toolchain-utils/crosperf/results_report.py

# -*- coding: utf-8 -*-
# Copyright 2013 The ChromiumOS Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""A module to handle the report format."""

import datetime
import functools
import itertools
import json
import os
import re
import time

from column_chart import ColumnChart
from cros_utils.tabulator import AmeanResult
from cros_utils.tabulator import Cell
from cros_utils.tabulator import CoeffVarFormat
from cros_utils.tabulator import CoeffVarResult
from cros_utils.tabulator import Column
from cros_utils.tabulator import Format
from cros_utils.tabulator import GmeanRatioResult
from cros_utils.tabulator import IterationResult
from cros_utils.tabulator import LiteralResult
from cros_utils.tabulator import MaxResult
from cros_utils.tabulator import MinResult
from cros_utils.tabulator import PValueFormat
from cros_utils.tabulator import PValueResult
from cros_utils.tabulator import RatioFormat
from cros_utils.tabulator import RawResult
from cros_utils.tabulator import SamplesTableGenerator
from cros_utils.tabulator import StdResult
from cros_utils.tabulator import TableFormatter
from cros_utils.tabulator import TableGenerator
from cros_utils.tabulator import TablePrinter
from results_organizer import OrganizeResults
import results_report_templates as templates
from update_telemetry_defaults import TelemetryDefaults


def ParseChromeosImage(chromeos_image):
    """Parse the chromeos_image string for the image and version.

  The chromeos_image string will probably be in one of two formats:
  1: <path-to-chroot>/src/build/images/<board>/<ChromeOS-version>.<datetime>/ \
     chromiumos_test_image.bin
  2: <path-to-chroot>/chroot/tmp/<buildbot-build>/<ChromeOS-version>/ \
      chromiumos_test_image.bin

  We parse these strings to find the 'chromeos_version' to store in the
  json archive (without the .datatime bit in the first case); and also
  the 'chromeos_image', which would be all of the first case, but only the
  part after '/chroot/tmp' in the second case.

  Args:
    chromeos_image: string containing the path to the chromeos_image that
    crosperf used for the test.

  Returns:
    version, image: The results of parsing the input string, as explained
    above.
  """
    # Find the Chromeos Version, e.g. R45-2345.0.0.....
    # chromeos_image should have been something like:
    # <path>/<board-trybot-release>/<chromeos-version>/chromiumos_test_image.bin"
    if chromeos_image.endswith("/chromiumos_test_image.bin"):
        full_version = chromeos_image.split("/")[-2]
        # Strip the date and time off of local builds (which have the format
        # "R43-2345.0.0.date-and-time").
        version, _ = os.path.splitext(full_version)
    else:
        version = ""

    # Find the chromeos image.  If it's somewhere in .../chroot/tmp/..., then
    # it's an official image that got downloaded, so chop off the download path
    # to make the official image name more clear.
    official_image_path = "/chroot/tmp"
    if official_image_path in chromeos_image:
        image = chromeos_image.split(official_image_path, 1)[1]
    else:
        image = chromeos_image
    return version, image


def _AppendUntilLengthIs(gen, the_list, target_len):
    """Appends to `list` until `list` is `target_len` elements long.

    Uses `gen` to generate elements.
    """
    the_list.extend(gen() for _ in range(target_len - len(the_list)))
    return the_list


def _FilterPerfReport(event_threshold, report):
    """Filters out entries with `< event_threshold` percent in a perf report."""

    def filter_dict(m):
        return {
            fn_name: pct for fn_name, pct in m.items() if pct >= event_threshold
        }

    return {event: filter_dict(m) for event, m in report.items()}


class _PerfTable(object):
    """Generates dicts from a perf table.

