Offload rrdtool calls and model to separate module

RRD.py

@@ -0,0 +1,343 @@
+import subprocess
+import re
+import io
+import os
+from tempfile import TemporaryFile
+from operator import xor, eq
+from functools import reduce
+from itertools import starmap
+import math
+
+class RRDIncompatibleException(Exception):
+    """
+    Is raised when an RRD doesn't have the desired definition and cannot be
+    upgraded to it.
+    """
+    pass
+class RRDOutdatedException(Exception):
+    """
+    Is raised when an RRD doesn't have the desired definition, but can be
+    upgraded to it.
+    """
+    pass
+
+if not hasattr(__builtins__, "FileNotFoundError"):
+    class FileNotFoundError(Exception):
+        pass
+
+class RRD:
+    """
+    An RRD is a Round Robin Database, a database which forgets old data and
+    aggregates multiple records into new ones.
+
+    It contains multiple Data Sources (DS) which can be thought of as columns,
+    and Round Robin Archives (RRA) which can be thought of as tables with the
+    DS as columns and time-dependant rows.
+    """
+
+    # rra[2].cdp_prep[0].value = 1,8583033333e+03
+    _info_regex = re.compile("""
+            (?P<section>[a-z_]+)
+            \[ (?P<key>[a-zA-Z0-9_]+) \]
+            \.
+        |
+            (?P<name>[a-z_]+)
+            \s*=\s*
+            "? (?P<value>.*?) "?
+        $""", re.X)
+    _cached_info = None
+
+    def _exec_rrdtool(self, cmd, *args, **kwargs):
+        pargs = ["rrdtool", cmd, self.filename]
+        for k,v in kwargs.items():
+            pargs.extend(["--" + k, str(v)])
+        pargs.extend(args)
+        subprocess.check_output(pargs)
+
+    def __init__(self, filename):
+        self.filename = filename
+
+    def ensureSanity(self, ds_list, rra_list, **kwargs):
+        """
+        Create or upgrade the RRD file if necessary to contain all DS in
+        ds_list. If it needs to be created, the RRAs in rra_list and any kwargs
+        will be used for creation. Note that RRAs and options of an existing
+        database are NOT modified!
+        """
+        try:
+            self.checkSanity(ds_list)
+        except FileNotFoundError:
+            self.create(ds_list, rra_list, **kwargs)
+        except RRDOutdatedException:
+            self.upgrade(ds_list)
+
+    def checkSanity(self, ds_list=()):
+        """
+        Check if the RRD file exists and contains (at least) the DS listed in
+        ds_list.
+        """
+        if not os.path.exists(self.filename):
+            raise FileNotFoundError(self.filename)
+        info = self.info()
+        if set(ds_list) - set(info['ds'].values()) != set():
+            if set((ds.name, ds.type) for ds in ds_list) \
+             - set((ds.name, ds.type) for ds in info['ds'].values()) != set():
+                raise RRDIncompatibleException()
+            else:
+                raise RRDOutdatedException()
+
+    def upgrade(self, dss):
+        """
+        Upgrade the DS definitions (!) of this RRD.
+        (To update its values, use update())
+
+        The list dss contains DSS objects to be updated or added. The
+        parameters of a DS can be changed, but not its type. New DS are always
+        added at the end in the order of their appearance in the list.
+
+        This is done internally via an rrdtool dump -> rrdtool restore and
+        modifying the dump on the fly.
+        """
+        info = self.info()
+        new_ds = list(info['ds'].values())
+        new_ds.sort(key=lambda ds: ds.index)
+        for ds in dss:
+            if ds.name in info['ds']:
+                old_ds = info['ds'][ds.name]
+                if info['ds'][ds.name].type != ds.type:
+                    raise RuntimeError('Cannot convert existing DS "%s" from type "%s" to "%s"' %
+                        (ds.name, old_ds.type, ds.type))
+                ds.index = old_ds.index
+                new_ds[ds.index] = ds
