#!/usr/bin/env python2.7
# Copyright 2015-2016, Google Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
#     * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
#     * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following disclaimer
# in the documentation and/or other materials provided with the
# distribution.
#     * Neither the name of Google Inc. nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

"""Run tests in parallel."""

import argparse
import ast
import glob
import hashlib
import itertools
import json
import multiprocessing
import os
import platform
import random
import re
import socket
import subprocess
import sys
import tempfile
import traceback
import time
import urllib2
import uuid

import jobset
import report_utils
import watch_dirs


ROOT = os.path.abspath(os.path.join(os.path.dirname(sys.argv[0]), '../..'))
os.chdir(ROOT)


_FORCE_ENVIRON_FOR_WRAPPERS = {}


def platform_string():
  return jobset.platform_string()


# SimpleConfig: just compile with CONFIG=config, and run the binary to test
class Config(object):

  def __init__(self, config, environ=None, timeout_multiplier=1, tool_prefix=[]):
    if environ is None:
      environ = {}
    self.build_config = config
    self.allow_hashing = (config != 'gcov')
    self.environ = environ
    self.environ['CONFIG'] = config
    self.tool_prefix = tool_prefix
    self.timeout_multiplier = timeout_multiplier

  def job_spec(self, cmdline, hash_targets, timeout_seconds=5*60,
               shortname=None, environ={}, cpu_cost=1.0):
    """Construct a jobset.JobSpec for a test under this config

       Args:
         cmdline:      a list of strings specifying the command line the test
                       would like to run
         hash_targets: either None (don't do caching of test results), or
                       a list of strings specifying files to include in a
                       binary hash to check if a test has changed
                       -- if used, all artifacts needed to run the test must
                          be listed
    """
    actual_environ = self.environ.copy()
    for k, v in environ.iteritems():
      actual_environ[k] = v
    return jobset.JobSpec(cmdline=self.tool_prefix + cmdline,
                          shortname=shortname,
                          environ=actual_environ,
                          cpu_cost=cpu_cost,
                          timeout_seconds=(self.timeout_multiplier * timeout_seconds if timeout_seconds else None),
                          hash_targets=hash_targets
                              if self.allow_hashing else None,
                          flake_retries=5 if args.allow_flakes else 0,
                          timeout_retries=3 if args.allow_flakes else 0)


def get_c_tests(travis, test_lang) :
  out = []
  platforms_str = 'ci_platforms' if travis else 'platforms'
  with open('tools/run_tests/tests.json') as f:
    js = json.load(f)
    return [tgt
            for tgt in js
            if tgt['language'] == test_lang and
                platform_string() in tgt[platforms_str] and
                not (travis and tgt['flaky'])]


class CLanguage(object):

  def __init__(self, make_target, test_lang):
    self.make_target = make_target
    self.platform = platform_string()
    self.test_lang = test_lang

  def test_specs(self, config, args):
    out = []
    binaries = get_c_tests(args.travis, self.test_lang)
    for target in binaries:
      if config.build_config in target['exclude_configs']:
        continue
      if self.platform == 'windows':
        binary = 'vsprojects/%s%s/%s.exe' % (
            'x64/' if args.arch == 'x64' else '',
            _WINDOWS_CONFIG[config.build_config],
            target['name'])
      else:
        binary = 'bins/%s/%s' % (config.build_config, target['name'])
      if os.path.isfile(binary):
        cmdline = [binary] + target['args']
        out.append(config.job_spec(cmdline, [binary],
                                   shortname=' '.join(cmdline),
                                   cpu_cost=target['cpu_cost'],
                                   environ={'GRPC_DEFAULT_SSL_ROOTS_FILE_PATH':
                                            os.path.abspath(os.path.dirname(
                                                sys.argv[0]) + '/../../src/core/tsi/test_creds/ca.pem')}))
      elif args.regex == '.*' or platform_string() == 'windows':
        print '\nWARNING: binary not found, skipping', binary
    return sorted(out)

  def make_targets(self, test_regex):
    if platform_string() != 'windows' and test_regex != '.*':
      # use the regex to minimize the number of things to build
      return [os.path.basename(target['name'])
              for target in get_c_tests(False, self.test_lang)
              if re.search(test_regex, '/' + target['name'])]
    if platform_string() == 'windows':
      # don't build tools on windows just yet
      return ['buildtests_%s' % self.make_target]
    return ['buildtests_%s' % self.make_target, 'tools_%s' % self.make_target]

  def make_options(self):
    return []

