Added JobQueue class.

# A FIFO queue based on a Redis list

#

#

import json

import redis

from config import Config

from job import Job

class JobQueue(object):

    def __init__(self, queueName):

        config = Config("vos_ts.conf")

        self.params = config.loadSection("job_cache")

        self.redisCli = redis.StrictRedis(host = self.params["host"],

                                          port = self.params["port"],

                                          db = self.params["db_sched"])

        self.queueName = queueName

    # Returns the number of jobs in the current queue

    def len(self):

        return self.redisCli.llen(self.queueName)

    # Returns the name of the current queue

    def name(self):

        return self.queueName

    # Gets a copy of the first job without moving it out from the current 

    # queue

    def getJob(self):

        jobObj = self.redisCli.lrange(self.queueName, self.len() - 1, self.len() - 1)[0].decode("utf-8")

        return json.loads(jobObj)

    # Pushes a new job into the queue

    def insertJob(self, jobObj):

        data = { "jobId": jobObj.jobId,

                 "phase": jobObj.phase,

                 "quote": jobObj.quote,

                 "startTime": jobObj.startTime,

                 "endTime": jobObj.endTime,

                 "executionDuration": jobObj.executionDuration,

                 "destruction": jobObj.destruction,

                 "parameters": jobObj.parameters,

                 "jobInfo": jobObj.jobInfo }

        self.redisCli.lpush(self.queueName, json.dumps(data))

    # Moves out a job from the end of the current queue and places it 

    # at the beginning of the next queue (this operation is atomic)

    def moveJobTo(self, nextQueueName):

        self.redisCli.brpoplpush(self.queueName, nextQueueName, timeout = 0)

# Test

#p = JobQueue("pending")

#r = JobQueue("ready")

#j1 = Job()

#j1.setPhase("PENDING")

#j2 = Job()

#j2.setPhase("PENDING")

#p.insertJob(j1)

#p.insertJob(j2)

#print(p.getJob())

#p.moveJobTo(r.name())

#print(r.getJob())