#!/usr/bin/env vpython3
# Copyright 2014 the V8 project authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""
Performance runner for d8.

Call e.g. with tools/run-perf.py --arch ia32 some_suite.json

The suite json format is expected to be:
{
  "path": <relative path chunks to perf resources and main file>,
  "owners": [<list of email addresses of benchmark owners (required)>],
  "name": <optional suite name, file name is default>,
  "archs": [<architecture name for which this suite is run>, ...],
  "binary": <name of binary to run, default "d8">,
  "flags": [<flag to d8>, ...],
  "test_flags": [<flag to the test file>, ...],
  "run_count": <how often will this suite run (optional)>,
  "run_count_XXX": <how often will this suite run for arch XXX (optional)>,
  "timeout": <how long test is allowed to run>,
  "timeout_XXX": <how long test is allowed run run for arch XXX>,
  "retry_count": <how many times to retry failures (in addition to first try)",
  "retry_count_XXX": <how many times to retry failures for arch XXX>
  "resources": [<js file to be moved to android device or "*">, ...]
  "variants": [
    {
      "name": <name of the variant>,
      "flags": [<flag to the test file>, ...],
      <other suite properties>
    }, ...
  ]
  "main": <main js perf runner file>,
  "results_regexp": <optional regexp>,
  "results_default": <optional result default value>,
  "results_processor": <optional python results processor script>,
  "units": <the unit specification for the performance dashboard>,
  "process_size": <flag - collect maximum memory used by the process>,
  "tests": [
    {
      "name": <name of the trace>,
      "results_regexp": <optional more specific regexp>,
      "results_default": <optional result default value>,
      "results_processor": <optional python results processor script>,
      "units": <the unit specification for the performance dashboard>,
      "process_size": <flag - collect maximum memory used by the process>,
    }, ...
  ]
}

The tests field can also nest other suites in arbitrary depth. A suite
with a "main" file is a leaf suite that can contain one more level of
tests.

A suite's results_regexp is expected to have one string place holder
"%s" for the trace name. A trace's results_regexp overwrites suite
defaults.

A suite's results_processor may point to an optional python script. If
specified, it is called after running the tests (with a path relative to the
suite level's path). It is expected to read the measurement's output text
on stdin and print the processed output to stdout.

The results_regexp will be applied to the processed output. If a
results_default value is provided, it will be used in case the regexp doesn't
match. Otherwise, an error is added to the output.

A suite without "tests" is considered a performance test itself.

Variants can be used to run different configurations at the current level. This
essentially copies the sub suites at the current level and can be used to avoid
duplicating a lot of nested "tests" were for instance only the "flags" change.

Full example (suite with one runner):
{
  "path": ["."],
  "owners": ["username@chromium.org"],
  "flags": ["--expose-gc"],
  "test_flags": ["5"],
  "archs": ["ia32", "x64"],
  "run_count": 5,
  "run_count_ia32": 3,
  "main": "run.js",
  "results_regexp": "^%s: (.+)$",
  "units": "score",
  "tests": [
    {"name": "Richards"},
    {"name": "DeltaBlue"},
    {"name": "NavierStokes",
     "results_regexp": "^NavierStokes: (.+)$"}
  ]
}

Full example (suite with several runners):
{
  "path": ["."],
  "owners": ["username@chromium.org", "otherowner@google.com"],
  "archs": ["ia32", "x64"],
  "flags": ["--expose-gc"]},
  "run_count": 5,
  "units": "score",
  "variants:" [
    {"name": "default", "flags": []},
    {"name": "future",  "flags": ["--future"]},
    {"name": "noopt",   "flags": ["--noopt"]},
  ],
  "tests": [
    {"name": "Richards",
     "path": ["richards"],
     "main": "run.js",
     "run_count": 3,
     "results_regexp": "^Richards: (.+)$"},
    {"name": "NavierStokes",
     "path": ["navier_stokes"],
     "main": "run.js",
     "results_regexp": "^NavierStokes: (.+)$"}
  ]
}

Path pieces are concatenated. D8 is always run with the suite's path as cwd.

The test flags are passed to the js test file after '--'.
"""

from abc import ABC, abstractmethod
from math import sqrt
from pathlib import Path
from statistics import mean, stdev

import argparse
import copy
import hjson
import json
import logging
import math
import os
import psutil
import re
import subprocess
import sys
import time
import traceback

from testrunner.local import android
from testrunner.local import command
from testrunner.local import utils
from testrunner.objects.output import Output, NULL_OUTPUT


SUPPORTED_ARCHS = ['arm',
                   'ia32',
                   'x64',
                   'arm64',
                   'riscv64']

GENERIC_RESULTS_RE = re.compile(r'^RESULT ([^:]+): ([^=]+)= ([^ ]+) ([^ ]*)$')
RESULT_STDDEV_RE = re.compile(r'^\{([^\}]+)\}$')
RESULT_LIST_RE = re.compile(r'^\[([^\]]+)\]$')
TOOLS_BASE = os.path.abspath(os.path.dirname(__file__))
INFRA_FAILURE_RETCODE = 87
MIN_RUNS_FOR_CONFIDENCE = 10

WARMUP_CACHE_FILE = Path.cwd() / 'cache' / 'v8_perf' / 'warmup_cache.json'


def GeometricMean(values):
  """Returns the geometric mean of a list of values.

  The mean is calculated using log to avoid overflow.
  """
  values = list(map(float, values))
  return math.exp(sum(map(math.log, values)) / len(values))


class ResultTracker(object):
  """Class that tracks trace/runnable results and produces script output.