  def pre_build_steps(self):
    if self.platform == 'windows':
      return [['tools\\run_tests\\pre_build_c.bat']]
    else:
      return []

  def build_steps(self):
    return []

  def post_tests_steps(self):
    if self.platform == 'windows':
      return []
    else:
      return [['tools/run_tests/post_tests_c.sh']]

  def makefile_name(self):
    return 'Makefile'

  def supports_multi_config(self):
    return True

  def dockerfile_dir(self, config, arch):
    return None

  def __str__(self):
    return self.make_target


class NodeLanguage(object):

  def test_specs(self, config, args):
    return [config.job_spec(['tools/run_tests/run_node.sh'], None,
                            environ=_FORCE_ENVIRON_FOR_WRAPPERS)]

  def pre_build_steps(self):
    # Default to 1 week cache expiration
    return [['tools/run_tests/pre_build_node.sh']]

  def make_targets(self, test_regex):
    return []

  def make_options(self):
    return []

  def build_steps(self):
    return [['tools/run_tests/build_node.sh']]

  def post_tests_steps(self):
    return []

  def makefile_name(self):
    return 'Makefile'

  def supports_multi_config(self):
    return False

  def dockerfile_dir(self, config, arch):
    return None

  def __str__(self):
    return 'node'


class PhpLanguage(object):

  def test_specs(self, config, args):
    return [config.job_spec(['src/php/bin/run_tests.sh'], None,
                            environ=_FORCE_ENVIRON_FOR_WRAPPERS)]

  def pre_build_steps(self):
    return []

  def make_targets(self, test_regex):
    return ['static_c', 'shared_c']

  def make_options(self):
    return []

  def build_steps(self):
    return [['tools/run_tests/build_php.sh']]

  def post_tests_steps(self):
    return [['tools/run_tests/post_tests_php.sh']]

  def makefile_name(self):
    return 'Makefile'

  def supports_multi_config(self):
    return False

  def dockerfile_dir(self, config, arch):
    return None

  def __str__(self):
    return 'php'


class PythonLanguage(object):

  def __init__(self):
    self._build_python_versions = ['2.7']
    self._has_python_versions = []

  def test_specs(self, config, args):
    environment = dict(_FORCE_ENVIRON_FOR_WRAPPERS)
    environment['PYVER'] = '2.7'
    return [config.job_spec(
        ['tools/run_tests/run_python.sh'],
        None,
        environ=environment,
        shortname='py.test',
        timeout_seconds=15*60
    )]

  def pre_build_steps(self):
    return []

  def make_targets(self, test_regex):
    return ['static_c', 'grpc_python_plugin', 'shared_c']

  def make_options(self):
    return []

  def build_steps(self):
    commands = []
    for python_version in self._build_python_versions:
      try:
        with open(os.devnull, 'w') as output:
          subprocess.check_call(['which', 'python' + python_version],
                                stdout=output, stderr=output)
        commands.append(['tools/run_tests/build_python.sh', python_version])
        self._has_python_versions.append(python_version)
      except:
        jobset.message('WARNING', 'Missing Python ' + python_version,
                       do_newline=True)
    return commands

  def post_tests_steps(self):
    return []

  def makefile_name(self):
    return 'Makefile'

  def supports_multi_config(self):
    return False

  def dockerfile_dir(self, config, arch):
    return None

  def __str__(self):
    return 'python'


class RubyLanguage(object):

  def test_specs(self, config, args):
    return [config.job_spec(['tools/run_tests/run_ruby.sh'], None,
                            environ=_FORCE_ENVIRON_FOR_WRAPPERS)]

  def pre_build_steps(self):
    return [['tools/run_tests/pre_build_ruby.sh']]

  def make_targets(self, test_regex):
    return ['static_c']

  def make_options(self):
    return []

  def build_steps(self):
    return [['tools/run_tests/build_ruby.sh']]

  def post_tests_steps(self):
    return [['tools/run_tests/post_tests_ruby.sh']]

  def makefile_name(self):
    return 'Makefile'

  def supports_multi_config(self):
    return False

  def dockerfile_dir(self, config, arch):
    return None

  def __str__(self):
    return 'ruby'


class CSharpLanguage(object):
  def __init__(self):
    self.platform = platform_string()

  def test_specs(self, config, args):
    with open('src/csharp/tests.json') as f:
      tests_json = json.load(f)
    assemblies = tests_json['assemblies']
    tests = tests_json['tests']

