#!/usr/bin/python

"""Utility module that executes management commands on the drone.

1. This is the module responsible for orchestrating processes on a drone.
2. It receives instructions via stdin and replies via stdout.
3. Each invocation is responsible for the initiation of a set of batched calls.
4. The batched calls may be synchronous or asynchronous.
5. The caller is responsible for monitoring asynchronous calls through pidfiles.
"""

#pylint: disable-msg=missing-docstring

import argparse
import collections
import datetime
import getpass
import itertools
import logging
import multiprocessing
import os
import pickle
import shutil
import signal
import subprocess
import sys
import time
import traceback

import common

from autotest_lib.client.common_lib import error
from autotest_lib.client.common_lib import global_config
from autotest_lib.client.common_lib import logging_manager
from autotest_lib.client.common_lib import utils
from autotest_lib.client.common_lib.cros import retry
from autotest_lib.scheduler import drone_logging_config
from autotest_lib.scheduler import scheduler_config
from autotest_lib.server import subcommand


# An environment variable we add to the environment to enable us to
# distinguish processes we started from those that were started by
# something else during recovery.  Name credit goes to showard. ;)
DARK_MARK_ENVIRONMENT_VAR = 'AUTOTEST_SCHEDULER_DARK_MARK'

_TEMPORARY_DIRECTORY = 'drone_tmp'
_TRANSFER_FAILED_FILE = '.transfer_failed'

# script and log file for cleaning up orphaned lxc containers.
LXC_CLEANUP_SCRIPT = os.path.join(common.autotest_dir, 'site_utils',
                                  'lxc_cleanup.py')
LXC_CLEANUP_LOG_FILE = os.path.join(common.autotest_dir, 'logs',
                                    'lxc_cleanup.log')


class _MethodCall(object):
    def __init__(self, method, args, kwargs):
        self._method = method
        self._args = args
        self._kwargs = kwargs


    def execute_on(self, drone_utility):
        method = getattr(drone_utility, self._method)
        return method(*self._args, **self._kwargs)


    def __str__(self):
        args = ', '.join(repr(arg) for arg in self._args)
        kwargs = ', '.join('%s=%r' % (key, value) for key, value in
                           self._kwargs.iteritems())
        full_args = ', '.join(item for item in (args, kwargs) if item)
        return '%s(%s)' % (self._method, full_args)


def call(method, *args, **kwargs):
    return _MethodCall(method, args, kwargs)


class DroneUtility(object):
    """
    This class executes actual OS calls on the drone machine.

    All paths going into and out of this class are absolute.
    """
    _WARNING_DURATION = 400

    def __init__(self):
        # Tattoo ourselves so that all of our spawn bears our mark.
        os.putenv(DARK_MARK_ENVIRONMENT_VAR, str(os.getpid()))

        self.warnings = []
        self._subcommands = []


    def initialize(self, results_dir):
        temporary_directory = os.path.join(results_dir, _TEMPORARY_DIRECTORY)
        if os.path.exists(temporary_directory):
            # TODO crbug.com/391111: before we have a better solution to
            # periodically cleanup tmp files, we have to use rm -rf to delete
            # the whole folder. shutil.rmtree has performance issue when a
            # folder has large amount of files, e.g., drone_tmp.
            os.system('rm -rf %s' % temporary_directory)
        self._ensure_directory_exists(temporary_directory)
        # TODO (sbasi) crbug.com/345011 - Remove this configuration variable
        # and clean up build_externals so it NO-OP's.
        build_externals = global_config.global_config.get_config_value(
                scheduler_config.CONFIG_SECTION, 'drone_build_externals',
                default=True, type=bool)
        if build_externals:
            build_extern_cmd = os.path.join(common.autotest_dir,
                                            'utils', 'build_externals.py')
            utils.run(build_extern_cmd)


    def _warn(self, warning):
        self.warnings.append(warning)


    def refresh(self, pidfile_paths):
        """Refreshes our view of the processes referred to by pdfile_paths.

        See drone_utility.ProcessRefresher.__call__ for details.
        """
        check_mark = global_config.global_config.get_config_value(
            'SCHEDULER', 'check_processes_for_dark_mark', bool, False)
        use_pool = global_config.global_config.get_config_value(
            'SCHEDULER', 'drone_utility_refresh_use_pool', bool, False)
        result, warnings = ProcessRefresher(check_mark, use_pool)(pidfile_paths)
        self.warnings += warnings
        return result


    def get_signal_queue_to_kill(self, process):
        """Get the signal queue needed to kill a process.

        autoserv process has a handle on SIGTERM, in which it can do some
        cleanup work. However, abort a process with SIGTERM then SIGKILL has
        its overhead, detailed in following CL:
        https://chromium-review.googlesource.com/230323
        This method checks the process's argument and determine if SIGTERM is
        required, and returns signal queue accordingly.

