lib/python/Components/Task.py

   1 # A Job consists of many "Tasks".
   2 # A task is the run of an external tool, with proper methods for failure handling
   3
   4 from Tools.CList import CList
   5
   6 class Job(object):
   7         NOT_STARTED, IN_PROGRESS, FINISHED, FAILED = range(4)
   8         def __init__(self, name):
   9                 self.tasks = [ ]
  10                 self.resident_tasks = [ ]
  11                 self.workspace = "/tmp"
  12                 self.current_task = 0
  13                 self.callback = None
  14                 self.name = name
  15                 self.finished = False
  16                 self.end = 100
  17                 self.__progress = 0
  18                 self.weightScale = 1
  19                 self.afterEvent = None
  20
  21                 self.state_changed = CList()
  22
  23                 self.status = self.NOT_STARTED
  24
  25         # description is a dict
  26         def fromDescription(self, description):
  27                 pass
  28
  29         def createDescription(self):
  30                 return None
  31
  32         def getProgress(self):
  33                 if self.current_task == len(self.tasks):
  34                         return self.end
  35                 t = self.tasks[self.current_task]
  36                 jobprogress = t.weighting * t.progress / float(t.end) + sum([task.weighting for task in self.tasks[:self.current_task]])
  37                 return int(jobprogress*self.weightScale)
  38
  39         progress = property(getProgress)
  40
  41         def getStatustext(self):
  42                 return { self.NOT_STARTED: _("Waiting"), self.IN_PROGRESS: _("In Progress"), self.FINISHED: _("Finished"), self.FAILED: _("Failed") }[self.status]
  43
  44         def task_progress_changed_CB(self):
  45                 self.state_changed()
  46
  47         def addTask(self, task):
  48                 task.job = self
  49                 task.task_progress_changed = self.task_progress_changed_CB
  50                 self.tasks.append(task)
  51
  52         def start(self, callback):
  53                 assert self.callback is None
  54                 self.callback = callback
  55                 self.restart()
  56
  57         def restart(self):
  58                 self.status = self.IN_PROGRESS
  59                 self.state_changed()
  60                 self.runNext()
  61                 sumTaskWeightings = sum([t.weighting for t in self.tasks]) or 1
  62                 self.weightScale = self.end / float(sumTaskWeightings)
  63
  64         def runNext(self):
  65                 if self.current_task == len(self.tasks):
  66                         if len(self.resident_tasks) == 0:
  67                                 self.status = self.FINISHED
  68                                 self.state_changed()
  69                                 self.callback(self, None, [])
  70                                 self.callback = None
  71                         else:
  72                                 print "still waiting for %d resident task(s) %s to finish" % (len(self.resident_tasks), str(self.resident_tasks))
  73                 else:
  74                         self.tasks[self.current_task].run(self.taskCallback)
  75                         self.state_changed()
  76
  77         def taskCallback(self, task, res, stay_resident = False):
  78                 cb_idx = self.tasks.index(task)
  79                 if stay_resident:
  80                         if cb_idx not in self.resident_tasks:
  81                                 self.resident_tasks.append(self.current_task)
  82                                 print "task going resident:", task
  83                         else:
  84                                 print "task keeps staying resident:", task
  85                                 return
  86                 if len(res):
  87                         print ">>> Error:", res
  88                         self.status = self.FAILED
  89                         self.state_changed()
  90                         self.callback(self, task, res)
  91                 if cb_idx != self.current_task:
  92                         if cb_idx in self.resident_tasks:
  93                                 print "resident task finished:", task
  94                                 self.resident_tasks.remove(cb_idx)
  95                 if res == []:
  96                         self.state_changed()
  97                         self.current_task += 1
  98                         self.runNext()
  99
 100         def retry(self):
 101                 assert self.status == self.FAILED
 102                 self.restart()
 103
 104         def abort(self):
 105                 if self.current_task < len(self.tasks):
 106                         self.tasks[self.current_task].abort()
 107                 for i in self.resident_tasks:
 108                         self.tasks[i].abort()
 109
 110         def cancel(self):
 111                 # some Jobs might have a better idea of how to cancel a job
 112                 self.abort()
 113
 114 class Task(object):
 115         def __init__(self, job, name):
 116                 self.name = name
 117                 self.immediate_preconditions = [ ]
 118                 self.global_preconditions = [ ]
 119                 self.postconditions = [ ]
 120                 self.returncode = None
 121                 self.initial_input = None
 122                 self.job = None
 123
 124                 self.end = 100
 125                 self.weighting = 100
 126                 self.__progress = 0
 127                 self.cmd = None
 128                 self.cwd = "/tmp"
 129                 self.args = [ ]
 130                 self.cmdline = None
 131                 self.task_progress_changed = None
 132                 self.output_line = ""
 133                 job.addTask(self)
 134                 self.container = None
 135
 136         def setCommandline(self, cmd, args):
 137                 self.cmd = cmd
 138                 self.args = args
 139
 140         def setTool(self, tool):
 141                 self.cmd = tool
 142                 self.args = [tool]
 143                 self.global_preconditions.append(ToolExistsPrecondition())
 144                 self.postconditions.append(ReturncodePostcondition())
 145
 146         def setCmdline(self, cmdline):
 147                 self.cmdline = cmdline
 148
 149         def checkPreconditions(self, immediate = False):
 150                 not_met = [ ]
 151                 if immediate:
