Source Code for Module ZenRRD.RRDUtil

  1  ########################################################################### 
  2  # 
  3  # This program is part of Zenoss Core, an open source monitoring platform. 
  4  # Copyright (C) 2007, Zenoss Inc. 
  5  # 
  6  # This program is free software; you can redistribute it and/or modify it 
  7  # under the terms of the GNU General Public License version 2 as published by 
  8  # the Free Software Foundation. 
  9  # 
 10  # For complete information please visit: http://www.zenoss.com/oss/ 
 11  # 
 12  ########################################################################### 
 13   
 14  __doc__ = """RRDUtil 
 15   
 16  Wrapper routines around the rrdtool library. 
 17  """ 
 18   
 19  import logging 
 20  log = logging.getLogger("zen.RRDUtil") 
 21   
 22 -def _checkUndefined(x): 
 23      """ 
 24      Sanity check on the min, max values 
 25   
 26      @param x: RRD min or max value 
 27      @type x: number 
 28      @return: Either the number or 'U' (for undefined) 
 29      @rtype: number or string 
 30      """ 
 31      if x is None or x == '' or x == -1 or x == '-1': 
 32          return 'U' 
 33      return x 
 34   
 35   
 36 -def convertToRRDTime(val): 
 37      """ 
 38      Convert any value that is passed in to a string that is acceptable to use 
 39      for RRDtool's start and end parameters. Raises ValueError if this is not 
 40      possible. 
 41       
 42      See the AT-STYLE TIME SPECIFICATION and TIME REFERENCE SPECIFICATION 
 43      sections of the following document. 
 44       
 45          http://oss.oetiker.ch/rrdtool/doc/rrdfetch.en.html 
 46       
 47      Note: Currently this method is only fixing floats by turning them into 
 48            strings with no decimal places. 
 49      """ 
 50      # Integers are ok. This will also strip decimal precision. 
 51      try: 
 52          result = int(val) 
 53          return str(result) 
 54      except ValueError: 
 55          pass 
 56   
 57      return str(val) 
 58   
 59   
 60 -class RRDUtil: 
 61      """ 
 62      Wrapper class around rrdtool 
 63      """ 
 64   
 65 -    def __init__(self, defaultRrdCreateCommand, defaultCycleTime): 
 66          """ 
 67          Initializer 
 68   
 69          The RRD creation command is only used if the RRD file doesn't 
 70          exist and no rrdCommand was specified with the save() method. 
 71   
 72          @param defaultRrdCreateCommand: RRD creation command 
 73          @type defaultRrdCreateCommand: string 
 74          @param defaultCycleTime: expected time to periodically collect data 
 75          @type defaultCycleTime: integer 
 76          """ 
 77          self.defaultRrdCreateCommand = defaultRrdCreateCommand 
 78          self.defaultCycleTime = defaultCycleTime 
 79          self.dataPoints = 0 
 80          self.cycleDataPoints = 0 
 81   
 82   
 83 -    def endCycle(self): 
 84          """ 
 85          Report on the number of data points collected in a cycle, 
 86          and reset the counter for a new cycle. 
 87   
 88          @return: number of data points collected during the cycle 
 89          @rtype: number 
 90          """ 
 91          result = self.cycleDataPoints 
 92          self.cycleDataPoints = 0 
 93          return result 
 94   
 95   
 96 -    def performancePath(self, path): 
 97          """ 
 98          Given a path, return its location from $ZENHOME and the 
 99          perf/ directories. 
100   
101          @param path: name for a datapoint in a path (eg device/component/datasource_datapoint) 
102          @type path: string 
103          @return: absolute path 
104          @rtype: string 
105          """ 
106          from Products.ZenModel.PerformanceConf import performancePath 
107          return performancePath(path) 
108   
109   
110 -    def save(self, path, value, rrdType, rrdCommand=None, cycleTime=None, 
111               min='U', max='U'): 
112          """ 
113          Save the value provided in the command to the RRD file specified in path. 
114   
115          If the RRD file does not exist, use the rrdType, rrdCommand, min and 
116          max parameters to create the file. 
117   
118          @param path: name for a datapoint in a path (eg device/component/datasource_datapoint) 
119          @type path: string 
120          @param value: value to store into the RRD file 
121          @type value: number 
122          @param rrdType: RRD data type (eg ABSOLUTE, DERIVE, COUNTER) 
123          @type rrdType: string 
124          @param rrdCommand: RRD file creation command 
125          @type rrdCommand: string 
126          @param cycleTime: length of a cycle 
127          @type cycleTime: number 
128          @param min: minimum value acceptable for this metric 
129          @type min: number 
130          @param max: maximum value acceptable for this metric 
131          @type max: number 
132          @return: the parameter value converted to a number 
133          @rtype: number or None 
134          """ 
135          import rrdtool, os 
136   
137          if value is None: return None 
138   
139          self.dataPoints += 1 
140          self.cycleDataPoints += 1 
141   
142          if cycleTime is None: 
143              cycleTime = self.defaultCycleTime 
144   
145          filename = self.performancePath(path) + '.rrd' 
146          if not rrdCommand: 
147              rrdCommand = self.defaultRrdCreateCommand 
148          if not os.path.exists(filename): 
149              log.debug("Creating new RRD file %s", filename) 
150              dirname = os.path.dirname(filename) 
151              if not os.path.exists(dirname): 
152                  os.makedirs(dirname, 0750) 
153   
154              min, max = map(_checkUndefined, (min, max)) 
155              dataSource = 'DS:%s:%s:%d:%s:%s' % ('ds0', rrdType, 
156                                                  3*cycleTime, min, max) 
157              rrdtool.create(filename, 
158                             "--step",  str(cycleTime), 
159                             str(dataSource), *rrdCommand.split()) 
160           
161          if rrdType in ('COUNTER', 'DERIVE'): 
162              try: 
163                  value = long(value) 
164              except (TypeError, ValueError): 
165                  return None 
166          else: 
167              value = float(value) 
168          try: 
169              rrdtool.update(filename, 'N:%s' % value) 
170              log.debug('%s: %r', filename, value) 
171          except rrdtool.error, err: 
172              # may get update errors when updating too quickly 
173              log.error('rrdtool reported error %s %s', err, path) 
174   
175          if rrdType in ('COUNTER', 'DERIVE'): 
176              startStop, names, values = \ 
177                  rrdtool.fetch(filename, 'AVERAGE', 
178                      '-s', 'now-%d' % (cycleTime*2), 
179                      '-e', 'now') 
180              values = [ v[0] for v in values if v[0] is not None ] 
181              if values: value = values[-1] 
182              else: value = None 
183          return value 
184