CgminerRPCClient.py

#
# class to access cgminer via RPC API
# instantiate class with host and port number of server where cgminer instance is running
# throws: generic exception message: Exception ("API Connection Error")
#
import socket
import time
import json

class CgminerRPCClient:
    #
    ## Class init
    #
    def __init__(self, host, port):
        self.host = host
        self.port = port

    #
    # execute cgminer API remote procedure call
    # parms: string containing the desired cgminer API command
    #
    def command(self, command):
        try:
            s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
            s.settimeout(10)
            s.connect((self.host, self.port))
            s.settimeout(None)
            s.sendall(json.dumps({"command": command})) # send API request formatted as json
            time.sleep(0.02)
    
            # loop until a zero byte indicates we got all the data
            data = ""
            while True:
                buffer = s.recv(65535)
                if '\x00' in buffer:
                    data += buffer # keep the buffer and bail from the loop - we got all the data
                    break # zero found, so we must have all the data TODO break in loop is ugly           
                else:
                    data += buffer # No zero found yet, append current buffer to data and loop for more 
            
            s.close() # close the socket
            
        except Exception as e:
            print "API Exception executing command: " + command
            print str(e) # TODO conditional logging?
            raise Exception ("API Connection Error")
      
        if data:                   
            try:
                data = data.replace('\x00', '') # the null byte makes json decoding unhappy
                decoded = json.loads(data)      # we sent a json request, so expect json response
                return decoded
            except:
                # TODO conditional loggging
                print "JSON decoding error - bad JSON sring:"
                print data
                pass # swallow the exception (normal use shouldn't throw one ?)