  The output is structured like this:
  {
    "traces": [
      {
        "graphs": ["path", "to", "trace", "config"],
        "units": <string describing units, e.g. "ms" or "KB">,
        "results": [<list of values measured over several runs>],
        "stddev": <stddev of the value if measure by script or ''>
      },
      ...
    ],
    "runnables": [
      {
        "graphs": ["path", "to", "runnable", "config"],
        "durations": [<list of durations of each runnable run in seconds>],
        "timeout": <timeout configured for runnable in seconds>,
      },
      ...
    ],
    "errors": [<list of strings describing errors>],
  }
  """
  def __init__(self):
    self.traces = {}
    self.errors = []
    self.runnables = {}

  def AddTraceResult(self, trace, result, stddev):
    if trace.name not in self.traces:
      self.traces[trace.name] = {
        'graphs': trace.graphs,
        'units': trace.units,
        'results': [result],
        'stddev': stddev or '',
      }
    else:
      existing_entry = self.traces[trace.name]
      assert trace.graphs == existing_entry['graphs']
      assert trace.units == existing_entry['units']
      if stddev:
        existing_entry['stddev'] = stddev
      existing_entry['results'].append(result)

  def TraceHasStdDev(self, trace):
    return trace.name in self.traces and self.traces[trace.name]['stddev'] != ''

  def AddError(self, error):
    self.errors.append(error)

  def AddRunnableDuration(self, runnable, duration):
    """Records a duration of a specific run of the runnable."""
    if runnable.name not in self.runnables:
      self.runnables[runnable.name] = {
        'graphs': runnable.graphs,
        'durations': [duration],
        'timeout': runnable.timeout,
      }
    else:
      existing_entry = self.runnables[runnable.name]
      assert runnable.timeout == existing_entry['timeout']
      assert runnable.graphs == existing_entry['graphs']
      existing_entry['durations'].append(duration)

  def ToDict(self):
    return {
        'traces': list(self.traces.values()),
        'errors': self.errors,
        'runnables': list(self.runnables.values()),
    }

  def WriteToFile(self, file_name):
    with open(file_name, 'w') as f:
      f.write(json.dumps(self.ToDict()))

  def HasEnoughRuns(self, graph_config, confidence_level):
    """Checks if the mean of the results for a given trace config is within
    0.1% of the true value with the specified confidence level.

    This assumes Gaussian distribution of the noise and based on
    https://en.wikipedia.org/wiki/68%E2%80%9395%E2%80%9399.7_rule.

    Args:
      graph_config: An instance of GraphConfig.
      confidence_level: Number of standard deviations from the mean that all
          values must lie within. Typical values are 1, 2 and 3 and correspond
          to 68%, 95% and 99.7% probability that the measured value is within
          0.1% of the true value.

    Returns:
      True if specified confidence level have been achieved.
    """
    if not isinstance(graph_config, LeafTraceConfig):
      return all(self.HasEnoughRuns(child, confidence_level)
                 for child in graph_config.children)

    trace = self.traces.get(graph_config.name, {})
    results = trace.get('results', [])
    logging.debug('HasEnoughRuns for %s', graph_config.name)

    if len(results) < MIN_RUNS_FOR_CONFIDENCE:
      logging.debug('  Ran %d times, need at least %d',
                    len(results), MIN_RUNS_FOR_CONFIDENCE)
      return False

    logging.debug('  Results: %d entries', len(results))
    avg = mean(results)
    avg_stderr = stdev(results) / sqrt(len(results))
    logging.debug('  Mean: %.2f, mean_stderr: %.2f', avg, avg_stderr)
    logging.info('>>> Confidence level is %.2f',
                 avg / max(1000.0 * avg_stderr, .1))
    return confidence_level * avg_stderr < avg / 1000.0

  def __str__(self):  # pragma: no cover
    return json.dumps(self.ToDict(), indent=2, separators=(',', ': '))


def RunResultsProcessor(results_processor, output, count):
  # Dummy pass through for null-runs.
  if output.stdout is None:
    return output

  # We assume the results processor is relative to the suite.
  assert os.path.exists(results_processor)
  p = subprocess.Popen(
      [sys.executable, results_processor],
      stdin=subprocess.PIPE,
      stdout=subprocess.PIPE,
      stderr=subprocess.PIPE,
  )
  new_output = copy.copy(output)
  new_output.stdout = p.communicate(
      input=output.stdout.encode('utf-8'))[0].decode('utf-8')
  logging.info('>>> Processed stdout (#%d):\n%s', count, output.stdout)
  return new_output


class Node(object):
  """Represents a node in the suite tree structure."""
  def __init__(self, *args):
    self._children = []

  def AppendChild(self, child):
    self._children.append(child)

  @property
  def children(self):
    return self._children

  def __iter__(self):
    yield self
    for child in self.children:
      yield from iter(child)


class DefaultSentinel(Node):
  """Fake parent node with all default values."""
  def __init__(self, binary = 'd8'):
    super(DefaultSentinel, self).__init__()
    self.binary = binary
    self.run_count = 10
    self.timeout = 60
    self.retry_count = 4
    self.path = []
    self.graphs = []
    self.flags = []
    self.test_flags = []
    self.process_size = False
    self.resources = []
    self.results_processor = None
    self.results_regexp = None
    self.results_default = None
    self.stddev_regexp = None
    self.units = 'score'
    self.total = False
    self.owners = []
    self.main = None

  def __str__(self):
    return type(self).__name__


class GraphConfig(Node):
  """Represents a suite definition.

  Can either be a leaf or an inner node that provides default values.
  """
  def __init__(self, suite, parent, arch):
    super(GraphConfig, self).__init__()
    self._suite = suite

    assert isinstance(suite.get('path', []), list)
    assert isinstance(suite.get('owners', []), list)
    assert isinstance(suite['name'], str)
    assert isinstance(suite.get('flags', []), list)
    assert isinstance(suite.get('test_flags', []), list)
    assert isinstance(suite.get('resources', []), list)

    # Only used by child classes
    self.main = suite.get('main', parent.main)
    # Keep parent for easier debugging
    self.parent = parent

    # Accumulated values.
    self.path = parent.path[:] + suite.get('path', [])
    self.graphs = parent.graphs[:] + [suite['name']]
    self.flags = parent.flags[:] + suite.get('flags', [])
    self.test_flags = parent.test_flags[:] + suite.get('test_flags', [])
    self.owners = parent.owners[:] + suite.get('owners', [])

