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loader.py

# Copyright (C) 2009, 2010  Roman Zimbelmann <romanz@lavabit.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

from collections import deque
from time import time, sleep
from subprocess import Popen, PIPE
from time import time
from ranger.core.shared import FileManagerAware
from ranger.ext.signals import SignalDispatcher
import math
import os
import sys
import select


00028 class Loadable(object):
      paused = False
      def __init__(self, gen, descr):
            self.load_generator = gen
            self.description = descr

      def get_description(self):
            return self.description

      def pause(self):
            self.paused = True

      def unpause(self):
            try:
                  del self.paused
            except:
                  pass

      def destroy(self):
            pass


00050 class CommandLoader(Loadable, SignalDispatcher, FileManagerAware):
      """
      Run an external command with the loader.

      Output from stderr will be reported.  Ensure that the process doesn't
      ever ask for input, otherwise the loader will be blocked until this
      object is removed from the queue (type ^C in ranger)
      """
      finished = False
      process = None
      def __init__(self, args, descr, silent=False, read=False):
            SignalDispatcher.__init__(self)
            Loadable.__init__(self, self.generate(), descr)
            self.args = args
            self.silent = silent
            self.read = read
            self.stdout_buffer = ""

      def generate(self):
            self.process = process = Popen(self.args,
                        stdout=PIPE, stderr=PIPE)
            self.signal_emit('before', process=process, loader=self)
            if self.silent and not self.read:
                  while process.poll() is None:
                        yield
                        sleep(0.03)
            else:
                  py3 = sys.version >= '3'
                  selectlist = []
                  if self.read:
                        selectlist.append(process.stdout)
                  if not self.silent:
                        selectlist.append(process.stderr)
                  while process.poll() is None:
                        yield
                        try:
                              rd, _, __ = select.select(selectlist, [], [], 0.03)
                              if rd:
                                    rd = rd[0]
                                    if rd == process.stderr:
                                          read = rd.readline()
                                          if py3:
                                                read = read.decode('utf-8')
                                          if read:
                                                self.fm.notify(read, bad=True)
                                    elif rd == process.stdout:
                                          read = rd.read(512)
                                          if py3:
                                                read = read.decode('utf-8')
                                          if read:
                                                self.stdout_buffer += read
                        except select.error:
                              sleep(0.03)
                  if not self.silent:
                        for l in process.stderr.readlines():
                              if py3:
                                    l = l.decode('utf-8')
                              self.fm.notify(l, bad=True)
                  if self.read:
                        read = process.stdout.read()
                        if py3:
                              read = read.decode('utf-8')
                        self.stdout_buffer += read
            self.finished = True
            self.signal_emit('after', process=process, loader=self)

      def pause(self):
            if not self.finished and not self.paused:
                  try:
                        self.process.send_signal(20)
                  except:
                        pass
            Loadable.pause(self)
            self.signal_emit('pause', process=self.process, loader=self)

      def unpause(self):
            if not self.finished and self.paused:
                  try:
                        self.process.send_signal(18)
                  except:
                        pass
            Loadable.unpause(self)
            self.signal_emit('unpause', process=self.process, loader=self)

      def destroy(self):
            self.signal_emit('destroy', process=self.process, loader=self)
            if self.process:
                  self.process.kill()


00140 class Loader(FileManagerAware):
      seconds_of_work_time = 0.03
      throbber_chars = r'/-\|'

      def __init__(self):
            self.queue = deque()
            self.item = None
            self.load_generator = None
            self.throbber_status = 0
            self.rotate()
            self.old_item = None

00152       def rotate(self):
            """Rotate the throbber"""
            # TODO: move all throbber logic to UI
            self.throbber_status = \
                  (self.throbber_status + 1) % len(self.throbber_chars)
            self.status = self.throbber_chars[self.throbber_status]

00159       def add(self, obj):
            """
            Add an object to the queue.
            It should have a load_generator method.
            """
            while obj in self.queue:
                  self.queue.remove(obj)
            self.queue.appendleft(obj)

      def move(self, _from, to):
            try:
                  item = self.queue[_from]
            except IndexError:
                  return

            del self.queue[_from]

            if to == 0:
                  self.queue.appendleft(item)
                  if _from != 0:
                        self.queue[1].pause()
            elif to == -1:
                  self.queue.append(item)
            else:
                  raise NotImplementedError

      def remove(self, item=None, index=None):
            if item is not None and index is None:
                  for i, test in enumerate(self.queue):
                        if test == item:
                              index = i 
                              break
                  else:
                        return

            if index is not None:
                  if item is None:
                        item = self.queue[index]
                  if hasattr(item, 'unload'):
                        item.unload()
                  item.destroy()
                  del self.queue[index]

00202       def work(self):
            """
            Load items from the queue if there are any.
            Stop after approximately self.seconds_of_work_time.
            """
            while True:
                  # get the first item with a proper load_generator
                  try:
                        item = self.queue[0]
                        if item.load_generator is None:
                              self.queue.popleft()
                        else:
                              break
                  except IndexError:
                        return

            self.rotate()
            if item != self.old_item:
                  if self.old_item:
                        self.old_item.pause()
                  self.old_item = item
            item.unpause()

            end_time = time() + self.seconds_of_work_time

            try:
                  while time() < end_time:
                        next(item.load_generator)
            except StopIteration:
                  item.load_generator = None
                  self.queue.remove(item)
            except Exception as err:
                  self.fm.notify(err)

00236       def has_work(self):
            """Is there anything to load?"""
            return bool(self.queue)

      def destroy(self):
            while self.queue:
                  self.queue.pop().destroy()

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