Source Code for Module rospy.impl.paramserver

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 32   
 33  """Parameter Server Cache""" 
 34   
 35  from __future__ import with_statement 
 36  import threading 
 37   
 38  #TODO: get rid of this routine entirely. It doesn't work with the current PS representation. 
 39 -class ParamServerCache(object): 
 40      """ 
 41      Cache of values on the parameter server. Implementation 
 42      is just a thread-safe dictionary. 
 43      """ 
 44       
 45 -    def __init__(self): 
 46          self.lock = threading.Lock() 
 47          self.d = {} 
 48          self.notifier = None 
 49           
 50      ## Delete parameter from cache 
 51 -    def delete(self, key): 
 52          with self.lock: 
 53              del self.d[key] 
 54   
 55 -    def set_notifier(self, notifier): 
 56          """ 
 57          Notifier implements any parameter subscription logic. The 
 58          notifier should be a function that takes in a key and value 
 59          that represents a parameter update. Notifier is called under 
 60          lock and thus must not implement any lengthy computation. 
 61          """ 
 62          self.notifier = notifier 
 63           
 64 -    def update(self, key, value): 
 65          """ 
 66          Update the value of the parameter in the cache 
 67          @param key: parameter key 
 68          @type  key: str 
 69          @param value: parameter value 
 70          @type  value: str 
 71          @raise: KeyError if key is not already in the cache. 
 72          """ 
 73          # TODOXXX: remove this code, as it is wrong. It is remaining 
 74          # in place to maintain a unit test until the correct logic is 
 75          # implemented. update() needs to check all subscribed keys and 
 76          # do a prefix match. The best way to do this is probably to 
 77          # pull the paramserver implementation from rosmaster and use 
 78          # it here. 
 79          if not key in self.d: 
 80              raise KeyError(key) 
 81          with self.lock: 
 82              self.d[key] = value 
 83              if self.notifier is not None: 
 84                  self.notifier(key, value) 
 85                   
 86 -    def set(self, key, value): 
 87          """ 
 88          Set the value of the parameter in the cache. This is a 
 89          prerequisite of calling update(). 
 90          @param key: parameter key 
 91          @type  key: str 
 92          @param value: parameter value 
 93          @type  value: str 
 94          """ 
 95          with self.lock: 
 96              self.d[key] = value 
 97               
 98 -    def get(self, key): 
 99          """ 
100          @param key: parameter key 
101          @type  key: str 
102          @return: Current value for parameter 
103          @raise: KeyError 
104          """ 
105          with self.lock: 
106              return self.d[key] 
107   
108  _param_server_cache = None 
109 -def get_param_server_cache(): 
110      """ 
111      Get a handle on the client-wide parameter server cache 
112      """ 
113      global _param_server_cache 
114      if _param_server_cache is None: 
115          _param_server_cache = ParamServerCache()         
116      return _param_server_cache 
117