    msbuild_config = _WINDOWS_CONFIG[config.build_config]
    assembly_files = ['%s/bin/%s/%s.dll' % (a, msbuild_config, a)
                      for a in assemblies]

    extra_args = ['-labels'] + assembly_files

    if self.platform == 'windows':
      script_name = 'tools\\run_tests\\run_csharp.bat'
      extra_args += ['-domain=None']
    else:
      script_name = 'tools/run_tests/run_csharp.sh'

    if config.build_config == 'gcov':
      # On Windows, we only collect C# code coverage.
      # On Linux, we only collect coverage for native extension.
      # For code coverage all tests need to run as one suite.
      return [config.job_spec([script_name] + extra_args, None,
                              shortname='csharp.coverage',
                              environ=_FORCE_ENVIRON_FOR_WRAPPERS)]
    else:
      specs = []
      for test in tests:
        cmdline = [script_name, '-run=%s' % test] + extra_args
        if self.platform == 'windows':
          # use different output directory for each test to prevent
          # TestResult.xml clash between parallel test runs.
          cmdline += ['-work=test-result/%s' % uuid.uuid4()]
        specs.append(config.job_spec(cmdline, None,
                                     shortname='csharp.%s' % test,
                                     environ=_FORCE_ENVIRON_FOR_WRAPPERS))
      return specs

  def pre_build_steps(self):
    if self.platform == 'windows':
      return [['tools\\run_tests\\pre_build_csharp.bat']]
    else:
      return [['tools/run_tests/pre_build_csharp.sh']]

  def make_targets(self, test_regex):
    # For Windows, this target doesn't really build anything,
    # everything is build by buildall script later.
    if self.platform == 'windows':
      return []
    else:
      return ['grpc_csharp_ext']

  def make_options(self):
    if self.platform == 'mac':
      # On Mac, official distribution of mono is 32bit.
      return ['CFLAGS=-arch i386', 'LDFLAGS=-arch i386']
    else:
      return []

  def build_steps(self):
    if self.platform == 'windows':
      return [['src\\csharp\\buildall.bat']]
    else:
      return [['tools/run_tests/build_csharp.sh']]

  def post_tests_steps(self):
    return []

  def makefile_name(self):
    return 'Makefile'

  def supports_multi_config(self):
    return False

  def dockerfile_dir(self, config, arch):
    return None

  def __str__(self):
    return 'csharp'


class ObjCLanguage(object):

  def test_specs(self, config, args):
    return [config.job_spec(['src/objective-c/tests/run_tests.sh'], None,
                            environ=_FORCE_ENVIRON_FOR_WRAPPERS)]

  def pre_build_steps(self):
    return []

  def make_targets(self, test_regex):
    return ['grpc_objective_c_plugin', 'interop_server']

  def make_options(self):
    return []

  def build_steps(self):
    return [['src/objective-c/tests/build_tests.sh']]

  def post_tests_steps(self):
    return []

  def makefile_name(self):
    return 'Makefile'

  def supports_multi_config(self):
    return False

  def dockerfile_dir(self, config, arch):
    return None

  def __str__(self):
    return 'objc'


class Sanity(object):

  def test_specs(self, config, args):
    import yaml
    with open('tools/run_tests/sanity/sanity_tests.yaml', 'r') as f:
      return [config.job_spec(cmd['script'].split(), None,
                              timeout_seconds=None, environ={'TEST': 'true'},
                              cpu_cost=cmd.get('cpu_cost', 1))
              for cmd in yaml.load(f)]

  def pre_build_steps(self):
    return []

  def make_targets(self, test_regex):
    return ['run_dep_checks']

  def make_options(self):
    return []

  def build_steps(self):
    return []

  def post_tests_steps(self):
    return []

  def makefile_name(self):
    return 'Makefile'

  def supports_multi_config(self):
    return False

  def dockerfile_dir(self, config, arch):
    return 'tools/dockerfile/grpc_sanity'

  def __str__(self):
    return 'sanity'


class Build(object):

  def test_specs(self, config, args):
    return []

  def pre_build_steps(self):
    return []

  def make_targets(self, test_regex):
    return ['static']

  def make_options(self):
    return []

  def build_steps(self):
    return []

  def post_tests_steps(self):
    return []

  def makefile_name(self):
    return 'Makefile'

  def supports_multi_config(self):
    return True

  def dockerfile_dir(self, config, arch):
    return None

  def __str__(self):
    return self.make_target


# different configurations we can run under
with open('tools/run_tests/configs.json') as f:
  _CONFIGS = dict((cfg['config'], Config(**cfg)) for cfg in ast.literal_eval(f.read()))