    Dicts look like:
    {'benchmark_name': {'perf_event_name': [LabelData]}}
    where LabelData is a list of perf dicts, each perf dict coming from the same
    label.
    Each perf dict looks like {'function_name': 0.10, ...} (where 0.10 is the
    percentage of time spent in function_name).
    """

    def __init__(
        self,
        benchmark_names_and_iterations,
        label_names,
        read_perf_report,
        event_threshold=None,
    ):
        """Constructor.

        read_perf_report is a function that takes a label name, benchmark name, and
        benchmark iteration, and returns a dictionary describing the perf output for
        that given run.
        """
        self.event_threshold = event_threshold
        self._label_indices = {name: i for i, name in enumerate(label_names)}
        self.perf_data = {}
        for label in label_names:
            for bench_name, bench_iterations in benchmark_names_and_iterations:
                for i in range(bench_iterations):
                    report = read_perf_report(label, bench_name, i)
                    self._ProcessPerfReport(report, label, bench_name, i)

    def _ProcessPerfReport(self, perf_report, label, benchmark_name, iteration):
        """Add the data from one run to the dict."""
        perf_of_run = perf_report
        if self.event_threshold is not None:
            perf_of_run = _FilterPerfReport(self.event_threshold, perf_report)
        if benchmark_name not in self.perf_data:
            self.perf_data[benchmark_name] = {
                event: [] for event in perf_of_run
            }
        ben_data = self.perf_data[benchmark_name]
        label_index = self._label_indices[label]
        for event in ben_data:
            _AppendUntilLengthIs(list, ben_data[event], label_index + 1)
            data_for_label = ben_data[event][label_index]
            _AppendUntilLengthIs(dict, data_for_label, iteration + 1)
            data_for_label[iteration] = (
                perf_of_run[event] if perf_of_run else {}
            )


def _GetResultsTableHeader(ben_name, iterations):
    benchmark_info = "Benchmark:  {0};  Iterations: {1}".format(
        ben_name, iterations
    )
    cell = Cell()
    cell.string_value = benchmark_info
    cell.header = True
    return [[cell]]


def _GetDSOHeader(cwp_dso):
    info = "CWP_DSO: %s" % cwp_dso
    cell = Cell()
    cell.string_value = info
    cell.header = False
    return [[cell]]


def _ParseColumn(columns, iteration):
    new_column = []
    for column in columns:
        if column.result.__class__.__name__ != "RawResult":
            new_column.append(column)
        else:
            new_column.extend(
                Column(LiteralResult(i), Format(), str(i + 1))
                for i in range(iteration)
            )
    return new_column


def _GetTables(benchmark_results, columns, table_type):
    iter_counts = benchmark_results.iter_counts
    result = benchmark_results.run_keyvals
    tables = []
    for bench_name, runs in result.items():
        iterations = iter_counts[bench_name]
        ben_table = _GetResultsTableHeader(bench_name, iterations)

        all_runs_empty = all(not dict for label in runs for dict in label)
        if all_runs_empty:
            cell = Cell()
            cell.string_value = (
                "This benchmark contains no result."
                " Is the benchmark name valid?"
            )
            cell_table = [[cell]]
        else:
            table = TableGenerator(
                runs, benchmark_results.label_names
            ).GetTable()
            parsed_columns = _ParseColumn(columns, iterations)
            tf = TableFormatter(table, parsed_columns)
            cell_table = tf.GetCellTable(table_type)
        tables.append(ben_table)
        tables.append(cell_table)
    return tables


def _GetPerfTables(benchmark_results, columns, table_type):
    p_table = _PerfTable(
        benchmark_results.benchmark_names_and_iterations,
        benchmark_results.label_names,
        benchmark_results.read_perf_report,
    )

    tables = []
    for benchmark in p_table.perf_data:
        iterations = benchmark_results.iter_counts[benchmark]
        ben_table = _GetResultsTableHeader(benchmark, iterations)
        tables.append(ben_table)
        benchmark_data = p_table.perf_data[benchmark]
        table = []
        for event in benchmark_data:
            tg = TableGenerator(
                benchmark_data[event],
                benchmark_results.label_names,
                sort=TableGenerator.SORT_BY_VALUES_DESC,
            )
            table = tg.GetTable(ResultsReport.PERF_ROWS)
            parsed_columns = _ParseColumn(columns, iterations)
            tf = TableFormatter(table, parsed_columns)
            tf.GenerateCellTable(table_type)
            tf.AddColumnName()
            tf.AddLabelName()
            tf.AddHeader(str(event))
            table = tf.GetCellTable(table_type, headers=False)
            tables.append(table)
    return tables


def _GetSamplesTables(benchmark_results, columns, table_type):
    tables = []
    dso_header_table = _GetDSOHeader(benchmark_results.cwp_dso)
    tables.append(dso_header_table)
    (table, new_keyvals, iter_counts) = SamplesTableGenerator(
        benchmark_results.run_keyvals,
        benchmark_results.label_names,
        benchmark_results.iter_counts,
        benchmark_results.weights,
    ).GetTable()
    parsed_columns = _ParseColumn(columns, 1)
    tf = TableFormatter(table, parsed_columns, samples_table=True)
    cell_table = tf.GetCellTable(table_type)
    tables.append(cell_table)
    return (tables, new_keyvals, iter_counts)


class ResultsReport(object):
    """Class to handle the report format."""

