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Corinna Vinschen 41d071d581 Cygwin: select: revamp non-polling code for signalfd
Rather than waiting for signalfd_select_wait in a thread, which is racy,
create a global event "my_pendingsigs_evt" which is set and reset by
wait_sig depending only on the fact if blocked signals are pending or not.

This in turn allows to WFMO on this event in select as soon as signalfds
are present in the read descriptor set.  Select's peek and verify
will then check if one of the present signalfds is affected.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
2020-10-14 10:53:59 -04:00

114 lines
2.8 KiB
C++

/* select.h
This file is part of Cygwin.
This software is a copyrighted work licensed under the terms of the
Cygwin license. Please consult the file "CYGWIN_LICENSE" for
details. */
#ifndef _SELECT_H_
#define _SELECT_H_
struct select_record
{
int fd;
HANDLE h;
fhandler_base *fh;
_cygtls *tls;
int thread_errno;
bool windows_handle;
bool read_ready, write_ready, except_ready;
bool read_selected, write_selected, except_selected;
bool except_on_write;
int (*startup) (select_record *, class select_stuff *);
int (*peek) (select_record *, bool);
int (*verify) (select_record *, fd_set *, fd_set *, fd_set *);
void (*cleanup) (select_record *, class select_stuff *);
struct select_record *next;
void set_select_errno () {__seterrno (); thread_errno = errno;}
int saw_error () {return thread_errno;}
select_record (int): next (NULL) {}
select_record () :
fd (0), h (NULL), fh (NULL), tls (&_my_tls), thread_errno (0),
windows_handle (false), read_ready (false), write_ready (false),
except_ready (false), read_selected (false), write_selected (false),
except_selected (false), except_on_write (false),
startup (NULL), peek (NULL), verify (NULL), cleanup (NULL),
next (NULL) {}
#ifdef DEBUGGING
void dump_select_record ();
#endif
};
struct select_info
{
cygthread *thread;
bool stop_thread;
select_record *start;
select_info (): thread (NULL), stop_thread (0), start (NULL) {}
};
struct select_pipe_info: public select_info
{
select_pipe_info (): select_info () {}
};
struct select_fifo_info: public select_info
{
select_fifo_info (): select_info () {}
};
struct select_socket_info: public select_info
{
int num_w4;
LONG *ser_num;
HANDLE *w4;
select_socket_info (): select_info (), num_w4 (0), ser_num (0), w4 (NULL) {}
};
struct select_serial_info: public select_info
{
select_serial_info (): select_info () {}
};
class select_stuff
{
public:
enum wait_states
{
select_signalled = -3,
select_error = -1,
select_ok = 0,
select_set_zero = 1
};
~select_stuff ();
bool return_on_signal;
bool always_ready, windows_used;
select_record start;
select_pipe_info *device_specific_pipe;
select_fifo_info *device_specific_fifo;
select_socket_info *device_specific_socket;
select_serial_info *device_specific_serial;
bool test_and_set (int, fd_set *, fd_set *, fd_set *);
int poll (fd_set *, fd_set *, fd_set *);
wait_states wait (fd_set *, fd_set *, fd_set *, LONGLONG);
void cleanup ();
void destroy ();
select_stuff (): return_on_signal (false), always_ready (false),
windows_used (false), start (),
device_specific_pipe (NULL),
device_specific_fifo (NULL),
device_specific_socket (NULL),
device_specific_serial (NULL)
{}
};
extern "C" int cygwin_select (int , fd_set *, fd_set *, fd_set *,
struct timeval *to);
#endif /* _SELECT_H_ */