    # Values independent of parent node.
    self.resources = suite.get('resources', [])

    # Descrete values (with parent defaults).
    self.binary = suite.get('binary', parent.binary)
    self.run_count = suite.get('run_count', parent.run_count)
    self.run_count = suite.get('run_count_%s' % arch, self.run_count)
    self.retry_count = suite.get('retry_count', parent.retry_count)
    self.retry_count = suite.get('retry_count_%s' % arch, self.retry_count)
    self.timeout = suite.get('timeout', parent.timeout)
    self.timeout = suite.get('timeout_%s' % arch, self.timeout)
    self.units = suite.get('units', parent.units)
    self.total = suite.get('total', parent.total)
    self.results_processor = suite.get(
        'results_processor', parent.results_processor)
    self.process_size = suite.get('process_size', parent.process_size)

    # A regular expression for results. If the parent graph provides a
    # regexp and the current suite has none, a string place holder for the
    # suite name is expected.
    # TODO(machenbach): Currently that makes only sense for the leaf level.
    # Multiple place holders for multiple levels are not supported.
    self.results_regexp = suite.get('results_regexp', None)
    if self.results_regexp is None and parent.results_regexp:
      try:
        self.results_regexp = parent.results_regexp % re.escape(suite['name'])
      except TypeError as e:
        raise TypeError(
            "Got error while preparing results_regexp: "
            "parent.results_regexp='%s' suite.name='%s' suite='%s', error: %s" %
            (parent.results_regexp, suite['name'], str(suite)[:100], e))

    self.results_default = suite.get('results_default', None)

    # A similar regular expression for the standard deviation (optional).
    if parent.stddev_regexp:
      stddev_default = parent.stddev_regexp % re.escape(suite['name'])
    else:
      stddev_default = None
    self.stddev_regexp = suite.get('stddev_regexp', stddev_default)

  @property
  def name(self):
    return '/'.join(self.graphs)

  def __str__(self):
    return "%s(%s)" % (type(self).__name__, self.name)


class VariantConfig(GraphConfig):
  """Represents an intermediate node that has children that are all
  variants of each other"""

  def __init__(self, suite, parent, arch):
    super(VariantConfig, self).__init__(suite, parent, arch)
    assert "variants" in suite
    for variant in suite.get('variants'):
      assert "variants" not in variant, \
        "Cannot directly nest variants:" + str(variant)[:100]
      assert "name" in variant, \
          "Variant must have 'name' property: " + str(variant)[:100]
      assert len(variant) >= 2, \
          "Variant must define other properties than 'name': " + str(variant)


class LeafTraceConfig(GraphConfig):
  """Represents a leaf in the suite tree structure."""
  def __init__(self, suite, parent, arch):
    super(LeafTraceConfig, self).__init__(suite, parent, arch)
    assert self.results_regexp
    if '%s' in self.results_regexp:
      raise Exception(
          "results_regexp at the wrong level. "
          "Regexp should not contain '%%s': results_regexp='%s' name=%s" %
          (self.results_regexp, self.name))

  def AppendChild(self, node):
    raise Exception("%s cannot have child configs." % type(self).__name__)

  def ConsumeOutput(self, output, result_tracker):
    """Extracts trace results from the output.

    Args:
      output: Output object from the test run.
      result_tracker: Result tracker to be updated.

    Returns:
      The raw extracted result value or None if an error occurred.
    """

    if len(self.children) > 0:
      results_for_total = []
      for trace in self.children:
        result = trace.ConsumeOutput(output, result_tracker)
        if result is not None:
          results_for_total.append(result)

    result = None
    stddev = None

    try:
      result = float(
        re.search(self.results_regexp, output.stdout, re.M).group(1))
    except ValueError:
      result_tracker.AddError(
          'Regexp "%s" returned a non-numeric for test %s.' %
          (self.results_regexp, self.name))
    except:
      if self.results_default is not None:
        result = float(self.results_default)
      else:
        result_tracker.AddError(
            'Regexp "%s" did not match for test %s.' %
            (self.results_regexp, self.name))

    try:
      if self.stddev_regexp:
        if result_tracker.TraceHasStdDev(self):
          result_tracker.AddError(
              'Test %s should only run once since a stddev is provided by the '
              'test.' % self.name)
        stddev = re.search(self.stddev_regexp, output.stdout, re.M).group(1)
    except:
      result_tracker.AddError(
          'Regexp "%s" did not match for test %s.' %
          (self.stddev_regexp, self.name))

    if result is not None:
      result_tracker.AddTraceResult(self, result, stddev)
    return result


class TraceConfig(GraphConfig):
  """
  A TraceConfig contains either TraceConfigs or LeafTraceConfigs
  """

  def ConsumeOutput(self, output, result_tracker):
    """Processes test run output and updates result tracker.

    Args:
      output: Output object from the test run.
      result_tracker: ResultTracker object to be updated.
      count: Index of the test run (used for better logging).
    """
    results_for_total = []
    for trace in self.children:
      result = trace.ConsumeOutput(output, result_tracker)
      if result is not None:
        results_for_total.append(result)

    if self.total:
      # Produce total metric only when all traces have produced results.
      if len(self.children) != len(results_for_total):
        result_tracker.AddError(
            'Not all traces have produced results. Can not compute total for '
            '%s.' % self.name)
        return

      # Calculate total as a the geometric mean for results from all traces.
      total_trace = LeafTraceConfig(
          {
              'name': 'Total',
              'units': self.children[0].units
          }, self, self.arch)
      result_tracker.AddTraceResult(total_trace,
                                    GeometricMean(results_for_total), '')

  def AppendChild(self, node):
    if node.__class__ not in (TraceConfig, LeafTraceConfig):
      raise Exception(
          "%s only allows TraceConfig and LeafTraceConfig as child configs." %
          type(self).__name__)
    super(TraceConfig, self).AppendChild(node)


class RunnableConfig(TraceConfig):
  """Represents a runnable suite definition (i.e. has a main file).
  """
  def __init__(self, suite, parent, arch):
    super(RunnableConfig, self).__init__(suite, parent, arch)
    self.arch = arch
    assert self.main, "No main js file provided"
    if not self.owners:
      logging.error("No owners provided for %s" % self.name)

  def ChangeCWD(self, suite_path):
    """Changes the cwd to to path defined in the current graph.

