runner.py

#!/usr/bin/env python2
# Copyright 2017 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.
"""Helper script to report exit code according to execution result."""

from __future__ import print_function
import argparse
import collections
import logging
import re
import subprocess
import sys
import textwrap
import time

from bisect_kit import cli
from bisect_kit import util
from bisect_kit import common

logger = logging.getLogger(__name__)

OLD = 'old'
NEW = 'new'
SKIP = 'skip'
FATAL = 'fatal'

EXIT_CODE_MAP = {
    OLD: 0,
    NEW: 1,
    SKIP: 125,
    FATAL: 126,
}


def argtype_ratio(s):
  """Checks ratio syntax for argument parsing.

  Args:
    s: argument string.

  Returns:
    (op, value):
      op: Operator, should be one of <, <=, =, ==, >, >=.
      value: Should be between 0 and 1.
  """
  m = re.match(r'^([<>=]=?)\s*(\d+(?:\.\d+)?)$', s)
  if not m:
    raise argparse.ArgumentTypeError('invalid ratio condition')
  op, value = m.group(1), float(m.group(2))
  if not 0 <= value <= 1:
    raise argparse.ArgumentTypeError('value should be between 0 and 1')
  return op, value


def create_argument_parser():
  """Creates command line argument parser.

  Returns:
    An argparse.ArgumentParser instance.
  """
  parser = argparse.ArgumentParser(
      description=textwrap.dedent("""
          Helper script to report exit code according to execution result.

          If precondition specified but not meet, returns SKIP. Returns WANT
          only if any conditions meet.
      """),
      formatter_class=argparse.RawDescriptionHelpFormatter)
  common.add_common_arguments(parser)
  group = parser.add_mutually_exclusive_group(required=True)
  group.add_argument(
      '--new',
      dest='want',
      action='store_const',
      const='new',
      help='Let WANT=NEW')
  group.add_argument(
      '--old',
      dest='want',
      action='store_const',
      const='old',
      help='Let WANT=OLD')
  parser.add_argument('exec_cmd')
  parser.add_argument('exec_args', nargs=argparse.REMAINDER)

  group = parser.add_argument_group(
      title='Preconditions to match (optional)',
      description='All specified preconditions must match, '
      'otherwise return SKIP.')
  group.add_argument(
      '--precondition_output',
      metavar='REGEX',
      type=re.compile,
      help='Precondition to match %(metavar)s')

  group = parser.add_argument_group(
      title='Conditions to match (mutual exclusive, required)',
      description='If the specified condition matches, return WANT.')
  group = group.add_mutually_exclusive_group(required=True)
  group.add_argument(
      '--output',
      metavar='REGEX',
      type=re.compile,
      help='Regex to match stdout|stderr')
  group.add_argument('--returncode', type=int, help='Value of exit code')
  group.add_argument(
      '--timeout',
      type=float,
      metavar='SECONDS',
      help='If command executes longer than SECONDS secs')

  group = parser.add_argument_group(
      title='Execution options',
      description='Controls how to execute, terminate, and how many times')
  group.add_argument(
      '--cwd', type=cli.argtype_dir_path, help='Working directory')
  group.add_argument(
      '--repeat',
      type=int,
      default=1,
      metavar='NUM',
      help='Repeat NUM times (default: %(default)s)')
  group.add_argument(
      '--ratio',
      default='=1',
      metavar='{op}{value}',
      type=argtype_ratio,
      help='Match if meet |ratio| condition. Example: ">0", "<0.5", "=1", etc. '
      '(default: %(default)r)')
  group.add_argument(
      '--noshortcut',
      action='store_true',
      help="Don't stop earlier if we know ratio will meet or not by calculation"
  )
  #parser.add_argument('--time_limit')
  group.add_argument(
      '--terminate_output',
      metavar='REGEX',
      type=re.compile,
      help='Once there is one line matching %(metavar)s, '
      'terminate the running program')

  return parser


def opposite(want):
  return NEW if want == OLD else OLD


def run_once(opts):
  """Runs command once and returns corresponding exit code.

  This is the main function of runner.py. It controls command execution and
  converts execution result (output, exit code, duration, etc.) to
  corresponding exit code according to conditions from command line arguments.

