view hglib/util.py @ 189:8054e925d9c7

client: kill the server on unrecoverable communication errors (issue5516)

Once an unrecoverable communication error occurs between the client and server,
it's no longer safe to send further commands to the same server.
On Windows, attempting to do so is known to cause lockups and memory leaks.

Close the client and kill the server when an such an error occurs. This way,
any further commands will fail gracefully with ValueError until the client
is reopened.

import os, subprocess, sys
from hglib import error
try:
    from io import BytesIO
except ImportError:
    from cStringIO import StringIO as BytesIO

if sys.version_info[0] > 2:
    izip = zip
    integertypes = (int,)

    def b(s):
        """Encode the string as bytes."""
        return s.encode('latin-1')
else:
    from itertools import izip
    integertypes = (long, int)
    bytes = str  # Defined in Python 2.6/2.7, but to the same value.

    def b(s):
        """Encode the string as bytes."""
        return s

def strtobytes(s):
    """Return the bytes of the string representation of an object."""
    return str(s).encode('latin-1')

def grouper(n, iterable):
    ''' list(grouper(2, range(4))) -> [(0, 1), (2, 3)] '''
    args = [iter(iterable)] * n
    return izip(*args)

def eatlines(s, n):
    """
    >>> eatlines(b("1\\n2"), 1) == b('2')
    True
    >>> eatlines(b("1\\n2"), 2) == b('')
    True
    >>> eatlines(b("1\\n2"), 3) == b('')
    True
    >>> eatlines(b("1\\n2\\n3"), 1) == b('2\\n3')
    True
    """
    cs = BytesIO(s)

    for line in cs:
        n -= 1
        if n == 0:
            return cs.read()
    return b('')

def skiplines(s, prefix):
    """
    Skip lines starting with prefix in s

    >>> skiplines(b('a\\nb\\na\\n'), b('a')) == b('b\\na\\n')
    True
    >>> skiplines(b('a\\na\\n'), b('a')) == b('')
    True
    >>> skiplines(b(''), b('a')) == b('')
    True
    >>> skiplines(b('a\\nb'), b('b')) == b('a\\nb')
    True
    """
    cs = BytesIO(s)

    for line in cs:
        if not line.startswith(prefix):
            return line + cs.read()

    return b('')

def _cmdval(val):
    if isinstance(val, bytes):
        return val
    else:
        return strtobytes(val)

def cmdbuilder(name, *args, **kwargs):
    """
    A helper for building the command arguments

    args are the positional arguments

    kwargs are the options
    keys that are single lettered are prepended with '-', others with '--',
    underscores are replaced with dashes

    keys with False boolean values are ignored, lists add the key multiple times

    None arguments are skipped

    >>> cmdbuilder(b('cmd'), a=True, b=False, c=None) == [b('cmd'), b('-a')]
    True
    >>> cmdbuilder(b('cmd'), long=True) == [b('cmd'), b('--long')]
    True
    >>> cmdbuilder(b('cmd'), str=b('s')) == [b('cmd'), b('--str'), b('s')]
    True
    >>> cmdbuilder(b('cmd'), d_ash=True) == [b('cmd'), b('--d-ash')]
    True
    >>> cmdbuilder(b('cmd'), _=True) == [b('cmd'), b('-')]
    True
    >>> expect = [b('cmd'), b('--list'), b('1'), b('--list'), b('2')]
    >>> cmdbuilder(b('cmd'), list=[1, 2]) == expect
    True
    >>> cmdbuilder(b('cmd'), None) == [b('cmd')]
    True
    """
    cmd = [name]
    for arg, val in kwargs.items():
        if val is None:
            continue

        arg = arg.encode('latin-1').replace(b('_'), b('-'))
        if arg != b('-'):
            if len(arg) == 1:
                arg = b('-') + arg
            else:
                arg = b('--') + arg
        if isinstance(val, bool):
            if val:
                cmd.append(arg)
        elif isinstance(val, list):
            for v in val:
                cmd.append(arg)
                cmd.append(_cmdval(v))
        else:
            cmd.append(arg)
            cmd.append(_cmdval(val))

    for a in args:
        if a is not None:
            cmd.append(a)

    return cmd

class reterrorhandler(object):
    """This class is meant to be used with rawcommand() error handler
    argument. It remembers the return value the command returned if
    it's one of allowed values, which is only 1 if none are given.
    Otherwise it raises a CommandError.

    >>> e = reterrorhandler('')
    >>> bool(e)
    True
    >>> e(1, 'a', '')
    'a'
    >>> bool(e)
    False

    """
    def __init__(self, args, allowed=None):
        self.args = args
        self.ret = 0
        if allowed is None:
            self.allowed = [1]
        else:
            self.allowed = allowed

    def __call__(self, ret, out, err):
        self.ret = ret
        if ret not in self.allowed:
            raise error.CommandError(self.args, ret, out, err)
        return out

    def __nonzero__(self):
        """ Returns True if the return code was 0, False otherwise """
        return self.ret == 0

    def __bool__(self):
        return self.__nonzero__()

class propertycache(object):
    """
    Decorator that remembers the return value of a function call.

    >>> execcount = 0
    >>> class obj(object):
    ...     def func(self):
    ...         global execcount
    ...         execcount += 1
    ...         return []
    ...     func = propertycache(func)
    >>> o = obj()
    >>> o.func
    []
    >>> execcount
    1
    >>> o.func
    []
    >>> execcount
    1
    """
    def __init__(self, func):
        self.func = func
        self.name = func.__name__
    def __get__(self, obj, type=None):
        result = self.func(obj)
        setattr(obj, self.name, result)
        return result

close_fds = os.name == 'posix'

startupinfo = None
if os.name == 'nt':
    startupinfo = subprocess.STARTUPINFO()
    startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW

def popen(args, env=None):
    environ = None
    if env:
        environ = dict(os.environ)
        environ.update(env)

    return subprocess.Popen(args, stdin=subprocess.PIPE, stdout=subprocess.PIPE,
                            stderr=subprocess.PIPE, close_fds=close_fds,
                            startupinfo=startupinfo, env=environ)