win32 gpoll: overcome the 64 handles limit

This is a new polling method allowing to poll more than 64 handles
based on the glib one.
When we reach the limit of 64 we create a thread and we poll
on that thread for a batch of handles this way we overcome the limit.

#1071
parent 0d2f7074
......@@ -72,6 +72,7 @@
#ifdef G_OS_WIN32
#define STRICT
#include <windows.h>
#include <process.h>
#endif /* G_OS_WIN32 */
#include "gpoll.h"
......@@ -130,6 +131,7 @@ g_poll (GPollFD *fds,
static int
poll_rest (GPollFD *msg_fd,
GPollFD *stop_fd,
HANDLE *handles,
GPollFD *handle_to_fd[],
gint nhandles,
......@@ -211,113 +213,279 @@ poll_rest (GPollFD *msg_fd,
/* If no timeout and handles to poll, recurse to poll them,
* too.
*/
recursed_result = poll_rest (NULL, handles, handle_to_fd, nhandles, 0);
recursed_result = poll_rest (NULL, stop_fd, handles, handle_to_fd, nhandles, 0);
return (recursed_result == -1) ? -1 : 1 + recursed_result;
}
else if (ready >= WAIT_OBJECT_0 && ready < WAIT_OBJECT_0 + nhandles)
{
int retval;
f = handle_to_fd[ready - WAIT_OBJECT_0];
f->revents = f->events;
if (_g_main_poll_debug)
g_print (" got event %p\n", (HANDLE) f->fd);
/* Do not count the stop_fd */
retval = (f != stop_fd) ? 1 : 0;
/* If no timeout and polling several handles, recurse to poll
* the rest of them.
*/
if (timeout_ms == 0 && nhandles > 1)
{
/* Poll the handles with index > ready */
HANDLE *shorter_handles;
{
/* Poll the handles with index > ready */
HANDLE *shorter_handles;
GPollFD **shorter_handle_to_fd;
gint shorter_nhandles;
gint shorter_nhandles;
shorter_handles = &handles[ready - WAIT_OBJECT_0 + 1];
shorter_handle_to_fd = &handle_to_fd[ready - WAIT_OBJECT_0 + 1];
shorter_nhandles = nhandles - (ready - WAIT_OBJECT_0 + 1);
recursed_result = poll_rest (NULL, shorter_handles, shorter_handle_to_fd, shorter_nhandles, 0);
return (recursed_result == -1) ? -1 : 1 + recursed_result;
}
return 1;
recursed_result = poll_rest (NULL, stop_fd, shorter_handles, shorter_handle_to_fd, shorter_nhandles, 0);
return (recursed_result == -1) ? -1 : retval + recursed_result;
}
return retval;
}
return 0;
}
gint
g_poll (GPollFD *fds,
guint nfds,
gint timeout)
typedef struct
{
HANDLE handles[MAXIMUM_WAIT_OBJECTS];
GPollFD *handle_to_fd[MAXIMUM_WAIT_OBJECTS];
GPollFD *msg_fd = NULL;
GPollFD *f;
gint nhandles = 0;
GPollFD *msg_fd;
GPollFD *stop_fd;
gint nhandles;
gint timeout_ms;
} GWin32PollThreadData;
static gint
poll_single_thread (GWin32PollThreadData *data)
{
int retval;
if (_g_main_poll_debug)
g_print ("g_poll: waiting for");
/* Polling for several things? */
if (data->nhandles > 1 || (data->nhandles > 0 && data->msg_fd != NULL))
{
/* First check if one or several of them are immediately
* available
*/
retval = poll_rest (data->msg_fd, data->stop_fd, data->handles, data->handle_to_fd, data->nhandles, 0);
/* If not, and we have a significant timeout, poll again with
* timeout then. Note that this will return indication for only
* one event, or only for messages.
