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