weather reporter example

weatherApp/weather.py

@@ -0,0 +1,160 @@
+# -*- coding: utf-8 -*-
+from __future__ import print_function
+
+import socket, time
+
+from weakref import WeakValueDictionary
+
+from devsup.hooks import addHook
+from devsup.util import StoppableThread
+from devsup.db import IOScanListBlock
+
+try:
+  import pymetar
+except ImportError:
+  print("The pymetar package could not be imported!")
+  raise
+
+_isofmt = '%Y-%m-%d %H:%M:%SZ'
+
+def iso2sec(str):
+  """Convert the string returned by pymetar to posix time.
+  """
+  rtime = time.mktime(time.strptime(str, _isofmt))
+  return rtime - (time.altzone if time.daylight else time.timezone)
+
+_stations = WeakValueDictionary()
+
+def getStation(name):
+  try:
+    return _stations[name]
+  except KeyError:
+    S = ReportScanner(name)
+    _stations[name] = S
+    return S
+
+class DataWatcher(object):
+  """Weather watcher device support.
+  
+  field(INP,"weather KISP getTemperatureCelsius")
+  of
+  field(INP,"weather KISP showID")
+  """
+
+  # disable automatic RVAL -> VAL conversion.
+  # We will update VAL ourselves.
+  raw = True
+
+  def __init__(self, rec, args):
+    station, name = args.split(None, 1)
+
+    self.staid = station
+    self.sta = getStation(station)
+    self.attr = name
+    self.last = None
+
+    if name.startswith('get'):
+      # Assume this is a method of pymetar.WeatherReport
+      self.allowScan = self.sta.scan.add
+      self.process = self.process_report
+    else:
+      # Our own internal info
+      self.allowScan = self.sta.intscan.add
+      self.process = getattr(self, name)
+      try:
+        rec.UDF = 0
+      except AttributeError:
+        pass
+
+  def detach(self, rec):
+    pass
+
+  def showID(self, rec, report):
+    rec.VAL = self.staid
+
+  def updatePeriod(self, rec, report):
+    rec.VAL = self.sta.updatePeriod/60.0
+
+  def process_report(self, rec, report):
+    if report is not None:
+      self.last = report
+    else:
+      report = self.last
+
+    if report is None:
+      rec.setSevr()
+      return
+
+    fn = getattr(self.last, self.attr)
+    newval = fn()
+    try:
+      rec.VAL = newval
+    except ValueError:
+      rec.setSevr()
+    try:
+      rec.UDF = 0
+    except AttributeError:
+      pass
+    if rec.TSE==-2:
+      rec.setTime(report._updatetime)
+
+build = DataWatcher
+
+class ReportScanner(StoppableThread):
+  """Driver thread which occasionally polls for new metar data
+  """
+
+  def __init__(self, station):
+    self.io = pymetar.ReportFetcher()
+    self.station = station
+    self.initPeriod = self.updatePeriod = 15*60.0
+    self.minPeriod = 10*60.0
+    self.maxPeriod = 2*60*60.0
+    self.lastUpdate = None # Time of last report
+    self.scan = IOScanListBlock() # I/O Intr scan for report data
+    self.intscan = IOScanListBlock() # scan for internal info
+
+    super(ReportScanner,self).__init__()
+
+    addHook('AfterIocRunning', self.start)
+    addHook('AtIocExit', self.join)
+
+  def run(self):
+    print("Starting scanner for ",self.station)
+
+    while self.shouldRun():
+      try:
+        report = self.io.FetchReport(self.station)
+        pymetar.ReportParser().ParseReport(report)
+
+        rtime = iso2sec(report.getISOTime())
+        report._updatetime = rtime
+        print('update',report.getISOTime(),rtime,self.lastUpdate)
+
+        if self.lastUpdate is not None:
+          if self.lastUpdate >= rtime:
+            #print('No update, Wait a little longer next time')
+            self.updatePeriod = self.initPeriod
+
+          else: # self.lastUpdate < rtime
+            #print('Got an update')
+            self.updatePeriod = rtime - self.lastUpdate
+            self.updatePeriod = max(self.minPeriod, min(self.updatePeriod, self.maxPeriod))
+            self.updatePeriod += 15*60.0
+            self.scan.interrupt(reason=report)
+        else:
+          self.scan.interrupt(reason=report)
+
+        self.lastUpdate = rtime
+
+      except socket.error, e:
+        print("download error for",self.station,":",e)
+        self.updatePeriod = self.initPeriod
+
+
+      self.intscan.interrupt()
+
+      #print('Waiting',self.updatePeriod)
+      self.sleep(self.updatePeriod)
+
+    print('Done')