倒读文件

file_reverse.py

import os, re, sys, time


def filerev(somefile, buffer=256):
    somefile.seek(0, os.SEEK_END)
    size = somefile.tell()
    lines = ['']
    rem = size % buffer
    pos = max(0, (size // buffer - 1) * buffer)
    while pos >= 0:
        somefile.seek(pos, os.SEEK_SET)
        data = somefile.read(rem + buffer) + lines[0]
        rem = 0
        pos -= buffer
        lines = re.findall(r'[^\n]*\n?', data)
        ix = len(lines) - 2
        while ix > 0:
            yield lines[ix]
            ix -= 1
    else:
        yield lines[0]


def main():
    st = time.time()
    with open('/Users/fengxu/Downloads/SecureCRT/log_201608051100/dev/shm/mqtt/red5.log', 'r') as f:
        for line in filerev(f):
            sys.stdout.write(line)