# A parallelized "find(1)" using the thread module.
# This demonstrates the use of a work queue and worker threads.
# It really does do more stats/sec when using multiple threads,
# although the improvement is only about 20-30 percent.
# (That was 8 years ago. In 2002, on Linux, I can't measure
# a speedup. :-( )
# I'm too lazy to write a command line parser for the full find(1)
# command line syntax, so the predicate it searches for is wired-in,
# see function selector() below. (It currently searches for files with
# world write permission.)
# Usage: parfind.py [-w nworkers] [directory] ...
# Default nworkers is 4
import sys
import getopt
import time
import os
from stat import *
import _thread as thread
# Work queue class. Usage:
# wq = WorkQ()
# wq.addwork(func, (arg1, arg2, ...)) # one or more calls
# wq.run(nworkers)
# The work is done when wq.run() completes.
# The function calls executed by the workers may add more work.
# Don't use keyboard interrupts!
class WorkQ:
 # Invariants:
 # - busy and work are only modified when mutex is locked
 # - len(work) is the number of jobs ready to be taken
 # - busy is the number of jobs being done
 # - todo is locked iff there is no work and somebody is busy
 def __init__(self):
  self.mutex = thread.allocate()
  self.todo = thread.allocate()
  self.todo.acquire()
  self.work = []
  self.busy = 0
 def addwork(self, func, args):
  job = (func, args)
  self.mutex.acquire()
  self.work.append(job)
  self.mutex.release()
  if len(self.work) == 1:
   self.todo.release()
 def _getwork(self):
  self.todo.acquire()
  self.mutex.acquire()
  if self.busy == 0 and len(self.work) == 0:
   self.mutex.release()
   self.todo.release()
   return None
  job = self.work[0]
  del self.work[0]
  self.busy = self.busy + 1
  self.mutex.release()
  if len(self.work) > 0:
   self.todo.release()
  return job
 def _donework(self):
  self.mutex.acquire()
  self.busy = self.busy - 1
  if self.busy == 0 and len(self.work) == 0:
   self.todo.release()
  self.mutex.release()
 def _worker(self):
  time.sleep(0.00001)  # Let other threads run
  while 1:
   job = self._getwork()
   if not job:
    break
   func, args = job
   func(*args)
   self._donework()
 def run(self, nworkers):
  if not self.work:
   return # Nothing to do
  for i in range(nworkers-1):
   thread.start_new(self._worker, ())
  self._worker()
  self.todo.acquire()
# Main program
def main():
 nworkers = 4
 #print(getopt.getopt(sys.argv[1:], '-w:'))
 opts, args = getopt.getopt(sys.argv[1:], '-w:')
 for opt, arg in opts:
  if opt == '-w':
   nworkers = int(arg)
 if not args:
  #print(os.curdir)
  args = [os.curdir]
 wq = WorkQ()
 for dir in args:
  wq.addwork(find, (dir, selector, wq))
 t1 = time.time()
 wq.run(nworkers)
 t2 = time.time()
 sys.stderr.write('Total time %r sec.\n' % (t2-t1))
# The predicate -- defines what files we look for.
# Feel free to change this to suit your purpose
def selector(dir, name, fullname, stat):
 # Look for world writable files that are not symlinks
 return (stat[ST_MODE] & 0o002) != 0 and not S_ISLNK(stat[ST_MODE])
# The find procedure -- calls wq.addwork() for subdirectories
def find(dir, pred, wq):
 try:
  names = os.listdir(dir)
 except os.error as msg:
  print(repr(dir), ':', msg)
  return
 for name in names:
  if name not in (os.curdir, os.pardir):
   fullname = os.path.join(dir, name)
   try:
    stat = os.lstat(fullname)
   except os.error as msg:
    print(repr(fullname), ':', msg)
    continue
   if pred(dir, name, fullname, stat):
    print(fullname)
   if S_ISDIR(stat[ST_MODE]):
    if not os.path.ismount(fullname):
     wq.addwork(find, (fullname, pred, wq))
# Call the main program
main()