_DEFAULT = ['opt']
_LANGUAGES = {
    'c++': CLanguage('cxx', 'c++'),
    'c': CLanguage('c', 'c'),
    'node': NodeLanguage(),
    'php': PhpLanguage(),
    'python': PythonLanguage(),
    'ruby': RubyLanguage(),
    'csharp': CSharpLanguage(),
    'objc' : ObjCLanguage(),
    'sanity': Sanity(),
    'build': Build(),
    }

_WINDOWS_CONFIG = {
    'dbg': 'Debug',
    'opt': 'Release',
    'gcov': 'Debug',
    }


def _windows_arch_option(arch):
  """Returns msbuild cmdline option for selected architecture."""
  if arch == 'default' or arch == 'x86':
    return '/p:Platform=Win32'
  elif arch == 'x64':
    return '/p:Platform=x64'
  else:
    print 'Architecture %s not supported.' % arch
    sys.exit(1)


def _check_arch_option(arch):
  """Checks that architecture option is valid."""
  if platform_string() == 'windows':
    _windows_arch_option(arch)
  elif platform_string() == 'linux':
    # On linux, we need to be running under docker with the right architecture.
    runtime_arch = platform.architecture()[0]
    if arch == 'default':
      return
    elif runtime_arch == '64bit' and arch == 'x64':
      return
    elif runtime_arch == '32bit' and arch == 'x86':
      return
    else:
      print 'Architecture %s does not match current runtime architecture.' % arch
      sys.exit(1)
  else:
    if args.arch != 'default':
      print 'Architecture %s not supported on current platform.' % args.arch
      sys.exit(1)


def _windows_build_bat(compiler):
  """Returns name of build.bat for selected compiler."""
  if compiler == 'default' or compiler == 'vs2013':
    return 'vsprojects\\build_vs2013.bat'
  elif compiler == 'vs2015':
    return 'vsprojects\\build_vs2015.bat'
  elif compiler == 'vs2010':
    return 'vsprojects\\build_vs2010.bat'
  else:
    print 'Compiler %s not supported.' % compiler
    sys.exit(1)


def _windows_toolset_option(compiler):
  """Returns msbuild PlatformToolset for selected compiler."""
  if compiler == 'default' or compiler == 'vs2013':
    return '/p:PlatformToolset=v120'
  elif compiler == 'vs2015':
    return '/p:PlatformToolset=v140'
  elif compiler == 'vs2010':
    return '/p:PlatformToolset=v100'
  else:
    print 'Compiler %s not supported.' % compiler
    sys.exit(1)


def _get_dockerfile_dir(language, cfg, arch):
  """Returns dockerfile to use"""
  custom = language.dockerfile_dir(cfg, arch)
  if custom:
    return custom
  else:
    if arch == 'default' or arch == 'x64':
      return 'tools/dockerfile/grpc_tests_multilang_x64'
    elif arch == 'x86':
      return 'tools/dockerfile/grpc_tests_multilang_x86'
    else:
      print 'Architecture %s not supported with current settings.' % arch
      sys.exit(1)

def runs_per_test_type(arg_str):
    """Auxilary function to parse the "runs_per_test" flag.

       Returns:
           A positive integer or 0, the latter indicating an infinite number of
           runs.

       Raises:
           argparse.ArgumentTypeError: Upon invalid input.
    """
    if arg_str == 'inf':
        return 0
    try:
        n = int(arg_str)
        if n <= 0: raise ValueError
        return n
    except:
        msg = '\'{}\' is not a positive integer or \'inf\''.format(arg_str)
        raise argparse.ArgumentTypeError(msg)

