#!/usr/bin/env python


# Try to determine how much RAM is currently being used per program.
# Note per _program_, not per process. So for example this script
# will report RAM used by all httpd process together. In detail it reports:
# sum(private RAM for program processes) + sum(Shared RAM for program processes)
# The shared RAM is problematic to calculate, and this script automatically
# selects the most accurate method available for your kernel.
# Notes:
#
# A warning is printed if overestimation is possible, depending on the kernel specs.
#
# I don't take account of memory allocated for a program
# by other programs. For e.g. memory used in the X server for
# a program could be determined, but is not.

import sys, os, string

if os.geteuid() != 0:
    sys.stderr.write("You must be root user to run this script!\n");
    sys.exit(1)

PAGESIZE=os.sysconf("SC_PAGE_SIZE")/1024 #KiB
our_pid=os.getpid()

#(major,minor,release)
def kernel_ver():
    kv=open("/proc/sys/kernel/osrelease").readline().split(".")[:3]
    for char in "-_":
        kv[2]=kv[2].split(char)[0]
    return (int(kv[0]), int(kv[1]), int(kv[2]))

kv=kernel_ver()

have_smaps=0
have_pss=0

#return Rss,Pss,Shared
#note Private = Rss-Shared
def getMemStats(pid):
    Shared_lines=[]
    Pss_lines=[]
    Rss=int(open("/proc/"+str(pid)+"/statm").readline().split()[1])*PAGESIZE
    if os.path.exists("/proc/"+str(pid)+"/smaps"): #stat
        global have_smaps
        have_smaps=1
        for line in open("/proc/"+str(pid)+"/smaps").readlines(): #open
            #Note in smaps Shared+Private = Rss above
            #The Rss in smaps includes video card mem etc.
            if line.startswith("Shared"):
                Shared_lines.append(line)
            elif line.startswith("Pss"):
                global have_pss
                have_pss=1
                Pss_lines.append(line)
        Shared=sum([int(line.split()[1]) for line in Shared_lines])
        Pss=sum([int(line.split()[1]) for line in Pss_lines])
    elif (2,6,1) <= kv <= (2,6,9):
        Pss=0
        Shared=0 #lots of overestimation, but what can we do?
    else:
        Pss=0
        Shared=int(open("/proc/"+str(pid)+"/statm").readline().split()[2])*PAGESIZE
    return (Rss, Pss, Shared)

cmds={}
shareds={}
count={}
for pid in os.listdir("/proc/"):
    try:
        pid = int(pid) #note Thread IDs not listed in /proc/
        if pid ==our_pid: continue
    except:
        continue
    cmd = file("/proc/%d/status" % pid).readline()[6:-1]
    try:
        exe = os.path.basename(os.path.realpath("/proc/%d/exe" % pid))
        if exe.startswith(cmd):
            cmd=exe #show non truncated version
            #Note because we show the non truncated name
            #one can have separated programs as follows:
            #584.0 KiB +   1.0 MiB =   1.6 MiB    mozilla-thunder (exe -> bash)
            # 56.0 MiB +  22.2 MiB =  78.2 MiB    mozilla-thunderbird-bin
    except:
        #permission denied or
        #kernel threads don't have exe links or
        #process gone
        continue
    try:
        rss, pss, shared = getMemStats(pid)
        private = rss-shared
        #Note shared is always a subset of rss (trs is not always)
    except:
        continue #process gone
    if shareds.get(cmd):
        if pss: #add shared portion of PSS together
            shareds[cmd]+=pss-private
        elif shareds[cmd] < shared: #just take largest shared val
            shareds[cmd]=shared
    else:
        if pss:
            shareds[cmd]=pss-private
        else:
            shareds[cmd]=shared
    cmds[cmd]=cmds.setdefault(cmd,0)+private
    if count.has_key(cmd):
       count[cmd] += 1
    else:
       count[cmd] = 1

#Add max shared mem for each program
total=0
for cmd in cmds.keys():
    cmds[cmd]=cmds[cmd]+shareds[cmd]
    total+=cmds[cmd] #valid if PSS available

sort_list = cmds.items()
sort_list.sort(lambda x,y:cmp(x[1],y[1]))
sort_list=filter(lambda x:x[1],sort_list) #get rid of zero sized processes

#The following matches "du -h" output
#see also human.py
def human(num, power="Ki"):
    powers=["Ki","Mi","Gi","Ti"]
    while num >= 1000: #4 digits
        num /= 1024.0
        power=powers[powers.index(power)+1]
    return "%.1f %s" % (num,power)

def cmd_with_count(cmd, count):
    if count>1:
       return "%s (%u)" % (cmd, count)
    else:
       return cmd

print " Private  +   Shared  =  RAM used\tProgram \n"
for cmd in sort_list:
    print "%8sB + %8sB = %8sB\t%s" % (human(cmd[1]-shareds[cmd[0]]), human(shareds[cmd[0]]), human(cmd[1]),
                                      cmd_with_count(cmd[0], count[cmd[0]]))
if have_pss:
    print "-" * 33
    print "                        %sB" % human(total)
    print "=" * 33
print "\n Private  +   Shared  =  RAM used\tProgram \n"

#Warn of possible inaccuracies
#2 = accurate & can total
#1 = accurate only considering each process in isolation
#0 = some shared mem not reported
#-1= all shared mem not reported
def shared_val_accuracy():
    """http://wiki.apache.org/spamassassin/TopSharedMemoryBug"""
    if kv[:2] == (2,4):
        if open("/proc/meminfo").read().find("Inact_") == -1:
            return 1
        return 0
    elif kv[:2] == (2,6):
        if os.path.exists("/proc/"+str(os.getpid())+"/smaps"):
            if open("/proc/"+str(os.getpid())+"/smaps").read().find("Pss:") != -1:
                return 2
            else:
                return 1
        if (2,6,1) <= kv <= (2,6,9):
            return -1
        return 0
    else:
        return 1

def current_memory_status():

	print "Displaying currently available memory...\n"
	print "--------------------------------------------------------------------------"
	showSysMemory = 'free -lmt'
	os.system(showSysMemory)
	print "--------------------------------------------------------------------------"
	print "\n"

current_memory_status()

vm_accuracy = shared_val_accuracy()
if vm_accuracy == -1:
    sys.stderr.write("Warning: Shared memory is not reported by this system.\n")
    sys.stderr.write("Values reported will be too large, and totals are not reported\n")
elif vm_accuracy == 0:
    sys.stderr.write("Warning: Shared memory is not reported accurately by this system.\n")
    sys.stderr.write("Values reported could be too large, and totals are not reported\n")
elif vm_accuracy == 1:
    sys.stderr.write("Warning: Shared memory is slightly over-estimated by this system\n")
    sys.stderr.write("for each program, so totals are not reported.\n")