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   
 37 -class RRDUtil: 
 38      """ 
 39      Wrapper class around rrdtool 
 40      """ 
 41   
 42 -    def __init__(self, defaultRrdCreateCommand, defaultCycleTime): 
 43          """ 
 44          Initializer 
 45   
 46          The RRD creation command is only used if the RRD file doesn't 
 47          exist and no rrdCommand was specified with the save() method. 
 48   
 49          @param defaultRrdCreateCommand: RRD creation command 
 50          @type defaultRrdCreateCommand: string 
 51          @param defaultCycleTime: expected time to periodically collect data 
 52          @type defaultCycleTime: integer 
 53          """ 
 54          self.defaultRrdCreateCommand = defaultRrdCreateCommand 
 55          self.defaultCycleTime = defaultCycleTime 
 56          self.dataPoints = 0 
 57          self.cycleDataPoints = 0 
 58   
 59   
 60 -    def endCycle(self): 
 61          """ 
 62          Report on the number of data points collected in a cycle, 
 63          and reset the counter for a new cycle. 
 64   
 65          @return: number of data points collected during the cycle 
 66          @rtype: number 
 67          """ 
 68          result = self.cycleDataPoints 
 69          self.cycleDataPoints = 0 
 70          return result 
 71   
 72   
 73 -    def performancePath(self, path): 
 74          """ 
 75          Given a path, return its location from $ZENHOME and the 
 76          perf/ directories. 
 77   
 78          @param path: name for a datapoint in a path (eg device/component/datasource_datapoint) 
 79          @type path: string 
 80          @return: absolute path 
 81          @rtype: string 
 82          """ 
 83          from Products.ZenModel.PerformanceConf import performancePath 
 84          return performancePath(path) 
 85   
 86   
 87 -    def save(self, path, value, rrdType, rrdCommand=None, cycleTime=None, 
 88               min='U', max='U'): 
 89          """ 
 90          Save the value provided in the command to the RRD file specified in path. 
 91   
 92          If the RRD file does not exist, use the rrdType, rrdCommand, min and 
 93          max parameters to create the file. 
 94   
 95          @param path: name for a datapoint in a path (eg device/component/datasource_datapoint) 
 96          @type path: string 
 97          @param value: value to store into the RRD file 
 98          @type value: number 
 99          @param rrdType: RRD data type (eg ABSOLUTE, DERIVE, COUNTER) 
100          @type rrdType: string 
101          @param rrdCommand: RRD file creation command 
102          @type rrdCommand: string 
103          @param cycleTime: length of a cycle 
104          @type cycleTime: number 
105          @param min: minimum value acceptable for this metric 
106          @type min: number 
107          @param max: maximum value acceptable for this metric 
108          @type max: number 
109          @return: the parameter value converted to a number 
110          @rtype: number or None 
111          """ 
112          import rrdtool, os 
113   
114          if value is None: return None 
115   
116          self.dataPoints += 1 
117          self.cycleDataPoints += 1 
118   
119          if cycleTime is None: 
120              cycleTime = self.defaultCycleTime 
121   
122          filename = self.performancePath(path) + '.rrd' 
123          if not rrdCommand: 
124              rrdCommand = self.defaultRrdCreateCommand 
125          if not os.path.exists(filename): 
126              log.debug("Creating new RRD file %s", filename) 
127              dirname = os.path.dirname(filename) 
128              if not os.path.exists(dirname): 
129                  os.makedirs(dirname, 0750) 
130   
131              min, max = map(_checkUndefined, (min, max)) 
132              dataSource = 'DS:%s:%s:%d:%s:%s' % ('ds0', rrdType, 
133                                                  3*cycleTime, min, max) 
134              rrdtool.create(filename, 
135                             "--step",  str(cycleTime), 
136                             str(dataSource), *rrdCommand.split()) 
137           
138          if rrdType in ('COUNTER', 'DERIVE'): 
139              try: 
140                  value = long(value) 
141              except (TypeError, ValueError): 
142                  return None 
143          else: 
144              value = float(value) 
145          try: 
146              rrdtool.update(filename, 'N:%s' % value) 
147              log.debug('%s: %r', filename, value) 
148          except rrdtool.error, err: 
149              # may get update errors when updating too quickly 
150              log.error('rrdtool reported error %s %s', err, path) 
151   
152          if rrdType in ('COUNTER', 'DERIVE'): 
153              startStop, names, values = \ 
154                  rrdtool.fetch(filename, 'AVERAGE', 
155                      '-s', 'now-%d' % (cycleTime*2), 
156                      '-e', 'now') 
157              values = [ v[0] for v in values if v[0] is not None ] 
158              if values: value = values[-1] 
159              else: value = None 
160          return value 
161