*/
if (retval == 0 && (data->timeout_ms == INFINITE || data->timeout_ms > 0))
retval = poll_rest (data->msg_fd, data->stop_fd, data->handles, data->handle_to_fd, data->nhandles, data->timeout_ms);
}
else
{
/* Just polling for one thing, so no need to check first if
* available immediately
*/
retval = poll_rest (data->msg_fd, data->stop_fd, data->handles, data->handle_to_fd, data->nhandles, data->timeout_ms);
}
return retval;
}
static void
fill_poll_thread_data (GPollFD *fds,
guint nfds,
gint timeout_ms,
GPollFD *stop_fd,
GWin32PollThreadData *data)
{
GPollFD *f;
data->timeout_ms = timeout_ms;
if (stop_fd != NULL)
{
if (_g_main_poll_debug)
g_print (" Stop FD: %p", (HANDLE) stop_fd->fd);
g_assert (data->nhandles < MAXIMUM_WAIT_OBJECTS);
data->stop_fd = stop_fd;
data->handle_to_fd[data->nhandles] = stop_fd;
data->handles[data->nhandles++] = (HANDLE) stop_fd->fd;
}
for (f = fds; f < &fds[nfds]; ++f)
{
if ((data->nhandles == MAXIMUM_WAIT_OBJECTS) ||
(data->msg_fd != NULL && (data->nhandles == MAXIMUM_WAIT_OBJECTS - 1)))
{
g_warning ("Too many handles to wait for!");
break;
}
if (f->fd == G_WIN32_MSG_HANDLE && (f->events & G_IO_IN))
{
if (_g_main_poll_debug && msg_fd == NULL)
if (_g_main_poll_debug && data->msg_fd == NULL)
g_print (" MSG");
msg_fd = f;
data->msg_fd = f;
}
else if (f->fd > 0)
{
if (nhandles == MAXIMUM_WAIT_OBJECTS)
{
g_warning ("Too many handles to wait for!");
break;
}
else
{
if (_g_main_poll_debug)
g_print (" %p", (HANDLE) f->fd);
handle_to_fd[nhandles] = f;
handles[nhandles++] = (HANDLE) f->fd;
}
if (_g_main_poll_debug)
g_print (" %p", (HANDLE) f->fd);
data->handle_to_fd[data->nhandles] = f;
data->handles[data->nhandles++] = (HANDLE) f->fd;
}
f->revents = 0;
}
}
if (_g_main_poll_debug)
g_print ("\n");
static guint __stdcall
poll_thread_run (gpointer user_data)
{
GWin32PollThreadData *data = user_data;
/* Docs say that it is safer to call _endthreadex by our own:
* https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/endthread-endthreadex
*/
_endthreadex (poll_single_thread (data));
g_assert_not_reached ();
return 0;
}
/* One slot for a possible msg object or the stop event */
#define MAXIMUM_WAIT_OBJECTS_PER_THREAD (MAXIMUM_WAIT_OBJECTS - 1)
gint
g_poll (GPollFD *fds,
guint nfds,
gint timeout)
{
guint nthreads, threads_remain;
HANDLE thread_handles[MAXIMUM_WAIT_OBJECTS];
GWin32PollThreadData *threads_data;
GPollFD stop_event = { 0, };
GPollFD *f;
guint i, fds_idx = 0;
DWORD ready;
DWORD thread_retval;
int retval;
GPollFD *msg_fd = NULL;
if (timeout == -1)
timeout = INFINITE;
/* Polling for several things? */
if (nhandles > 1 || (nhandles > 0 && msg_fd != NULL))
/* Simple case without extra threads */
if (nfds <= MAXIMUM_WAIT_OBJECTS)
{
/* First check if one or several of them are immediately
* available
*/
retval = poll_rest (msg_fd, handles, handle_to_fd, nhandles, 0);
GWin32PollThreadData data = { 0, };
/* If not, and we have a significant timeout, poll again with
* timeout then. Note that this will return indication for only
* one event, or only for messages.