    The tests are supposed to be relative to the suite configuration.
    """
    suite_dir = os.path.abspath(os.path.dirname(suite_path))
    bench_dir = os.path.normpath(os.path.join(*self.path))
    cwd = os.path.join(suite_dir, bench_dir)
    logging.debug('Changing CWD to: %s' % cwd)
    os.chdir(cwd)

  def GetCommandFlags(self, extra_flags=None):
    suffix = ['--'] + self.test_flags if self.test_flags else []
    return self.flags + (extra_flags or []) + [self.main] + suffix

  def GetCommand(self, cmd_prefix, shell_dir, extra_flags=None):
    # TODO(machenbach): This requires +.exe if run on windows.
    extra_flags = extra_flags or []
    if self.binary != 'd8' and '--prof' in extra_flags:
      logging.info('Profiler supported only on a benchmark run with d8')

    if self.process_size:
      cmd_prefix = ['/usr/bin/time', '--format=MaxMemory: %MKB'] + cmd_prefix
    if self.binary.endswith('.py'):
      # Copy cmd_prefix instead of update (+=).
      cmd_prefix = cmd_prefix + [sys.executable]

    return command.Command(
        cmd_prefix=cmd_prefix,
        shell=os.path.join(shell_dir, self.binary),
        args=self.GetCommandFlags(extra_flags=extra_flags),
        timeout=self.timeout or 60,
        handle_sigterm=True)

  def ProcessOutput(self, output, result_tracker, count):
    """Processes test run output and updates result tracker.

    Args:
      output: Output object from the test run.
      result_tracker: ResultTracker object to be updated.
      count: Index of the test run (used for better logging).
    """
    if self.results_processor:
      output = RunResultsProcessor(self.results_processor, output, count)

    self.ConsumeOutput(output, result_tracker)


class RunnableLeafTraceConfig(LeafTraceConfig, RunnableConfig):
  """Represents a runnable suite definition that is a leaf."""
  def __init__(self, suite, parent, arch):
    super(RunnableLeafTraceConfig, self).__init__(suite, parent, arch)
    if not self.owners:
      logging.error("No owners provided for %s" % self.name)

  def ProcessOutput(self, output, result_tracker, count):
    self.ConsumeOutput(output, result_tracker)


def MakeGraphConfig(suite, parent, arch):
  cls = GetGraphConfigClass(suite, parent)
  return cls(suite, parent, arch)


def GetGraphConfigClass(suite, parent):
  """Factory method for making graph configuration objects."""
  if isinstance(parent, TraceConfig):
    if suite.get("tests"):
      return TraceConfig
    return LeafTraceConfig
  elif suite.get('main') is not None:
    # A main file makes this graph runnable. Empty strings are accepted.
    if suite.get('tests'):
      # This graph has subgraphs (traces).
      return RunnableConfig
    else:
      # This graph has no subgraphs, it's a leaf.
      return RunnableLeafTraceConfig
  elif suite.get('tests'):
    # This is neither a leaf nor a runnable.
    return GraphConfig
  else:  # pragma: no cover
    raise Exception('Invalid suite configuration.' + str(suite)[:200])


def BuildGraphConfigs(suite, parent, arch):
  """Builds a tree structure of graph objects that corresponds to the suite
  configuration.

  - GraphConfig:
    - Can have arbitrary children
    - can be used to store properties used by its children

  - VariantConfig
    - Has variants of the same (any) type as children

  For all other configs see the override AppendChild methods.

  Example 1:
  - GraphConfig
    - RunnableLeafTraceConfig (no children)
    -  ...

  Example 2:
  - RunnableConfig
    - LeafTraceConfig (no children)
    - ...

  Example 3:
  - RunnableConfig
    - LeafTraceConfig (optional)
    - TraceConfig
      - LeafTraceConfig (no children)
      - ...
      - TraceConfig (optional)
        - ...
      - ...

  Example 4:
  - VariantConfig
    - RunnableConfig
      - ...
    - RunnableConfig
      - ...
  """
  # TODO(machenbach): Implement notion of cpu type?
  if arch not in suite.get('archs', SUPPORTED_ARCHS):
    return None

  variants = suite.get('variants', [])
  if len(variants) == 0:
    graph = MakeGraphConfig(suite, parent, arch)
    for subsuite in suite.get('tests', []):
      BuildGraphConfigs(subsuite, graph, arch)
  else:
    graph = VariantConfig(suite, parent, arch)
    variant_class = GetGraphConfigClass(suite, parent)
    for variant_suite in variants:
      # Propagate down the results_regexp and default if they are not
      # overridden in the variant.
      variant_suite.setdefault('results_regexp',
                               suite.get('results_regexp', None))
      variant_suite.setdefault('results_default',
                               suite.get('results_default', None))
      variant_graph = variant_class(variant_suite, graph, arch)
      graph.AppendChild(variant_graph)
      for subsuite in suite.get('tests', []):
        BuildGraphConfigs(subsuite, variant_graph, arch)
      # Add variant specific tests.
      for subsuite in variant_suite.get('tests', []):
        BuildGraphConfigs(subsuite, variant_graph, arch)
  parent.AppendChild(graph)
  return graph


def FlattenRunnables(node, node_cb):
  """Generator that traverses the tree structure and iterates over all
  runnables.
  """
  node_cb(node)
  if isinstance(node, RunnableConfig):
    yield node
  elif isinstance(node, Node):
    for child in node._children:
      for result in FlattenRunnables(child, node_cb):
        yield result
  else:  # pragma: no cover
    raise Exception('Invalid suite configuration.')


def find_build_directory(base_path, arch):
  """Returns the location of d8 or node in the build output directory.

