calc_offset.py

import sys
import collections

class Buf():
    def __init__(self, buf=0, size=0):
        self.buf = buf
        self.size = size

    def __repr__(self):
        return 'buf: {}, size: {}'.format(self.buf, self.size)

def server_thread(file_size, buf_size, thread_num):
    server = [Buf(buf=0, size=0) for _ in range(thread_num)]

    if (file_size % buf_size):
        total_file_size = ((file_size / buf_size) + 1) * buf_size
    else:
        total_file_size = file_size

    offset = total_file_size / thread_num
    extra_file_size = total_file_size + buf_size

    if (offset % buf_size):
        server[0].size = ((offset / buf_size) + 1) * buf_size
    else:
        server[0].size = offset

    for i in range(1, thread_num):
        server[i].size = server[i-1].size
        server[i].buf = server[i-1].buf + offset

    print('extra_file_size: {}'.format(extra_file_size))
    for i, buf in enumerate(server):
        print(i, buf)

    return server, extra_file_size

def get_fraction_for_each_client(file_size, buf_size, thread_num):
    if (file_size % buf_size):
        total_file_size = ((file_size / buf_size) + 1) * buf_size
    else:
        total_file_size = file_size

    return total_file_size / thread_num


if __name__ == '__main__':
    if len(sys.argv) < 4:
        print('usage <file_size> <buf_size> <thread_num>')
        exit(1)

    (file_size, buf_size, thread_num) = tuple(map(int, sys.argv[1:]))

    server, extra_file_size = server_thread(file_size, buf_size, thread_num)
    fraction = get_fraction_for_each_client(file_size, buf_size, thread_num)

    for offset in range(0, fraction+1, buf_size):
        for thread in server:
            thread.buf += buf_size
            if thread.buf > extra_file_size:
                print("overflow")
                exit(1)

    exit(0)