# Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

import logging
import os
import re
import time

from math import sqrt

from autotest_lib.client.bin import test, utils
from autotest_lib.client.common_lib import error
from autotest_lib.client.common_lib.cros import chrome
from autotest_lib.client.cros.graphics import graphics_utils
from autotest_lib.client.cros.video import helper_logger

TEST_PAGE = 'content.html'

# The keys to access the content of memry stats.
KEY_RENDERER = 'Renderer'
KEY_BROWSER = 'Browser'
KEY_GPU = 'Gpu'
KEY_RSS = 'WorkingSetSize'

# The number of iterations to be run before measuring the memory usage.
# Just ensure we have fill up the caches/buffers so that we can get
# a more stable/correct result.
WARMUP_COUNT = 50

# Number of iterations per measurement.
EVALUATION_COUNT = 70

# The minimal number of samples for memory-leak test.
MEMORY_LEAK_CHECK_MIN_COUNT = 20

# The approximate values of the student's t-distribution at 95% confidence.
# See http://en.wikipedia.org/wiki/Student's_t-distribution
T_095 = [None, # No value for degree of freedom 0
    12.706205, 4.302653, 3.182446, 2.776445, 2.570582, 2.446912, 2.364624,
     2.306004, 2.262157, 2.228139, 2.200985, 2.178813, 2.160369, 2.144787,
     2.131450, 2.119905, 2.109816, 2.100922, 2.093024, 2.085963, 2.079614,
     2.073873, 2.068658, 2.063899, 2.059539, 2.055529, 2.051831, 2.048407,
     2.045230, 2.042272, 2.039513, 2.036933, 2.034515, 2.032245, 2.030108,
     2.028094, 2.026192, 2.024394, 2.022691, 2.021075, 2.019541, 2.018082,
     2.016692, 2.015368, 2.014103, 2.012896, 2.011741, 2.010635, 2.009575,
     2.008559, 2.007584, 2.006647, 2.005746, 2.004879, 2.004045, 2.003241,
     2.002465, 2.001717, 2.000995, 2.000298, 1.999624, 1.998972, 1.998341,
     1.997730, 1.997138, 1.996564, 1.996008, 1.995469, 1.994945, 1.994437,
     1.993943, 1.993464, 1.992997, 1.992543, 1.992102, 1.991673, 1.991254,
     1.990847, 1.990450, 1.990063, 1.989686, 1.989319, 1.988960, 1.988610,
     1.988268, 1.987934, 1.987608, 1.987290, 1.986979, 1.986675, 1.986377,
     1.986086, 1.985802, 1.985523, 1.985251, 1.984984, 1.984723, 1.984467,
     1.984217, 1.983972, 1.983731]

# The memory leak (bytes/iteration) we can tolerate.
MEMORY_LEAK_THRESHOLD = 1024 * 1024

# Regular expression used to parse the content of '/proc/meminfo'
# The content of the file looks like:
# MemTotal:       65904768 kB
# MemFree:        14248152 kB
# Buffers:          508836 kB
MEMINFO_RE = re.compile('^(\w+):\s+(\d+)', re.MULTILINE)
MEMINFO_PATH = '/proc/meminfo'

# We sum up the following values in '/proc/meminfo' to represent
# the kernel memory usage.
KERNEL_MEMORY_ENTRIES = ['Slab', 'Shmem', 'KernelStack', 'PageTables']

MEM_TOTAL_ENTRY = 'MemTotal'

# The default sleep time, in seconds.
SLEEP_TIME = 1.5


def _get_kernel_memory_usage():
    with file(MEMINFO_PATH) as f:
        mem_info = {x.group(1): int(x.group(2))
                   for x in MEMINFO_RE.finditer(f.read())}
    # Sum up the kernel memory usage (in KB) in mem_info
    return sum(map(mem_info.get, KERNEL_MEMORY_ENTRIES))

def _get_graphics_memory_usage():
    """Get the memory usage (in KB) of the graphics module."""
    key = 'gem_objects_bytes'
    graphics_kernel_memory = graphics_utils.GraphicsKernelMemory()
    usage = graphics_kernel_memory.get_memory_keyvals().get(key, 0)

    if graphics_kernel_memory.num_errors:
        logging.warning('graphics memory info is not available')
        return 0

    return usage

def _get_linear_regression_slope(x, y):
    """
    Gets slope and the confidence interval of the linear regression based on
    the given xs and ys.

