ovs-dpctl-top.in

#! @PYTHON3@
#
# Copyright (c) 2013 Nicira, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at:
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
#
# The approximate_size code was copied from
# http://getpython3.com/diveintopython3/your-first-python-program.html#divingin
# which is licensed under # "Dive Into Python 3," Copyright 2011 Mark Pilgrim,
# used under a Creative Commons Attribution-Share-Alike license:
# http://creativecommons.org/licenses/by-sa/3.0/
#
#

"""Top like behavior for ovs-dpctl dump-flows output.

This program summarizes ovs-dpctl flow content by aggregating the number
of packets, total bytes and occurrence of the following fields:

  - Datapath in_port

  - Ethernet type

  - Source and destination MAC addresses

  - IP protocol

  - Source and destination IPv4 addresses

  - Source and destination IPv6 addresses

  - UDP and TCP destination port

  - Tunnel source and destination addresses


Output shows four values:
  - FIELDS: the flow fields for example in_port(1).

  - PACKETS: the total number of packets containing the flow field.

  - BYTES: the total number of bytes containing the flow field. If units are
  not present then values are in bytes.

  - AVERAGE: the average packets size (BYTES/PACKET).

  - COUNT: the number of lines in the dump-flow output contain the flow field.

Top Behavior

While in top mode, the default behavior, the following single character
commands are supported:

  a - toggles top in accumulate and live mode. Accumulate mode is described
  below.

  s - toggles which column is used to sort content in decreasing order. A
  DESC title is placed over the column.

  _ - a space indicating to collect dump-flow content again

  h - halt output. Any character will restart sampling

  f - cycle through flow fields. The initial field is in_port

  q - q for quit.

Accumulate Mode

There are two supported modes: live and accumulate. The default is live.
The parameter --accumulate  or the 'a' character in top mode enables the
latter. In live mode, recent dump-flow content is presented.
Where as accumulate mode keeps track of the prior historical
information until the flow is reset not when the flow is purged. Reset
flows are determined when the packet count for a flow has decreased from
its previous sample. There is one caveat, eventually the system will
run out of memory if, after the accumulate-decay period any flows that
have not been refreshed are purged. The goal here is to free memory
of flows that are not active. Statistics are not decremented. Their purpose
is to reflect the overall history of the flow fields.


Debugging Errors

Parsing errors are counted and displayed in the status line at the beginning
of the output. Use the --verbose option with --script to see what output
 was not parsed, like this:
$ ovs-dpctl dump-flows | ovs-dpctl-top --script --verbose

Error messages will identify content that failed to parse.


Access Remote Hosts

The --host must follow the format user@hostname. This script simply calls
'ssh user@Hostname' without checking for login credentials therefore public
keys should be installed on the system identified by hostname, such as:

$ ssh-copy-id user@hostname

Consult ssh-copy-id man pages for more details.


Expected usage

$ ovs-dpctl-top

or to run as a script:
$ ovs-dpctl dump-flows > dump-flows.log
$ ovs-dpctl-top --script --flow-file dump-flows.log

"""

# pylint: disable-msg=C0103
# pylint: disable-msg=C0302
# pylint: disable-msg=R0902
# pylint: disable-msg=R0903
# pylint: disable-msg=R0904
# pylint: disable-msg=R0912
# pylint: disable-msg=R0913
# pylint: disable-msg=R0914

import sys
import os
try:
    ##
    # Arg parse is not installed on older Python distributions.
    # ovs ships with a version in the directory mentioned below.
    import argparse
except ImportError:
    sys.path.append(os.path.join("@pkgdatadir@", "python"))
    import argparse
import logging
import re
import unittest
import copy
import curses
import operator
import subprocess
import fcntl
import struct
import termios
import datetime
import threading
import time
import socket


##
# The following two definitions provide the necessary netaddr functionality.
# Python netaddr module is not part of the core installation. Packaging
# netaddr was involved and seems inappropriate given that only two
# methods where used.
def ipv4_to_network(ip_str):
    """ Calculate the network given a ipv4/mask value.
    If a mask is not present simply return ip_str.
    """
    pack_length = '!HH'
    try:
        (ip, mask) = ip_str.split("/")
    except ValueError:
        # just an ip address no mask.
        return ip_str

    ip_p = socket.inet_pton(socket.AF_INET, ip)
    ip_t = struct.unpack(pack_length, ip_p)
    mask_t = struct.unpack(pack_length, socket.inet_pton(socket.AF_INET, mask))
    network_n = [ii & jj for (ii, jj) in zip(ip_t, mask_t)]

    return socket.inet_ntop(socket.AF_INET,
                            struct.pack('!HH', network_n[0], network_n[1]))


def ipv6_to_network(ip_str):
    """ Calculate the network given a ipv6/mask value.
    If a mask is not present simply return ip_str.
    """
    pack_length = '!HHHHHHHH'
    try:
        (ip, mask) = ip_str.split("/")
    except ValueError:
        # just an ip address no mask.
        return ip_str

    ip_p = socket.inet_pton(socket.AF_INET6, ip)
    ip_t = struct.unpack(pack_length, ip_p)
    mask_t = struct.unpack(pack_length,
                           socket.inet_pton(socket.AF_INET6, mask))
    network_n = [ii & jj for (ii, jj) in zip(ip_t, mask_t)]

    return socket.inet_ntop(socket.AF_INET6,
                            struct.pack(pack_length,
                                        network_n[0], network_n[1],
                                        network_n[2], network_n[3],
                                        network_n[4], network_n[5],
                                        network_n[6], network_n[7]))


##
# columns displayed
##
class Columns:
    """ Holds column specific content.
    Titles needs to be less than 8 characters.
    """
    VALUE_WIDTH = 9
    FIELDS = "fields"
    PACKETS = "packets"
    COUNT = "count"
    BYTES = "bytes"
    AVERAGE = "average"

    def __init__(self):
        pass

    @staticmethod
    def assoc_list(obj):
        """ Return a associated list. """
        return [(Columns.FIELDS, repr(obj)),
                (Columns.PACKETS, obj.packets),
                (Columns.BYTES, obj.bytes),
                (Columns.COUNT, obj.count),
                (Columns.AVERAGE, obj.average),
                ]


def element_eth_get(field_type, element, stats_dict):
    """ Extract eth frame src and dst from a dump-flow element."""
    fmt = "%s(src=%s,dst=%s)"

    element = fmt % (field_type, element["src"], element["dst"])
    return SumData(field_type, element, stats_dict["packets"],
                   stats_dict["bytes"], element)


def element_ipv4_get(field_type, element, stats_dict):
    """ Extract src and dst from a dump-flow element."""
    fmt = "%s(src=%s,dst=%s)"
    element_show = fmt % (field_type, element["src"], element["dst"])

    element_key = fmt % (field_type, ipv4_to_network(element["src"]),
                         ipv4_to_network(element["dst"]))

    return SumData(field_type, element_show, stats_dict["packets"],
                       stats_dict["bytes"], element_key)


def element_tunnel_get(field_type, element, stats_dict):
    """ Extract src and dst from a tunnel."""
    return element_ipv4_get(field_type, element, stats_dict)


def element_ipv6_get(field_type, element, stats_dict):
    """ Extract src and dst from a dump-flow element."""