    MAX_COLOR_CODE = 255
    PERF_ROWS = 5

    def __init__(self, results):
        self.benchmark_results = results

    def _GetTablesWithColumns(self, columns, table_type, summary_type):
        if summary_type == "perf":
            get_tables = _GetPerfTables
        elif summary_type == "samples":
            get_tables = _GetSamplesTables
        else:
            get_tables = _GetTables
        ret = get_tables(self.benchmark_results, columns, table_type)
        # If we are generating a samples summary table, the return value of
        # get_tables will be a tuple, and we will update the benchmark_results for
        # composite benchmark so that full table can use it.
        if isinstance(ret, tuple):
            self.benchmark_results.run_keyvals = ret[1]
            self.benchmark_results.iter_counts = ret[2]
            ret = ret[0]
        return ret

    def GetFullTables(self, perf=False):
        ignore_min_max = self.benchmark_results.ignore_min_max
        columns = [
            Column(RawResult(), Format()),
            Column(MinResult(), Format()),
            Column(MaxResult(), Format()),
            Column(AmeanResult(ignore_min_max), Format()),
            Column(StdResult(ignore_min_max), Format(), "StdDev"),
            Column(
                CoeffVarResult(ignore_min_max), CoeffVarFormat(), "StdDev/Mean"
            ),
            Column(
                GmeanRatioResult(ignore_min_max), RatioFormat(), "GmeanSpeedup"
            ),
            Column(PValueResult(ignore_min_max), PValueFormat(), "p-value"),
        ]
        return self._GetTablesWithColumns(columns, "full", perf)

    def GetSummaryTables(self, summary_type=""):
        ignore_min_max = self.benchmark_results.ignore_min_max
        columns = []
        if summary_type == "samples":
            columns += [
                Column(IterationResult(), Format(), "Iterations [Pass:Fail]")
            ]
        columns += [
            Column(
                AmeanResult(ignore_min_max),
                Format(),
                "Weighted Samples Amean" if summary_type == "samples" else "",
            ),
            Column(StdResult(ignore_min_max), Format(), "StdDev"),
            Column(
                CoeffVarResult(ignore_min_max), CoeffVarFormat(), "StdDev/Mean"
            ),
            Column(
                GmeanRatioResult(ignore_min_max), RatioFormat(), "GmeanSpeedup"
            ),
            Column(PValueResult(ignore_min_max), PValueFormat(), "p-value"),
        ]
        return self._GetTablesWithColumns(columns, "summary", summary_type)


def _PrintTable(tables, out_to):
    # tables may be None.
    if not tables:
        return ""

    if out_to == "HTML":
        out_type = TablePrinter.HTML
    elif out_to == "PLAIN":
        out_type = TablePrinter.PLAIN
    elif out_to == "CONSOLE":
        out_type = TablePrinter.CONSOLE
    elif out_to == "TSV":
        out_type = TablePrinter.TSV
    elif out_to == "EMAIL":
        out_type = TablePrinter.EMAIL
    else:
        raise ValueError("Invalid out_to value: %s" % (out_to,))

    printers = (TablePrinter(table, out_type) for table in tables)
    return "".join(printer.Print() for printer in printers)


class TextResultsReport(ResultsReport):
    """Class to generate text result report."""