# parse command line
argp = argparse.ArgumentParser(description='Run grpc tests.')
argp.add_argument('-c', '--config',
                  choices=['all'] + sorted(_CONFIGS.keys()),
                  nargs='+',
                  default=_DEFAULT)
argp.add_argument('-n', '--runs_per_test', default=1, type=runs_per_test_type,
        help='A positive integer or "inf". If "inf", all tests will run in an '
             'infinite loop. Especially useful in combination with "-f"')
argp.add_argument('-r', '--regex', default='.*', type=str)
argp.add_argument('-j', '--jobs', default=multiprocessing.cpu_count(), type=int)
argp.add_argument('-s', '--slowdown', default=1.0, type=float)
argp.add_argument('-f', '--forever',
                  default=False,
                  action='store_const',
                  const=True)
argp.add_argument('-t', '--travis',
                  default=False,
                  action='store_const',
                  const=True)
argp.add_argument('--newline_on_success',
                  default=False,
                  action='store_const',
                  const=True)
argp.add_argument('-l', '--language',
                  choices=['all'] + sorted(_LANGUAGES.keys()),
                  nargs='+',
                  default=['all'])
argp.add_argument('-S', '--stop_on_failure',
                  default=False,
                  action='store_const',
                  const=True)
argp.add_argument('--use_docker',
                  default=False,
                  action='store_const',
                  const=True,
                  help='Run all the tests under docker. That provides ' +
                  'additional isolation and prevents the need to install ' +
                  'language specific prerequisites. Only available on Linux.')
argp.add_argument('--allow_flakes',
                  default=False,
                  action='store_const',
                  const=True,
                  help='Allow flaky tests to show as passing (re-runs failed tests up to five times)')
argp.add_argument('--arch',
                  choices=['default', 'x86', 'x64'],
                  default='default',
                  help='Selects architecture to target. For some platforms "default" is the only supported choice.')
argp.add_argument('--compiler',
                  choices=['default', 'vs2010', 'vs2013', 'vs2015'],
                  default='default',
                  help='Selects compiler to use. For some platforms "default" is the only supported choice.')
argp.add_argument('--build_only',
                  default=False,
                  action='store_const',
                  const=True,
                  help='Perform all the build steps but dont run any tests.')
argp.add_argument('--measure_cpu_costs', default=False, action='store_const', const=True,
                  help='Measure the cpu costs of tests')
argp.add_argument('--update_submodules', default=[], nargs='*',
                  help='Update some submodules before building. If any are updated, also run generate_projects. ' +
                       'Submodules are specified as SUBMODULE_NAME:BRANCH; if BRANCH is omitted, master is assumed.')
argp.add_argument('-a', '--antagonists', default=0, type=int)
argp.add_argument('-x', '--xml_report', default=None, type=str,
        help='Generates a JUnit-compatible XML report')
args = argp.parse_args()

jobset.measure_cpu_costs = args.measure_cpu_costs

# update submodules if necessary
need_to_regenerate_projects = False
for spec in args.update_submodules:
  spec = spec.split(':', 1)
  if len(spec) == 1:
    submodule = spec[0]
    branch = 'master'
  elif len(spec) == 2:
    submodule = spec[0]
    branch = spec[1]
  cwd = 'third_party/%s' % submodule
  def git(cmd, cwd=cwd):
    print 'in %s: git %s' % (cwd, cmd)
    subprocess.check_call('git %s' % cmd, cwd=cwd, shell=True)
  git('fetch')
  git('checkout %s' % branch)
  git('pull origin %s' % branch)
  if os.path.exists('src/%s/gen_build_yaml.py' % submodule):
    need_to_regenerate_projects = True
if need_to_regenerate_projects:
  if jobset.platform_string() == 'linux':
    subprocess.check_call('tools/buildgen/generate_projects.sh', shell=True)
  else:
    print 'WARNING: may need to regenerate projects, but since we are not on'
    print '         Linux this step is being skipped. Compilation MAY fail.'


# grab config
run_configs = set(_CONFIGS[cfg]
                  for cfg in itertools.chain.from_iterable(
                      _CONFIGS.iterkeys() if x == 'all' else [x]
                      for x in args.config))
build_configs = set(cfg.build_config for cfg in run_configs)

if args.travis:
  _FORCE_ENVIRON_FOR_WRAPPERS = {'GRPC_TRACE': 'api'}

if 'all' in args.language:
  lang_list = _LANGUAGES.keys()
else:
  lang_list = args.language
# We don't support code coverage on some languages
if 'gcov' in args.config:
  for bad in ['objc', 'sanity', 'build']:
    if bad in lang_list:
      lang_list.remove(bad)

languages = set(_LANGUAGES[l] for l in lang_list)

if len(build_configs) > 1:
  for language in languages:
    if not language.supports_multi_config():
      print language, 'does not support multiple build configurations'
      sys.exit(1)

language_make_options=[]
if any(language.make_options() for language in languages):
  if len(languages) != 1:
    print 'languages with custom make options cannot be built simultaneously with other languages'
    sys.exit(1)
  else:
    language_make_options = next(iter(languages)).make_options()

if len(languages) != 1 or len(build_configs) != 1:
  print 'Multi-language and multi-config testing is not supported.'
  sys.exit(1)

