def test(self): # pylint:disable=too-many-locals
# If this test is broken, there are a few failure modes.
# - In the original examples, the parent process just hangs, because the
# child has raced ahead, spawned the greenlet and read the data. When the
# greenlet goes to read in the parent, it blocks, and the hub and loop
# wait for it.
# - Here, our child detects the greenlet ran when it shouldn't and
# raises an error, which translates to a non-zero exit status,
# which the parent checks for and fails by raising an exception before
# returning control to the hub. We can replicate the hang by removing the
# assertion in the child.
from time import sleep as hang
from gevent import get_hub
from gevent import spawn
from gevent.socket import wait_read
from gevent.os import nb_read
from gevent.os import nb_write
from gevent.os import make_nonblocking
from gevent.os import fork
from gevent.os import waitpid
pipe_read_fd, pipe_write_fd = os.pipe()
make_nonblocking(pipe_read_fd)
make_nonblocking(pipe_write_fd)
run = []
def reader():
run.append(1)
return nb_read(pipe_read_fd, 4096)
# Put data in the pipe
DATA = b'test'
nb_write(pipe_write_fd, DATA)
# Make sure we're ready to read it
wait_read(pipe_read_fd)
# Schedule a greenlet to start
reader = spawn(reader)
hub = get_hub()
pid = fork()
if pid == 0:
# Child destroys the hub. The reader should not have run.
hub.destroy(destroy_loop=True)
self.assertFalse(run)
os._exit(0)
return
# The parent.
# Briefly prevent us from spinning our event loop.
hang(0.5)
wait_child_result = waitpid(pid, 0)
self.assertEqual(wait_child_result, (pid, 0))
# We should get the data; the greenlet only runs in the parent.
data = reader.get()
self.assertEqual(run, [1])
self.assertEqual(data, DATA)
def non_blocking_write(file_obj, input_buffer):
if not input_buffer:
return
try:
from gevent.os import nb_write
nb_write(file_obj.fileno(), input_buffer)
except ImportError:
return retry_loop_on_eagain(file_obj.write, input_buffer)
def non_blocking_write(file_obj, input_buffer):
if not input_buffer:
return
try:
from gevent.os import nb_write
nb_write(file_obj.fileno(), input_buffer)
except ImportError:
return retry_loop_on_eagain(file_obj.write, input_buffer)
def write_unsigned(fd, n):
msg = UNSIGNED_STRUCT.pack(n)
while msg:
nbytes = nb_write(fd, msg)
if nbytes == 0:
raise RuntimeError('should not get here')
msg = msg[nbytes:]
def _send(self, cmd, name):
self.ensure_running()
msg = '{0}:{1}\n'.format(cmd, name).encode('ascii')
if len(name) > 512:
# posix guarantees that writes to a pipe of less than PIPE_BUF
# bytes are atomic, and that PIPE_BUF >= 512
raise ValueError('name too long')
nbytes = nb_write(self._fd, msg)
assert nbytes == len(msg)
def write(self, *args):
return os.nb_write(*args)
def write(self, fd, count):
return os.nb_write(fd, count)
def write(self, *args):
return os.nb_write(*args)