    H1_STR = "==========================================="
    H2_STR = "-------------------------------------------"

    def __init__(self, results, email=False, experiment=None):
        super(TextResultsReport, self).__init__(results)
        self.email = email
        self.experiment = experiment

    @staticmethod
    def _MakeTitle(title):
        header_line = TextResultsReport.H1_STR
        # '' at the end gives one newline.
        return "\n".join([header_line, title, header_line, ""])

    @staticmethod
    def _MakeSection(title, body):
        header_line = TextResultsReport.H2_STR
        # '\n' at the end gives us two newlines.
        return "\n".join([header_line, title, header_line, body, "\n"])

    @staticmethod
    def FromExperiment(experiment, email=False):
        results = BenchmarkResults.FromExperiment(experiment)
        return TextResultsReport(results, email, experiment)

    def GetStatusTable(self):
        """Generate the status table by the tabulator."""
        table = [["", ""]]
        columns = [
            Column(LiteralResult(iteration=0), Format(), "Status"),
            Column(LiteralResult(iteration=1), Format(), "Failing Reason"),
        ]

        for benchmark_run in self.experiment.benchmark_runs:
            status = [
                benchmark_run.name,
                [
                    benchmark_run.timeline.GetLastEvent(),
                    benchmark_run.failure_reason,
                ],
            ]
            table.append(status)
        cell_table = TableFormatter(table, columns).GetCellTable("status")
        return [cell_table]

    def GetTotalWaitCooldownTime(self):
        """Get cooldown wait time in seconds from experiment benchmark runs.

        Returns:
          Dictionary {'dut': int(wait_time_in_seconds)}
        """
        waittime_dict = {}
        for dut in self.experiment.machine_manager.GetMachines():
            waittime_dict[dut.name] = dut.GetCooldownWaitTime()
        return waittime_dict

    def GetReport(self):
        """Generate the report for email and console."""
        output_type = "EMAIL" if self.email else "CONSOLE"
        experiment = self.experiment

        sections = []
        if experiment is not None:
            title_contents = "Results report for '%s'" % (experiment.name,)
        else:
            title_contents = "Results report"
        sections.append(self._MakeTitle(title_contents))

        if not self.benchmark_results.cwp_dso:
            summary_table = _PrintTable(self.GetSummaryTables(), output_type)
        else:
            summary_table = _PrintTable(
                self.GetSummaryTables(summary_type="samples"), output_type
            )
        sections.append(self._MakeSection("Summary", summary_table))

        if experiment is not None:
            table = _PrintTable(self.GetStatusTable(), output_type)
            sections.append(self._MakeSection("Benchmark Run Status", table))

        if not self.benchmark_results.cwp_dso:
            perf_table = _PrintTable(
                self.GetSummaryTables(summary_type="perf"), output_type
            )
            sections.append(self._MakeSection("Perf Data", perf_table))

        if experiment is not None:
            experiment_file = experiment.experiment_file
            sections.append(
                self._MakeSection("Experiment File", experiment_file)
            )

            cpu_info = experiment.machine_manager.GetAllCPUInfo(
                experiment.labels
            )
            sections.append(self._MakeSection("CPUInfo", cpu_info))

            totaltime = (
                (time.time() - experiment.start_time)
                if experiment.start_time
                else 0
            )
            totaltime_str = "Total experiment time:\n%d min" % (totaltime // 60)
            cooldown_waittime_list = ["Cooldown wait time:"]
            # When running experiment on multiple DUTs cooldown wait time may vary
            # on different devices. In addition its combined time may exceed total
            # experiment time which will look weird but it is reasonable.
            # For this matter print cooldown time per DUT.
            for dut, waittime in sorted(
                self.GetTotalWaitCooldownTime().items()
            ):
                cooldown_waittime_list.append(
                    "DUT %s: %d min" % (dut, waittime // 60)
                )
            cooldown_waittime_str = "\n".join(cooldown_waittime_list)
            sections.append(
                self._MakeSection(
                    "Duration",
                    "\n\n".join([totaltime_str, cooldown_waittime_str]),
                )
            )

        return "\n".join(sections)


def _GetHTMLCharts(label_names, test_results):
    charts = []
    for item, runs in test_results.items():
        # Fun fact: label_names is actually *entirely* useless as a param, since we
        # never add headers. We still need to pass it anyway.
        table = TableGenerator(runs, label_names).GetTable()
        columns = [
            Column(AmeanResult(), Format()),
            Column(MinResult(), Format()),
            Column(MaxResult(), Format()),
        ]
        tf = TableFormatter(table, columns)
        data_table = tf.GetCellTable("full", headers=False)

