thread_specific_instance_ = instance;
}
else
{
// Prevent massive mess-up.
g_return_val_if_fail(instance->context_ == context, nullptr);
}
++instance->ref_count_; // initially 0
return instance;
}
// static
void DispatchNotifier::unreference_instance(
DispatchNotifier* notifier, Dispatcher::Impl* dispatcher_impl)
{
DispatchNotifier* const instance = thread_specific_instance_;
// Yes, the notifier argument is only used to check for sanity.
g_return_if_fail(instance == notifier);
if (instance->pipe_is_empty())
{
// No messages in the pipe. Delete the Dispatcher::Impl immediately.
delete dispatcher_impl;
instance->orphaned_dispatcher_impl_.clear();
}
else
{
// There are messages in the pipe, possibly to the orphaned Dispatcher::Impl.
// Keep it around until it can safely be deleted.
// Delete all slots connected to the Dispatcher. Then the signal emission
// in pipe_io_handler() will do nothing.
dispatcher_impl->signal_.clear();
instance->orphaned_dispatcher_impl_.push_front(UniqueImplPtr(dispatcher_impl));
}
if (--instance->ref_count_ <= 0)
{
g_return_if_fail(instance->ref_count_ == 0); // could be < 0 if messed up
delete thread_specific_instance_;
thread_specific_instance_ = nullptr;
}
}
void DispatchNotifier::send_notification(Dispatcher::Impl* dispatcher_impl)
{
#ifdef G_OS_WIN32
{
const std::lock_guard<std::mutex> lock(mutex_);
const bool was_empty = notify_queue_.empty();
notify_queue_.emplace_back(DispatchNotifyData(dispatcher_impl, 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_impl, 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_is_empty()
{
#ifdef G_OS_WIN32
return notify_queue_.empty();
#else
PollFD poll_fd(fd_receiver_, Glib::IOCondition::IO_IN);
// GPollFD*, number of file descriptors to poll, timeout (ms)
g_poll(poll_fd.gobj(), 1, 0);
return static_cast<int>(poll_fd.get_revents() & Glib::IOCondition::IO_IN) == 0;
#endif
}
bool DispatchNotifier::pipe_io_handler(Glib::IOCondition)
{
DispatchNotifyData data;
#ifdef G_OS_WIN32
{
const std::lock_guard<std::mutex> 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);
// 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
{
data.dispatcher_impl->signal_(); // emit
}
catch (...)
{
Glib::exception_handlers_invoke();
}
// Stop if a signal handler, called by data.dispatcher_impl->signal_(),
// deletes the last Dispatcher in this thread and thus this DispatchNotifier.
// https://gitlab.gnome.org/GNOME/glibmm/-/issues/116
if (!thread_specific_instance_)
return false;
if (!orphaned_dispatcher_impl_.empty() && pipe_is_empty())
orphaned_dispatcher_impl_.clear();
return true;
}
/**** Glib::Dispatcher and Glib::Dispatcher::Impl **************************/
Dispatcher::Impl::Impl(const Glib::RefPtr<MainContext>& context)
: signal_(),
notifier_(DispatchNotifier::reference_instance(context))
{
}
Dispatcher::Dispatcher()
: impl_(new Dispatcher::Impl(MainContext::get_default()))
{}
Dispatcher::Dispatcher(const Glib::RefPtr<MainContext>& context)
: impl_(new Dispatcher::Impl(context))
{
}
Dispatcher::~Dispatcher() noexcept
{
DispatchNotifier::unreference_instance(impl_->notifier_, impl_);
}
#ifndef GLIBMM_DISABLE_DEPRECATED
void
Dispatcher::emit()
{
impl_->notifier_->send_notification(impl_);
}
void
Dispatcher::operator()()
{
impl_->notifier_->send_notification(impl_);
}
#endif // GLIBMM_DISABLE_DEPRECATED
void
Dispatcher::emit() const
{
impl_->notifier_->send_notification(impl_);
}
void
Dispatcher::operator()() const
{
impl_->notifier_->send_notification(impl_);
}
sigc::connection
Dispatcher::connect(const sigc::slot<void()>& slot)
{
return impl_->signal_.connect(slot);
}
sigc::connection
Dispatcher::connect(sigc::slot<void()>&& slot)
{
return impl_->signal_.connect(std::move(slot));
}
} // namespace Glib
|