        @param process: A drone_manager.Process object to be killed.

        @return: The signal queue needed to kill a process.

        """
        signal_queue_with_sigterm = (signal.SIGTERM, signal.SIGKILL)
        try:
            ps_output = subprocess.check_output(
                    ['/bin/ps', '-p', str(process.pid), '-o', 'args'])
            # For test running with server-side packaging, SIGTERM needs to be
            # sent for autoserv process to destroy container used by the test.
            if '--require-ssp' in ps_output:
                logging.debug('PID %d requires SIGTERM to abort to cleanup '
                              'container.', process.pid)
                return signal_queue_with_sigterm
        except subprocess.CalledProcessError:
            # Ignore errors, return the signal queue with SIGTERM to be safe.
            return signal_queue_with_sigterm
        # Default to kill the process with SIGKILL directly.
        return (signal.SIGKILL,)


    def kill_processes(self, process_list):
        """Send signals escalating in severity to the processes in process_list.

        @param process_list: A list of drone_manager.Process objects
                             representing the processes to kill.
        """
        try:
            logging.info('List of process to be killed: %s', process_list)
            processes_to_kill = {}
            for p in process_list:
                signal_queue = self.get_signal_queue_to_kill(p)
                processes_to_kill[signal_queue] = (
                        processes_to_kill.get(signal_queue, []) + [p])
            sig_counts = {}
            for signal_queue, processes in processes_to_kill.iteritems():
                sig_counts.update(utils.nuke_pids(
                        [-process.pid for process in processes],
                        signal_queue=signal_queue))
        except error.AutoservRunError as e:
            self._warn('Error occured when killing processes. Error: %s' % e)


    def _ensure_directory_exists(self, path):
        if not os.path.exists(path):
            os.makedirs(path)
            return
        if os.path.isdir(path):
            return
        assert os.path.isfile(path)
        if '/hosts/' in path:
            return
        raise IOError('Path %s exists as a file, not a directory')


    def execute_command(self, command, working_directory, log_file,
                        pidfile_name):
        out_file = None
        if log_file:
            self._ensure_directory_exists(os.path.dirname(log_file))
            try:
                out_file = open(log_file, 'a')
                separator = ('*' * 80) + '\n'
                out_file.write('\n' + separator)
                out_file.write("%s> %s\n" % (time.strftime("%X %x"), command))
                out_file.write(separator)
            except (OSError, IOError):
                pass

        if not out_file:
            out_file = open('/dev/null', 'w')

        in_devnull = open('/dev/null', 'r')

        self._ensure_directory_exists(working_directory)
        pidfile_path = os.path.join(working_directory, pidfile_name)
        if os.path.exists(pidfile_path):
            self._warn('Pidfile %s already exists' % pidfile_path)
            os.remove(pidfile_path)

        subprocess.Popen(command, stdout=out_file, stderr=subprocess.STDOUT,
                         stdin=in_devnull)
        out_file.close()
        in_devnull.close()


    def write_to_file(self, file_path, contents, is_retry=False):
        """Write the specified contents to the end of the given file.

        @param file_path: Path to the file.
        @param contents: Content to be written to the file.
        @param is_retry: True if this is a retry after file permission be
                         corrected.
        """
        self._ensure_directory_exists(os.path.dirname(file_path))
        try:
            file_object = open(file_path, 'a')
            file_object.write(contents)
            file_object.close()
        except IOError as e:
            # TODO(dshi): crbug.com/459344 Remove following retry when test
            # container can be unprivileged container.
            # If write failed with error 'Permission denied', one possible cause
            # is that the file was created in a container and thus owned by
            # root. If so, fix the file permission, and try again.
            if e.errno == 13 and not is_retry:
                logging.error('Error write to file %s: %s. Will be retried.',
                              file_path, e)
                utils.run('sudo chown %s "%s"' % (os.getuid(), file_path))
                utils.run('sudo chgrp %s "%s"' % (os.getgid(), file_path))
                self.write_to_file(file_path, contents, is_retry=True)
            else:
                self._warn('Error write to file %s: %s' % (file_path, e))


