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Cygwin: fhandler_fifo::hit_eof: improve reliability 

Use the writer count introduced in the previous commit to help detect
EOF.  Drop the maybe_eof method, which is no longer needed.
This commit is contained in:
Ken Brown 2020-07-11 14:23:11 -04:00
parent 8ca713d70a
commit e10425e1e3
3 changed files with 6 additions and 30 deletions
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7
winsup/cygwin/fhandler.h
View File

@ -1392,7 +1392,6 @@ class fhandler_fifo: public fhandler_base
UNICODE_STRING pipe_name;
WCHAR pipe_name_buf[CYGWIN_FIFO_PIPE_NAME_LEN + 1];
bool _maybe_eof;
fifo_client_handler *fc_handler; /* Dynamically growing array. */
int shandlers; /* Size (capacity) of the array. */
int nhandlers; /* Number of elements in the array. */
@ -1473,9 +1472,9 @@ class fhandler_fifo: public fhandler_base
public:
fhandler_fifo ();
bool hit_eof ();
bool maybe_eof () const { return _maybe_eof; }
void maybe_eof (bool val) { _maybe_eof = val; }
/* Called if we appear to be at EOF after polling fc_handlers. */
bool hit_eof () const
{ return !nwriters () && !IsEventSignalled (writer_opening); }
int get_nhandlers () const { return nhandlers; }
fifo_client_handler &get_fc_handler (int i) { return fc_handler[i]; }
PUNICODE_STRING get_pipe_name ();

26
winsup/cygwin/fhandler_fifo.cc
View File

@ -87,7 +87,7 @@ fhandler_fifo::fhandler_fifo ():
fhandler_base (),
read_ready (NULL), write_ready (NULL), writer_opening (NULL),
owner_needed_evt (NULL), owner_found_evt (NULL), update_needed_evt (NULL),
cancel_evt (NULL), thr_sync_evt (NULL), _maybe_eof (false),
cancel_evt (NULL), thr_sync_evt (NULL),
fc_handler (NULL), shandlers (0), nhandlers (0),
reader (false), writer (false), duplexer (false),
max_atomic_write (DEFAULT_PIPEBUFSIZE),
@ -361,8 +361,6 @@ fhandler_fifo::record_connection (fifo_client_handler& fc,
fifo_client_connect_state s)
{
fc.state = s;
maybe_eof (false);
ResetEvent (writer_opening);
set_pipe_non_blocking (fc.h, true);
}
@ -1173,25 +1171,6 @@ fhandler_fifo::raw_write (const void *ptr, size_t len)
return ret;
}
/* A reader is at EOF if the pipe is empty and no writers are open.
hit_eof is called by raw_read and select.cc:peek_fifo if it appears
that we are at EOF after polling the fc_handlers. We recheck this
in case a writer opened while we were polling. */
bool
fhandler_fifo::hit_eof ()
{
bool ret = maybe_eof () && !IsEventSignalled (writer_opening);
if (ret)
{
yield ();
/* Wait for the reader thread to finish recording any connection. */
fifo_client_lock ();
fifo_client_unlock ();
ret = maybe_eof ();
}
return ret;
}
/* Called from raw_read and select.cc:peek_fifo. */
void
fhandler_fifo::take_ownership ()
@ -1261,9 +1240,8 @@ fhandler_fifo::raw_read (void *in_ptr, size_t& len)
break;
}
}
maybe_eof (!nconnected && !IsEventSignalled (writer_opening));
fifo_client_unlock ();
if (maybe_eof () && hit_eof ())
if (!nconnected && hit_eof ())
{
reading_unlock ();
len = 0;

3
winsup/cygwin/select.cc
View File

@ -883,9 +883,8 @@ peek_fifo (select_record *s, bool from_select)
goto out;
}
}
fh->maybe_eof (!nconnected);
fh->fifo_client_unlock ();
if (fh->maybe_eof () && fh->hit_eof ())
if (!nconnected && fh->hit_eof ())
{
select_printf ("read: %s, saw EOF", fh->get_name ());
gotone += s->read_ready = true;