 152                         preconditions = self.immediate_preconditions
 153                 else:
 154                         preconditions = self.global_preconditions
 155                 for precondition in preconditions:
 156                         if not precondition.check(self):
 157                                 not_met.append(precondition)
 158                 return not_met
 159
 160         def run(self, callback):
 161                 failed_preconditions = self.checkPreconditions(True) + self.checkPreconditions(False)
 162                 if len(failed_preconditions):
 163                         callback(self, failed_preconditions)
 164                         return
 165                 self.prepare()
 166
 167                 self.callback = callback
 168                 from enigma import eConsoleAppContainer
 169                 self.container = eConsoleAppContainer()
 170                 self.container.appClosed.append(self.processFinished)
 171                 self.container.stdoutAvail.append(self.processStdout)
 172                 self.container.stderrAvail.append(self.processStderr)
 173
 174                 if self.cwd is not None:
 175                         self.container.setCWD(self.cwd)
 176
 177                 if not self.cmd and self.cmdline:
 178                         print "execute:", self.container.execute(self.cmdline), self.cmdline
 179                 else:
 180                         assert self.cmd is not None
 181                         assert len(self.args) >= 1
 182                         print "execute:", self.container.execute(self.cmd, *self.args), ' '.join(self.args)
 183                 if self.initial_input:
 184                         self.writeInput(self.initial_input)
 185
 186         def prepare(self):
 187                 pass
 188
 189         def cleanup(self, failed):
 190                 pass
 191
 192         def processStdout(self, data):
 193                 self.processOutput(data)
 194
 195         def processStderr(self, data):
 196                 self.processOutput(data)
 197
 198         def processOutput(self, data):
 199                 self.output_line += data
 200                 while True:
 201                         i = self.output_line.find('\n')
 202                         if i == -1:
 203                                 break
 204                         self.processOutputLine(self.output_line[:i+1])
 205                         self.output_line = self.output_line[i+1:]
 206
 207         def processOutputLine(self, line):
 208                 pass
 209
 210         def processFinished(self, returncode):
 211                 self.returncode = returncode
 212                 self.finish()
 213
 214         def abort(self):
 215                 if self.container:
 216                         self.container.kill()
 217                 self.finish(aborted = True)
 218
 219         def finish(self, aborted = False):
 220                 self.afterRun()
 221                 not_met = [ ]
 222                 if aborted:
 223                         not_met.append(AbortedPostcondition())
 224                 else:
 225                         for postcondition in self.postconditions:
 226                                 if not postcondition.check(self):
 227                                         not_met.append(postcondition)
 228                 self.cleanup(not_met)
 229                 self.callback(self, not_met)
 230
 231         def afterRun(self):
 232                 pass
 233
 234         def writeInput(self, input):
 235                 self.container.write(input)
 236
 237         def getProgress(self):
 238                 return self.__progress
 239
 240         def setProgress(self, progress):
 241                 if progress > self.end:
 242                         progress = self.end
 243                 if progress < 0:
 244                         progress = 0
 245                 self.__progress = progress
 246                 if self.task_progress_changed:
 247                         self.task_progress_changed()
 248
 249         progress = property(getProgress, setProgress)
 250
 251 # The jobmanager will execute multiple jobs, each after another.
 252 # later, it will also support suspending jobs (and continuing them after reboot etc)
 253 # It also supports a notification when some error occured, and possibly a retry.
 254 class JobManager:
 255         def __init__(self):
 256                 self.active_jobs = [ ]
 257                 self.failed_jobs = [ ]
 258                 self.job_classes = [ ]
 259                 self.in_background = False
 260                 self.active_job = None
 261
 262         def AddJob(self, job):
 263                 self.active_jobs.append(job)
 264                 self.kick()
 265
 266         def kick(self):
 267                 if self.active_job is None:
 268                         if len(self.active_jobs):
 269                                 self.active_job = self.active_jobs.pop(0)
 270                                 self.active_job.start(self.jobDone)
 271
 272         def jobDone(self, job, task, problems):
 273                 print "job", job, "completed with", problems, "in", task
 274                 from Tools import Notifications
 275                 if self.in_background:
 276                         from Screens.TaskView import JobView
 277                         self.in_background = False
 278                         Notifications.AddNotification(JobView, self.active_job)
 279                 if problems:
 280                         from Screens.MessageBox import MessageBox
 281                         if problems[0].RECOVERABLE:
 282                                 Notifications.AddNotificationWithCallback(self.errorCB, MessageBox, _("Error: %s\nRetry?") % (problems[0].getErrorMessage(task)))
 283                         else:
 284                                 Notifications.AddNotification(MessageBox, _("Error") + (': %s') % (problems[0].getErrorMessage(task)), type = MessageBox.TYPE_ERROR )
 285                                 self.errorCB(False)
 286                         return
 287                         #self.failed_jobs.append(self.active_job)
 288
 289                 self.active_job = None
 290                 self.kick()
 291
 292         def errorCB(self, answer):
 293                 if answer:
 294                         print "retrying job"
 295                         self.active_job.retry()
 296                 else:
 297                         print "not retrying job."