    fmt = "%s(src=%s,dst=%s)"
    element_show = fmt % (field_type, element["src"], element["dst"])

    element_key = fmt % (field_type, ipv6_to_network(element["src"]),
                         ipv6_to_network(element["dst"]))

    return SumData(field_type, element_show, stats_dict["packets"],
                       stats_dict["bytes"], element_key)


def element_dst_port_get(field_type, element, stats_dict):
    """ Extract src and dst from a dump-flow element."""
    element_key = "%s(dst=%s)" % (field_type, element["dst"])
    return SumData(field_type, element_key, stats_dict["packets"],
                   stats_dict["bytes"], element_key)


def element_passthrough_get(field_type, element, stats_dict):
    """ Extract src and dst from a dump-flow element."""
    element_key = "%s(%s)" % (field_type, element)
    return SumData(field_type, element_key,
                   stats_dict["packets"], stats_dict["bytes"], element_key)


# pylint: disable-msg=R0903
class OutputFormat:
    """ Holds field_type and function to extract element value. """
    def __init__(self, field_type, elements, generator):
        self.field_type = field_type
        self.elements = elements
        self.generator = generator

##
# The order below is important. The initial flow field depends on whether
# --script or top mode is used. In top mode, the expected behavior, in_port
# flow fields are shown first. A future feature will allow users to
# filter output by selecting a row. Filtering by in_port is a natural
# filtering starting point.
#
# In script mode, all fields are shown. The expectation is that users could
# filter output by piping through grep.
#
# In top mode, the default flow field is in_port. In --script mode,
# the default flow field is all.
#
# All is added to the end of the OUTPUT_FORMAT list.
##
OUTPUT_FORMAT = [
    OutputFormat("in_port", (), element_passthrough_get),
    OutputFormat("eth", ("src","dst"), element_eth_get),
    OutputFormat("eth_type", (), element_passthrough_get),
    OutputFormat("ipv4", ("src","dst"), element_ipv4_get),
    OutputFormat("ipv6", ("src","dst"), element_ipv6_get),
    OutputFormat("udp", ("src","dst"), element_dst_port_get),
    OutputFormat("tcp", ("src","dst"), element_dst_port_get),
    OutputFormat("tunnel", ("src","dst"), element_tunnel_get),
    ]
##


ELEMENT_KEY = {
    "udp": "udp.dst",
    "tcp": "tcp.dst"
    }


def top_input_get(args):
    """ Return subprocess stdout."""
    cmd = []
    if (args.host):
        cmd += ["ssh", args.host]
    cmd += ["ovs-dpctl", "dump-flows"]

    return subprocess.Popen(cmd, stderr=subprocess.STDOUT,
                            stdout=subprocess.PIPE).stdout


def args_get():
    """ read program parameters handle any necessary validation of input. """

    parser = argparse.ArgumentParser(
                          formatter_class=argparse.RawDescriptionHelpFormatter,
                          description=__doc__)
    ##
    # None is a special value indicating to read flows from stdin.
    # This handles the case
    #   ovs-dpctl dump-flows | ovs-dpctl-flows.py
    parser.add_argument("-v", "--version", version="@VERSION@",
                        action="version", help="show version")
    parser.add_argument("-f", "--flow-file", dest="flowFiles", default=None,
                        action="append",
                        help="file containing flows from ovs-dpctl dump-flow")
    parser.add_argument("-V", "--verbose", dest="verbose",
                        default=logging.CRITICAL,
                        action="store_const", const=logging.DEBUG,
                        help="enable debug level verbosity")
    parser.add_argument("-s", "--script", dest="top", action="store_false",
                        help="Run from a script (no user interface)")
    parser.add_argument("--host", dest="host",
                        help="Specify a user@host for retrieving flows see"
                             "Accessing Remote Hosts for more information")

    parser.add_argument("-a", "--accumulate", dest="accumulate",
                        action="store_true", default=False,
                        help="Accumulate dump-flow content")
    parser.add_argument("--accumulate-decay", dest="accumulateDecay",
                        default=5.0 * 60, type=float,
                        help="Decay old accumulated flows. "
                        "The default is 5 minutes. "
                        "A value of 0 disables decay.")
    parser.add_argument("-d", "--delay", dest="delay", type=int,
                        default=1000,
                        help="Delay in milliseconds to collect dump-flow "
                             "content (sample rate).")

    args = parser.parse_args()

    logging.basicConfig(level=args.verbose)

    return args

###
# Code to parse a single line in dump-flow
###
# key(values)
FIELDS_CMPND = re.compile("([\w]+)\((.+)\)")
# key:value
FIELDS_CMPND_ELEMENT = re.compile("([\w:]+)=([/\.\w:]+)")
FIELDS_ELEMENT = re.compile("([\w]+):([-\.\w]+)")


def flow_line_iter(line):
    """ iterate over flow dump elements.
    return tuples of (true, element) or (false, remaining element)
    """
    # splits by , except for when in a (). Actions element was not
    # split properly but we don't need it.
    rc = []

    element = ""
    paren_count = 0

    for ch in line:
        if (ch == '('):
            paren_count += 1
        elif (ch == ')'):
            paren_count -= 1

        if (ch == ' '):
            # ignore white space.
            continue
        elif ((ch == ',') and (paren_count == 0)):
            rc.append(element)
            element = ""
        else:
            element += ch

    if (paren_count):
        raise ValueError(line)
    else:
        if (len(element) > 0):
            rc.append(element)
    return rc


def flow_line_compound_parse(compound):
    """ Parse compound element
    for example
    src=00:50:56:b4:4e:f8,dst=33:33:00:01:00:03
    which is in
    eth(src=00:50:56:b4:4e:f8,dst=33:33:00:01:00:03)
    """
    result = {}
    for element in flow_line_iter(compound):
        match = FIELDS_CMPND_ELEMENT.search(element)
        if (match):
            key = match.group(1)
            value = match.group(2)
            result[key] = value

        match = FIELDS_CMPND.search(element)
        if (match):
            key = match.group(1)
            value = match.group(2)
            result[key] = flow_line_compound_parse(value)
            continue

    if (len(result.keys()) == 0):
        return compound
    return result


def flow_line_split(line):
    """ Convert a flow dump line into ([fields], [stats], actions) tuple.
    Where fields and stats are lists.
    This function relies on a the following ovs-dpctl dump-flow
    output characteristics:
    1. The dumpe flow line consists of a list of frame fields, list of stats
       and action.
    2. list of frame fields, each stat and action field are delimited by ', '.
    3. That all other non stat field are not delimited by ', '.

    """

    results = re.split(', ', line)

    (field, stats, action) = (results[0], results[1:-1], results[-1])

    fields = flow_line_iter(field)
    return (fields, stats, action)


def elements_to_dict(elements):
    """ Convert line to a hierarchy of dictionaries. """
    result = {}
    for element in elements:
        if (element == "eth()"):
            continue
        match = FIELDS_CMPND.search(element)
        if (match):
            key = match.group(1)
            value = match.group(2)
            result[key] = flow_line_compound_parse(value)
            continue

        match = FIELDS_ELEMENT.search(element)
        if (match):
            key = match.group(1)
            value = match.group(2)
            result[key] = value
        else:
            raise ValueError("can't parse >%s<" % element)
    return result


# pylint: disable-msg=R0903
class SumData(object):
    """ Interface that all data going into SumDb must implement.
    Holds the flow field and its corresponding count, total packets,
    total bytes and calculates average.

