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                 task.task_progress_changed = self.task_progress_changed_CB
  49                 self.tasks.append(task)
  50
  51         def start(self, callback):
  52                 assert self.callback is None
  53                 self.callback = callback
  54                 self.restart()
  55
  56         def restart(self):
  57                 self.status = self.IN_PROGRESS
  58                 self.state_changed()
  59                 self.runNext()
  60                 sumTaskWeightings = sum([t.weighting for t in self.tasks]) or 1
  61                 self.weightScale = self.end / float(sumTaskWeightings)
  62
  63         def runNext(self):
  64                 if self.current_task == len(self.tasks):
  65                         if len(self.resident_tasks) == 0:
  66                                 cb = self.callback
  67                                 self.callback = None
  68                                 self.status = self.FINISHED
  69                                 self.state_changed()
  70                                 cb(self, 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.task_progress_changed = None
 131                 self.output_line = ""
 132                 job.addTask(self)
 133
 134         def setCommandline(self, cmd, args):
 135                 self.cmd = cmd
 136                 self.args = args
 137
 138         def setTool(self, tool):
 139                 self.cmd = tool
 140                 self.args = [tool]
 141                 self.global_preconditions.append(ToolExistsPrecondition())
 142                 self.postconditions.append(ReturncodePostcondition())
 143
 144         def checkPreconditions(self, immediate = False):
 145                 not_met = [ ]
 146                 if immediate:
 147                         preconditions = self.immediate_preconditions
 148                 else:
 149                         preconditions = self.global_preconditions
 150                 for precondition in preconditions:
 151                         if not precondition.check(self):
 152                                 not_met.append(precondition)
 153                 return not_met
 154
 155         def run(self, callback):
 156                 failed_preconditions = self.checkPreconditions(True) + self.checkPreconditions(False)
 157                 if len(failed_preconditions):
 158                         callback(self, failed_preconditions)
 159                         return
 160                 self.prepare()
 161
 162                 self.callback = callback
 163                 from enigma import eConsoleAppContainer
 164                 self.container = eConsoleAppContainer()
 165                 self.container.appClosed.append(self.processFinished)
 166                 self.container.stdoutAvail.append(self.processStdout)
 167                 self.container.stderrAvail.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, 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                 if self.task_progress_changed:
 239                         self.task_progress_changed()
 240
 241         progress = property(getProgress, setProgress)
 242
 243 # The jobmanager will execute multiple jobs, each after another.
 244 # later, it will also support suspending jobs (and continuing them after reboot etc)
 245 # It also supports a notification when some error occured, and possibly a retry.
 246 class JobManager:
 247         def __init__(self):
 248                 self.active_jobs = [ ]
 249                 self.failed_jobs = [ ]
 250                 self.job_classes = [ ]
 251                 self.in_background = False
 252                 self.active_job = None
 253
 254         def AddJob(self, job):
 255                 self.active_jobs.append(job)
 256                 self.kick()
 257
 258         def kick(self):
 259                 if self.active_job is None:
 260                         if len(self.active_jobs):
 261                                 self.active_job = self.active_jobs.pop(0)
 262                                 self.active_job.start(self.jobDone)
 263
 264         def jobDone(self, job, task, problems):
 265                 print "job", job, "completed with", problems, "in", task
 266                 from Tools import Notifications
 267                 if self.in_background:
 268                         from Screens.TaskView import JobView
 269                         self.in_background = False
 270                         Notifications.AddNotification(JobView, self.active_job)
 271                 if problems:
 272                         from Screens.MessageBox import MessageBox
 273                         if problems[0].RECOVERABLE:
 274                                 Notifications.AddNotificationWithCallback(self.errorCB, MessageBox, _("Error: %s\nRetry?") % (problems[0].getErrorMessage(task)))
 275                         else:
 276                                 Notifications.AddNotification(MessageBox, _("Error") + (': %s') % (problems[0].getErrorMessage(task)), type = MessageBox.TYPE_ERROR )
 277                                 self.errorCB(False)
 278                         return
 279                         #self.failed_jobs.append(self.active_job)
 280
 281                 self.active_job = None
 282                 self.kick()
 283
 284         def errorCB(self, answer):
 285                 if answer:
 286                         print "retrying job"
 287                         self.active_job.retry()
 288                 else:
 289                         print "not retrying job."