 298                         self.failed_jobs.append(self.active_job)
 299                         self.active_job = None
 300                         self.kick()
 301
 302         def getPendingJobs(self):
 303                 list = [ ]
 304                 if self.active_job:
 305                         list.append(self.active_job)
 306                 list += self.active_jobs
 307                 return list
 308 # some examples:
 309 #class PartitionExistsPostcondition:
 310 #       def __init__(self, device):
 311 #               self.device = device
 312 #
 313 #       def check(self, task):
 314 #               import os
 315 #               return os.access(self.device + "part1", os.F_OK)
 316 #
 317 #class CreatePartitionTask(Task):
 318 #       def __init__(self, device):
 319 #               Task.__init__(self, _("Create Partition"))
 320 #               self.device = device
 321 #               self.setTool("/sbin/sfdisk")
 322 #               self.args += ["-f", self.device + "disc"]
 323 #               self.initial_input = "0,\n;\n;\n;\ny\n"
 324 #               self.postconditions.append(PartitionExistsPostcondition(self.device))
 325 #
 326 #class CreateFilesystemTask(Task):
 327 #       def __init__(self, device, partition = 1, largefile = True):
 328 #               Task.__init__(self, _("Create Filesystem"))
 329 #               self.setTool("/sbin/mkfs.ext")
 330 #               if largefile:
 331 #                       self.args += ["-T", "largefile"]
 332 #               self.args.append("-m0")
 333 #               self.args.append(device + "part%d" % partition)
 334 #
 335 #class FilesystemMountTask(Task):
 336 #       def __init__(self, device, partition = 1, filesystem = "ext3"):
 337 #               Task.__init__(self, _("Mounting Filesystem"))
 338 #               self.setTool("/bin/mount")
 339 #               if filesystem is not None:
 340 #                       self.args += ["-t", filesystem]
 341 #               self.args.append(device + "part%d" % partition)
 342
 343 class Condition:
 344         RECOVERABLE = False
 345
 346         def getErrorMessage(self, task):
 347                 return _("An unknown error occured!") + " (%s @ task %s)" % (self.__class__.__name__, task.__class__.__name__)
 348
 349 class WorkspaceExistsPrecondition(Condition):
 350         def check(self, task):
 351                 return os.access(task.job.workspace, os.W_OK)
 352
 353 class DiskspacePrecondition(Condition):
 354         def __init__(self, diskspace_required):
 355                 self.diskspace_required = diskspace_required
 356                 self.diskspace_available = 0
 357
 358         def check(self, task):
 359                 import os
 360                 try:
 361                         s = os.statvfs(task.job.workspace)
 362                         self.diskspace_available = s.f_bsize * s.f_bavail
 363                         return self.diskspace_available >= self.diskspace_required
 364                 except OSError:
 365                         return False
 366
 367         def getErrorMessage(self, task):
 368                 return _("Not enough diskspace. Please free up some diskspace and try again. (%d MB required, %d MB available)") % (self.diskspace_required / 1024 / 1024, self.diskspace_available / 1024 / 1024)
 369
 370 class ToolExistsPrecondition(Condition):
 371         def check(self, task):
 372                 import os
 373
 374                 if task.cmd[0]=='/':
 375                         self.realpath = task.cmd
 376                         print "[Task.py][ToolExistsPrecondition] WARNING: usage of absolute paths for tasks should be avoided!"
 377                         return os.access(self.realpath, os.X_OK)
 378                 else:
 379                         self.realpath = task.cmd
 380                         path = os.environ.get('PATH', '').split(os.pathsep)
 381                         path.append(task.cwd + '/')
 382                         absolutes = filter(lambda file: os.access(file, os.X_OK), map(lambda directory, file = task.cmd: os.path.join(directory, file), path))
 383                         if len(absolutes) > 0:
 384                                 self.realpath = task.cmd[0]
 385                                 return True
 386                 return False
 387
 388         def getErrorMessage(self, task):
 389                 return _("A required tool (%s) was not found.") % (self.realpath)
 390
 391 class AbortedPostcondition(Condition):
 392         def getErrorMessage(self, task):
 393                 return "Cancelled upon user request"
 394
 395 class ReturncodePostcondition(Condition):
 396         def check(self, task):
 397                 return task.returncode == 0
 398
 399 #class HDDInitJob(Job):
 400 #       def __init__(self, device):
 401 #               Job.__init__(self, _("Initialize Harddisk"))
 402 #               self.device = device
 403 #               self.fromDescription(self.createDescription())
 404 #
 405 #       def fromDescription(self, description):
 406 #               self.device = description["device"]
 407 #               self.addTask(CreatePartitionTask(self.device))
 408 #               self.addTask(CreateFilesystemTask(self.device))
 409 #               self.addTask(FilesystemMountTask(self.device))
 410 #
 411 #       def createDescription(self):
 412 #               return {"device": self.device}
 413
 414 job_manager = JobManager()