    __repr__ is used as key into SumData singleton.
    __str__ is used as human readable output.
    """

    def __init__(self, field_type, field, packets, flow_bytes, key):
        # Count is the number of lines in the dump-flow log.
        self.field_type = field_type
        self.field = field
        self.count = 1
        self.packets = int(packets)
        self.bytes = int(flow_bytes)
        self.key = key

    def decrement(self, decr_packets, decr_bytes, decr_count):
        """ Decrement content to calculate delta from previous flow sample."""
        self.packets -= decr_packets
        self.bytes -= decr_bytes
        self.count -= decr_count

    def __iadd__(self, other):
        """ Add two objects. """

        if (self.key != other.key):
            raise ValueError("adding two unrelated types")

        self.count += other.count
        self.packets += other.packets
        self.bytes += other.bytes
        return self

    def __isub__(self, other):
        """ Decrement two objects. """

        if (self.key != other.key):
            raise ValueError("adding two unrelated types")

        self.count -= other.count
        self.packets -= other.packets
        self.bytes -= other.bytes
        return self

    def __getattr__(self, name):
        """ Handle average. """
        if (name == "average"):
            if (self.packets == 0):
                return float(0.0)
            else:
                return float(self.bytes) / float(self.packets)
        raise AttributeError(name)

    def __str__(self):
        """ Used for debugging. """
        return "%s %s %s %s" % (self.field, self.count,
                                   self.packets, self.bytes)

    def __repr__(self):
        """ Used as key in the FlowDB table. """
        return self.key


def flow_aggregate(fields_dict, stats_dict):
    """ Search for content in a line.
    Passed the flow port of the dump-flows plus the current stats consisting
    of packets, bytes, etc
    """
    result = []

    for output_format in OUTPUT_FORMAT:
        field = fields_dict.get(output_format.field_type, None)
        if (field) and all (k in field for k in output_format.elements):
            obj = output_format.generator(output_format.field_type,
                                          field, stats_dict)
            result.append(obj)

    return result


def flows_read(ihdl, flow_db):
    """ read flow content from ihdl and insert into flow_db. """

    done = False
    while (not done):
        line = ihdl.readline()
        if (len(line) == 0):
            # end of input
            break

        try:
            flow_db.flow_line_add(line)
        except ValueError as arg:
            logging.error(arg)

    return flow_db


def get_terminal_size():
    """
    return column width and height of the terminal
    """
    for fd_io in [0, 1, 2]:
        try:
            result = struct.unpack('hh',
                                   fcntl.ioctl(fd_io, termios.TIOCGWINSZ,
                                               '1234'))
        except IOError:
            result = None
            continue

    if (result is None or result == (0, 0)):
        # Maybe we can't get the width. In that case assume (25, 80)
        result = (25, 80)

    return result

##
# Content derived from:
# http://getpython3.com/diveintopython3/your-first-python-program.html#divingin
##
SUFFIXES = {1000: ['KB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB'],
            1024: ['KiB', 'MiB', 'GiB', 'TiB', 'PiB', 'EiB', 'ZiB', 'YiB']}


def approximate_size(size, a_kilobyte_is_1024_bytes=True):
    """Convert a file size to human-readable form.

    Keyword arguments:
    size -- file size in bytes
    a_kilobyte_is_1024_bytes -- if True (default), use multiples of 1024
                                    if False, use multiples of 1000

    Returns: string

    """
    size = float(size)
    if size < 0:
        raise ValueError('number must be non-negative')

    if (a_kilobyte_is_1024_bytes):
        multiple = 1024
    else:
        multiple = 1000
    for suffix in SUFFIXES[multiple]:
        size /= multiple
        if size < multiple:
            return "%.1f %s" % (size, suffix)

    raise ValueError('number too large')


##
# End copied content
##
class ColMeta:
    """ Concepts about columns. """
    def __init__(self, sortable, width):
        self.sortable = sortable
        self.width = width


class RowMeta:
    """ How to render rows. """
    def __init__(self, label, fmt):
        self.label = label
        self.fmt = fmt


def fmt_packet(obj, width):
    """ Provide a string for packets that is appropriate for output."""
    return str(obj.packets).rjust(width)


def fmt_count(obj, width):
    """ Provide a string for average that is appropriate for output."""
    return str(obj.count).rjust(width)


def fmt_avg(obj, width):
    """ Provide a string for average that is appropriate for output."""
    return str(int(obj.average)).rjust(width)


def fmt_field(obj, width):
    """ truncate really long flow and insert ellipses to help make it
    clear.
    """

    ellipses = " ... "
    value = obj.field
    if (len(obj.field) > width):
        value = value[:(width - len(ellipses))] + ellipses
    return value.ljust(width)


def fmt_bytes(obj, width):
    """ Provide a string for average that is appropriate for output."""
    if (len(str(obj.bytes)) <= width):
        value = str(obj.bytes)
    else:
        value = approximate_size(obj.bytes)
    return value.rjust(width)


def title_center(value, width):
    """ Center a column title."""
    return value.upper().center(width)


def title_rjust(value, width):
    """ Right justify a column title. """
    return value.upper().rjust(width)


def column_picker(order, obj):
    """ return the column as specified by order. """
    if (order == 1):
        return obj.count
    elif (order == 2):
        return obj.packets
    elif (order == 3):
        return obj.bytes
    elif (order == 4):
        return obj.average
    else:
        raise ValueError("order outside of range %s" % order)


class Render:
    """ Renders flow data.

    The two FIELD_SELECT variables should be set to the actual field minus
    1. During construction, an internal method increments and initializes
    this object.
    """
    FLOW_FIELDS = [_field.field_type for _field in OUTPUT_FORMAT] + ["all"]

    FIELD_SELECT_SCRIPT = 7
    FIELD_SELECT_TOP = -1

    def __init__(self, console_width, field_select):
        """ Calculate column widths taking into account changes in format."""

        self._start_time = datetime.datetime.now()

        self._cols = [ColMeta(False, 0),
                      ColMeta(True, Columns.VALUE_WIDTH),
                      ColMeta(True, Columns.VALUE_WIDTH),
                      ColMeta(True, Columns.VALUE_WIDTH),
                      ColMeta(True, Columns.VALUE_WIDTH)]
        self._console_width = console_width
        self.console_width_set(console_width)

        # Order in this array dictate the order of the columns.
        # The 0 width for the first entry is a place holder. This is
        # dynamically calculated. The first column is special. We need a
        # way to indicate which field are presented.
        self._descs = [RowMeta("", title_rjust),
                       RowMeta("", title_rjust),
                       RowMeta("", title_rjust),
                       RowMeta("", title_rjust),
                       RowMeta("", title_rjust)]
        self._column_sort_select = 0
        self.column_select_event()

        self._titles = [
            RowMeta(Columns.FIELDS, title_center),
            RowMeta(Columns.COUNT, title_rjust),
            RowMeta(Columns.PACKETS, title_rjust),
            RowMeta(Columns.BYTES, title_rjust),
            RowMeta(Columns.AVERAGE, title_rjust)
        ]

        self._datas = [
            RowMeta(None, fmt_field),
            RowMeta(None, fmt_count),
            RowMeta(None, fmt_packet),
            RowMeta(None, fmt_bytes),
            RowMeta(None, fmt_avg)
            ]