+            else:
+                ds.index = len(new_ds)
+                new_ds.append(ds)
+        added_ds_num = len(new_ds) - len(info['ds'])
+
+        dump = subprocess.Popen(
+            ["rrdtool", "dump", self.filename],
+            stdout=subprocess.PIPE
+        )
+        restore = subprocess.Popen(
+            ["rrdtool", "restore", "-", self.filename + ".new"],
+            stdin=subprocess.PIPE
+        )
+        echo = True
+        ds_definitions = True
+        for line in dump.stdout:
+            if ds_definitions and b'<ds>' in line:
+                echo = False
+            if b'<!-- Round Robin Archives -->' in line:
+                ds_definitions = False
+                for ds in new_ds:
+                    restore.stdin.write(bytes("""
+                        <ds>
+                           <name> %s </name>
+                           <type> %s </type>
+                           <minimal_heartbeat>%i</minimal_heartbeat>
+                           <min>%s</min>
+                           <max>%s</max>
+
+                           <!-- PDP Status -->
+                           <last_ds>%s</last_ds>
+                           <value>%s</value>
+                           <unknown_sec> %i </unknown_sec>
+                        </ds>
+                        """ % (
+                            ds.name,
+                            ds.type,
+                            ds.args[0],
+                            ds.args[1],
+                            ds.args[2],
+                            ds.last_ds,
+                            ds.value,
+                            ds.unknown_sec)
+                    , "utf-8"))
+
+            if b'</cdp_prep>' in line:
+                restore.stdin.write(added_ds_num*b"""
+                        <ds>
+                        <primary_value> NaN </primary_value>
+                        <secondary_value> NaN </secondary_value>
+                        <value> NaN </value>
+                        <unknown_datapoints> 0 </unknown_datapoints>
+                        </ds>
+                """)
+
+            # echoing of input line
+            if echo:
+                restore.stdin.write(
+                    line.replace(
+                        b'</row>',
+                        (added_ds_num*b'<v>NaN</v>')+b'</row>'
+                    )
+                )
+
+            if ds_definitions and b'</ds>' in line:
+                echo = True
+        dump.stdout.close()
+        restore.stdin.close()
+        try:
+            dump.wait(1)
+        except subprocess.TimeoutExpired:
+            dump.kill()
+        try:
+            restore.wait(2)
+        except subprocess.TimeoutExpired:
+            dump.kill()
+            raise RuntimeError("rrdtool restore process killed")
+
+        os.rename(self.filename + ".new", self.filename)
+        self._cached_info = None
+
+    def create(self, ds_list, rra_list, **kwargs):
+        """
+        Create a new RRD file with the specified list of RRAs and DSs.
+
+        Any kwargs are passed as --key=value to rrdtool create.
+        """
+        self._exec_rrdtool(
+            "create",
+            *map(str, rra_list + ds_list),
+            **kwargs
+        )
+        self._cached_info = None
+
+    def update(self, V):
+        """
+        Update the RRD with new values V.
+
+        V can be either list or dict:
+        * If it is a dict, its keys must be DS names in the RRD and it is
+          ensured that the correct DS are updated with the correct values, by
+          passing a "template" to rrdtool update (see man rrdupdate).
+        * If it is a list, no template is generated and the order of the
+          values in V must be the same as that of the DS in the RRD.
+        """
+        try:
+            args = ['N:' + ':'.join(map(str, V.values()))]
+            kwargs = {'template': ':'.join(V.keys())}