    This function returns a tuple (beta, delta), where the beta is the slope
    of the linear regression and delta is the range of the confidence
    interval, i.e., confidence interval = (beta + delta, beta - delta).
    """
    assert len(x) == len(y)
    n = len(x)
    sx, sy = sum(x), sum(y)
    sxx = sum(v * v for v in x)
    syy = sum(v * v for v in y)
    sxy = sum(u * v for u, v in zip(x, y))
    beta = float(n * sxy - sx * sy) / (n * sxx - sx * sx)
    alpha = float(sy - beta * sx) / n
    stderr2 = (n * syy - sy * sy -
               beta * beta * (n * sxx - sx * sx)) / (n * (n - 2))
    std_beta = sqrt((n * stderr2) / (n * sxx - sx * sx))
    return (beta, T_095[n - 2] * std_beta)


def _assert_no_memory_leak(name, mem_usage, threshold = MEMORY_LEAK_THRESHOLD):
    """Helper function to check memory leak"""
    index = range(len(mem_usage))
    slope, delta = _get_linear_regression_slope(index, mem_usage)
    logging.info('confidence interval: %s - %s, %s',
                 name, slope - delta, slope + delta)
    if (slope - delta > threshold):
        logging.debug('memory usage for %s - %s', name, mem_usage)
        raise error.TestError('leak detected: %s - %s' % (name, slope - delta))


def _output_entries(out, entries):
    out.write(' '.join(str(x) for x in entries) + '\n')
    out.flush()


class MemoryTest(object):
    """The base class of all memory tests"""

    def __init__(self, bindir):
        self._bindir = bindir


    def _open_new_tab(self, page_to_open):
        tab = self.browser.tabs.New()
        tab.Activate()
        tab.Navigate(self.browser.platform.http_server.UrlOf(
                os.path.join(self._bindir, page_to_open)))
        tab.WaitForDocumentReadyStateToBeComplete()
        return tab


    def _get_memory_usage(self):
        """Helper function to get the memory usage.

        It returns a tuple of six elements:
            (browser_usage, renderer_usage, gpu_usage, kernel_usage,
             total_usage, graphics_usage)
        All are expected in the unit of KB.

        browser_usage: the RSS of the browser process
        rednerers_usage: the total RSS of all renderer processes
        rednerers_usage: the total RSS of all gpu processes
        kernel_usage: the memory used in kernel
        total_usage: the sum of the above memory usages. The graphics_usage is
                     not included because the composition of the graphics
                     memory is much more complicated (could be from video card,
                     user space, or kenerl space). It doesn't make so much
                     sense to sum it up with others.
        graphics_usage: the memory usage reported by the graphics driver
        """
        # Force to collect garbage before measuring memory
        for i in xrange(len(self.browser.tabs)):
            # TODO(owenlin): Change to "for t in tabs" once
            #                http://crbug.com/239735 is resolved
            self.browser.tabs[i].CollectGarbage()

        m = self.browser.memory_stats

        result = (m[KEY_BROWSER][KEY_RSS] / 1024,
                  m[KEY_RENDERER][KEY_RSS] / 1024,
                  m[KEY_GPU][KEY_RSS] / 1024,
                  _get_kernel_memory_usage())

        # total = browser + renderer + gpu + kernal
        result += (sum(result), _get_graphics_memory_usage())
        return result


    def initialize(self):
        """A callback function. It is just called before the main loops."""
        pass


    def loop(self):
        """A callback function. It is the main memory test function."""
        pass


    def cleanup(self):
        """A callback function, executed after loop()."""
        pass


    def run(self, name, browser, videos, test,
            warmup_count=WARMUP_COUNT,
            eval_count=EVALUATION_COUNT):
        """Runs this memory test case.

        @param name: the name of the test.
        @param browser: the telemetry entry of the browser under test.
        @param videos: the videos to be used in the test.
        @param test: the autotest itself, used to output performance values.
        @param warmup_count: run loop() for warmup_count times to make sure the
               memory usage has been stabalize.
        @param eval_count: run loop() for eval_count times to measure the memory
               usage.
        """

        self.browser = browser
        self.videos = videos
        self.name = name

        names = ['browser', 'renderers', 'gpu', 'kernel', 'total', 'graphics']
        result_log = open(os.path.join(test.resultsdir, '%s.log' % name), 'wt')
        _output_entries(result_log, names)

        self.initialize()
        try:
            for i in xrange(warmup_count):
                self.loop()
                _output_entries(result_log, self._get_memory_usage())

            metrics = []
            for i in xrange(eval_count):
                self.loop()
                results = self._get_memory_usage()
                _output_entries(result_log, results)
                metrics.append(results)