        ##
        # _field_types hold which fields are displayed in the field
        # column, with the keyword all implying all fields.
        ##
        self._field_types = Render.FLOW_FIELDS

        ##
        # The default is to show all field types.
        ##
        self._field_type_select = field_select
        self.field_type_toggle()

    def _field_type_select_get(self):
        """ Return which field type to display. """
        return self._field_types[self._field_type_select]

    def field_type_toggle(self):
        """ toggle which field types to show. """
        self._field_type_select += 1
        if (self._field_type_select >= len(self._field_types)):
            self._field_type_select = 0
        value = Columns.FIELDS + " (%s)" % self._field_type_select_get()
        self._titles[0].label = value

    def column_select_event(self):
        """ Handles column select toggle. """

        self._descs[self._column_sort_select].label = ""
        for _ in range(len(self._cols)):
            self._column_sort_select += 1
            if (self._column_sort_select >= len(self._cols)):
                self._column_sort_select = 0

            # Now look for the next sortable column
            if (self._cols[self._column_sort_select].sortable):
                break
        self._descs[self._column_sort_select].label = "DESC"

    def console_width_set(self, console_width):
        """ Adjust the output given the new console_width. """
        self._console_width = console_width

        spaces = len(self._cols) - 1
        ##
        # Calculating column width can be tedious but important. The
        # flow field value can be long. The goal here is to dedicate
        # fixed column space for packets, bytes, average and counts. Give the
        # remaining space to the flow column. When numbers get large
        # transition output to output generated by approximate_size which
        # limits output to ###.# XiB in other words 9 characters.
        ##
        # At this point, we know the maximum length values. We may
        # truncate the flow column to get everything to fit.
        self._cols[0].width = 0
        values_max_length = sum([ii.width for ii in self._cols]) + spaces
        flow_max_length = console_width - values_max_length
        self._cols[0].width = flow_max_length

    def format(self, flow_db):
        """ shows flows based on --script parameter."""

        rc = []
        ##
        # Top output consists of
        # Title
        # Column title (2 rows)
        # data
        # statistics and status

        ##
        # Title
        ##
        rc.append("Flow Summary".center(self._console_width))

        stats = " Total: %(flow_total)s  errors: %(flow_errors)s " % \
                  flow_db.flow_stats_get()
        accumulate = flow_db.accumulate_get()
        if (accumulate):
            stats += "Accumulate: on "
        else:
            stats += "Accumulate: off "

        duration = datetime.datetime.now() - self._start_time
        stats += "Duration: %s " % str(duration)
        rc.append(stats.ljust(self._console_width))

        ##
        # 2 rows for columns.
        ##
        # Indicate which column is in descending order.
        rc.append(" ".join([ii.fmt(ii.label, col.width)
                            for (ii, col) in zip(self._descs, self._cols)]))

        rc.append(" ".join([ii.fmt(ii.label, col.width)
                         for (ii, col) in zip(self._titles, self._cols)]))

        ##
        # Data.
        ##
        for dd in flow_db.field_values_in_order(self._field_type_select_get(),
                                                self._column_sort_select):
            rc.append(" ".join([ii.fmt(dd, col.width)
                                for (ii, col) in zip(self._datas,
                                                     self._cols)]))

        return rc


def curses_screen_begin():
    """ begin curses screen control. """
    stdscr = curses.initscr()
    curses.cbreak()
    curses.noecho()
    stdscr.keypad(1)
    return stdscr


def curses_screen_end(stdscr):
    """ end curses screen control. """
    curses.nocbreak()
    stdscr.keypad(0)
    curses.echo()
    curses.endwin()


class FlowDB:
    """ Implements live vs accumulate mode.

    Flows are stored as key value pairs. The key consists of the content
    prior to stat fields. The value portion consists of stats in a dictionary
    form.

    @ \todo future add filtering here.
    """
    def __init__(self, accumulate):
        self._accumulate = accumulate
        self._error_count = 0
        # Values are (stats, last update time.)
        # The last update time is used for aging.
        self._flow_lock = threading.Lock()
        # This dictionary holds individual flows.
        self._flows = {}
        # This dictionary holds aggregate of flow fields.
        self._fields = {}

    def accumulate_get(self):
        """ Return the current accumulate state. """
        return self._accumulate

    def accumulate_toggle(self):
        """ toggle accumulate flow behavior. """
        self._accumulate = not self._accumulate

    def begin(self):
        """ Indicate the beginning of processing flow content.
        if accumulate is false clear current set of flows. """

        if (not self._accumulate):
            self._flow_lock.acquire()
            try:
                self._flows.clear()
            finally:
                self._flow_lock.release()
            self._fields.clear()

    def flow_line_add(self, line):
        """ Split a line from a ovs-dpctl dump-flow into key and stats.
        The order of the content in the flow should be:
        - flow content
        - stats for the flow
        - actions

        This method also assumes that the dump flow output does not
        change order of fields of the same flow.
        """

        if not isinstance(line, str):
           line = str(line)

        line = line.rstrip("\n")
        (fields, stats, _) = flow_line_split(line)

        try:
            fields_dict = elements_to_dict(fields)

            if (len(fields_dict) == 0):
                raise ValueError("flow fields are missing %s", line)

            stats_dict = elements_to_dict(stats)
            if not all (k in stats_dict for k in ("packets","bytes")):
                raise ValueError("statistics are missing %s.", line)

            ##
            # In accumulate mode, the Flow database can reach 10,000's of
            # persistent flows. The interaction of the script with this many
            # flows is too slow. Instead, delta are sent to the flow_db
            # database allow incremental changes to be done in O(m) time
            # where m is the current flow list, instead of iterating over
            # all flows in O(n) time where n is the entire history of flows.
            key = ",".join(fields)

            self._flow_lock.acquire()
            try:
                (stats_old_dict, _) = self._flows.get(key, (None, None))
            finally:
                self._flow_lock.release()

            self.flow_event(fields_dict, stats_old_dict, stats_dict)

        except ValueError as arg:
            logging.error(arg)
            self._error_count += 1
            raise

        self._flow_lock.acquire()
        try:
            self._flows[key] = (stats_dict, datetime.datetime.now())
        finally:
            self._flow_lock.release()

    def decay(self, decayTimeInSeconds):
        """ Decay content. """
        now = datetime.datetime.now()
        for (key, value) in self._flows.items():
            (stats_dict, updateTime) = value
            delta = now - updateTime

            if (delta.seconds > decayTimeInSeconds):
                self._flow_lock.acquire()
                try:
                    del self._flows[key]

                    fields_dict = elements_to_dict(flow_line_iter(key))
                    matches = flow_aggregate(fields_dict, stats_dict)
                    for match in matches:
                        self.field_dec(match)

                finally:
                    self._flow_lock.release()

    def flow_stats_get(self):
        """ Return statistics in a form of a dictionary. """
        rc = None
        self._flow_lock.acquire()
        try:
            rc = {"flow_total": len(self._flows),
                  "flow_errors": self._error_count}
        finally:
            self._flow_lock.release()
        return rc

