actions.py

   1 from const import reactor
   2
   3 from hash import intify
   4 from knode import KNode as Node
   5 from ktable import KTable, K
   6 # concurrent FIND_NODE/VALUE requests!
   7 N = 3
   8
   9 class ActionBase:
  10     """ base class for some long running asynchronous proccesses like finding nodes or values """
  11     def __init__(self, table, target, callback):
  12         self.table = table
  13         self.target = target
  14         self.int = intify(target)
  15         self.found = {}
  16         self.queried = {}
  17         self.answered = {}
  18         self.callback = callback
  19         self.outstanding = 0
  20         self.finished = 0
  21
  22         def sort(a, b, int=self.int):
  23             """ this function is for sorting nodes relative to the ID we are looking for """
  24             x, y = int ^ a.int, int ^ b.int
  25             if x > y:
  26                 return 1
  27             elif x < y:
  28                 return -1
  29             return 0
  30         self.sort = sort
  31
  32     def goWithNodes(self, t):
  33         pass
  34
  35
  36
  37 FIND_NODE_TIMEOUT = 15
  38
  39 class FindNode(ActionBase):
  40     """ find node action merits it's own class as it is a long running stateful process """
  41     def handleGotNodes(self, args):
  42         l, sender = args
  43         if self.finished or self.answered.has_key(sender['id']):
  44             # a day late and a dollar short
  45             return
  46         self.outstanding = self.outstanding - 1
  47         self.answered[sender['id']] = 1
  48         for node in l:
  49             if not self.found.has_key(node['id']):
  50                 n = Node(node['id'], node['host'], node['port'])
  51                 self.found[n.id] = n
  52                 self.table.insertNode(n)
  53         self.schedule()
  54
  55     def schedule(self):
  56         """
  57             send messages to new peers, if necessary
  58         """
  59         if self.finished:
  60             return
  61         l = self.found.values()
  62         l.sort(self.sort)
  63
  64         for node in l[:K]:
  65             if node.id == self.target:
  66                 self.finished=1
  67                 return self.callback([node])
  68             if not self.queried.has_key(node.id) and node.id != self.table.node.id:
  69                 #xxxx t.timeout = time.time() + FIND_NODE_TIMEOUT
  70                 df = node.findNode(self.target, self.table.node.senderDict())
  71                 df.addCallbacks(self.handleGotNodes, self.defaultGotNodes)
  72                 self.outstanding = self.outstanding + 1
  73                 self.queried[node.id] = 1
  74             if self.outstanding >= N:
  75                 break
  76         assert(self.outstanding) >=0
  77         if self.outstanding == 0:
  78             ## all done!!
  79             self.finished=1
  80             reactor.callFromThread(self.callback, l[:K])
  81
  82     def defaultGotNodes(self, t):
  83         if self.finished:
  84             return
  85         self.outstanding = self.outstanding - 1
  86         self.schedule()
  87
  88
  89     def goWithNodes(self, nodes):
  90         """
  91             this starts the process, our argument is a transaction with t.extras being our list of nodes
  92             it's a transaction since we got called from the dispatcher
  93         """
  94         for node in nodes:
  95             if node.id == self.table.node.id:
  96                 continue
  97             self.found[node.id] = node
  98             #xxx t.timeout = time.time() + FIND_NODE_TIMEOUT
  99             df = node.findNode(self.target, self.table.node.senderDict())
 100             df.addCallbacks(self.handleGotNodes, self.defaultGotNodes)
 101             self.outstanding = self.outstanding + 1
 102             self.queried[node.id] = 1
 103         if self.outstanding == 0:
 104             self.callback(nodes)
 105
 106
 107 GET_VALUE_TIMEOUT = 15
 108 class GetValue(FindNode):
 109     """ get value task """
 110     def handleGotNodes(self, args):
 111         l, sender = args
 112         if self.finished or self.answered.has_key(sender['id']):
 113             # a day late and a dollar short
 114             return
 115         self.outstanding = self.outstanding - 1
 116         self.answered[sender['id']] = 1
 117         # go through nodes
 118         # if we have any closer than what we already got, query them
 119         if l.has_key('nodes'):
 120             for node in l['nodes']:
 121                 if not self.found.has_key(node['id']):
 122                     n = Node(node['id'], node['host'], node['port'])
 123                     self.found[n.id] = n
 124                     self.table.insertNode(n)
 125         elif l.has_key('values'):
 126             ## done
 127             self.finished = 1
 128             reactor.callFromThread(self.callback, l['values'])
 129         self.schedule()
 130
 131     ## get value
 132     def schedule(self):
 133         if self.finished:
 134             return
 135         l = self.found.values()
 136         l.sort(self.sort)
 137
 138         for node in l[:K]:
 139             if not self.queried.has_key(node.id) and node.id != self.table.node.id:
 140                 #xxx t.timeout = time.time() + GET_VALUE_TIMEOUT
 141                 df = node.findValue(self.target, self.table.node.senderDict())
 142                 df.addCallback(self.handleGotNodes)
 143                 df.addErrback(self.defaultGotNodes)
 144                 self.outstanding = self.outstanding + 1
 145                 self.queried[node.id] = 1
 146             if self.outstanding >= N:
 147                 break
 148         assert(self.outstanding) >=0
 149         if self.outstanding == 0:
 150             ## all done, didn't find it!!
 151             self.finished=1
 152             reactor.callFromThread(self.callback,[])
 153
 154     ## get value
 155     def goWithNodes(self, nodes):
 156         for node in nodes:
 157             if node.id == self.table.node.id:
 158                 continue
 159             self.found[node.id] = node
 160             #xxx t.timeout = time.time() + FIND_NODE_TIMEOUT
 161             df = node.findValue(self.target, self.table.node.senderDict())
 162             df.addCallbacks(self.handleGotNodes, self.defaultGotNodes)
 163             self.outstanding = self.outstanding + 1
 164             self.queried[node.id] = 1
 165         if self.outstanding == 0:
 166             reactor.callFromThread(self.callback, [])
 167