        for cur_row_data in data_table:
            test_key = cur_row_data[0].string_value
            title = "{0}: {1}".format(item, test_key.replace("/", ""))
            chart = ColumnChart(title, 300, 200)
            chart.AddColumn("Label", "string")
            chart.AddColumn("Average", "number")
            chart.AddColumn("Min", "number")
            chart.AddColumn("Max", "number")
            chart.AddSeries("Min", "line", "black")
            chart.AddSeries("Max", "line", "black")
            cur_index = 1
            for label in label_names:
                chart.AddRow(
                    [
                        label,
                        cur_row_data[cur_index].value,
                        cur_row_data[cur_index + 1].value,
                        cur_row_data[cur_index + 2].value,
                    ]
                )
                if isinstance(cur_row_data[cur_index].value, str):
                    chart = None
                    break
                cur_index += 3
            if chart:
                charts.append(chart)
    return charts


class HTMLResultsReport(ResultsReport):
    """Class to generate html result report."""

    def __init__(self, benchmark_results, experiment=None):
        super(HTMLResultsReport, self).__init__(benchmark_results)
        self.experiment = experiment

    @staticmethod
    def FromExperiment(experiment):
        return HTMLResultsReport(
            BenchmarkResults.FromExperiment(experiment), experiment=experiment
        )

    def GetReport(self):
        label_names = self.benchmark_results.label_names
        test_results = self.benchmark_results.run_keyvals
        charts = _GetHTMLCharts(label_names, test_results)
        chart_javascript = "".join(chart.GetJavascript() for chart in charts)
        chart_divs = "".join(chart.GetDiv() for chart in charts)

        if not self.benchmark_results.cwp_dso:
            summary_table = self.GetSummaryTables()
            perf_table = self.GetSummaryTables(summary_type="perf")
        else:
            summary_table = self.GetSummaryTables(summary_type="samples")
            perf_table = None
        full_table = self.GetFullTables()

        experiment_file = ""
        if self.experiment is not None:
            experiment_file = self.experiment.experiment_file
        # Use kwargs for code readability, and so that testing is a bit easier.
        return templates.GenerateHTMLPage(
            perf_table=perf_table,
            chart_js=chart_javascript,
            summary_table=summary_table,
            print_table=_PrintTable,
            chart_divs=chart_divs,
            full_table=full_table,
            experiment_file=experiment_file,
        )


def ParseStandardPerfReport(report_data):
    """Parses the output of `perf report`.

    It'll parse the following:
    {{garbage}}
    # Samples: 1234M of event 'foo'

    1.23% command shared_object location function::name

    1.22% command shared_object location function2::name

    # Samples: 999K of event 'bar'

    0.23% command shared_object location function3::name
    {{etc.}}

    Into:
      {'foo': {'function::name': 1.23, 'function2::name': 1.22},
       'bar': {'function3::name': 0.23, etc.}}
    """
    # This function fails silently on its if it's handed a string (as opposed to a
    # list of lines). So, auto-split if we do happen to get a string.
    if isinstance(report_data, str):
        report_data = report_data.splitlines()
    # When switching to python3 catch the case when bytes are passed.
    elif isinstance(report_data, bytes):
        raise TypeError()

    # Samples: N{K,M,G} of event 'event-name'
    samples_regex = re.compile(r"#\s+Samples: \d+\S? of event '([^']+)'")

    # We expect lines like:
    # N.NN%  command  samples  shared_object  [location] symbol
    #
    # Note that we're looking at stripped lines, so there is no space at the
    # start.
    perf_regex = re.compile(
        r"^(\d+(?:.\d*)?)%"  # N.NN%
        r"\s*\d+"  # samples count (ignored)
        r"\s*\S+"  # command (ignored)
        r"\s*\S+"  # shared_object (ignored)
        r"\s*\[.\]"  # location (ignored)
        r"\s*(\S.+)"  # function
    )

    stripped_lines = (l.strip() for l in report_data)
    nonempty_lines = (l for l in stripped_lines if l)
    # Ignore all lines before we see samples_regex
    interesting_lines = itertools.dropwhile(
        lambda x: not samples_regex.match(x), nonempty_lines
    )

    first_sample_line = next(interesting_lines, None)
    # Went through the entire file without finding a 'samples' header. Quit.
    if first_sample_line is None:
        return {}