  This supports a seamless transition between legacy build location
  (out/Release) and new build location (out/build).
  """
  def is_build(path):
    # We support d8 or node as executables. We don't support testing on
    # Windows.
    return (os.path.isfile(os.path.join(path, 'd8')) or
            os.path.isfile(os.path.join(path, 'node')))
  possible_paths = [
    # Location developer wrapper scripts is using.
    '%s.release' % arch,
    # Current build location on bots.
    'build',
    # Legacy build location on bots.
    'Release',
  ]
  possible_paths = [os.path.join(base_path, p) for p in possible_paths]
  actual_paths = list(filter(is_build, possible_paths))
  assert actual_paths, 'No build directory found.'
  assert len(
      actual_paths
  ) == 1, 'Found ambiguous build directories use --binary-override-path.'
  return actual_paths[0]


class CacheHandler:
  def __init__(self, cache_file):
    self.cache_file = cache_file

  def read_cache(self):
    try:
      with open(self.cache_file) as f:
        return hjson.load(f)
    except FileNotFoundError:
      logging.info(f"{self.cache_file} doesn't exist yet. Creating new.")
    return {}

  def write_cache(self, cache):
    with open(self.cache_file, 'w') as f:
      return json.dump(cache, f)


class WarmupManager(ABC):
  @abstractmethod
  def maybe_warm_up(self, name, warmup_fun):
    """Run the warmup_fun if needed, e.g. after a system reboot."""


class NullWarmupManager(WarmupManager):
  """Null-object place-holder used when warm-up isn't activated or for
  platforms where it isn't implemented.
  """
  def maybe_warm_up(self, name, warmup_fun):
    pass


class CachedWarmupManager(WarmupManager):
  """On-demand warm-up based on system reboot.

  The warm-up function is run once after reboot for every benchmark key.
  The keys are cached in a file in cache/v8_perf. This relies on the caller
  creating this directory.
  """
  def __init__(self):
    self.cache_handler = CacheHandler(WARMUP_CACHE_FILE)
    self.cache = self.cache_handler.read_cache()
    self.last_reboot = psutil.boot_time()
    self.trim_cache()
    # Ensure the trimmed version is on disk.
    self.cache_handler.write_cache(self.cache)

  def is_warmed_up(self, timestamp):
    return timestamp > self.last_reboot

  def trim_cache(self):
    """Prevent obsolete entries occupying the cache file."""
    self.cache = dict(
        (k, v) for k, v in self.cache.items() if self.is_warmed_up(v))

  def maybe_warm_up(self, name, warmup_fun):
    if self.is_warmed_up(self.cache.get(name, 0)):
      return

    logging.info(f'Warm-up run of {name} - disregarding output.')
    try:
      warmup_fun()
    finally:
      self.cache[name] = time.time()
      self.cache_handler.write_cache(self.cache)
      logging.info(f'Warm-up done.')


class Platform(object):
  def __init__(self, args):
    self.shell_dir = args.shell_dir
    self.shell_dir_secondary = args.shell_dir_secondary
    self.is_dry_run = args.dry_run
    self.extra_flags = args.extra_flags.split()
    self.args = args
    self.warmup_manager = NullWarmupManager()

  @staticmethod
  def ReadBuildConfig(args):
    config_path = os.path.join(args.shell_dir, 'v8_build_config.json')
    if not os.path.isfile(config_path):
      return {}
    with open(config_path) as f:
      return hjson.load(f)

  @staticmethod
  def GetPlatform(args):
    if Platform.ReadBuildConfig(args).get('is_android', False):
      return AndroidPlatform(args)
    else:
      return DesktopPlatform(args)

  def _Run(self, runnable, count, secondary=False, post_process=True):
    raise NotImplementedError()  # pragma: no cover

  def _LoggedRun(self, runnable, count, secondary=False, post_process=True):
    suffix = ' - secondary' if secondary else ''
    title = '>>> %%s (#%d)%s:' % ((count + 1), suffix)
    try:
      output = self._Run(runnable, count, secondary, post_process)
    except OSError:
      logging.exception(title % 'OSError')
      raise
    if output.stdout:
      logging.info(title % 'Stdout' + '\n%s', output.stdout)
    if output.stderr:  # pragma: no cover
      # Print stderr for debugging.
      logging.info(title % 'Stderr' + '\n%s', output.stderr)
    if output.HasTimedOut():
      logging.warning('>>> Test timed out after %ss.', runnable.timeout)
    if output.exit_code != 0:
      logging.warning('>>> Test crashed with exit code %d.', output.exit_code)
    return output

  def Run(self, runnable, count, secondary):
    """Execute the benchmark's main file.

    Args:
      runnable: A Runnable benchmark instance.
      count: The number of this (repeated) run.
      secondary: True if secondary run should be executed.

    Returns:
      A tuple with the two benchmark outputs. The latter will be NULL_OUTPUT if
      secondary is False.
    """
    self.warmup_manager.maybe_warm_up(
        runnable.name,
        lambda: self._LoggedRun(
            runnable, 0, secondary=False, post_process=False))
    output = self._LoggedRun(runnable, count, secondary=False)
    if secondary:
      return output, self._LoggedRun(runnable, count, secondary=True)
    else:
      return output, NULL_OUTPUT


class DesktopPlatform(Platform):
  def __init__(self, args):
    super(DesktopPlatform, self).__init__(args)
    self.command_prefix = []