    def field_types_get(self):
        """ Return the set of types stored in the singleton. """
        types = set((ii.field_type for ii in self._fields.values()))
        return types

    def field_add(self, data):
        """ Collect dump-flow data to sum number of times item appears. """
        current = self._fields.get(repr(data), None)
        if (current is None):
            current = copy.copy(data)
        else:
            current += data
        self._fields[repr(current)] = current

    def field_dec(self, data):
        """ Collect dump-flow data to sum number of times item appears. """
        current = self._fields.get(repr(data), None)
        if (current is None):
            raise ValueError("decrementing field missing %s" % repr(data))

        current -= data
        self._fields[repr(current)] = current
        if (current.count == 0):
            del self._fields[repr(current)]

    def field_values_in_order(self, field_type_select, column_order):
        """ Return a list of items in order maximum first. """
        values = self._fields.values()
        if (field_type_select != "all"):
            # If a field type other than "all" then reduce the list.
            values = [ii for ii in values
                      if (ii.field_type == field_type_select)]
        values = [(column_picker(column_order, ii), ii) for ii in values]
        values.sort(key=operator.itemgetter(0))
        values.reverse()
        values = [ii[1] for ii in values]
        return values

    def flow_event(self, fields_dict, stats_old_dict, stats_new_dict):
        """ Receives new flow information. """

        # In order to avoid processing every flow at every sample
        # period, changes in flow packet count is used to determine the
        # delta in the flow statistics. This delta is used in the call
        # to self.decrement prior to self.field_add

        if (stats_old_dict is None):
            # This is a new flow
            matches = flow_aggregate(fields_dict, stats_new_dict)
            for match in matches:
                self.field_add(match)
        else:
            old_packets = int(stats_old_dict.get("packets", 0))
            new_packets = int(stats_new_dict.get("packets", 0))
            if (old_packets == new_packets):
                # ignore. same data.
                pass
            else:
                old_bytes = stats_old_dict.get("bytes", 0)
                # old_packets != new_packets
                # if old_packets > new_packets then we end up decrementing
                # packets and bytes.
                matches = flow_aggregate(fields_dict, stats_new_dict)
                for match in matches:
                    match.decrement(int(old_packets), int(old_bytes), 1)
                    self.field_add(match)


class DecayThread(threading.Thread):
    """ Periodically call flow database to see if any flows are old. """
    def __init__(self, flow_db, interval):
        """ Start decay thread. """
        threading.Thread.__init__(self)

        self._interval = max(1, interval)
        self._min_interval = min(1, interval / 10)
        self._flow_db = flow_db
        self._event = threading.Event()
        self._running = True

        self.daemon = True

    def run(self):
        """ Worker thread which handles decaying accumulated flows. """

        while(self._running):
            self._event.wait(self._min_interval)
            if (self._running):
                self._flow_db.decay(self._interval)

    def stop(self):
        """ Stop thread. """
        self._running = False
        self._event.set()
        ##
        # Give the calling thread time to terminate but not too long.
        # this thread is a daemon so the application will terminate if
        # we timeout during the join. This is just a cleaner way to
        # release resources.
        self.join(2.0)


def flow_top_command(stdscr, render, flow_db):
    """ Handle input while in top mode. """
    ch = stdscr.getch()
    ##
    # Any character will restart sampling.
    if (ch == ord('h')):
        # halt output.
        ch = stdscr.getch()
        while (ch == -1):
            ch = stdscr.getch()

    if (ch == ord('s')):
        # toggle which column sorts data in descending order.
        render.column_select_event()
    elif (ch == ord('a')):
        flow_db.accumulate_toggle()
    elif (ch == ord('f')):
        render.field_type_toggle()
    elif (ch == ord(' ')):
        # resample
        pass

    return ch


def decay_timer_start(flow_db, accumulateDecay):
    """ If accumulateDecay greater than zero then start timer. """
    if (accumulateDecay > 0):
        decay_timer = DecayThread(flow_db, accumulateDecay)
        decay_timer.start()
        return decay_timer
    else:
        return None


def flows_top(args):
    """ handles top like behavior when --script is not specified. """

    flow_db = FlowDB(args.accumulate)
    render = Render(0, Render.FIELD_SELECT_TOP)

    decay_timer = decay_timer_start(flow_db, args.accumulateDecay)
    lines = []

    try:
        stdscr = curses_screen_begin()
        try:
            ch = 'X'
            #stdscr.nodelay(1)
            stdscr.timeout(args.delay)

            while (ch != ord('q')):
                flow_db.begin()

                try:
                    ihdl = top_input_get(args)
                    try:
                        flows_read(ihdl, flow_db)
                    finally:
                        ihdl.close()
                except OSError as arg:
                    logging.critical(arg)
                    break

                (console_height, console_width) = stdscr.getmaxyx()
                render.console_width_set(console_width)

                output_height = console_height - 1
                line_count = range(output_height)
                line_output = render.format(flow_db)
                lines = zip(line_count, line_output[:output_height])

                stdscr.erase()
                for (count, line) in lines:
                    stdscr.addstr(count, 0, line[:console_width])
                stdscr.refresh()

                ch = flow_top_command(stdscr, render, flow_db)

        finally:
            curses_screen_end(stdscr)
    except KeyboardInterrupt:
        pass
    if (decay_timer):
        decay_timer.stop()

    # repeat output
    for (count, line) in lines:
        print(line)


def flows_script(args):
    """ handles --script option. """

    flow_db = FlowDB(args.accumulate)
    flow_db.begin()

    if (args.flowFiles is None):
        logging.info("reading flows from stdin")
        flow_db = flows_read(sys.stdin, flow_db)
    else:
        for flowFile in args.flowFiles:
            logging.info("reading flows from %s", flowFile)
            ihdl = open(flowFile, "r")
            try:
                flow_db = flows_read(ihdl, flow_db)
            finally:
                ihdl.close()

    (_, console_width) = get_terminal_size()
    render = Render(console_width, Render.FIELD_SELECT_SCRIPT)

    for line in render.format(flow_db):
        print(line)


def main():
    """ Return 0 on success or 1 on failure.

    Algorithm
    There are four stages to the process ovs-dpctl dump-flow content.
    1. Retrieve current input
    2. store in FlowDB and maintain history
    3. Iterate over FlowDB and aggregating stats for each flow field
    4. present data.

    Retrieving current input is currently trivial, the ovs-dpctl dump-flow
    is called. Future version will have more elaborate means for collecting
    dump-flow content. FlowDB returns all data as in the form of a hierarchical
    dictionary. Input will vary.

    In the case of accumulate mode, flows are not purged from the FlowDB
    manager. Instead at the very least, merely the latest statistics are
    kept. In the case, of live output the FlowDB is purged prior to sampling
    data.

    Aggregating results requires identify flow fields to aggregate out
    of the flow and summing stats.

