# Copyright (c) 2005, Enthought, Inc.
# All rights reserved.
#
# This software is provided without warranty under the terms of the BSD
# license included in /LICENSE.txt and may be redistributed only
# under the conditions described in the aforementioned license.  The license
# is also available online at http://www.enthought.com/licenses/BSD.txt
# Thanks for using Enthought open source!
#
# Author: David C. Morrill
# Date: 03/03/2003
# Description: Perform timing tests on various trait styles to determine the
#              amount of overhead that traits add.

from __future__ import absolute_import

from time import time
from ..api import Any, DelegatesTo, HasTraits, Int, Range

# Number of iterations to perform:
n = 1000000

# Loop overhead time (actual value determined first time a measurement is made)
t0 = -1.0


#  Measure how long it takes to execute a specified function:
def measure(func):
    now = time()
    func()
    return time() - now


#  'Old style' Python attribute get/set:
class old_style_value:

    def measure(self, reference_get=1.0, reference_set=1.0):
        global t0
        self.init()

        if t0 < 0.0:
            t0 = measure(self.null)
        t1 = measure(self.do_get)
        t2 = measure(self.do_set)

        scale = 1.0e6 / n
        get_time = max(t1 - t0, 0.0) * scale
        set_time = max(t2 - t0, 0.0) * scale

        return get_time, set_time

    def null(self):
        for i in range(n):
            pass

    def init(self):
        self.value = -1

    def do_set(self):
        for i in range(n):
            self.value = i

    def do_get(self):
        for i in range(n):
            self.value


#  'New style' Python attribute get/set:
class new_style_value(object):

    def measure(self):
        global t0
        self.init()

        if t0 < 0.0:
            t0 = measure(self.null)
        t1 = measure(self.do_get)
        t2 = measure(self.do_set)

        scale = 1.0e6 / n
        get_time = max(t1 - t0, 0.0) * scale
        set_time = max(t2 - t0, 0.0) * scale

        return get_time, set_time

    def null(self):
        for i in range(n):
            pass

    def init(self):
        self.value = -1

    def do_set(self):
        for i in range(n):
            self.value = i

    def do_get(self):
        for i in range(n):
            self.value


#  Python 'property' get/set:
class property_value(new_style_value):

    def get_value(self):
        return self._value

    def set_value(self, value):
        self._value = value

    value = property(get_value, set_value)


#  Python 'global' get/set:
class global_value(new_style_value):

    def init(self):
        global gvalue
        gvalue = -1

    def do_set(self):
        global gvalue
        for i in range(n):
            gvalue = i

    def do_get(self):
        global gvalue
        for i in range(n):
            gvalue


#  Trait that can have any value:
class any_value(HasTraits, new_style_value):

    value = Any


#  Trait that can only have 'float' values:
class int_value(any_value):

    value = Int


#  Trait that can only have 'range' values:
class range_value(any_value):

    value = Range(-1, 2000000000)


#  Executes method when float trait is changed:
class change_value(int_value):

    def _value_changed(self, old, new):
        pass


#  Notifies handler when float trait is changed:
class monitor_value(int_value):

    def init(self):
        self.on_trait_change(self.on_value_change, 'value')

    def on_value_change(self, object, trait_name, old, new):
        pass


#  Float trait is delegated to another object:
class delegate_value(HasTraits, new_style_value):

    value = DelegatesTo('delegate')
    delegate = Any

    def init(self):
        self.delegate = int_value()


#  Float trait is delegated through one object to another object:
class delegate_2_value(delegate_value):

    def init(self):
        delegate = delegate_value()
        delegate.init()
        self.delegate = delegate


#  Float trait is delegated through two objects to another object:
class delegate_3_value(delegate_value):

    def init(self):
        delegate = delegate_2_value()
        delegate.init()
        self.delegate = delegate


#  Run the timing measurements:
def report(name, get_time, set_time, ref_get_time, ref_set_time):
    """ Return string containing a benchmark report.

    The arguments are the name of the benchmark case, the times to do a 'get'
    or a 'set' operation for that benchmark case in usec, and the
    corresponding times for a reference operation (e.g., getting and
    setting an attribute on a new-style instance.
    """

    template = (
        '{name:^30}: Get {get_time:02.3f} us (x {get_speed_up:02.3f}), '
        'Set {set_time:02.3f} us (x {set_speed_up:02.3f})'
        )

    report = template.format(
        name=name,
        get_time=get_time,
        get_speed_up=ref_get_time / get_time,
        set_time=set_time,
        set_speed_up=ref_set_time / set_time,
        )

    return report


def run_benchmark(klass, ref_get_time, ref_set_time):
    benchmark_name = klass.__name__
    get_time, set_time = klass().measure()
    print report(benchmark_name,
                 get_time, set_time,
                 ref_get_time, ref_set_time)


def main():
    ref_get_time, ref_set_time = new_style_value().measure()

    benchmarks = [
        global_value,
        old_style_value,
        new_style_value,
        property_value,
        any_value,
        int_value,
        range_value,
        change_value,
        monitor_value,
        delegate_value,
        delegate_2_value,
        delegate_3_value
    ]

    for benchmark in benchmarks:
        run_benchmark(benchmark, ref_get_time, ref_set_time)

if __name__ == '__main__':
    main()