if args.use_docker:
  if not args.travis:
    print 'Seen --use_docker flag, will run tests under docker.'
    print
    print 'IMPORTANT: The changes you are testing need to be locally committed'
    print 'because only the committed changes in the current branch will be'
    print 'copied to the docker environment.'
    time.sleep(5)

  child_argv = [ arg for arg in sys.argv if not arg == '--use_docker' ]
  run_tests_cmd = 'python tools/run_tests/run_tests.py %s' % ' '.join(child_argv[1:])

  env = os.environ.copy()
  env['RUN_TESTS_COMMAND'] = run_tests_cmd
  env['DOCKERFILE_DIR'] = _get_dockerfile_dir(next(iter(languages)),
                                              next(iter(build_configs)),
                                              args.arch)
  env['DOCKER_RUN_SCRIPT'] = 'tools/jenkins/docker_run_tests.sh'
  if args.xml_report:
    env['XML_REPORT'] = args.xml_report
  if not args.travis:
    env['TTY_FLAG'] = '-t'  # enables Ctrl-C when not on Jenkins.

  subprocess.check_call(['tools/jenkins/build_docker_and_run_tests.sh'],
                        shell=True,
                        env=env)
  sys.exit(0)

if platform_string() != 'windows' and args.compiler != 'default':
    print 'Compiler %s not supported on current platform.' % args.compiler
    sys.exit(1)

_check_arch_option(args.arch)

def make_jobspec(cfg, targets, makefile='Makefile'):
  if platform_string() == 'windows':
    extra_args = []
    # better do parallel compilation
    # empirically /m:2 gives the best performance/price and should prevent
    # overloading the windows workers.
    extra_args.extend(['/m:2'])
    # disable PDB generation: it's broken, and we don't need it during CI
    extra_args.extend(['/p:Jenkins=true'])
    return [
      jobset.JobSpec([_windows_build_bat(args.compiler),
                      'vsprojects\\%s.sln' % target,
                      '/p:Configuration=%s' % _WINDOWS_CONFIG[cfg],
                      _windows_toolset_option(args.compiler),
                      _windows_arch_option(args.arch)] +
                      extra_args +
                      language_make_options,
                      shell=True, timeout_seconds=None)
      for target in targets]
  else:
    if targets:
      return [jobset.JobSpec([os.getenv('MAKE', 'make'),
                              '-f', makefile,
                              '-j', '%d' % args.jobs,
                              'EXTRA_DEFINES=GRPC_TEST_SLOWDOWN_MACHINE_FACTOR=%f' % args.slowdown,
                              'CONFIG=%s' % cfg] +
                              language_make_options +
                             ([] if not args.travis else ['JENKINS_BUILD=1']) +
                             targets,
                             timeout_seconds=None)]
    else:
      return []

make_targets = {}
for l in languages:
  makefile = l.makefile_name()
  make_targets[makefile] = make_targets.get(makefile, set()).union(
      set(l.make_targets(args.regex)))

def build_step_environ(cfg):
  environ = {'CONFIG': cfg}
  msbuild_cfg = _WINDOWS_CONFIG.get(cfg)
  if msbuild_cfg:
    environ['MSBUILD_CONFIG'] = msbuild_cfg
  return environ

build_steps = list(set(
                   jobset.JobSpec(cmdline, environ=build_step_environ(cfg), flake_retries=5)
                   for cfg in build_configs
                   for l in languages
                   for cmdline in l.pre_build_steps()))
if make_targets:
  make_commands = itertools.chain.from_iterable(make_jobspec(cfg, list(targets), makefile) for cfg in build_configs for (makefile, targets) in make_targets.iteritems())
  build_steps.extend(set(make_commands))
build_steps.extend(set(
                   jobset.JobSpec(cmdline, environ=build_step_environ(cfg), timeout_seconds=None)
                   for cfg in build_configs
                   for l in languages
                   for cmdline in l.build_steps()))

post_tests_steps = list(set(
                        jobset.JobSpec(cmdline, environ=build_step_environ(cfg))
                        for cfg in build_configs
                        for l in languages
                        for cmdline in l.post_tests_steps()))
runs_per_test = args.runs_per_test
forever = args.forever


class TestCache(object):
  """Cache for running tests."""