    def copy_file_or_directory(self, source_path, destination_path):
        """
        This interface is designed to match server.hosts.abstract_ssh.get_file
        (and send_file).  That is, if the source_path ends with a slash, the
        contents of the directory are copied; otherwise, the directory iself is
        copied.
        """
        if self._same_file(source_path, destination_path):
            return
        self._ensure_directory_exists(os.path.dirname(destination_path))
        if source_path.endswith('/'):
            # copying a directory's contents to another directory
            assert os.path.isdir(source_path)
            assert os.path.isdir(destination_path)
            for filename in os.listdir(source_path):
                self.copy_file_or_directory(
                    os.path.join(source_path, filename),
                    os.path.join(destination_path, filename))
        elif os.path.isdir(source_path):
            try:
                shutil.copytree(source_path, destination_path, symlinks=True)
            except shutil.Error:
                # Ignore copy directory error due to missing files. The cause
                # of this behavior is that, gs_offloader zips up folders with
                # too many files. There is a race condition that repair job
                # tries to copy provision job results to the test job result
                # folder, meanwhile gs_offloader is uploading the provision job
                # result and zipping up folders which contains too many files.
                pass
        elif os.path.islink(source_path):
            # copied from shutil.copytree()
            link_to = os.readlink(source_path)
            os.symlink(link_to, destination_path)
        else:
            try:
                shutil.copy(source_path, destination_path)
            except IOError:
                # Ignore copy error following the same above reason.
                pass


    def _same_file(self, source_path, destination_path):
        """Checks if the source and destination are the same

        Returns True if the destination is the same as the source, False
        otherwise. Also returns False if the destination does not exist.
        """
        if not os.path.exists(destination_path):
            return False
        return os.path.samefile(source_path, destination_path)


    def cleanup_orphaned_containers(self):
        """Run lxc_cleanup script to clean up orphaned container.
        """
        # The script needs to run with sudo as the containers are privileged.
        # TODO(dshi): crbug.com/459344 Call lxc_cleanup.main when test
        # container can be unprivileged container.
        command = ['sudo', LXC_CLEANUP_SCRIPT, '-x', '-v', '-l',
                   LXC_CLEANUP_LOG_FILE]
        logging.info('Running %s', command)
        # stdout and stderr needs to be direct to /dev/null, otherwise existing
        # of drone_utils process will kill lxc_cleanup script.
        subprocess.Popen(
                command, shell=False, stdin=None, stdout=open('/dev/null', 'w'),
                stderr=open('/dev/null', 'a'), preexec_fn=os.setpgrp)


    def wait_for_all_async_commands(self):
        for subproc in self._subcommands:
            subproc.fork_waitfor()
        self._subcommands = []


    def _poll_async_commands(self):
        still_running = []
        for subproc in self._subcommands:
            if subproc.poll() is None:
                still_running.append(subproc)
        self._subcommands = still_running


    def _wait_for_some_async_commands(self):
        self._poll_async_commands()
        max_processes = scheduler_config.config.max_transfer_processes
        while len(self._subcommands) >= max_processes:
            time.sleep(1)
            self._poll_async_commands()


    def run_async_command(self, function, args):
        subproc = subcommand.subcommand(function, args)
        self._subcommands.append(subproc)
        subproc.fork_start()


    def _sync_get_file_from(self, hostname, source_path, destination_path):
        logging.debug('_sync_get_file_from hostname: %s, source_path: %s,'
                      'destination_path: %s', hostname, source_path,
                      destination_path)
        self._ensure_directory_exists(os.path.dirname(destination_path))
        host = create_host(hostname)
        host.get_file(source_path, destination_path, delete_dest=True)


    def get_file_from(self, hostname, source_path, destination_path):
        self.run_async_command(self._sync_get_file_from,
                               (hostname, source_path, destination_path))


    def _sync_send_file_to(self, hostname, source_path, destination_path,
                           can_fail):
        logging.debug('_sync_send_file_to. hostname: %s, source_path: %s, '
                      'destination_path: %s, can_fail:%s', hostname,
                      source_path, destination_path, can_fail)
        host = create_host(hostname)
        try:
            host.run('mkdir -p ' + os.path.dirname(destination_path))
            host.send_file(source_path, destination_path, delete_dest=True)
        except error.AutoservError:
            if not can_fail:
                raise

