mirror of
https://github.com/pre-commit/pre-commit.git
synced 2026-01-13 04:20:28 -06:00
147 lines
4.3 KiB
Python
147 lines
4.3 KiB
Python
from __future__ import absolute_import
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from __future__ import division
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from __future__ import unicode_literals
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import concurrent.futures
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import contextlib
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import math
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import os
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import sys
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import six
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from pre_commit import parse_shebang
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from pre_commit.util import cmd_output
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def _environ_size(_env=None):
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environ = _env if _env is not None else getattr(os, 'environb', os.environ)
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size = 8 * len(environ) # number of pointers in `envp`
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for k, v in environ.items():
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size += len(k) + len(v) + 2 # c strings in `envp`
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return size
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def _get_platform_max_length(): # pragma: no cover (platform specific)
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if os.name == 'posix':
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maximum = os.sysconf(str('SC_ARG_MAX')) - 2048 - _environ_size()
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maximum = max(min(maximum, 2 ** 17), 2 ** 12)
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return maximum
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elif os.name == 'nt':
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return 2 ** 15 - 2048 # UNICODE_STRING max - headroom
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else:
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# posix minimum
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return 2 ** 12
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def _command_length(*cmd):
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full_cmd = ' '.join(cmd)
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# win32 uses the amount of characters, more details at:
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# https://github.com/pre-commit/pre-commit/pull/839
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if sys.platform == 'win32':
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# the python2.x apis require bytes, we encode as UTF-8
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if six.PY2:
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return len(full_cmd.encode('utf-8'))
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else:
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return len(full_cmd.encode('utf-16le')) // 2
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else:
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return len(full_cmd.encode(sys.getfilesystemencoding()))
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class ArgumentTooLongError(RuntimeError):
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pass
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def partition(cmd, varargs, target_concurrency, _max_length=None):
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_max_length = _max_length or _get_platform_max_length()
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# Generally, we try to partition evenly into at least `target_concurrency`
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# partitions, but we don't want a bunch of tiny partitions.
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max_args = max(4, math.ceil(len(varargs) / target_concurrency))
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cmd = tuple(cmd)
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ret = []
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ret_cmd = []
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# Reversed so arguments are in order
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varargs = list(reversed(varargs))
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total_length = _command_length(*cmd) + 1
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while varargs:
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arg = varargs.pop()
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arg_length = _command_length(arg) + 1
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if (
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total_length + arg_length <= _max_length and
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len(ret_cmd) < max_args
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):
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ret_cmd.append(arg)
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total_length += arg_length
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elif not ret_cmd:
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raise ArgumentTooLongError(arg)
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else:
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# We've exceeded the length, yield a command
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ret.append(cmd + tuple(ret_cmd))
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ret_cmd = []
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total_length = _command_length(*cmd) + 1
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varargs.append(arg)
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ret.append(cmd + tuple(ret_cmd))
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return tuple(ret)
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@contextlib.contextmanager
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def _thread_mapper(maxsize):
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if maxsize == 1:
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yield map
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else:
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with concurrent.futures.ThreadPoolExecutor(maxsize) as ex:
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yield ex.map
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def xargs(cmd, varargs, **kwargs):
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"""A simplified implementation of xargs.
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negate: Make nonzero successful and zero a failure
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target_concurrency: Target number of partitions to run concurrently
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"""
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negate = kwargs.pop('negate', False)
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target_concurrency = kwargs.pop('target_concurrency', 1)
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max_length = kwargs.pop('_max_length', _get_platform_max_length())
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retcode = 0
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stdout = b''
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stderr = b''
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try:
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cmd = parse_shebang.normalize_cmd(cmd)
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except parse_shebang.ExecutableNotFoundError as e:
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return e.to_output()
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partitions = partition(cmd, varargs, target_concurrency, max_length)
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def run_cmd_partition(run_cmd):
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return cmd_output(*run_cmd, encoding=None, retcode=None, **kwargs)
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threads = min(len(partitions), target_concurrency)
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with _thread_mapper(threads) as thread_map:
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results = thread_map(run_cmd_partition, partitions)
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for proc_retcode, proc_out, proc_err in results:
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# This is *slightly* too clever so I'll explain it.
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# First the xor boolean table:
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# T | F |
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# +-------+
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# T | F | T |
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# --+-------+
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# F | T | F |
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# --+-------+
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# When negate is True, it has the effect of flipping the return
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# code. Otherwise, the returncode is unchanged.
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retcode |= bool(proc_retcode) ^ negate
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stdout += proc_out
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stderr += proc_err
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return retcode, stdout, stderr
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