    # Setup command class to OS specific version.
    command.setup(utils.GuessOS(), args.device)

    if args.prioritize or args.affinitize is not None:
      self.command_prefix = ['schedtool']
      if args.prioritize:
        self.command_prefix += ['-n', '-20']
      if args.affinitize is not None:
        # schedtool expects a bit pattern when setting affinity, where each
        # bit set to '1' corresponds to a core where the process may run on.
        # First bit corresponds to CPU 0. Since the 'affinitize' parameter is
        # a core number, we need to map to said bit pattern.
        cpu = int(args.affinitize)
        core = 1 << cpu
        self.command_prefix += ['-a', ('0x%x' % core)]
      self.command_prefix += ['-e']

    if args.checked_warmup:
      self.warmup_manager = CachedWarmupManager()

  def PreExecution(self):
    pass

  def PostExecution(self):
    pass

  def PreTests(self, node, path):
    if isinstance(node, RunnableConfig):
      node.ChangeCWD(path)

  def _Run(self, runnable, count, secondary=False, post_process=True):
    shell_dir = self.shell_dir_secondary if secondary else self.shell_dir
    cmd = runnable.GetCommand(self.command_prefix, shell_dir, self.extra_flags)
    logging.debug('Running command: %s' % cmd)
    output = Output() if self.is_dry_run else cmd.execute()

    if (not self.is_dry_run and
        post_process and
        output.IsSuccess() and
        '--prof' in self.extra_flags):
      os_prefix = {'linux': 'linux', 'macos': 'mac'}.get(utils.GuessOS())
      if os_prefix:
        tick_tools = os.path.join(TOOLS_BASE, '%s-tick-processor' % os_prefix)
        subprocess.check_call(tick_tools + ' --only-summary', shell=True)
      else:  # pragma: no cover
        logging.warning(
            'Profiler option currently supported on Linux and Mac OS.')

    # /usr/bin/time outputs to stderr
    if runnable.process_size:
      output.stdout += output.stderr
    return output


class AndroidPlatform(Platform):  # pragma: no cover

  def __init__(self, args):
    super(AndroidPlatform, self).__init__(args)
    self.driver = android.Driver.instance(args.device)

  def PreExecution(self):
    self.driver.set_high_perf_mode()

  def PostExecution(self):
    self.driver.set_default_perf_mode()
    self.driver.tear_down()

  def PreTests(self, node, path):
    if isinstance(node, RunnableConfig):
      node.ChangeCWD(path)
    suite_dir = os.path.abspath(os.path.dirname(path))
    if node.path:
      bench_rel = os.path.normpath(os.path.join(*node.path))
      bench_abs = os.path.join(suite_dir, bench_rel)
    else:
      bench_rel = '.'
      bench_abs = suite_dir

    self.driver.push_executable(self.shell_dir, 'bin', node.binary)
    if self.shell_dir_secondary:
      self.driver.push_executable(
          self.shell_dir_secondary, 'bin_secondary', node.binary)

    if isinstance(node, RunnableConfig):
      self.driver.push_file(bench_abs, node.main, bench_rel)
    for resource in node.resources:
      if resource == '*':
        self.driver.push_files_rec(bench_abs, bench_rel)
      else:
        self.driver.push_file(bench_abs, resource, bench_rel)

  def _Run(self, runnable, count, secondary=False, post_process=True):
    target_dir = 'bin_secondary' if secondary else 'bin'
    self.driver.drop_ram_caches()

    # Relative path to benchmark directory.
    if runnable.path:
      bench_rel = os.path.normpath(os.path.join(*runnable.path))
    else:
      bench_rel = '.'

    logcat_file = None
    if self.args.dump_logcats_to:
      runnable_name = '-'.join(runnable.graphs)
      logcat_file = os.path.join(
          self.args.dump_logcats_to, 'logcat-%s-#%d%s.log' % (
            runnable_name, count + 1, '-secondary' if secondary else ''))
      logging.debug('Dumping logcat into %s', logcat_file)

    output = Output()
    output.start_time = time.time()
    try:
      if not self.is_dry_run:
        output.stdout = self.driver.run(
            target_dir=target_dir,
            binary=runnable.binary,
            args=runnable.GetCommandFlags(self.extra_flags),
            rel_path=bench_rel,
            timeout=runnable.timeout,
            logcat_file=logcat_file,
        )
    except android.CommandFailedException as e:
      output.stdout = e.output
      output.exit_code = e.status
    except android.TimeoutException as e:
      output.stdout = e.output
      output.timed_out = True
    if runnable.process_size:
      output.stdout += 'MaxMemory: Unsupported'
    output.end_time = time.time()
    return output


class CustomMachineConfiguration:
  def __init__(self, disable_aslr = False, governor = None):
    self.aslr_backup = None
    self.governor_backup = None
    self.disable_aslr = disable_aslr
    self.governor = governor

  def __enter__(self):
    if self.disable_aslr:
      self.aslr_backup = CustomMachineConfiguration.GetASLR()
      CustomMachineConfiguration.SetASLR(0)
    if self.governor is not None:
      self.governor_backup = CustomMachineConfiguration.GetCPUGovernor()
      CustomMachineConfiguration.SetCPUGovernor(self.governor)
    return self

  def __exit__(self, type, value, traceback):
    if self.aslr_backup is not None:
      CustomMachineConfiguration.SetASLR(self.aslr_backup)
    if self.governor_backup is not None:
      CustomMachineConfiguration.SetCPUGovernor(self.governor_backup)

  @staticmethod
  def GetASLR():
    try:
      with open('/proc/sys/kernel/randomize_va_space', 'r') as f:
        return int(f.readline().strip())
    except Exception:
      logging.exception('Failed to get current ASLR settings.')
      raise

  @staticmethod
  def SetASLR(value):
    try:
      with open('/proc/sys/kernel/randomize_va_space', 'w') as f:
        f.write(str(value))
    except Exception:
      logging.exception(
          'Failed to update ASLR to %s. Are we running under sudo?', value)
      raise

    new_value = CustomMachineConfiguration.GetASLR()
    if value != new_value:
      raise Exception('Present value is %s' % new_value)

  @staticmethod
  def GetCPUCoresRange():
    try:
      with open('/sys/devices/system/cpu/present', 'r') as f:
        indexes = f.readline()
        r = list(map(int, indexes.split('-')))
        if len(r) == 1:
          return list(range(r[0], r[0] + 1))
        return list(range(r[0], r[1] + 1))
    except Exception:
      logging.exception('Failed to retrieve number of CPUs.')
      raise