            if os.path.isdir(source_path):
                failed_file = os.path.join(source_path, _TRANSFER_FAILED_FILE)
                file_object = open(failed_file, 'w')
                try:
                    file_object.write('%s:%s\n%s\n%s' %
                                      (hostname, destination_path,
                                       datetime.datetime.now(),
                                       traceback.format_exc()))
                finally:
                    file_object.close()
            else:
                copy_to = destination_path + _TRANSFER_FAILED_FILE
                self._ensure_directory_exists(os.path.dirname(copy_to))
                self.copy_file_or_directory(source_path, copy_to)


    def send_file_to(self, hostname, source_path, destination_path,
                     can_fail=False):
        self.run_async_command(self._sync_send_file_to,
                               (hostname, source_path, destination_path,
                                can_fail))


    def _report_long_execution(self, calls, duration):
        call_count = {}
        for call in calls:
            call_count.setdefault(call._method, 0)
            call_count[call._method] += 1
        call_summary = '\n'.join('%d %s' % (count, method)
                                 for method, count in call_count.iteritems())
        self._warn('Execution took %f sec\n%s' % (duration, call_summary))


    def execute_calls(self, calls):
        results = []
        start_time = time.time()
        max_processes = scheduler_config.config.max_transfer_processes
        for method_call in calls:
            results.append(method_call.execute_on(self))
            if len(self._subcommands) >= max_processes:
                self._wait_for_some_async_commands()
        self.wait_for_all_async_commands()

        duration = time.time() - start_time
        if duration > self._WARNING_DURATION:
            self._report_long_execution(calls, duration)

        warnings = self.warnings
        self.warnings = []
        return dict(results=results, warnings=warnings)


_MAX_REFRESH_POOL_SIZE = 50

class ProcessRefresher(object):
    """Object to refresh process information from give pidfiles.

    Usage: ProcessRefresh(True)(pidfile_list)
    """

    def __init__(self, check_mark, use_pool=False):
        """
        @param check_mark: If True, only consider processes that were
                explicitly marked by a former drone_utility call as autotest
                related processes.
        @param use_pool: If True, use a multiprocessing.Pool to parallelize
                costly operations.
        """
        self._check_mark = check_mark
        self._use_pool = use_pool
        self._pool = None


    def __call__(self, pidfile_paths):
        """
        @param pidfile_paths: A list of paths to check for pidfiles.

        @returns (result, warnings)
            where result is a dict with the following keys:
            - pidfiles: dict mapping pidfile paths to file contents, for
              pidfiles that exist.
            - all_processes: list of dicts corresponding to all running
              processes. Each dict contain pid, pgid, ppid, comm, and args (see
              "man ps" for details).
            - autoserv_processes: likewise, restricted to autoserv processes.
            - parse_processes: likewise, restricted to parse processes.
            - pidfiles_second_read: same info as pidfiles, but gathered after
              the processes are scanned.
            and warnings is a list of warnings genearted during process refresh.
        """

        if self._use_pool:
            pool_size = max(
                    min(len(pidfile_paths), _MAX_REFRESH_POOL_SIZE),
                    1)
            self._pool = multiprocessing.Pool(pool_size)
        else:
            pool_size = 0
        logging.info('Refreshing %d pidfiles with %d helper processes',
                     len(pidfile_paths), pool_size)

        warnings = []
        # It is necessary to explicitly force this to be a list because results
        # are pickled by DroneUtility.
        proc_infos = list(_get_process_info())

        autoserv_processes, extra_warnings = self._filter_proc_infos(
                proc_infos, 'autoserv')
        warnings += extra_warnings
        parse_processes, extra_warnings = self._filter_proc_infos(proc_infos,
                                                                  'parse')
        warnings += extra_warnings
        site_parse_processes, extra_warnings = self._filter_proc_infos(
                proc_infos, 'site_parse')
        warnings += extra_warnings

        result = {
                'pidfiles': self._read_pidfiles(pidfile_paths),
                'all_processes': proc_infos,
                'autoserv_processes': autoserv_processes,
                'parse_processes': (parse_processes + site_parse_processes),
                'pidfiles_second_read': self._read_pidfiles(pidfile_paths),
        }
        return result, warnings


    def _read_pidfiles(self, pidfile_paths):
        """Uses a process pool to read requested pidfile_paths."""
        if self._use_pool:
            contents = self._pool.map(_read_pidfile, pidfile_paths)
            contents = [c for c in contents if c is not None]
            return {k: v for k, v in contents}
        else:
            pidfiles = {}
            for path in pidfile_paths:
                content = _read_pidfile(path)
                if content is None:
                    continue
                pidfiles[content.path] = content.content
            return pidfiles


    def _filter_proc_infos(self, proc_infos, command_name):
        """Filters process info for the given command_name.

