import optparse
import os
import select
import socket
import sys
import time


parser = optparse.OptionParser()
parser.add_option("-r", dest='nb_ready', type=int,
                  help="Number of ready FDs")
parser.add_option("-m", dest='nb_max', type=int,
                  help="Total number of FDs/highest FD")
parser.add_option("-s", dest='sparse', default=False, action='store_true',
                  help="Use sparse FDs allocation")
parser.add_option("-t", dest='fd_type', default='socket',
                  help="FD type ('socket', 'pipe', 'tty'")
options, args = parser.parse_args()

nb_ready = options.nb_ready
nb_max = options.nb_max
sparse = options.sparse
fd_type = options.fd_type

# prepare FDs and events
events = []

if fd_type == 'socket':
    r, w = socket.socketpair()
    rd = os.dup(r.fileno())
    wr = os.dup(w.fileno())
    r.close()
    w.close()
elif fd_type == 'tty':
    rd = os.dup(sys.stdin.fileno())
    wr = os.dup(sys.stdout.fileno())
else:
    rd, wr = os.pipe()

if sparse:
    # in sparse mode, only allocate ready FDs in the upper range
    print("Trying with {} FDs starting at {}, type {}".format(nb_ready, nb_max,
                                                              fd_type))

    for i in range(nb_max - nb_ready, nb_max):
        os.dup2(wr, i)
        events.append((i, select.SELECT_OUT))
else:
    # allocate ready and non ready FDs monotonically
    print("Trying with {} ready FDs out of {}, type {}".format(nb_ready, nb_max,
                                                               fd_type))

    for i in range(nb_max - nb_ready):
        events.append((os.dup(rd), select.SELECT_IN))

    for i in range(nb_ready):
        events.append((os.dup(wr), select.SELECT_OUT))

os.close(rd)
os.close(wr)

# benchmark each implementation
for selector in (select.EpollSelector, select.PollSelector,
                 select.SelectSelector):
    print(selector)

    with selector() as s:
        # register events
        for fd, mask in events:
            s.register(fd, mask)

        t = time.perf_counter()
        for i in range(1024):
            ready = s.select()
        print(time.perf_counter() - t)

for fd, mask in events:
    os.close(fd)