 290                         self.failed_jobs.append(self.active_job)
 291                         self.active_job = None
 292                         self.kick()
 293
 294         def getPendingJobs(self):
 295                 list = [ ]
 296                 if self.active_job:
 297                         list.append(self.active_job)
 298                 list += self.active_jobs
 299                 return list
 300 # some examples:
 301 #class PartitionExistsPostcondition:
 302 #       def __init__(self, device):
 303 #               self.device = device
 304 #
 305 #       def check(self, task):
 306 #               import os
 307 #               return os.access(self.device + "part1", os.F_OK)
 308 #
 309 #class CreatePartitionTask(Task):
 310 #       def __init__(self, device):
 311 #               Task.__init__(self, _("Create Partition"))
 312 #               self.device = device
 313 #               self.setTool("/sbin/sfdisk")
 314 #               self.args += ["-f", self.device + "disc"]
 315 #               self.initial_input = "0,\n;\n;\n;\ny\n"
 316 #               self.postconditions.append(PartitionExistsPostcondition(self.device))
 317 #
 318 #class CreateFilesystemTask(Task):
 319 #       def __init__(self, device, partition = 1, largefile = True):
 320 #               Task.__init__(self, _("Create Filesystem"))
 321 #               self.setTool("/sbin/mkfs.ext")
 322 #               if largefile:
 323 #                       self.args += ["-T", "largefile"]
 324 #               self.args.append("-m0")
 325 #               self.args.append(device + "part%d" % partition)
 326 #
 327 #class FilesystemMountTask(Task):
 328 #       def __init__(self, device, partition = 1, filesystem = "ext3"):
 329 #               Task.__init__(self, _("Mounting Filesystem"))
 330 #               self.setTool("/bin/mount")
 331 #               if filesystem is not None:
 332 #                       self.args += ["-t", filesystem]
 333 #               self.args.append(device + "part%d" % partition)
 334
 335 class Condition:
 336         RECOVERABLE = False
 337
 338         def getErrorMessage(self, task):
 339                 return _("An unknown error occured!") + " (%s @ task %s)" % (self.__class__.__name__, task.__class__.__name__)
 340
 341 class WorkspaceExistsPrecondition(Condition):
 342         def check(self, task):
 343                 return os.access(task.job.workspace, os.W_OK)
 344
 345 class DiskspacePrecondition(Condition):
 346         def __init__(self, diskspace_required):
 347                 self.diskspace_required = diskspace_required
 348                 self.diskspace_available = 0
 349
 350         def check(self, task):
 351                 import os
 352                 try:
 353                         s = os.statvfs(task.job.workspace)
 354                         self.diskspace_available = s.f_bsize * s.f_bavail
 355                         return self.diskspace_available >= self.diskspace_required
 356                 except OSError:
 357                         return False
 358
 359         def getErrorMessage(self, task):
 360                 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)
 361
 362 class ToolExistsPrecondition(Condition):
 363         def check(self, task):
 364                 import os
 365                 if task.cmd[0]=='/':
 366                         realpath = task.cmd
 367                 else:
 368                         realpath = task.cwd + '/' + task.cmd
 369                 self.realpath = realpath
 370                 return os.access(realpath, os.X_OK)
 371
 372         def getErrorMessage(self, task):
 373                 return _("A required tool (%s) was not found.") % (self.realpath)
 374
 375 class AbortedPostcondition(Condition):
 376         def getErrorMessage(self, task):
 377                 return "Cancelled upon user request"
 378
 379 class ReturncodePostcondition(Condition):
 380         def check(self, task):
 381                 return task.returncode == 0
 382
 383 #class HDDInitJob(Job):
 384 #       def __init__(self, device):
 385 #               Job.__init__(self, _("Initialize Harddisk"))
 386 #               self.device = device
 387 #               self.fromDescription(self.createDescription())
 388 #
 389 #       def fromDescription(self, description):
 390 #               self.device = description["device"]
 391 #               self.addTask(CreatePartitionTask(self.device))
 392 #               self.addTask(CreateFilesystemTask(self.device))
 393 #               self.addTask(FilesystemMountTask(self.device))
 394 #
 395 #       def createDescription(self):
 396 #               return {"device": self.device}
 397
 398 job_manager = JobManager()