[Bf-extensions-cvs] [958dee9] temp-blend-utils: Utility module for non-blocking pipes

[Campbell Barton]

Commit: 958dee94e8689ac67887458f70dbcd080e4f3ed7
Author: Campbell Barton
Date:   Thu Jan 28 15:02:20 2016 +1100
Branches: temp-blend-utils
https://developer.blender.org/rBA958dee94e8689ac67887458f70dbcd080e4f3ed7

Utility module for non-blocking pipes

===================================================================

A	io_blend_utils/utils/pipe_non_blocking.py

===================================================================

diff --git a/io_blend_utils/utils/pipe_non_blocking.py b/io_blend_utils/utils/pipe_non_blocking.py
new file mode 100644
index 0000000..ead0a73
--- /dev/null
+++ b/io_blend_utils/utils/pipe_non_blocking.py
@@ -0,0 +1,100 @@
+# ##### BEGIN GPL LICENSE BLOCK #####
+#
+#  This program is free software; you can redistribute it and/or
+#  modify it under the terms of the GNU General Public License
+#  as published by the Free Software Foundation; either version 2
+#  of the License, or (at your option) any later version.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License
+#  along with this program; if not, write to the Free Software Foundation,
+#  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+#
+# ##### END GPL LICENSE BLOCK #####
+
+# <pep8 compliant>
+
+"""
+Example use:
+
+    p = subprocess.Popen(
+            command,
+            stdout=subprocess.PIPE,
+            )
+
+    pipe_non_blocking_set(p.stdout.fileno())
+
+    try:
+        data = os.read(p.stdout.fileno(), 1)
+    except PortableBlockingIOError as ex:
+        if not pipe_non_blocking_is_error_blocking(ex):
+            raise ex
+"""
+
+
+__all__ = (
+    "pipe_non_blocking_set",
+    "pipe_non_blocking_is_error_blocking",
+    "PortableBlockingIOError",
+    )
+
+import os
+
+
+if os.name == "nt":
+    # MS-Windows Version
+    def pipe_non_blocking_set(fd):
+        # Constant could define globally but avoid polluting the name-space
+        # thanks to: http://stackoverflow.com/questions/34504970
+        import msvcrt
+
+        from ctypes import windll, byref, wintypes, WinError, POINTER
+        from ctypes.wintypes import HANDLE, DWORD, BOOL
+
+        LPDWORD = POINTER(DWORD)
+
+        PIPE_NOWAIT = wintypes.DWORD(0x00000001)
+
+        def pipe_no_wait(pipefd):
+            SetNamedPipeHandleState = windll.kernel32.SetNamedPipeHandleState
+            SetNamedPipeHandleState.argtypes = [HANDLE, LPDWORD, LPDWORD, LPDWORD]
+            SetNamedPipeHandleState.restype = BOOL
+
+            h = msvcrt.get_osfhandle(pipefd)
+
+            res = windll.kernel32.SetNamedPipeHandleState(h, byref(PIPE_NOWAIT), None, None)
+            if res == 0:
+                print(WinError())
+                return False
+            return True
+
+        return pipe_no_wait(fd)
+
+    def pipe_non_blocking_is_error_blocking(ex):
+        if not isinstance(ex, PortableBlockingIOError):
+            return False
+        from ctypes import GetLastError
+        ERROR_NO_DATA = 232
+
+        return (GetLastError() == ERROR_NO_DATA)
+
+    PortableBlockingIOError = OSError
+else:
+    # Posix Version
+    def pipe_non_blocking_set(fd):
+        import fcntl
+        fl = fcntl.fcntl(fd, fcntl.F_GETFL)
+        fcntl.fcntl(fd, fcntl.F_SETFL, fl | os.O_NONBLOCK)
+        return True
+
+    # only for compatibility with 'nt' version.
+    def pipe_non_blocking_is_error_blocking(ex):
+        if not isinstance(ex, PortableBlockingIOError):
+            return False
+        return True
+
+    PortableBlockingIOError = BlockingIOError