# -*- coding: GBK -*-
import urlparse
import datetime
import os
from multiprocessing import Process,Queue,Array,RLock
"""
多進程分塊讀取文件
"""
WORKERS = 4
BLOCKSIZE = 100000000
FILE_SIZE = 0
def getFilesize(file):
  """
    獲取要讀取文件的大小
  """
  global FILE_SIZE
  fstream = open(file,'r')
  fstream.seek(0,os.SEEK_END)
  FILE_SIZE = fstream.tell()
  fstream.close()
def process_found(pid,array,file,rlock):
  global FILE_SIZE
  global JOB
  global PREFIX
  """
    進程處理
    Args:
      pid:進程編號
      array:進程間共享隊列，用于標記各進程所讀的文件塊結束位置
      file:所讀文件名稱
    各個進程先從array中獲取當前最大的值為起始位置startpossition
    結束的位置endpossition (startpossition+BLOCKSIZE) if (startpossition+BLOCKSIZE)<FILE_SIZE else FILE_SIZE
    if startpossition==FILE_SIZE則進程結束
    if startpossition==0則從0開始讀取
    if startpossition!=0為防止行被block截斷的情況，先讀一行不處理，從下一行開始正式處理
    if 當前位置 <=endpossition 就readline
    否則越過邊界，就從新查找array中的最大值
  """
  fstream = open(file,'r')
  while True:
    rlock.acquire()
    print 'pid%s'%pid,','.join([str(v) for v in array])
    startpossition = max(array)      
    endpossition = array[pid] = (startpossition+BLOCKSIZE) if (startpossition+BLOCKSIZE)<FILE_SIZE else FILE_SIZE
    rlock.release()
    if startpossition == FILE_SIZE:#end of the file
      print 'pid%s end'%(pid)
      break
    elif startpossition !=0:
      fstream.seek(startpossition)
      fstream.readline()
    pos = ss = fstream.tell()
    ostream = open('/data/download/tmp_pid'+str(pid)+'_jobs'+str(endpossition),'w')
    while pos<endpossition:
      #處理line
      line = fstream.readline()
      ostream.write(line)
      pos = fstream.tell()
    print 'pid:%s,startposition:%s,endposition:%s,pos:%s'%(pid,ss,pos,pos)
    ostream.flush()
    ostream.close()
    ee = fstream.tell()
  fstream.close()
def main():
  global FILE_SIZE
  print datetime.datetime.now().strftime("%Y/%d/%m %H:%M:%S") 
  file = "/data/pds/download/scmcc_log/tmp_format_2011004.log"
  getFilesize(file)
  print FILE_SIZE
  rlock = RLock()
  array = Array('l',WORKERS,lock=rlock)
  threads=[]
  for i in range(WORKERS):
    p=Process(target=process_found, args=[i,array,file,rlock])
    threads.append(p)
  for i in range(WORKERS):
    threads[i].start()
  for i in range(WORKERS):
    threads[i].join()
  print datetime.datetime.now().strftime("%Y/%d/%m %H:%M:%S") 
if __name__ == '__main__':
  main()