#!/usr/bin/env python
import time
import os

# [ reference ]
# Detect number of cpus
# http://www.boduch.ca/2009/06/python-cpus.html 
# Get cpu usage (But this example is not working 100%)
# http://ubuntuforums.org/showpost.php?p=853257&postcount=4 

INTERVAL = 2

class CPUUsage:
    def __init__(self):
        self.cores = self.detectCPUs()

    def createCoreArray(self):
        cores = []
        for i in range(self.cores):
            cores.append("")
        return cores

    def detectCPUs(self):
        if hasattr(os, "sysconf"):
            if os.sysconf_names.has_key("SC_NPROCESSORS_ONLN"):
                ncpus = os.sysconf("SC_NPROCESSORS_ONLN")
                if isinstance(ncpus, int) and ncpus > 0:
                    return ncpus
        return 1 # Default

    def getTimeList(self):
        core = self.createCoreArray()

        statFile = file("/proc/stat", "r")
        if not self.cores == 1:
            statFile.readline()

        # this FOR will split lines from proc/stat for every active core
        for cid in range(self.cores):
            # when have just one core, split a different range
            if self.cores == 1:
                core[cid] = statFile.readline().split(" ")[2:7] # 2:6
            else:
                core[cid] = statFile.readline().split(" ")[1:6] # 1:5
        statFile.close()

        # convert all itens in splited list from STR to INT for every core
        for i in range(len(core[0])):
            for cid in range(self.cores):
                core[cid][i] = int(core[cid][i])

        # return the core list now with INT values inside their cpu values
        # like this: ([core,1,values],[core,2,values],[core,3,values]) 
        return core

    def deltaTime(self,interval):
        coreT1=self.createCoreArray()
        coreT2=self.createCoreArray()

        # get core TIME 1 state per core
        coreT1 = self.getTimeList()
        # wait X seconds to get new state core
        time.sleep(interval)
        # get core TIME 2 state per core
        coreT2 = self.getTimeList()

        #Get the diference of coreT2.item[i] and coreT1.item[i] for every core
        for i in range(len(coreT1[0])):
            for cid in range(self.cores):
                coreT2[cid][i] -= coreT1[cid][i]
        return coreT2

    def Usage(self):
        core = self.createCoreArray()
        cpuUsage = []

        core = self.deltaTime(INTERVAL)

        for cid in range(self.cores):
            # sum of user,system and nice usage
            tmp_use = core[cid][0] + core[cid][1]+core[cid][2]
            # 100.00 * usage / sum of usage + idle + waiting 
            usage = "%.2f" % ((100.00 * tmp_use) / sum(core[cid]))
            cpuUsage.append(usage)
        return cpuUsage

if __name__ == "__main__":
    # Show usage per core
    #print CPUUsage().Usage()

    x = 0
    for item in CPUUsage().Usage():
        x = x + 1
        print "CPU[%s]: %s" % (str(x),str(item))