Source Code for Module Ganga.Utility.external.ARDAMDClient.mdtable

 1  ################################################################################ 
 2  # Ganga Project. http://cern.ch/ganga 
 3  # 
 4  # $Id: mdtable.py,v 1.1 2008-07-17 16:41:02 moscicki Exp $ 
 5  ################################################################################ 
 6  import os 
 7  import time 
 8  from extendedLists import Entries, Attributes 
 9  from diskutils import RLock 
10  from mdinterface import CommandException 
11   
12 -class EmptyTableException(Exception): 
13 -      def __init__(self): 
14            self.raised = True 
15   
16   
17 -class MDTable: 
18 -    def __init__(self, dirname, 
19                   attributes = None, 
20                   entries = None, 
21                   blocklength  = 1000, 
22                   cache_size   = 3, 
23                   tries_limit  = 200): 
24          """dirname is system path to the table files""" 
25          self.dirname = dirname 
26          if attributes == None: 
27              attributes = Attributes(dirname = dirname, 
28                                      blocklength = blocklength, 
29                                      cache_size  = cache_size,    
30                                      tries_limit = tries_limit) 
31          if entries == None: 
32              entries = Entries(dirname = dirname, 
33                                blocklength = blocklength, 
34                                cache_size  = cache_size, 
35                                tries_limit = tries_limit) 
36          self.attributes = attributes 
37          self.entries = entries 
38          self.timestamp = time.time() 
39          self.update() 
40          self._lock = RLock(lockfile    = os.path.join(dirname, 'LOCK'), 
41                             tries_limit = tries_limit) 
42   
43   
44 -    def lock(self): 
45          return self._lock.acquire() 
46       
47           
48 -    def unlock(self): 
49          self._lock.release() 
50   
51   
52 -    def load(self): 
53          if os.path.isdir(self.dirname): 
54              if self.lock(): 
55                  try: 
56                      self.attributes.load(self.dirname) 
57                      self.entries.load(self.dirname) 
58                      self.timestamp = time.time() 
59                      self.update() 
60                  finally: 
61                      self.unlock() 
62              else: 
63                  raise CommandException(9, 'Could not acquire table lock %s' % self.dirname) 
64           
65   
66 -    def save(self): 
67  #        mkdir(self.dirname) 
68          if self.lock(): 
69              try: 
70                  self.update() 
71                  self.attributes.save(self.dirname) 
72                  self.entries.save(self.dirname) 
73              finally: 
74                  self.unlock() 
75          else: 
76              raise CommandException(9, 'Could not acquire table lock %s' % self.dirname) 
77   
78   
79 -    def update(self): 
80          self.attributeDict = {} 
81          self.typeDict = {} 
82          for i in range(0, len(self.attributes)): 
83              a, t=self.attributes[i] # Was a, t=self.attributes[i].split(' ', 1) 
84              self.attributeDict[a]=i 
85              self.typeDict[a] = t 
86          self.initRowPointer() 
87           
88   
89 -    def initRowPointer(self): 
90          self.currentRow = 0 
91          if not len(self.entries): 
92              self.currentRow = -1 
93