    """
    args = args_get()

    try:
        if (args.top):
            flows_top(args)
        else:
            flows_script(args)
    except KeyboardInterrupt:
        return 1
    return 0

if __name__ == '__main__':
    sys.exit(main())
elif __name__ == 'ovs-dpctl-top':
    # pylint: disable-msg=R0915

    ##
    # Test case beyond this point.
    # pylint: disable-msg=R0904
    class TestsuiteFlowParse(unittest.TestCase):
        """
        parse flow into hierarchy of dictionaries.
        """
        def test_flow_parse(self):
            """ test_flow_parse. """
            line = "in_port(4),eth(src=00:50:56:b4:4e:f8,"\
                   "dst=33:33:00:01:00:03),eth_type(0x86dd),"\
                   "ipv6(src=fe80::55bf:fe42:bc96:2812,dst=ff02::1:3,"\
                   "label=0,proto=17,tclass=0,hlimit=1,frag=no),"\
                   "udp(src=61252,dst=5355), packets:1, bytes:92, "\
                   "used:0.703s, actions:3,8,11,14,17,20,23,26,29,32,35,"\
                   "38,41,44,47,50,53,56,59,62,65"

            (fields, stats, _) = flow_line_split(line)
            flow_dict = elements_to_dict(fields + stats)
            self.assertEqual(flow_dict["eth"]["src"], "00:50:56:b4:4e:f8")
            self.assertEqual(flow_dict["eth"]["dst"], "33:33:00:01:00:03")
            self.assertEqual(flow_dict["ipv6"]["src"],
                             "fe80::55bf:fe42:bc96:2812")
            self.assertEqual(flow_dict["ipv6"]["dst"], "ff02::1:3")
            self.assertEqual(flow_dict["packets"], "1")
            self.assertEqual(flow_dict["bytes"], "92")

            line = "in_port(4),eth(src=00:50:56:b4:4e:f8,"\
                   "dst=33:33:00:01:00:03),eth_type(0x86dd),"\
                   "ipv6(src=fe80::55bf:fe42:bc96:2812,dst=ff02::1:3,"\
                   "label=0,proto=17,tclass=0,hlimit=1,frag=no),"\
                   "udp(src=61252,dst=5355), packets:1, bytes:92, "\
                   "used:-0.703s, actions:3,8,11,14,17,20,23,26,29,32,35,"\
                   "38,41,44,47,50,53,56,59,62,65"

            (fields, stats, _) = flow_line_split(line)
            flow_dict = elements_to_dict(fields + stats)
            self.assertEqual(flow_dict["used"], "-0.703s")
            self.assertEqual(flow_dict["packets"], "1")
            self.assertEqual(flow_dict["bytes"], "92")

        def test_flow_sum(self):
            """ test_flow_sum. """
            line = "in_port(4),eth(src=00:50:56:b4:4e:f8,"\
                   "dst=33:33:00:01:00:03),eth_type(0x86dd),"\
                   "ipv6(src=fe80::55bf:fe42:bc96:2812,dst=ff02::1:3,"\
                   "label=0,proto=17,tclass=0,hlimit=1,frag=no),"\
                   "udp(src=61252,dst=5355), packets:2, bytes:92, "\
                   "used:0.703s, actions:3,8,11,14,17,20,23,26,29,32,35,"\
                   "38,41,44,47,50,53,56,59,62,65"

            (fields, stats, _) = flow_line_split(line)
            stats_dict = elements_to_dict(stats)
            fields_dict = elements_to_dict(fields)
            ##
            # Test simple case of one line.
            flow_db = FlowDB(False)
            matches = flow_aggregate(fields_dict, stats_dict)
            for match in matches:
                flow_db.field_add(match)

            flow_types = flow_db.field_types_get()
            expected_flow_types = ["eth", "eth_type", "udp", "in_port", "ipv6"]
            self.assert_(len(flow_types) == len(expected_flow_types))
            for flow_type in flow_types:
                self.assertTrue(flow_type in expected_flow_types)

            for flow_type in flow_types:
                sum_value = flow_db.field_values_in_order("all", 1)
                self.assert_(len(sum_value) == 5)
                self.assert_(sum_value[0].packets == 2)
                self.assert_(sum_value[0].count == 1)
                self.assert_(sum_value[0].bytes == 92)

            ##
            # Add line again just to see counts go up.
            matches = flow_aggregate(fields_dict, stats_dict)
            for match in matches:
                flow_db.field_add(match)

            flow_types = flow_db.field_types_get()
            self.assert_(len(flow_types) == len(expected_flow_types))
            for flow_type in flow_types:
                self.assertTrue(flow_type in expected_flow_types)

            for flow_type in flow_types:
                sum_value = flow_db.field_values_in_order("all", 1)
                self.assert_(len(sum_value) == 5)
                self.assert_(sum_value[0].packets == 4)
                self.assert_(sum_value[0].count == 2)
                self.assert_(sum_value[0].bytes == 2 * 92)

        def test_assoc_list(self):
            """ test_assoc_list. """
            line = "in_port(4),eth(src=00:50:56:b4:4e:f8,"\
                   "dst=33:33:00:01:00:03),eth_type(0x86dd),"\
                   "ipv6(src=fe80::55bf:fe42:bc96:2812,dst=ff02::1:3,"\
                   "label=0,proto=17,tclass=0,hlimit=1,frag=no),"\
                   "udp(src=61252,dst=5355), packets:2, bytes:92, "\
                   "used:0.703s, actions:3,8,11,14,17,20,23,26,29,32,35,"\
                   "38,41,44,47,50,53,56,59,62,65"

            valid_flows = [
                'eth_type(0x86dd)',
                'udp(dst=5355)',
                'in_port(4)',
                'ipv6(src=fe80::55bf:fe42:bc96:2812,dst=ff02::1:3)',
                'eth(src=00:50:56:b4:4e:f8,dst=33:33:00:01:00:03)'
                ]

            (fields, stats, _) = flow_line_split(line)
            stats_dict = elements_to_dict(stats)
            fields_dict = elements_to_dict(fields)

            ##
            # Test simple case of one line.
            flow_db = FlowDB(False)
            matches = flow_aggregate(fields_dict, stats_dict)
            for match in matches:
                flow_db.field_add(match)

            for sum_value in flow_db.field_values_in_order("all", 1):
                assoc_list = Columns.assoc_list(sum_value)
                for item in assoc_list:
                    if (item[0] == "fields"):
                        self.assertTrue(item[1] in valid_flows)
                    elif (item[0] == "packets"):
                        self.assertTrue(item[1] == 2)
                    elif (item[0] == "count"):
                        self.assertTrue(item[1] == 1)
                    elif (item[0] == "average"):
                        self.assertTrue(item[1] == 46.0)
                    elif (item[0] == "bytes"):
                        self.assertTrue(item[1] == 92)
                    else:
                        raise ValueError("unknown %s", item[0])

        def test_human_format(self):
            """ test_assoc_list. """

            self.assertEqual(approximate_size(0.0), "0.0 KiB")
            self.assertEqual(approximate_size(1024), "1.0 KiB")
            self.assertEqual(approximate_size(1024 * 1024), "1.0 MiB")
            self.assertEqual(approximate_size((1024 * 1024) + 100000),
                             "1.1 MiB")
            value = (1024 * 1024 * 1024) + 100000000
            self.assertEqual(approximate_size(value), "1.1 GiB")