+        except AttributeError:
+            args = ['N:' + ':'.join(map(str, V))]
+            kwargs = {}
+        self._exec_rrdtool("update", *args, **kwargs)
+        self._cached_info = None
+
+    def info(self):
+        """
+        Return a dictionary with information about the RRD.
+
+        See `man rrdinfo` for more details.
+        """
+        if self._cached_info:
+            return self._cached_info
+        env = os.environ.copy()
+        env["LC_ALL"] = "C"
+        proc = subprocess.Popen(
+            ["rrdtool", "info", self.filename],
+            stdout=subprocess.PIPE,
+            env=env
+        )
+        out, err = proc.communicate()
+        out = out.decode()
+        info = {}
+        for line in out.splitlines():
+            base = info
+            for match in self._info_regex.finditer(line):
+                section, key, name, value = match.group("section", "key", "name", "value")
+                if section and key:
+                    try:
+                        key = int(key)
+                    except ValueError:
+                        pass
+                    if section not in base:
+                        base[section] = {}
+                    if key not in base[section]:
+                        base[section][key] = {}
+                    base = base[section][key]
+                if name and value:
+                    try:
+                        base[name] = int(value)
+                    except ValueError:
+                        try:
+                            base[name] = float(value)
+                        except:
+                            base[name] = value
+        dss = {}
+        for name, ds in info['ds'].items():
+            ds_obj = DS(name, ds['type'], ds['minimal_heartbeat'], ds['min'], ds['max'])
+            ds_obj.index = ds['index']
+            ds_obj.last_ds = ds['last_ds']
+            ds_obj.value = ds['value']
+            ds_obj.unknown_sec = ds['unknown_sec']
+            dss[name] = ds_obj
+        info['ds'] = dss
+        rras = []
+        for rra in info['rra'].values():
+            rras.append(RRA(rra['cf'], rra['xff'], rra['pdp_per_row'], rra['rows']))
+        info['rra'] = rras
+        self._cached_info = info
+        return info
+
+class DS:
+    """
+    DS stands for Data Source and represents one line of data points in a Round
+    Robin Database (RRD).
+    """
+    name = None
+    type = None
+    args = []
+    index = -1
+    last_ds = 'U'
+    value = 0
+    unknown_sec = 0
+    def __init__(self, name, dst, *args):
+        self.name = name
+        self.type = dst
+        self.args = args
+
+    def __str__(self):
+        return "DS:%s:%s:%s" % (
+            self.name,
+            self.type,
+            ":".join(map(str, self._nan_to_U_args()))
+        )
+
+    def __repr__(self):
+        return "%s(%r, %r, %s)" % (
+            self.__class__.__name__,
+            self.name,
+            self.type,
+            ", ".join(map(repr, self.args))
+        )
+
+    def __eq__(self, other):
+        return all(starmap(eq, zip(self._compare_keys(), other._compare_keys())))
+
+    def __hash__(self):
+        return reduce(xor, map(hash, self._compare_keys()))
+
+    def _nan_to_U_args(self):
+        return tuple(
+            'U' if type(arg) is float and math.isnan(arg)
+            else arg
+            for arg in self.args
+        )
+
+    def _compare_keys(self):
+        return (self.name, self.type, self._nan_to_U_args())
+
+class RRA:
+    def __init__(self, cf, *args):
+        self.cf = cf
+        self.args = args
+
+    def __str__(self):
+        return "RRA:%s:%s" % (self.cf, ":".join(map(str, self.args)))
+
+    def __repr__(self):
+        return "%s(%r, %s)" % (
+            self.__class__.__name__,
+            self.cf,
+            ", ".join(map(repr, self.args))
+        )