                # Check memory leak when we have enough samples
                if len(metrics) >= MEMORY_LEAK_CHECK_MIN_COUNT:
                    # Assert no leak in the 'total' and 'graphics' usages
                    for index in map(names.index, ('total', 'graphics')):
                        _assert_no_memory_leak(
                            self.name, [m[index] for m in metrics])

            indices = range(len(metrics))

            # Prefix the test name to each metric's name
            fullnames = ['%s.%s' % (name, n) for n in names]

            # Transpose metrics, and iterate each type of memory usage
            for name, metric in zip(fullnames, zip(*metrics)):
                memory_increase_per_run, _ = _get_linear_regression_slope(
                    indices, metric)
                logging.info('memory increment for %s - %s',
                    name, memory_increase_per_run)
                test.output_perf_value(description=name,
                        value=memory_increase_per_run,
                        units='KB', higher_is_better=False)
        finally:
            self.cleanup()


def _change_source_and_play(tab, video):
    tab.EvaluateJavaScript('changeSourceAndPlay("%s")' % video)


def _assert_video_is_playing(tab):
    if not tab.EvaluateJavaScript('isVideoPlaying()'):
        raise error.TestError('video is stopped')

    # The above check may fail. Be sure the video time is advancing.
    startTime = tab.EvaluateJavaScript('getVideoCurrentTime()')

    def _is_video_playing():
        return startTime != tab.EvaluateJavaScript('getVideoCurrentTime()')

    utils.poll_for_condition(
            _is_video_playing, exception=error.TestError('video is stuck'))


class OpenTabPlayVideo(MemoryTest):
    """A memory test case:
        Open a tab, play a video and close the tab.
    """

    def loop(self):
        tab = self._open_new_tab(TEST_PAGE)
        _change_source_and_play(tab, self.videos[0])
        _assert_video_is_playing(tab)
        time.sleep(SLEEP_TIME)
        tab.Close()

        # Wait a while for the closed tab to clean up all used resources
        time.sleep(SLEEP_TIME)


class PlayVideo(MemoryTest):
    """A memory test case: keep playing a video."""

    def initialize(self):
        super(PlayVideo, self).initialize()
        self.activeTab = self._open_new_tab(TEST_PAGE)
        _change_source_and_play(self.activeTab, self.videos[0])


    def loop(self):
        time.sleep(SLEEP_TIME)
        _assert_video_is_playing(self.activeTab)


    def cleanup(self):
        self.activeTab.Close()


class ChangeVideoSource(MemoryTest):
    """A memory test case: change the "src" property of <video> object to
    load different video sources."""

    def initialize(self):
        super(ChangeVideoSource, self).initialize()
        self.activeTab = self._open_new_tab(TEST_PAGE)


    def loop(self):
        for video in self.videos:
            _change_source_and_play(self.activeTab, video)
            time.sleep(SLEEP_TIME)
            _assert_video_is_playing(self.activeTab)


    def cleanup(self):
        self.activeTab.Close()


def _get_testcase_name(class_name, videos):
    # Convert from Camel to underscrore.
    s = re.sub('(.)([A-Z][a-z]+)', r'\1_\2', class_name)
    s = re.sub('([a-z0-9])([A-Z])', r'\1_\2', s).lower()

    # Get a shorter name from the first video's URL.
    # For example, get 'tp101.mp4' from the URL:
    # 'http://host/path/tpe101-1024x768-9123456780123456.mp4'
    m = re.match('.*/(\w+)-.*\.(\w+)', videos[0])

    return '%s.%s.%s' % (m.group(1), m.group(2), s)


# Deprecate the logging messages at DEBUG level (and lower) in telemetry.
# http://crbug.com/331992
class TelemetryFilter(logging.Filter):
    """Filter for telemetry logging."""

    def filter(self, record):
        return (record.levelno > logging.DEBUG or
            'telemetry' not in record.pathname)


class video_VideoDecodeMemoryUsage(test.test):
    """This is a memory usage test for video playback."""
    version = 1

    @helper_logger.video_log_wrapper
    def run_once(self, testcases):
        last_error = None
        logging.getLogger().addFilter(TelemetryFilter())

        with chrome.Chrome(
                extra_browser_args=helper_logger.chrome_vmodule_flag(),
                init_network_controller=True) as cr:
            cr.browser.platform.SetHTTPServerDirectories(self.bindir)
            for class_name, videos in testcases:
                name = _get_testcase_name(class_name, videos)
                logging.info('run: %s - %s', name, videos)
                try :
                    test_case_class = globals()[class_name]
                    test_case_class(self.bindir).run(
                            name, cr.browser, videos, self)
                except Exception as last_error:
                    logging.exception('%s fail', name)
                    # continue to next test case

        if last_error:
            raise  # the last_error