        def test_flow_line_split(self):
            """ Splitting a flow line is not trivial.
            There is no clear delimiter. Comma is used liberally."""
            expected_fields = ["in_port(4)",
                            "eth(src=00:50:56:b4:4e:f8,dst=33:33:00:01:00:03)",
                            "eth_type(0x86dd)",
                           "ipv6(src=fe80::55bf:fe42:bc96:2812,dst=ff02::1:3,"
                           "label=0,proto=17,tclass=0,hlimit=1,frag=no)",
                           "udp(src=61252,dst=5355)"]
            expected_stats = ["packets:2", "bytes:92", "used:0.703s"]
            expected_actions = "actions:3,8,11,14,17,20,23,26,29,32,35," \
                               "38,41,44,47,50,53,56,59,62,65"

            line = "in_port(4),eth(src=00:50:56:b4:4e:f8,"\
                   "dst=33:33:00:01:00:03),eth_type(0x86dd),"\
                   "ipv6(src=fe80::55bf:fe42:bc96:2812,dst=ff02::1:3,"\
                   "label=0,proto=17,tclass=0,hlimit=1,frag=no),"\
                   "udp(src=61252,dst=5355), packets:2, bytes:92, "\
                   "used:0.703s, actions:3,8,11,14,17,20,23,26,29,32,35,"\
                   "38,41,44,47,50,53,56,59,62,65"

            (fields, stats, actions) = flow_line_split(line)

            self.assertEqual(fields, expected_fields)
            self.assertEqual(stats, expected_stats)
            self.assertEqual(actions, expected_actions)

        def test_accumulate_decay(self):
            """ test_accumulate_decay: test accumulated decay. """
            lines = ["in_port(1),eth(src=00:50:56:4f:dc:3b,"
                     "dst=ff:ff:ff:ff:ff:ff),"
                     "eth_type(0x0806),arp(sip=10.24.105.107/255.255.255.255,"
                     "tip=10.24.104.230/255.255.255.255,op=1/0xff,"
                     "sha=00:50:56:4f:dc:3b/00:00:00:00:00:00,"
                     "tha=00:00:00:00:00:00/00:00:00:00:00:00), "
                     "packets:1, bytes:120, used:0.004s, actions:1"]

            flow_db = FlowDB(True)
            flow_db.begin()
            flow_db.flow_line_add(lines[0])

            # Make sure we decay
            time.sleep(4)
            self.assertEqual(flow_db.flow_stats_get()["flow_total"], 1)
            flow_db.decay(1)
            self.assertEqual(flow_db.flow_stats_get()["flow_total"], 0)

            flow_db.flow_line_add(lines[0])
            self.assertEqual(flow_db.flow_stats_get()["flow_total"], 1)
            flow_db.decay(30)
            # Should not be deleted.
            self.assertEqual(flow_db.flow_stats_get()["flow_total"], 1)

            flow_db.flow_line_add(lines[0])
            self.assertEqual(flow_db.flow_stats_get()["flow_total"], 1)
            timer = decay_timer_start(flow_db, 2)
            time.sleep(10)
            self.assertEqual(flow_db.flow_stats_get()["flow_total"], 0)
            timer.stop()

        def test_accumulate(self):
            """ test_accumulate test that FlowDB supports accumulate. """

            lines = ["in_port(1),eth(src=00:50:56:4f:dc:3b,"
                     "dst=ff:ff:ff:ff:ff:ff),"
                     "eth_type(0x0806),arp(sip=10.24.105.107/255.255.255.255,"
                     "tip=10.24.104.230/255.255.255.255,op=1/0xff,"
                     "sha=00:50:56:4f:dc:3b/00:00:00:00:00:00,"
                     "tha=00:00:00:00:00:00/00:00:00:00:00:00), "
                     "packets:1, bytes:120, used:0.004s, actions:1",
                     "in_port(2),"
                     "eth(src=68:ef:bd:25:ef:c0,dst=33:33:00:00:00:66),"
                     "eth_type(0x86dd),ipv6(src=fe80::6aef:bdff:fe25:efc0/::,"
                     "dst=ff02::66/::,label=0/0,proto=17/0xff,tclass=0xe0/0,"
                     "hlimit=255/0,frag=no/0),udp(src=2029,dst=2029), "
                     "packets:2, bytes:5026, used:0.348s, actions:1",
                     "in_port(1),eth(src=ee:ee:ee:ee:ee:ee,"
                     "dst=ff:ff:ff:ff:ff:ff),"
                     "eth_type(0x0806),arp(sip=10.24.105.107/255.255.255.255,"
                     "tip=10.24.104.230/255.255.255.255,op=1/0xff,"
                     "sha=00:50:56:4f:dc:3b/00:00:00:00:00:00,"
                     "tha=00:00:00:00:00:00/00:00:00:00:00:00), packets:2, "
                     "bytes:240, used:0.004s, actions:1"]

            lines = [
                "in_port(1),eth_type(0x0806), packets:1, bytes:120, actions:1",
                "in_port(2),eth_type(0x0806), packets:2, bytes:126, actions:1",
                "in_port(1),eth_type(0x0806), packets:2, bytes:240, actions:1",
                "in_port(1),eth_type(0x0800), packets:1, bytes:120, actions:1",
                "in_port(1),eth_type(0x0800), packets:2, bytes:240, actions:1",
                "in_port(1),eth_type(0x0806), packets:1, bytes:120, actions:1",
                ]

            # Turn on accumulate.
            flow_db = FlowDB(True)
            flow_db.begin()

            flow_db.flow_line_add(lines[0])

            # Test one flow exist.
            sum_values = flow_db.field_values_in_order("all", 1)
            in_ports = [ii for ii in sum_values if (repr(ii) == "in_port(1)")]
            self.assertEqual(len(in_ports), 1)
            self.assertEqual(in_ports[0].packets, 1)
            self.assertEqual(in_ports[0].bytes, 120)
            self.assertEqual(in_ports[0].count, 1)

            # simulate another sample
            # Test two different flows exist.
            flow_db.begin()
            flow_db.flow_line_add(lines[1])
            sum_values = flow_db.field_values_in_order("all", 1)
            in_ports = [ii for ii in sum_values if (repr(ii) == "in_port(1)")]
            self.assertEqual(len(in_ports), 1)
            self.assertEqual(in_ports[0].packets, 1)
            self.assertEqual(in_ports[0].bytes, 120)
            self.assertEqual(in_ports[0].count, 1)

            in_ports = [ii for ii in sum_values if (repr(ii) == "in_port(2)")]
            self.assertEqual(len(in_ports), 1)
            self.assertEqual(in_ports[0].packets, 2)
            self.assertEqual(in_ports[0].bytes, 126)
            self.assertEqual(in_ports[0].count, 1)

            # Test first flow increments packets.
            flow_db.begin()
            flow_db.flow_line_add(lines[2])
            sum_values = flow_db.field_values_in_order("all", 1)
            in_ports = [ii for ii in sum_values if (repr(ii) == "in_port(1)")]
            self.assertEqual(len(in_ports), 1)
            self.assertEqual(in_ports[0].packets, 2)
            self.assertEqual(in_ports[0].bytes, 240)
            self.assertEqual(in_ports[0].count, 1)

            in_ports = [ii for ii in sum_values if (repr(ii) == "in_port(2)")]
            self.assertEqual(len(in_ports), 1)
            self.assertEqual(in_ports[0].packets, 2)
            self.assertEqual(in_ports[0].bytes, 126)
            self.assertEqual(in_ports[0].count, 1)