  @staticmethod
  def GetCPUPathForId(cpu_index):
    ret = '/sys/devices/system/cpu/cpu'
    ret += str(cpu_index)
    ret += '/cpufreq/scaling_governor'
    return ret

  @staticmethod
  def GetCPUGovernor():
    try:
      cpu_indices = CustomMachineConfiguration.GetCPUCoresRange()
      ret = None
      for cpu_index in cpu_indices:
        cpu_device = CustomMachineConfiguration.GetCPUPathForId(cpu_index)
        with open(cpu_device, 'r') as f:
          # We assume the governors of all CPUs are set to the same value
          val = f.readline().strip()
          if ret is None:
            ret = val
          elif ret != val:
            raise Exception('CPU cores have differing governor settings')
      return ret
    except Exception:
      logging.exception('Failed to get the current CPU governor. Is the CPU '
                        'governor disabled? Check BIOS.')
      raise

  @staticmethod
  def SetCPUGovernor(value):
    try:
      cpu_indices = CustomMachineConfiguration.GetCPUCoresRange()
      for cpu_index in cpu_indices:
        cpu_device = CustomMachineConfiguration.GetCPUPathForId(cpu_index)
        with open(cpu_device, 'w') as f:
          f.write(value)

    except Exception:
      logging.exception('Failed to change CPU governor to %s. Are we '
                        'running under sudo?', value)
      raise

    cur_value = CustomMachineConfiguration.GetCPUGovernor()
    if cur_value != value:
      raise Exception('Could not set CPU governor. Present value is %s'
                      % cur_value )


class MaxTotalDurationReachedError(Exception):
  """Exception used to stop running tests when max total duration is reached."""
  pass


def Main(argv):
  parser = argparse.ArgumentParser(epilog="""example:
      ./run_perf.py --d8-path=out/Release/d8 $V8_PERF/benchmarks/JetStream2/JetStream2.json
    """)
  parser.add_argument('--arch',
                      help='The architecture to run tests for. Pass "auto" '
                      'to auto-detect.', default='x64',
                      choices=SUPPORTED_ARCHS + ['auto'])
  parser.add_argument('--buildbot',
                      help='Deprecated',
                      default=False, action='store_true')
  parser.add_argument('-d', '--device',
                      help='The device ID to run Android tests on. If not '
                      'given it will be autodetected.')
  parser.add_argument('--extra-flags',
                      help='Additional flags to pass to the test executable',
                      default='')
  parser.add_argument('--json-test-results',
                      help='Path to a file for storing json results.')
  parser.add_argument('--json-test-results-secondary',
                      help='Path to a file for storing json results from run '
                      'without patch or for reference build run.')
  parser.add_argument('--outdir', help='Base directory with compile output',
                      default='out')
  parser.add_argument('--outdir-secondary',
                      help='Base directory with compile output without patch '
                      'or for reference build')
  parser.add_argument(
      '--binary-override-path',
      '--d8-path',
      '--d8',
      metavar="D8_BINARY_PATH",
      help='JavaScript engine binary. By default, d8 under '
      'architecture-specific build dir. '
      'Not supported in conjunction with outdir-secondary.')
  parser.add_argument('--prioritize',
                      help='Raise the priority to nice -20 for the '
                      'benchmarking process.Requires Linux, schedtool, and '
                      'sudo privileges.', default=False, action='store_true')
  parser.add_argument('--affinitize',
                      help='Run benchmarking process on the specified core. '
                      'For example: --affinitize=0 will run the benchmark '
                      'process on core 0. --affinitize=3 will run the '
                      'benchmark process on core 3. Requires Linux, schedtool, '
                      'and sudo privileges.', default=None)
  parser.add_argument('--noaslr',
                      help='Disable ASLR for the duration of the benchmarked '
                      'process. Requires Linux and sudo privileges.',
                      default=False, action='store_true')
  parser.add_argument('--cpu-governor',
                      help='Set cpu governor to specified policy for the '
                      'duration of the benchmarked process. Typical options: '
                      '"powersave" for more stable results, or "performance" '
                      'for shorter completion time of suite, with potentially '
                      'more noise in results.')
  parser.add_argument(
      '--filter',
      help='Only run the benchmarks matching with this '
      'regex. For example: '
      '--filter=JSTests/TypedArrays/ will run only TypedArray '
      'benchmarks from the JSTests suite.')
  parser.add_argument('--confidence-level', type=float,
                      help='Repeatedly runs each benchmark until specified '
                      'confidence level is reached. The value is interpreted '
                      'as the number of standard deviations from the mean that '
                      'all values must lie within. Typical values are 1, 2 and '
                      '3 and correspond to 68%%, 95%% and 99.7%% probability '
                      'that the measured value is within 0.1%% of the true '
                      'value. Larger values result in more retries and thus '
                      'longer runtime, but also provide more reliable results. '
                      'Also see --max-total-duration flag.')
  parser.add_argument('--max-total-duration', type=int, default=7140,  # 1h 59m
                      help='Max total duration in seconds allowed for retries '
                      'across all tests. This is especially useful in '
                      'combination with the --confidence-level flag.')
  parser.add_argument('--dump-logcats-to',
                      help='Writes logcat output from each test into specified '
                      'directory. Only supported for android targets.')
  parser.add_argument(
      '--run-count',
      "--repeat",
      type=int,
      default=0,
      help='Override the run count specified by the test '
      'suite. The default 0 uses the suite\'s config.')
  parser.add_argument(
      '--dry-run',
      default=False,
      action='store_true',
      help='Do not run any actual tests.')
  parser.add_argument('-v', '--verbose', default=False, action='store_true',
                      help='Be verbose and print debug output.')
  parser.add_argument('--checked-warmup', default=False, action='store_true',
                      help='Warm up benchmarks not run since last reboot.')
  parser.add_argument('suite', nargs='+', help='Path to the suite config file.')

