def test_thread_loop_runs_in_background():
# This is a high-level test, but with threads there's not much choice.
read_fd, write_fd = os.pipe()
strings = []
def process_input(fd, events):
while True:
try:
data = os.read(fd, 4096)
except (Error.EAGAIN, Error.EINTR):
continue
except (Error.EPIPE, Error.ECONNRESET, Error.EIO):
loop.stop()
return
break
if not data:
loop.stop()
strings.append(data)
loop = ThreadLoop()
loop.add_handler(read_fd, process_input, loop.READ)
with loop.background():
os.write(write_fd, "Message 1\n")
os.write(write_fd, "Message 2\n")
os.close(write_fd)
assert ''.join(strings) == "Message 1\nMessage 2\n"
os.close(read_fd)
def tee(input_fd, output_fds, bufsize=DEFAULT_BUFSIZE):
"""
Create a ThreadLoop which tees from one input to many outputs.
Example:
>>> in_pipe, out_pipe = Pipe(), Pipe()
>>> with tee(in_pipe.read_fd, (out_pipe.write_fd, sys.stdout)):
... os.write(in_pipe.write_fd, "FooBar\n")
... assert os.read(out_pipe.read_fd, 8192) == "FooBar\n"
FooBar
In this case, input written to one pipe is copied to both stdout *and*
another pipe. This is useful for capturing output and having it display on
the console in real-time.
"""
loop = ThreadLoop()
input_fd = ensure_fd(input_fd)
# Every output file descriptor gets its own buffer, to begin with.
buffers = {}
for output_fd in output_fds:
buffers[ensure_fd(output_fd)] = collections.deque()
def schedule_clean_up_writers():
for output_fd, output_buffer in buffers.iteritems():
if not output_buffer:
try_remove_handler(loop, output_fd)
close_fd(output_fd)
else:
loop.add_handler(output_fd, partial(writer, terminating=True),
loop.WRITE | loop.ERROR)
def clean_up_reader(input_fd, close=False):
try_remove_handler(loop, input_fd)
if close:
close_fd(input_fd)
def reader(fd, events):
# If there's an error on the input, flush the output buffers, close and
# clean up the reader, and stop.
if events & loop.ERROR:
schedule_clean_up_writers()
clean_up_reader(fd, close=True)
return
# If there are no file descriptors to write to any more, stop, but
# don't close the input.
if not buffers:
clean_up_reader(fd, close=False)
return
# The loop is necessary for errors like EAGAIN and EINTR.
while True:
try:
data = os.read(fd, bufsize)
except (Error.EAGAIN, Error.EINTR):
continue
except (Error.EPIPE, Error.ECONNRESET, Error.EIO):
schedule_clean_up_writers()
clean_up_reader(fd, close=True)
return
break
# The source of the data for the input FD has been closed.
if not data:
schedule_clean_up_writers()
clean_up_reader(fd, close=True)
return
# Put the chunk of data in the buffer of every registered output.
# If an output FD has been closed, remove it from the list of buffers.
bad_fds = []
for output_fd, buffer in buffers.iteritems():
buffer.appendleft(data)
try:
loop.add_handler(output_fd, writer, loop.WRITE | loop.ERROR)
except Error.EBADF:
bad_fds.append(output_fd)
for bad_fd in bad_fds:
del buffers[bad_fd]
def writer(fd, events, terminating=False):
if events & loop.ERROR:
try_remove_handler(loop, fd)
del buffers[fd]
return
# There's no input -- unschedule the writer, it'll be rescheduled again
# when there's something for it to write.
if not buffers[fd]:
try_remove_handler(loop, fd)
if terminating:
close_fd(fd)
return
data = buffers[fd].pop()
while True:
try:
os.write(fd, data)
except (Error.EPIPE, Error.ECONNRESET, Error.EIO, Error.EBADF):
del buffers[fd]
try_remove_handler(loop, fd)
except (Error.EAGAIN, Error.EINTR):
continue
break
# Start with just the reader.
loop.add_handler(input_fd, reader, loop.READ | loop.ERROR)
return loop