            # Test third flow but with the same in_port(1) as the first flow.
            flow_db.begin()
            flow_db.flow_line_add(lines[3])
            sum_values = flow_db.field_values_in_order("all", 1)
            in_ports = [ii for ii in sum_values if (repr(ii) == "in_port(1)")]
            self.assertEqual(len(in_ports), 1)
            self.assertEqual(in_ports[0].packets, 3)
            self.assertEqual(in_ports[0].bytes, 360)
            self.assertEqual(in_ports[0].count, 2)

            in_ports = [ii for ii in sum_values if (repr(ii) == "in_port(2)")]
            self.assertEqual(len(in_ports), 1)
            self.assertEqual(in_ports[0].packets, 2)
            self.assertEqual(in_ports[0].bytes, 126)
            self.assertEqual(in_ports[0].count, 1)

            # Third flow has changes.
            flow_db.begin()
            flow_db.flow_line_add(lines[4])
            sum_values = flow_db.field_values_in_order("all", 1)
            in_ports = [ii for ii in sum_values if (repr(ii) == "in_port(1)")]
            self.assertEqual(len(in_ports), 1)
            self.assertEqual(in_ports[0].packets, 4)
            self.assertEqual(in_ports[0].bytes, 480)
            self.assertEqual(in_ports[0].count, 2)

            in_ports = [ii for ii in sum_values if (repr(ii) == "in_port(2)")]
            self.assertEqual(len(in_ports), 1)
            self.assertEqual(in_ports[0].packets, 2)
            self.assertEqual(in_ports[0].bytes, 126)
            self.assertEqual(in_ports[0].count, 1)

            # First flow reset.
            flow_db.begin()
            flow_db.flow_line_add(lines[5])
            sum_values = flow_db.field_values_in_order("all", 1)
            in_ports = [ii for ii in sum_values if (repr(ii) == "in_port(1)")]
            self.assertEqual(len(in_ports), 1)
            self.assertEqual(in_ports[0].packets, 3)
            self.assertEqual(in_ports[0].bytes, 360)
            self.assertEqual(in_ports[0].count, 2)

            in_ports = [ii for ii in sum_values if (repr(ii) == "in_port(2)")]
            self.assertEqual(len(in_ports), 1)
            self.assertEqual(in_ports[0].packets, 2)
            self.assertEqual(in_ports[0].bytes, 126)
            self.assertEqual(in_ports[0].count, 1)

        def test_parse_character_errors(self):
            """ test_parsing errors.
            The flow parses is purposely loose. Its not designed to validate
            input. Merely pull out what it can but there are situations
            that a parse error can be detected.
            """

            lines = ["complete garbage",
                     "in_port(2),eth(src=68:ef:bd:25:ef:c0,"
                     "dst=33:33:00:00:00:66),"
                     "eth_type(0x86dd),ipv6(src=fe80::6aef:bdff:fe25:efc0/::,"
                     "dst=ff02::66/::,label=0/0,proto=17/0xff,tclass=0xe0/0,"
                     "hlimit=255/0,frag=no/0),udp(src=2029,dst=2029),"
                     "packets:2,bytes:5026,actions:1"]

            flow_db = FlowDB(False)
            flow_db.begin()
            for line in lines:
                try:
                    flow_db.flow_line_add(line)
                except ValueError:
                    # We want an exception. That is how we know we have
                    # correctly found a simple parsing error. We are not
                    # looking to validate flow output just catch simple issues.
                    continue
                self.assertTrue(False)

        def test_tunnel_parsing(self):
            """ test_tunnel_parsing test parse flows with tunnel. """
            lines = [
                "tunnel(tun_id=0x0,src=192.168.1.1,dst=192.168.1.10,"
                "tos=0x0,ttl=64,flags(key)),in_port(1),"
                "eth(src=9e:40:f5:ef:ec:ee,dst=01:23:20:00:00:30),"
                "eth_type(0x8902), packets:6, bytes:534, used:0.128s, "
                "actions:userspace(pid=4294962691,slow_path(cfm))"
                ]
            flow_db = FlowDB(False)
            flow_db.begin()
            flow_db.flow_line_add(lines[0])
            sum_values = flow_db.field_values_in_order("all", 1)
            in_ports = [ii for ii in sum_values if (repr(ii) == "in_port(1)")]
            self.assertEqual(len(in_ports), 1)
            self.assertEqual(in_ports[0].packets, 6)
            self.assertEqual(in_ports[0].bytes, 534)
            self.assertEqual(in_ports[0].count, 1)

        def test_flow_multiple_paren(self):
            """ test_flow_multiple_paren. """
            line = "tunnel(tun_id=0x0,src=192.168.1.1,flags(key)),in_port(2)"
            valid = ["tunnel(tun_id=0x0,src=192.168.1.1,flags(key))",
                     "in_port(2)"]
            rc = flow_line_iter(line)
            self.assertEqual(valid, rc)

        def test_to_network(self):
            """ test_to_network test ipv4_to_network and ipv6_to_network. """
            ipv4s = [
                ("192.168.0.1", "192.168.0.1"),
                ("192.168.0.1/255.255.255.255", "192.168.0.1"),
                ("192.168.0.1/255.255.255.0", "192.168.0.0"),
                ("192.168.0.1/255.255.0.0", "192.168.0.0"),
                ("192.168.0.1/255.0.0.0", "192.0.0.0"),
                ("192.168.0.1/0.0.0.0", "0.0.0.0"),
                ("10.24.106.230/255.255.255.255", "10.24.106.230"),
                ("10.24.106.230/255.255.255.0", "10.24.106.0"),
                ("10.24.106.0/255.255.255.0", "10.24.106.0"),
                ("10.24.106.0/255.255.252.0", "10.24.104.0")
                ]

            ipv6s = [
                ("1::192:168:0:1", "1::192:168:0:1"),
                ("1::192:168:0:1/1::ffff:ffff:ffff:ffff", "1::192:168:0:1"),
                ("1::192:168:0:1/1::ffff:ffff:ffff:0", "1::192:168:0:0"),
                ("1::192:168:0:1/1::ffff:ffff:0:0", "1::192:168:0:0"),
                ("1::192:168:0:1/1::ffff:0:0:0", "1::192:0:0:0"),
                ("1::192:168:0:1/1::0:0:0:0", "1::"),
                ("1::192:168:0:1/::", "::")
                ]

            for (ipv4_test, ipv4_check) in ipv4s:
                self.assertEqual(ipv4_to_network(ipv4_test), ipv4_check)

            for (ipv6_test, ipv6_check) in ipv6s:
                self.assertEqual(ipv6_to_network(ipv6_test), ipv6_check)

        def test_ui(self):
            """ test_ui: test expected ui behavior. """
            #pylint: disable=W0212
            top_render = Render(80, Render.FIELD_SELECT_TOP)
            script_render = Render(80, Render.FIELD_SELECT_SCRIPT)
            self.assertEqual(top_render._field_type_select_get(), "in_port")
            self.assertEqual(script_render._field_type_select_get(), "all")
            #pylint: enable=W0212