    sample_name = samples_regex.match(first_sample_line).group(1)
    current_result = {}
    results = {sample_name: current_result}
    for line in interesting_lines:
        samples_match = samples_regex.match(line)
        if samples_match:
            sample_name = samples_match.group(1)
            current_result = {}
            results[sample_name] = current_result
            continue

        match = perf_regex.match(line)
        if not match:
            continue
        percentage_str, func_name = match.groups()
        try:
            percentage = float(percentage_str)
        except ValueError:
            # Couldn't parse it; try to be "resilient".
            continue
        current_result[func_name] = percentage
    return results


def _ReadExperimentPerfReport(
    results_directory, label_name, benchmark_name, benchmark_iteration
):
    """Reads a perf report for the given benchmark. Returns {} on failure.

    The result should be a map of maps; it should look like:
    {perf_event_name: {function_name: pct_time_spent}}, e.g.
    {'cpu_cycles': {'_malloc': 10.0, '_free': 0.3, ...}}
    """
    raw_dir_name = label_name + benchmark_name + str(benchmark_iteration + 1)
    dir_name = "".join(c for c in raw_dir_name if c.isalnum())
    file_name = os.path.join(results_directory, dir_name, "perf.data.report.0")
    try:
        with open(file_name) as in_file:
            return ParseStandardPerfReport(in_file)
    except IOError:
        # Yes, we swallow any IO-related errors.
        return {}


# Split out so that testing (specifically: mocking) is easier
def _ExperimentToKeyvals(experiment, for_json_report):
    """Converts an experiment to keyvals."""
    return OrganizeResults(
        experiment.benchmark_runs,
        experiment.labels,
        json_report=for_json_report,
    )


class BenchmarkResults(object):
    """The minimum set of fields that any ResultsReport will take."""

    def __init__(
        self,
        label_names,
        benchmark_names_and_iterations,
        run_keyvals,
        ignore_min_max=False,
        read_perf_report=None,
        cwp_dso=None,
        weights=None,
    ):
        if read_perf_report is None:

            def _NoPerfReport(*_args, **_kwargs):
                return {}

            read_perf_report = _NoPerfReport

        self.label_names = label_names
        self.benchmark_names_and_iterations = benchmark_names_and_iterations
        self.iter_counts = dict(benchmark_names_and_iterations)
        self.run_keyvals = run_keyvals
        self.ignore_min_max = ignore_min_max
        self.read_perf_report = read_perf_report
        self.cwp_dso = cwp_dso
        self.weights = dict(weights) if weights else None

    @staticmethod
    def FromExperiment(experiment, for_json_report=False):
        label_names = [label.name for label in experiment.labels]
        benchmark_names_and_iterations = [
            (benchmark.name, benchmark.iterations)
            for benchmark in experiment.benchmarks
        ]
        run_keyvals = _ExperimentToKeyvals(experiment, for_json_report)
        ignore_min_max = experiment.ignore_min_max
        read_perf_report = functools.partial(
            _ReadExperimentPerfReport, experiment.results_directory
        )
        cwp_dso = experiment.cwp_dso
        weights = [
            (benchmark.name, benchmark.weight)
            for benchmark in experiment.benchmarks
        ]
        return BenchmarkResults(
            label_names,
            benchmark_names_and_iterations,
            run_keyvals,
            ignore_min_max,
            read_perf_report,
            cwp_dso,
            weights,
        )


def _GetElemByName(name, from_list):
    """Gets an element from the given list by its name field.

    Raises an error if it doesn't find exactly one match.
    """
    elems = [e for e in from_list if e.name == name]
    if len(elems) != 1:
        raise ValueError(
            "Expected 1 item named %s, found %d" % (name, len(elems))
        )
    return elems[0]


def _Unlist(l):
    """If l is a list, extracts the first element of l. Otherwise, returns l."""
    return l[0] if isinstance(l, list) else l


class JSONResultsReport(ResultsReport):
    """Class that generates JSON reports for experiments."""

    def __init__(
        self,
        benchmark_results,
        benchmark_date=None,
        benchmark_time=None,
        experiment=None,
        json_args=None,
    ):
        """Construct a JSONResultsReport.

