public inbox for cygwin-cvs@sourceware.org
help / color / mirror / Atom feed
* [newlib-cygwin] Cygwin: pipe: Stop counting reader and read all available data.
@ 2021-09-14 15:06 Corinna Vinschen
0 siblings, 0 replies; only message in thread
From: Corinna Vinschen @ 2021-09-14 15:06 UTC (permalink / raw)
To: cygwin-cvs
https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=fadbedd9ca5f9117aba38b8aa0d7bf705d4c8d5d
commit fadbedd9ca5f9117aba38b8aa0d7bf705d4c8d5d
Author: Takashi Yano <takashi.yano@nifty.ne.jp>
Date: Mon Sep 6 20:12:16 2021 +0900
Cygwin: pipe: Stop counting reader and read all available data.
- By guarding read with read_mtx, no more than one ReadFile can
be called simultaneously. So couting read handles is no longer
necessary.
- Make raw_read code as similar as possible to raw_write code.
Diff:
---
winsup/cygwin/fhandler_pipe.cc | 100 ++++++++++++++++++++++++-----------------
1 file changed, 60 insertions(+), 40 deletions(-)
diff --git a/winsup/cygwin/fhandler_pipe.cc b/winsup/cygwin/fhandler_pipe.cc
index 68974eb80..fe0bf0ca2 100644
--- a/winsup/cygwin/fhandler_pipe.cc
+++ b/winsup/cygwin/fhandler_pipe.cc
@@ -221,12 +221,10 @@ fhandler_pipe::get_proc_fd_name (char *buf)
void __reg3
fhandler_pipe::raw_read (void *ptr, size_t& len)
{
- NTSTATUS status;
+ size_t nbytes = 0;
+ NTSTATUS status = STATUS_SUCCESS;
IO_STATUS_BLOCK io;
HANDLE evt = NULL;
- DWORD waitret = WAIT_OBJECT_0;
- bool keep_looping = false;
- size_t orig_len = len;
if (!len)
return;
@@ -239,43 +237,59 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
return;
}
- do
+ DWORD timeout = is_nonblocking () ? 0 : INFINITE;
+ DWORD waitret = cygwait (read_mtx, timeout);
+ switch (waitret)
{
- len = orig_len;
- keep_looping = false;
+ case WAIT_OBJECT_0:
+ break;
+ case WAIT_TIMEOUT:
+ set_errno (EAGAIN);
+ len = (size_t) -1;
+ return;
+ default:
+ set_errno (EINTR);
+ len = (size_t) -1;
+ return;
+ }
+ while (nbytes < len)
+ {
+ ULONG_PTR nbytes_now = 0;
+ size_t left = len - nbytes;
+ ULONG len1 = (ULONG) left;
+ waitret = WAIT_OBJECT_0;
+
if (evt)
ResetEvent (evt);
if (!is_nonblocking ())
{
FILE_PIPE_LOCAL_INFORMATION fpli;
- ULONG reader_count;
- ULONG max_len = 64;
-
- WaitForSingleObject (read_mtx, INFINITE);
- /* If the pipe is empty, don't request more bytes than half the
- pipe buffer size. Every pending read lowers WriteQuotaAvailable
- on the write side and thus affects select's ability to return
- more or less reliable info whether a write succeeds or not.
-
- Let the size of the request depend on the number of readers
- at the time. */
+ /* If the pipe is empty, don't request more bytes than pipe
+ buffer size - 1. Pending read lowers WriteQuotaAvailable on
+ the write side and thus affects select's ability to return
+ more or less reliable info whether a write succeeds or not. */
+ ULONG chunk = max_atomic_write - 1;
status = NtQueryInformationFile (get_handle (), &io,
&fpli, sizeof (fpli),
FilePipeLocalInformation);
- if (NT_SUCCESS (status) && fpli.ReadDataAvailable == 0)
+ if (NT_SUCCESS (status))
{
- reader_count = get_obj_handle_count (get_handle ());
- if (reader_count < 10)
- max_len = fpli.InboundQuota / (2 * reader_count);
- if (len > max_len)
- len = max_len;
+ if (fpli.ReadDataAvailable > 0)
+ chunk = left;
+ else if (nbytes != 0)
+ break;
+ else
+ chunk = fpli.InboundQuota - 1;
}
+ else if (nbytes != 0)
+ break;
+
+ if (len1 > chunk)
+ len1 = chunk;
}
status = NtReadFile (get_handle (), evt, NULL, NULL, &io, ptr,
- len, NULL, NULL);
- if (!is_nonblocking ())
- ReleaseMutex (read_mtx);
+ len1, NULL, NULL);
if (evt && status == STATUS_PENDING)
{
waitret = cygwait (evt);
@@ -292,13 +306,13 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
set_errno (EBADF);
else
__seterrno ();
- len = (size_t) -1;
+ nbytes = (size_t) -1;
}
else if (NT_SUCCESS (status))
{
- len = io.Information;
- if (len == 0)
- keep_looping = true;
+ nbytes_now = io.Information;
+ ptr = ((char *) ptr) + nbytes_now;
+ nbytes += nbytes_now;
}
else
{
@@ -308,40 +322,46 @@ fhandler_pipe::raw_read (void *ptr, size_t& len)
case STATUS_END_OF_FILE:
case STATUS_PIPE_BROKEN:
/* This is really EOF. */
- len = 0;
break;
case STATUS_MORE_ENTRIES:
case STATUS_BUFFER_OVERFLOW:
/* `io.Information' is supposedly valid. */
- len = io.Information;
- if (len == 0)
- keep_looping = true;
+ nbytes_now = io.Information;
+ ptr = ((char *) ptr) + nbytes_now;
+ nbytes += nbytes_now;
break;
case STATUS_PIPE_LISTENING:
case STATUS_PIPE_EMPTY:
+ if (nbytes != 0)
+ break;
if (is_nonblocking ())
{
set_errno (EAGAIN);
- len = (size_t) -1;
+ nbytes = (size_t) -1;
break;
}
fallthrough;
default:
__seterrno_from_nt_status (status);
- len = (size_t) -1;
+ nbytes = (size_t) -1;
break;
}
}
- } while (keep_looping);
+
+ if (nbytes_now == 0)
+ break;
+ }
+ ReleaseMutex (read_mtx);
if (evt)
CloseHandle (evt);
- if (status == STATUS_THREAD_SIGNALED)
+ if (status == STATUS_THREAD_SIGNALED && nbytes == 0)
{
set_errno (EINTR);
- len = (size_t) -1;
+ nbytes = (size_t) -1;
}
else if (status == STATUS_THREAD_CANCELED)
pthread::static_cancel_self ();
+ len = nbytes;
}
ssize_t __reg3
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2021-09-14 15:06 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-09-14 15:06 [newlib-cygwin] Cygwin: pipe: Stop counting reader and read all available data Corinna Vinschen
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).