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:
   7         NOT_STARTED, IN_PROGRESS, FINISHED, FAILED = range(4)
   8         def __init__(self, name):
   9                 self.tasks = [ ]
  10                 self.current_task = 0
  11                 self.callback = None
  12                 self.name = name
  13                 self.finished = False
  14
  15                 self.state_changed = CList()
  16
  17                 self.status = self.NOT_STARTED
  18
  19         # description is a dict
  20         def fromDescription(self, description):
  21                 pass
  22
  23         def createDescription(self):
  24                 return None
  25
  26         def addTask(self, task):
  27                 self.tasks.append(task)
  28
  29         def start(self, callback):
  30                 assert self.callback is None
  31                 self.callback = callback
  32                 self.status = self.IN_PROGRESS
  33                 self.state_changed()
  34                 self.runNext()
  35
  36         def runNext(self):
  37                 if self.current_task == len(self.tasks):
  38                         self.callback(self, [])
  39                         self.status = self.FINISHED
  40                         self.state_changed()
  41                 else:
  42                         self.tasks[self.current_task].run(self.taskCallback)
  43                         self.state_changed()
  44
  45         def taskCallback(self, res):
  46                 if len(res):
  47                         print ">>> Error:", res
  48                         self.status = self.FAILED
  49                         self.state_changed()
  50                         self.callback(self, res)
  51                 else:
  52                         self.current_task += 1
  53                         self.runNext()
  54
  55 class Task:
  56         def __init__(self, name):
  57                 self.name = name
  58                 self.workspace = "/tmp"
  59                 self.immediate_preconditions = [ ]
  60                 self.global_preconditions = [ ]
  61                 self.postconditions = [ ]
  62                 self.returncode = None
  63                 self.initial_input = None
  64
  65                 self.cmd = None
  66                 self.args = [ ]
  67
  68         def setCommandline(self, cmd, args):
  69                 self.cmd = cmd
  70                 self.args = args
  71
  72         def setTool(self, tool):
  73                 self.cmd = tool
  74                 self.args = [tool]
  75                 self.global_preconditions.append(ToolExistsPrecondition())
  76                 self.postconditions.append(ReturncodePostcondition())
  77
  78         def checkPreconditions(self, immediate = False):
  79                 not_met = [ ]
  80                 if immediate:
  81                         preconditions = self.immediate_preconditions
  82                 else:
  83                         preconditions = self.global_preconditions
  84                 for precondition in preconditions:
  85                         if not precondition.check(self):
  86                                 not_met.append(precondition)
  87                 return not_met
  88
  89         def run(self, callback):
  90                 failed_preconditions = self.checkPreconditions(True)
  91                 if len(failed_preconditions):
  92                         errback(failed_preconditions)
  93                         return
  94
  95                 self.callback = callback
  96                 from enigma import eConsoleAppContainer
  97                 self.container = eConsoleAppContainer()
  98                 self.container.appClosed.get().append(self.processFinished)
  99                 self.container.dataAvail.get().append(self.processOutput)
 100
 101                 assert self.cmd is not None
 102                 assert len(self.args) >= 1
 103
 104                 print "execute:", self.container.execute(self.cmd, self.args), self.cmd, self.args
 105                 if self.initial_input:
 106                         self.writeInput(self.initial_input)
 107
 108         def prepare(self):
 109                 pass
 110
 111         def cleanup(self, failed):
 112                 pass
 113
 114         def processOutput(self, data):
 115                 pass
 116
 117         def processFinished(self, returncode):
 118                 self.returncode = returncode
 119                 self.finish()
 120
 121         def finish(self):
 122                 self.afterRun()
 123                 not_met = [ ]
 124                 for postcondition in self.postconditions:
 125                         if not postcondition.check(self):
 126                                 not_met.append(postcondition)
 127
 128                 self.callback(not_met)
 129
 130         def afterRun(self):
 131                 pass
 132
 133         def writeInput(self, input):
 134                 self.container.write(input)
 135
 136 class JobManager:
 137         def __init__(self):
 138                 self.active_jobs = [ ]
 139                 self.failed_jobs = [ ]
 140                 self.job_classes = [ ]
 141                 self.active_job = None
 142
 143         def AddJob(self, job):
 144                 self.active_jobs.append(job)
 145                 self.kick()
 146
 147         def kick(self):
 148                 if self.active_job is None:
 149                         if len(self.active_jobs):
 150                                 self.active_job = self.active_jobs.pop(0)
 151                                 self.active_job.start(self.jobDone)
 152
 153         def jobDone(self, job, problems):
 154                 print "job", job, "completed with", problems
 155                 if problems:
 156                         self.failed_jobs.append(self.active_job)
 157
 158                 self.active_job = None
 159                 self.kick()
 160
 161 # some examples:
 162 #class PartitionExistsPostcondition:
 163 #       def __init__(self, device):
 164 #               self.device = device
 165 #
 166 #       def check(self, task):
 167 #               import os
 168 #               return os.access(self.device + "part1", os.F_OK)
 169 #
 170 #class CreatePartitionTask(Task):
 171 #       def __init__(self, device):
 172 #               Task.__init__(self, _("Create Partition"))
 173 #               self.device = device
 174 #               self.setTool("/sbin/sfdisk")
 175 #               self.args += ["-f", self.device + "disc"]
 176 #               self.initial_input = "0,\n;\n;\n;\ny\n"
 177 #               self.postconditions.append(PartitionExistsPostcondition(self.device))
 178 #
 179 #class CreateFilesystemTask(Task):
 180 #       def __init__(self, device, partition = 1, largefile = True):
 181 #               Task.__init__(self, _("Create Filesystem"))
 182 #               self.setTool("/sbin/mkfs.ext")
 183 #               if largefile:
 184 #                       self.args += ["-T", "largefile"]
 185 #               self.args.append("-m0")
 186 #               self.args.append(device + "part%d" % partition)
 187 #
 188 #class FilesystemMountTask(Task):
 189 #       def __init__(self, device, partition = 1, filesystem = "ext3"):
 190 #               Task.__init__(self, _("Mounting Filesystem"))
 191 #               self.setTool("/bin/mount")
 192 #               if filesystem is not None:
 193 #                       self.args += ["-t", filesystem]
 194 #               self.args.append(device + "part%d" % partition)
 195 #
 196 #class DiskspacePrecondition:
 197 #       def __init__(self, diskspace_required):
 198 #               self.diskspace_required = diskspace_required
 199 #
 200 #       def check(self, task):
 201 #               return getFreeDiskspace(task.workspace) >= self.diskspace_required
 202 #
 203 class ToolExistsPrecondition:
 204         def check(self, task):
 205                 import os
 206                 return os.access(task.cmd, os.X_OK)
 207
 208 class ReturncodePostcondition:
 209         def check(self, task):
 210                 return task.returncode == 0
 211
 212 #class HDDInitJob(Job):
 213 #       def __init__(self, device):
 214 #               Job.__init__(self, _("Initialize Harddisk"))
 215 #               self.device = device
 216 #               self.fromDescription(self.createDescription())
 217 #
 218 #       def fromDescription(self, description):
 219 #               self.device = description["device"]
 220 #               self.addTask(CreatePartitionTask(self.device))
 221 #               self.addTask(CreateFilesystemTask(self.device))
 222 #               self.addTask(FilesystemMountTask(self.device))
 223 #
 224 #       def createDescription(self):
 225 #               return {"device": self.device}
 226
 227 job_manager = JobManager()