*/
if (retval == 0 && (timeout == INFINITE || timeout > 0))
retval = poll_rest (msg_fd, handles, handle_to_fd, nhandles, timeout);
if (_g_main_poll_debug)
g_print ("g_poll: waiting for");
fill_poll_thread_data (fds, nfds, timeout, NULL, &data);
if (_g_main_poll_debug)
g_print ("\n");
retval = poll_single_thread (&data);
if (retval == -1)
for (f = fds; f < &fds[nfds]; ++f)
f->revents = 0;
return retval;
}
if (_g_main_poll_debug)
g_print ("g_poll: polling with threads\n");
nthreads = nfds / MAXIMUM_WAIT_OBJECTS_PER_THREAD;
threads_remain = nfds % MAXIMUM_WAIT_OBJECTS_PER_THREAD;
if (threads_remain > 0)
nthreads++;
if (nthreads > MAXIMUM_WAIT_OBJECTS_PER_THREAD)
{
g_warning ("Too many handles to wait for in threads!");
nthreads = MAXIMUM_WAIT_OBJECTS_PER_THREAD;
}
#if GLIB_SIZEOF_VOID_P == 8
stop_event.fd = (gint64)CreateEventW (NULL, TRUE, FALSE, NULL);
#else
stop_event.fd = (gint)CreateEventW (NULL, TRUE, FALSE, NULL);
#endif
stop_event.events = G_IO_IN;
threads_data = g_new0 (GWin32PollThreadData, nthreads);
for (i = 0; i < nthreads; i++)
{
guint thread_fds;
guint ignore;
if (i == (nthreads - 1) && threads_remain > 0)
thread_fds = threads_remain;
else
thread_fds = MAXIMUM_WAIT_OBJECTS_PER_THREAD;
fill_poll_thread_data (fds + fds_idx, thread_fds, timeout, &stop_event, &threads_data[i]);
fds_idx += thread_fds;
/* We must poll for messages from the same thread, so poll it along with the threads */
if (threads_data[i].msg_fd != NULL)
{
msg_fd = threads_data[i].msg_fd;
threads_data[i].msg_fd = NULL;
}
thread_handles[i] = (HANDLE) _beginthreadex (NULL, 0, poll_thread_run, &threads_data[i], 0, &ignore);
}
/* Wait for at least one thread to return */
if (msg_fd != NULL)
ready = MsgWaitForMultipleObjectsEx (nthreads, thread_handles, timeout,
QS_ALLINPUT, MWMO_ALERTABLE);
else
ready = WaitForMultipleObjects (nthreads, thread_handles, timeout > 0, timeout);
/* Signal the stop in case any of the threads did not stop yet */
if (!SetEvent ((HANDLE)stop_event.fd))
{
/* Just polling for one thing, so no need to check first if
* available immediately
*/
retval = poll_rest (msg_fd, handles, handle_to_fd, nhandles, timeout);
gchar *emsg = g_win32_error_message (GetLastError ());
g_warning ("gpoll: failed to signal the stop event: %s", emsg);
g_free (emsg);
}
/* Wait for the rest of the threads to finish */
WaitForMultipleObjects (nthreads, thread_handles, TRUE, INFINITE);
/* The return value of all the threads give us all the fds that changed state */
retval = 0;
if (msg_fd != NULL && ready == WAIT_OBJECT_0 + nthreads)
{
msg_fd->revents |= G_IO_IN;
retval = 1;
}
for (i = 0; i < nthreads; i++)
{
if (GetExitCodeThread (thread_handles[i], &thread_retval))
retval = retval == -1 ? -1 : thread_retval == -1 ? -1 : retval + thread_retval;
CloseHandle (thread_handles[i]);
}
if (retval == -1)
for (f = fds; f < &fds[nfds]; ++f)
f->revents = 0;
g_free (threads_data);
CloseHandle ((HANDLE)stop_event.fd);
return retval;
}
......
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