        json_args is the dict of arguments we pass to json.dumps in GetReport().
        """
        super(JSONResultsReport, self).__init__(benchmark_results)

        defaults = TelemetryDefaults()
        defaults.ReadDefaultsFile()
        summary_field_defaults = defaults.GetDefault()
        if summary_field_defaults is None:
            summary_field_defaults = {}
        self.summary_field_defaults = summary_field_defaults

        if json_args is None:
            json_args = {}
        self.json_args = json_args

        self.experiment = experiment
        if not benchmark_date:
            timestamp = datetime.datetime.strftime(
                datetime.datetime.now(), "%Y-%m-%d %H:%M:%S"
            )
            benchmark_date, benchmark_time = timestamp.split(" ")
        self.date = benchmark_date
        self.time = benchmark_time

    @staticmethod
    def FromExperiment(
        experiment, benchmark_date=None, benchmark_time=None, json_args=None
    ):
        benchmark_results = BenchmarkResults.FromExperiment(
            experiment, for_json_report=True
        )
        return JSONResultsReport(
            benchmark_results,
            benchmark_date,
            benchmark_time,
            experiment,
            json_args,
        )

    def GetReportObjectIgnoringExperiment(self):
        """Gets the JSON report object specifically for the output data.

        Ignores any experiment-specific fields (e.g. board, machine checksum, ...).
        """
        benchmark_results = self.benchmark_results
        label_names = benchmark_results.label_names
        summary_field_defaults = self.summary_field_defaults
        final_results = []
        for test, test_results in benchmark_results.run_keyvals.items():
            for label_name, label_results in zip(label_names, test_results):
                for iter_results in label_results:
                    passed = iter_results.get("retval") == 0
                    json_results = {
                        "date": self.date,
                        "time": self.time,
                        "label": label_name,
                        "test_name": test,
                        "pass": passed,
                    }
                    final_results.append(json_results)

                    if not passed:
                        continue

                    # Get overall results.
                    summary_fields = summary_field_defaults.get(test)
                    if summary_fields is not None:
                        value = []
                        json_results["overall_result"] = value
                        for f in summary_fields:
                            v = iter_results.get(f)
                            if v is None:
                                continue
                            # New telemetry results format: sometimes we get a list of lists
                            # now.
                            v = _Unlist(_Unlist(v))
                            value.append((f, float(v)))

                    # Get detailed results.
                    detail_results = {}
                    json_results["detailed_results"] = detail_results
                    for k, v in iter_results.items():
                        if (
                            k == "retval"
                            or k == "PASS"
                            or k == ["PASS"]
                            or v == "PASS"
                        ):
                            continue

                        v = _Unlist(v)
                        if "machine" in k:
                            json_results[k] = v
                        elif v is not None:
                            if isinstance(v, list):
                                detail_results[k] = [float(d) for d in v]
                            else:
                                detail_results[k] = float(v)
        return final_results

    def GetReportObject(self):
        """Generate the JSON report, returning it as a python object."""
        report_list = self.GetReportObjectIgnoringExperiment()
        if self.experiment is not None:
            self._AddExperimentSpecificFields(report_list)
        return report_list

    def _AddExperimentSpecificFields(self, report_list):
        """Add experiment-specific data to the JSON report."""
        board = self.experiment.labels[0].board
        manager = self.experiment.machine_manager
        for report in report_list:
            label_name = report["label"]
            label = _GetElemByName(label_name, self.experiment.labels)

            img_path = os.path.realpath(
                os.path.expanduser(label.chromeos_image)
            )
            ver, img = ParseChromeosImage(img_path)

            report.update(
                {
                    "board": board,
                    "chromeos_image": img,
                    "chromeos_version": ver,
                    "chrome_version": label.chrome_version,
                    "compiler": label.compiler,
                }
            )

            if not report["pass"]:
                continue
            if "machine_checksum" not in report:
                report["machine_checksum"] = manager.machine_checksum[
                    label_name
                ]
            if "machine_string" not in report:
                report["machine_string"] = manager.machine_checksum_string[
                    label_name
                ]

    def GetReport(self):
        """Dump the results of self.GetReportObject() to a string as JSON."""
        # This exists for consistency with the other GetReport methods.
        # Specifically, they all return strings, so it's a bit awkward if the JSON
        # results reporter returns an object.
        return json.dumps(self.GetReportObject(), **self.json_args)