  try:
    args = parser.parse_args(argv)
  except SystemExit:
    return INFRA_FAILURE_RETCODE

  logging.basicConfig(
      level=logging.DEBUG if args.verbose else logging.INFO,
      format='%(asctime)s %(levelname)-8s  %(message)s')

  if args.arch == 'auto':  # pragma: no cover
    args.arch = utils.DefaultArch()
    if args.arch not in SUPPORTED_ARCHS:
      logging.error(
          'Auto-detected architecture "%s" is not supported.', args.arch)
      return INFRA_FAILURE_RETCODE

  if (args.json_test_results_secondary and
      not args.outdir_secondary):  # pragma: no cover
    logging.error('For writing secondary json test results, a secondary outdir '
                  'patch must be specified.')
    return INFRA_FAILURE_RETCODE

  workspace = os.path.abspath(os.path.join(os.path.dirname(__file__), '..'))

  if args.binary_override_path is None:
    args.shell_dir = find_build_directory(
        os.path.join(workspace, args.outdir), args.arch)
    default_binary_name = 'd8'
  else:
    path = Path(args.binary_override_path).expanduser().resolve()
    if not path.is_file():
      logging.error(f'binary-override-path "{path}" must be a file name')
      return INFRA_FAILURE_RETCODE
    if args.outdir_secondary:
      logging.error('specify either binary-override-path or outdir-secondary')
      return INFRA_FAILURE_RETCODE
    args.shell_dir = str(path.parent)
    default_binary_name = path.name

  if args.outdir_secondary:
    args.shell_dir_secondary = find_build_directory(
        os.path.join(workspace, args.outdir_secondary), args.arch)
  else:
    args.shell_dir_secondary = None

  if args.json_test_results:
    args.json_test_results = os.path.abspath(args.json_test_results)

  if args.json_test_results_secondary:
    args.json_test_results_secondary = os.path.abspath(
        args.json_test_results_secondary)

  try:
    if args.filter:
      args.filter = re.compile(args.filter)
  except re.error:
    logging.error("Invalid regular expression for --filter=%s" % args.filter)
    return INFRA_FAILURE_RETCODE

  # Ensure all arguments have absolute path before we start changing current
  # directory.
  args.suite = list(map(os.path.abspath, args.suite))

  platform = Platform.GetPlatform(args)

  result_tracker = ResultTracker()
  result_tracker_secondary = ResultTracker()
  have_failed_tests = False
  with CustomMachineConfiguration(governor = args.cpu_governor,
                                  disable_aslr = args.noaslr) as conf:
    for path in args.suite:
      if not os.path.exists(path):  # pragma: no cover
        result_tracker.AddError('Configuration file %s does not exist.' % path)
        continue

      with open(path) as f:
        suite = hjson.loads(f.read())

      # If no name is given, default to the file name without .json.
      suite.setdefault('name', os.path.splitext(os.path.basename(path))[0])

      # Setup things common to one test suite.
      platform.PreExecution()

      # Build the graph/trace tree structure.
      default_parent = DefaultSentinel(default_binary_name)
      root = BuildGraphConfigs(suite, default_parent, args.arch)

      if logging.DEBUG >= logging.root.level:
        logging.debug("Config tree:")
        for node in iter(root):
          logging.debug("  %s", node)

      # Callback to be called on each node on traversal.
      def NodeCB(node):
        platform.PreTests(node, path)

      # Traverse graph/trace tree and iterate over all runnables.
      start = time.time()
      try:
        for runnable in FlattenRunnables(root, NodeCB):
          runnable_name = '/'.join(runnable.graphs)
          if args.filter and not args.filter.match(runnable_name):
            logging.info('Skipping suite "%s" due to filter', runnable_name)
            continue
          logging.info('>>> Running suite: %s', runnable_name)

          def RunGenerator(runnable):
            if args.confidence_level:
              counter = 0
              while not result_tracker.HasEnoughRuns(
                  runnable, args.confidence_level):
                yield counter
                counter += 1
            else:
              for i in range(0, max(1, args.run_count or runnable.run_count)):
                yield i

          for i in RunGenerator(runnable):
            attempts_left = runnable.retry_count + 1
            while attempts_left:
              total_duration = time.time() - start
              if total_duration > args.max_total_duration:
                logging.info(
                    '>>> Stopping now since running for too long (%ds > %ds)',
                    total_duration, args.max_total_duration)
                raise MaxTotalDurationReachedError()

              output, output_secondary = platform.Run(
                  runnable, i, secondary=args.shell_dir_secondary)
              result_tracker.AddRunnableDuration(runnable, output.duration)
              result_tracker_secondary.AddRunnableDuration(
                  runnable, output_secondary.duration)

              if output.IsSuccess() and output_secondary.IsSuccess():
                runnable.ProcessOutput(output, result_tracker, i)
                if output_secondary is not NULL_OUTPUT:
                  runnable.ProcessOutput(
                      output_secondary, result_tracker_secondary, i)
                break

              attempts_left -= 1
              if not attempts_left:
                logging.info('>>> Suite %s failed after %d retries',
                             runnable_name, runnable.retry_count + 1)
                have_failed_tests = True
              else:
                logging.info('>>> Retrying suite: %s', runnable_name)
      except MaxTotalDurationReachedError:
        have_failed_tests = True

      platform.PostExecution()

    if args.json_test_results:
      result_tracker.WriteToFile(args.json_test_results)
    else:  # pragma: no cover
      print('Primary results:', result_tracker)

  if args.shell_dir_secondary:
    if args.json_test_results_secondary:
      result_tracker_secondary.WriteToFile(args.json_test_results_secondary)
    else:  # pragma: no cover
      print('Secondary results:', result_tracker_secondary)

  if (result_tracker.errors or result_tracker_secondary.errors or
      have_failed_tests):
    return 1

  return 0


def MainWrapper():
  try:
    return Main(sys.argv[1:])
  except:
    # Log uncaptured exceptions and report infra failure to the caller.
    traceback.print_exc()
    return INFRA_FAILURE_RETCODE


if __name__ == '__main__':  # pragma: no cover
  sys.exit(MainWrapper())