  Returns:
    OLD: Execution result is considered as old behavior.
    NEW: Execution result is considered as old behavior.
    SKIP: Preconditions are not meet.
    FATAL: Fatal errors like command not found.
  """
  cmdline = subprocess.list2cmdline([opts.exec_cmd] + opts.exec_args)

  output_result = dict(
      output_matched=False,
      precondition_output_matched=False,
      meet_terminate=False)

  def output_handler(line):
    if opts.output and not output_result['output_matched']:
      if opts.output.search(line):
        logger.debug('matched output')
        output_result['output_matched'] = True
    if (opts.precondition_output and
        not output_result['precondition_output_matched']):
      if opts.precondition_output.search(line):
        logger.debug('matched precondition_output')
        output_result['precondition_output_matched'] = True
    if opts.terminate_output and not output_result['meet_terminate']:
      if opts.terminate_output.search(line):
        logger.debug('terminate condition matched, stop execution')
        output_result['meet_terminate'] = True
        p.terminate()

  p = util.Popen(
      cmdline,
      cwd=opts.cwd,
      shell=True,
      stdout_callback=output_handler,
      stderr_callback=output_handler)

  logger.debug('returncode %s', p.wait())

  found = False
  if opts.output and output_result['output_matched']:
    found = True
  if opts.timeout and p.duration > opts.timeout:
    found = True
  if opts.returncode is not None and opts.returncode == p.returncode:
    found = True

  if not found and not output_result['meet_terminate']:
    if p.returncode > 125:
      logger.warning('fatal return, FATAL')
      return FATAL
    if p.returncode < 0:
      logger.warning('got signal, FATAL')
      return FATAL

  if opts.precondition_output and \
      not output_result['precondition_output_matched']:
    logger.warning("precondition doesn't meet, SKIP")
    return SKIP

  return opts.want if found else opposite(opts.want)


def criteria_is_met(ratio, counter, rest, want):
  """Determines if current count of exit code meets specified threshold.

  After several runs of execution, `counter` contains how many times the exit
  code is 'new' or 'old'. This function answers whether the ratio, 'new' versus
  'old', meets specified threshold.

  For example,
    >>> criteria_is_met(('>=', 0.9), dict(new=20, old=1), 0, 'new')
    True
  It's True because 20/(20+1) >= 0.9.

  This function may be called before all loop iterations are completed (rest >
  0). For such case, the result (meet or not) is unknown (due to uncertainty)
  and thus return value is None.

  Args:
    ratio: (operator, value). For example, ('>=', 0.9) means the calculated
        value needs to be greater than or equal to 0.9.
    counter: (dict) count of execution result.
    rest: remaining execution count.
    want: the goal metric. 'new' or 'old'.

  Returns:
    None if the result is unknown, True if the `ratio` condition is meet, False
    otherwise.
  """
  other = opposite(want)
  if counter[want] + counter[other] == 0:
    return None

  # Assume no more SKIP.
  max_run = counter[want] + counter[other] + rest
  max_possible = float(counter[want] + rest) / max_run
  min_possible = float(counter[want]) / max_run

  op, v = ratio
  if op == '>':
    if max_possible > v >= min_possible:
      return None
    return min_possible > v
  if op == '>=':
    if max_possible >= v > min_possible:
      return None
    return min_possible >= v
  if op == '<':
    if min_possible < v <= max_possible:
      return None
    return min_possible < v
  if op == '<=':
    if min_possible <= v < max_possible:
      return None
    return min_possible <= v

  assert op in ('=', '==')
  # If the final count is not near an integer, it is certain (impossible to
  # meet).
  if abs(round(v * max_run) - v * max_run) > 1e-5:
    return False
  if min_possible != max_possible and min_possible <= v <= max_possible:
    return None
  return abs(min_possible - v) < 1e-3


def main(args=None):
  common.init()
  parser = create_argument_parser()
  opts = parser.parse_args(args)
  common.config_logging(opts)

  counter = collections.Counter()

  runtime = []
  for i in xrange(opts.repeat):
    t0 = time.time()
    status = run_once(opts)
    t1 = time.time()
    runtime.append(t1 - t0)

    counter[status] += 1
    logger.info('%(ith)d/%(num)d old=%(old)d, new=%(new)d, skip=%(skip)d;'
                ' avg time=%(avgtime).2f',
                dict(
                    ith=i + 1,
                    num=opts.repeat,
                    old=counter[OLD],
                    new=counter[NEW],
                    skip=counter[SKIP],
                    avgtime=float(sum(runtime)) / len(runtime)))

    if status == SKIP:
      continue
    if status == FATAL:
      return FATAL
    assert status in (OLD, NEW)

    rest = opts.repeat - i - 1
    meet = criteria_is_met(opts.ratio, counter, rest, opts.want)
    if rest > 0 and not opts.noshortcut and meet is not None:
      logger.info('impossible to change result of ratio:"%s", break the loop',
                  opts.ratio)
      break

  if counter[OLD] == counter[NEW] == 0:
    status = SKIP
  elif meet:
    status = opts.want
  else:
    assert meet is not None
    status = opposite(opts.want)

  logger.info(
      'Runner final result %(status)s: old=%(old)d, new=%(new)d, skip=%(skip)d;'
      ' avg time=%(avgtime).2f',
      dict(
          status=status,
          old=counter[OLD],
          new=counter[NEW],
          skip=counter[SKIP],
          avgtime=float(sum(runtime)) / len(runtime)))

  return status


if __name__ == '__main__':
  sys.exit(EXIT_CODE_MAP[main()])