  def __init__(self, use_cache_results):
    self._last_successful_run = {}
    self._use_cache_results = use_cache_results
    self._last_save = time.time()

  def should_run(self, cmdline, bin_hash):
    if cmdline not in self._last_successful_run:
      return True
    if self._last_successful_run[cmdline] != bin_hash:
      return True
    if not self._use_cache_results:
      return True
    return False

  def finished(self, cmdline, bin_hash):
    self._last_successful_run[cmdline] = bin_hash
    if time.time() - self._last_save > 1:
      self.save()

  def dump(self):
    return [{'cmdline': k, 'hash': v}
            for k, v in self._last_successful_run.iteritems()]

  def parse(self, exdump):
    self._last_successful_run = dict((o['cmdline'], o['hash']) for o in exdump)

  def save(self):
    with open('.run_tests_cache', 'w') as f:
      f.write(json.dumps(self.dump()))
    self._last_save = time.time()

  def maybe_load(self):
    if os.path.exists('.run_tests_cache'):
      with open('.run_tests_cache') as f:
        self.parse(json.loads(f.read()))


def _start_port_server(port_server_port):
  # check if a compatible port server is running
  # if incompatible (version mismatch) ==> start a new one
  # if not running ==> start a new one
  # otherwise, leave it up
  try:
    version = int(urllib2.urlopen(
        'http://localhost:%d/version_number' % port_server_port,
        timeout=1).read())
    print 'detected port server running version %d' % version
    running = True
  except Exception as e:
    print 'failed to detect port server: %s' % sys.exc_info()[0]
    print e.strerror
    running = False
  if running:
    current_version = int(subprocess.check_output(
        [sys.executable, os.path.abspath('tools/run_tests/port_server.py'),
         'dump_version']))
    print 'my port server is version %d' % current_version
    running = (version >= current_version)
    if not running:
      print 'port_server version mismatch: killing the old one'
      urllib2.urlopen('http://localhost:%d/quitquitquit' % port_server_port).read()
      time.sleep(1)
  if not running:
    fd, logfile = tempfile.mkstemp()
    os.close(fd)
    print 'starting port_server, with log file %s' % logfile
    args = [sys.executable, os.path.abspath('tools/run_tests/port_server.py'),
            '-p', '%d' % port_server_port, '-l', logfile]
    env = dict(os.environ)
    env['BUILD_ID'] = 'pleaseDontKillMeJenkins'
    if platform_string() == 'windows':
      # Working directory of port server needs to be outside of Jenkins
      # workspace to prevent file lock issues.
      tempdir = tempfile.mkdtemp()
      port_server = subprocess.Popen(
          args,
          env=env,
          cwd=tempdir,
          creationflags = 0x00000008, # detached process
          close_fds=True)
    else:
      port_server = subprocess.Popen(
          args,
          env=env,
          preexec_fn=os.setsid,
          close_fds=True)
    time.sleep(1)
    # ensure port server is up
    waits = 0
    while True:
      if waits > 10:
        print 'killing port server due to excessive start up waits'
        port_server.kill()
      if port_server.poll() is not None:
        print 'port_server failed to start'
        # try one final time: maybe another build managed to start one
        time.sleep(1)
        try:
          urllib2.urlopen('http://localhost:%d/get' % port_server_port,
                          timeout=1).read()
          print 'last ditch attempt to contact port server succeeded'
          break
        except:
          traceback.print_exc();
          port_log = open(logfile, 'r').read()
          print port_log
          sys.exit(1)
      try:
        urllib2.urlopen('http://localhost:%d/get' % port_server_port,
                        timeout=1).read()
        print 'port server is up and ready'
        break
      except socket.timeout:
        print 'waiting for port_server: timeout'
        traceback.print_exc();
        time.sleep(1)
        waits += 1
      except urllib2.URLError:
        print 'waiting for port_server: urlerror'
        traceback.print_exc();
        time.sleep(1)
        waits += 1
      except:
        traceback.print_exc();
        port_server.kill()
        raise


def _calculate_num_runs_failures(list_of_results):
  """Caculate number of runs and failures for a particular test.

  Args:
    list_of_results: (List) of JobResult object.
  Returns:
    A tuple of total number of runs and failures.
  """
  num_runs = len(list_of_results)  # By default, there is 1 run per JobResult.
  num_failures = 0
  for jobresult in list_of_results:
    if jobresult.retries > 0:
      num_runs += jobresult.retries
    if jobresult.num_failures > 0:
      num_failures += jobresult.num_failures
  return num_runs, num_failures


# _build_and_run results
class BuildAndRunError(object):

  BUILD = object()
  TEST = object()
  POST_TEST = object()


