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Cygwin: FIFO: improve EOF detection 

Add a hit_eof method that tries to detect whether any clients are
connected.  Before concluding that there are none, it gives the
listen_client thread time to update the client data.
This commit is contained in:
Ken Brown 2019-03-22 19:30:38 +00:00 committed by Corinna Vinschen
parent c75e077f99
commit c6e221c036
2 changed files with 21 additions and 1 deletions
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1
winsup/cygwin/fhandler.h
View File

@ -1277,6 +1277,7 @@ class fhandler_fifo: public fhandler_base
bool listen_client ();
public:
fhandler_fifo ();
bool hit_eof ();
PUNICODE_STRING get_pipe_name ();
DWORD listen_client_thread ();
void fifo_client_lock () { _fifo_client_lock.lock (); }

21
winsup/cygwin/fhandler_fifo.cc
View File

@ -654,6 +654,25 @@ fhandler_fifo::raw_write (const void *ptr, size_t len)
return ret;
}
/* A FIFO open for reading is at EOF if no process has it open for
writing. We test this by checking nconnected. But we must take
account of the possible delay from the time of connection to the
time the connection is recorded by the listen_client thread. */
bool
fhandler_fifo::hit_eof ()
{
fifo_client_lock ();
bool eof = (nconnected == 0);
fifo_client_unlock ();
if (eof)
{
/* Give the listen_client thread time to catch up, then recheck. */
Sleep (1);
eof = (nconnected == 0);
}
return eof;
}
void __reg3
fhandler_fifo::raw_read (void *in_ptr, size_t& len)
{
@ -665,7 +684,7 @@ fhandler_fifo::raw_read (void *in_ptr, size_t& len)
while (1)
{
if (nconnected == 0) /* EOF */
if (hit_eof ())
{
len = 0;
return;