From 252fa9a50c264e9827c42c631291749ad62d0f4d Mon Sep 17 00:00:00 2001 From: Zac Medico Date: Thu, 2 Sep 2010 00:05:06 -0700 Subject: Adjust EbuildIpcDaemon pickle read and write code in order to ensure atomc reading and writing of whole pickles. This should be the least error-prone approach, given the non-blocking nature of the streams. --- bin/ebuild-ipc.py | 30 ++++++++++++++++++++++++++---- 1 file changed, 26 insertions(+), 4 deletions(-) (limited to 'bin') diff --git a/bin/ebuild-ipc.py b/bin/ebuild-ipc.py index cbb8c5570..52fb08226 100755 --- a/bin/ebuild-ipc.py +++ b/bin/ebuild-ipc.py @@ -48,13 +48,35 @@ class EbuildIpc(object): def _communicate(self, args): input_fd = os.open(self.ipc_out_fifo, os.O_RDONLY|os.O_NONBLOCK) - input_file = os.fdopen(input_fd, 'rb') - output_file = open(self.ipc_in_fifo, 'wb') - pickle.dump(args, output_file) + + # File streams are in unbuffered mode since we do atomic + # read and write of whole pickles. + input_file = os.fdopen(input_fd, 'rb', 0) + output_file = open(self.ipc_in_fifo, 'wb', 0) + + # Write the whole pickle in a single atomic write() call, + # since the reader is in non-blocking mode and we want + # it to get the whole pickle at once. + output_file.write(pickle.dumps(args)) output_file.flush() events = select.select([input_file], [], []) - reply = pickle.load(input_file) + + # Read the whole pickle in a single read() call since + # this stream is in non-blocking mode and pickle.load() + # has been known to raise the following exception when + # reading from a non-blocking stream: + # + # File "/usr/lib64/python2.6/pickle.py", line 1370, in load + # return Unpickler(file).load() + # File "/usr/lib64/python2.6/pickle.py", line 858, in load + # dispatch[key](self) + # File "/usr/lib64/python2.6/pickle.py", line 1195, in load_setitem + # value = stack.pop() + # IndexError: pop from empty list + + pickle_str = input_file.read() + reply = pickle.loads(pickle_str) output_file.close() input_file.close() -- cgit v1.2.3-1-g7c22