# returns a list of things that failed (or an empty list on success)
def _build_and_run(
    check_cancelled, newline_on_success, cache, xml_report=None, build_only=False):
  """Do one pass of building & running tests."""
  # build latest sequentially
  num_failures, resultset = jobset.run(
      build_steps, maxjobs=1, stop_on_failure=True,
      newline_on_success=newline_on_success, travis=args.travis)
  if num_failures:
    return [BuildAndRunError.BUILD]

  if build_only:
    if xml_report:
      report_utils.render_junit_xml_report(resultset, xml_report)
    return []

  # start antagonists
  antagonists = [subprocess.Popen(['tools/run_tests/antagonist.py'])
                 for _ in range(0, args.antagonists)]
  port_server_port = 32767
  _start_port_server(port_server_port)
  resultset = None
  num_test_failures = 0
  try:
    infinite_runs = runs_per_test == 0
    one_run = set(
      spec
      for config in run_configs
      for language in languages
      for spec in language.test_specs(config, args)
      if re.search(args.regex, spec.shortname))
    # When running on travis, we want out test runs to be as similar as possible
    # for reproducibility purposes.
    if args.travis:
      massaged_one_run = sorted(one_run, key=lambda x: x.shortname)
    else:
      # whereas otherwise, we want to shuffle things up to give all tests a
      # chance to run.
      massaged_one_run = list(one_run)  # random.shuffle needs an indexable seq.
      random.shuffle(massaged_one_run)  # which it modifies in-place.
    if infinite_runs:
      assert len(massaged_one_run) > 0, 'Must have at least one test for a -n inf run'
    runs_sequence = (itertools.repeat(massaged_one_run) if infinite_runs
                     else itertools.repeat(massaged_one_run, runs_per_test))
    all_runs = itertools.chain.from_iterable(runs_sequence)

    num_test_failures, resultset = jobset.run(
        all_runs, check_cancelled, newline_on_success=newline_on_success,
        travis=args.travis, infinite_runs=infinite_runs, maxjobs=args.jobs,
        stop_on_failure=args.stop_on_failure,
        cache=cache if not xml_report else None,
        add_env={'GRPC_TEST_PORT_SERVER': 'localhost:%d' % port_server_port})
    if resultset:
      for k, v in resultset.iteritems():
        num_runs, num_failures = _calculate_num_runs_failures(v)
        if num_failures == num_runs:  # what about infinite_runs???
          jobset.message('FAILED', k, do_newline=True)
        elif num_failures > 0:
          jobset.message(
              'FLAKE', '%s [%d/%d runs flaked]' % (k, num_failures, num_runs),
              do_newline=True)
        else:
          jobset.message('PASSED', k, do_newline=True)
  finally:
    for antagonist in antagonists:
      antagonist.kill()
    if xml_report and resultset:
      report_utils.render_junit_xml_report(resultset, xml_report)

  number_failures, _ = jobset.run(
      post_tests_steps, maxjobs=1, stop_on_failure=True,
      newline_on_success=newline_on_success, travis=args.travis)

  out = []
  if number_failures:
    out.append(BuildAndRunError.POST_TEST)
  if num_test_failures:
    out.append(BuildAndRunError.TEST)

  if cache: cache.save()

  return out


test_cache = TestCache(runs_per_test == 1)
test_cache.maybe_load()

if forever:
  success = True
  while True:
    dw = watch_dirs.DirWatcher(['src', 'include', 'test', 'examples'])
    initial_time = dw.most_recent_change()
    have_files_changed = lambda: dw.most_recent_change() != initial_time
    previous_success = success
    errors = _build_and_run(check_cancelled=have_files_changed,
                            newline_on_success=False,
                            cache=test_cache,
                            build_only=args.build_only) == 0
    if not previous_success and not errors:
      jobset.message('SUCCESS',
                     'All tests are now passing properly',
                     do_newline=True)
    jobset.message('IDLE', 'No change detected')
    while not have_files_changed():
      time.sleep(1)
else:
  errors = _build_and_run(check_cancelled=lambda: False,
                          newline_on_success=args.newline_on_success,
                          cache=test_cache,
                          xml_report=args.xml_report,
                          build_only=args.build_only)
  if not errors:
    jobset.message('SUCCESS', 'All tests passed', do_newline=True)
  else:
    jobset.message('FAILED', 'Some tests failed', do_newline=True)
  exit_code = 0
  if BuildAndRunError.BUILD in errors:
    exit_code |= 1
  if BuildAndRunError.TEST in errors and not args.travis:
    exit_code |= 2
  if BuildAndRunError.POST_TEST in errors:
    exit_code |= 4
  sys.exit(exit_code)