        Examines ps output as returned by get_process_info and return
        the process dicts for processes matching the given command name.

        @proc_infos: ps output as returned by _get_process_info.
        @param command_name: The name of the command, eg 'autoserv'.

        @return: (proc_infos, warnings) where proc_infos is a list of ProcInfo
                as returned by _get_process_info and warnings is a list of
                warnings generated while filtering.
                """
        proc_infos = [info for info in proc_infos
                      if info['comm'] == command_name]
        if not self._check_mark:
            return proc_infos, []

        if self._use_pool:
            dark_marks = self._pool.map(
                    _process_has_dark_mark,
                    [info['pid'] for info in proc_infos]
            )
        else:
            dark_marks = [_process_has_dark_mark(info['pid'])
                          for info in proc_infos]

        marked_proc_infos = []
        warnings = []
        for marked, info in itertools.izip(dark_marks, proc_infos):
            if marked:
                marked_proc_infos.append(info)
            else:
                warnings.append(
                        '%(comm)s process pid %(pid)s has no dark mark; '
                        'ignoring.' % info)
        return marked_proc_infos, warnings


def create_host(hostname):
    # TODO(crbug.com/739466) Delay import to avoid a ~0.7 second penalty
    # drone_utility calls that don't actually interact with DUTs.
    from autotest_lib.server import hosts
    username = global_config.global_config.get_config_value(
        'SCHEDULER', hostname + '_username', default=getpass.getuser())
    return hosts.SSHHost(hostname, user=username)


def parse_input():
    input_chunks = []
    chunk_of_input = sys.stdin.read()
    while chunk_of_input:
        input_chunks.append(chunk_of_input)
        chunk_of_input = sys.stdin.read()
    pickled_input = ''.join(input_chunks)

    try:
        return pickle.loads(pickled_input)
    except Exception:
        separator = '*' * 50
        raise ValueError('Unpickling input failed\n'
                         'Input: %r\n'
                         'Exception from pickle:\n'
                         '%s\n%s\n%s' %
                         (pickled_input, separator, traceback.format_exc(),
                          separator))


def _parse_args(args):
    parser = argparse.ArgumentParser(description='Local drone process manager.')
    parser.add_argument('--call_time',
                        help='Time this process was invoked from the master',
                        default=None, type=float)
    return parser.parse_args(args)


def return_data(data):
    print pickle.dumps(data)

def _process_has_dark_mark(pid):
    """Checks if a process was launched earlier by drone_utility.

    @param pid: The pid of the process to check.
    """
    try:
        with open('/proc/%s/environ' % pid, 'rb') as env_file:
            env_data = env_file.read()
    except EnvironmentError:
        return False
    return DARK_MARK_ENVIRONMENT_VAR in env_data


_PS_ARGS = ('pid', 'pgid', 'ppid', 'comm', 'args')
def _get_process_info():
    """Parse ps output for all process information.

    @returns A generator of dicts. Each dict has the following keys:
        - comm: command_name,
        - pgid: process group id,
        - ppid: parent process id,
        - pid: process id,
        - args: args the command was invoked with,
    """
    @retry.retry(subprocess.CalledProcessError,
                    timeout_min=0.5, delay_sec=0.25)
    def run_ps():
        return subprocess.check_output(
                ['/bin/ps', '--no-header', 'x', '-o', ','.join(_PS_ARGS)])

    ps_output = run_ps()
    # split each line into the columns output by ps
    split_lines = [line.split(None, 4) for line in ps_output.splitlines()]
    return (dict(itertools.izip(_PS_ARGS, line_components))
            for line_components in split_lines)


_PidfileContent = collections.namedtuple('_PidfileContent', ['path', 'content'])
def _read_pidfile(pidfile_path):
    """Reads the content of the given pidfile if it exists

    @param: pidfile_path: Path of the file to read.
    @returns: _PidfileContent tuple on success, None otherwise.
    """
    if not os.path.exists(pidfile_path):
        return None
    try:
        with open(pidfile_path, 'r') as file_object:
            return _PidfileContent(pidfile_path, file_object.read())
    except IOError:
        return None


def main():
    logging_manager.configure_logging(
            drone_logging_config.DroneLoggingConfig())
    calls = parse_input()
    args = _parse_args(sys.argv[1:])

    drone_utility = DroneUtility()
    return_value = drone_utility.execute_calls(calls)
    return_data(return_value)


if __name__ == '__main__':
    main()