rrd.py

@@ -2,6 +2,7 @@
 import subprocess
 import time
 import os
+from RRD import RRD, DS, RRA
 
 class rrd:
   def __init__( self
@@ -11,7 +12,7 @@ class rrd:
               , displayTimeNode = "1d"
               ):
     self.dbPath = databaseDirectory
-    self.globalDbFile = databaseDirectory + "/nodes.rrd"
+    self.globalDb = RRD(databaseDirectory + "/nodes.rrd")
     self.imagePath = imagePath
     self.displayTimeGlobal = displayTimeGlobal
     self.displayTimeNode = displayTimeNode
@@ -24,39 +25,29 @@ class rrd:
     except:
       os.mkdir(self.imagePath)
 
-  def checkAndCreateIfNeededGlobalDatabase(self):
-    """ Creates the global database file iff it did not exist.
-    """
-    if not os.path.exists(self.globalDbFile):
-      # Create Database with rrdtool
-      args =  ["rrdtool",'create', self.globalDbFile
-              ,'--start', str(round(self.currentTimeInt - 60))
-              ,'--step' , '60'
-              # Number of nodes available
-              ,'DS:nodes:GAUGE:120:0:U'
-              # Number of client available
-              ,'DS:clients:GAUGE:120:0:U'
-              ,'RRA:AVERAGE:0.5:1:120'
-              ,'RRA:AVERAGE:0.5:60:744'
-              ,'RRA:AVERAGE:0.5:1440:1780'
-              ]
-      subprocess.call(args)
-
   def updateGlobalDatabase(self,nodeCount,clientCount):
     """ Adds a new (#Nodes,#Clients) entry to the global database.
     """
-    # Update Global RRDatabase
+    self.globalDb.ensureSanity(
-    args =  ["rrdtool",'updatev', self.globalDbFile
+      [
-            # #Nodes #Clients
+        # Number of nodes available
-            , self.currentTime + ":"+str(nodeCount)+":"+str(clientCount)
+        DS('nodes', 'GAUGE', 120, 0, float('NaN')),
-            ]
+        # Number of client available
-    subprocess.check_output(args)
+        DS('clients', 'GAUGE', 120, 0, float('NaN')),
+      ], [
+        RRA('LAST', 0, 1, 44640),
+        RRA('LAST', 0, 60, 744),
+        RRA('LAST', 0, 1440, 1780),
+      ],
+      step=60,
+    )
+    self.globalDb.update({'nodes': nodeCount, 'clients': clientCount})
 
   def createGlobalGraph(self):
     nodeGraph = self.imagePath + "/" + "globalGraph.png"
     args = ["rrdtool", 'graph', nodeGraph, '-s', '-' + self.displayTimeGlobal, '-w', '800', '-h' '400'
-           ,'DEF:nodes=' + self.globalDbFile + ':nodes:AVERAGE', 'LINE1:nodes#F00:nodes\\l'
+           ,'DEF:nodes=' + self.globalDb.filename + ':nodes:AVERAGE', 'LINE1:nodes#F00:nodes\\l'
-           ,'DEF:clients=' + self.globalDbFile + ':clients:AVERAGE','LINE2:clients#00F:clients'
+           ,'DEF:clients=' + self.globalDb.filename + ':clients:AVERAGE','LINE2:clients#00F:clients'
            ]
     subprocess.check_output(args)
 
@@ -67,26 +58,20 @@ class rrd:
   def nodeMACToPNGFile(self,nodeMAC):
     return self.imagePath + "/" + str(nodeMAC).replace(":","") + ".png"
 
-  def checkAndCreateIfNeededNodeDatabase(self,nodePrimaryMAC):
-    # TODO check for bad nodeNames
-    nodeFile = self.nodeMACToRRDFile(nodePrimaryMAC);
-    if not os.path.exists(nodeFile):
-      # TODO Skalen anpassen
-      args = ["rrdtool",'create',nodeFile
-             ,'--start',str(round(self.currentTimeInt - 60))
-             ,'--step' , '60'
-             ,'DS:upstate:GAUGE:120:0:1'
-             ,'DS:clients:GAUGE:120:0:200'
-             ,'RRA:AVERAGE:0.5:1:120'
-             ,'RRA:AVERAGE:0.5:5:1440'
-             ,'RRA:AVERAGE:0.5:60:720'
-             ,'RRA:AVERAGE:0.5:720:730'
-             ]
-      subprocess.check_output(args)
-
   # Call only if node is up
   def updateNodeDatabase(self,nodePrimaryMAC,clientCount):
+    # TODO check for bad nodeNames
     nodeFile = self.nodeMACToRRDFile(nodePrimaryMAC)
+    nodeRRD = RRD(nodeFile)
+    nodeRRD.ensureSanity(
+      [
+        DS('upstate', 'GAUGE', 120, 0, 1),
+        DS('clients', 'GAUGE', 120, 0, float('NaN')),
+      ], [
+        RRA('LAST', 0, 1, 44640),
+      ],
+      step=60,
+    )
     # Update Global RRDatabase
     args =  ["rrdtool",'updatev', nodeFile
             # #Upstate #Clients
@@ -128,10 +113,8 @@ class rrd:
       elif target in nodes and not source in nodes:
         nodes[target].clients += 1
 
-    self.checkAndCreateIfNeededGlobalDatabase()
     self.updateGlobalDatabase(len(nodes),clientCount)
     for mac in nodes:
-      self.checkAndCreateIfNeededNodeDatabase(mac)
       self.updateNodeDatabase(mac,nodes[mac].clients)
 
   def update_images(self):