Function xargs

pre_commit/xargs.py:131–184

A simplified implementation of xargs. color: Make a pty if on a platform that supports it target_concurrency: Target number of partitions to run concurrently

(
        cmd: tuple[str, ...],
        varargs: Sequence[str],
        *,
        color: bool = False,
        target_concurrency: int = 1,
        _max_length: int = _get_platform_max_length(),
        **kwargs: Any,
)

def xargs(
        cmd: tuple[str, ...],
        varargs: Sequence[str],
        *,
        color: bool = False,
        target_concurrency: int = 1,
        _max_length: int = _get_platform_max_length(),
        **kwargs: Any,
) -> tuple[int, bytes]:
    """A simplified implementation of xargs.

    color: Make a pty if on a platform that supports it
    target_concurrency: Target number of partitions to run concurrently
    """
    cmd_fn = cmd_output_p if color else cmd_output_b
    retcode = 0
    stdout = b''

    try:
        cmd = parse_shebang.normalize_cmd(cmd)
    except parse_shebang.ExecutableNotFoundError as e:
        return e.to_output()[:2]

    # on windows, batch files have a separate length limit than windows itself
    if (
            sys.platform == 'win32' and
            cmd[0].lower().endswith(('.bat', '.cmd'))
    ):  # pragma: win32 cover
        # this is implementation details but the command gets translated into
        # full/path/to/cmd.exe /c *cmd
        cmd_exe = parse_shebang.find_executable('cmd.exe')
        # 1024 is additionally subtracted to give headroom for further
        # expansion inside the batch file
        _max_length = 8192 - len(cmd_exe) - len(' /c ') - 1024

    partitions = partition(cmd, varargs, target_concurrency, _max_length)

    def run_cmd_partition(
            run_cmd: tuple[str, ...],
    ) -> tuple[int, bytes, bytes | None]:
        return cmd_fn(
            *run_cmd, check=False, stderr=subprocess.STDOUT, **kwargs,
        )

    threads = min(len(partitions), target_concurrency)
    with _thread_mapper(threads) as thread_map:
        results = thread_map(run_cmd_partition, partitions)

        for proc_retcode, proc_out, _ in results:
            if abs(proc_retcode) > abs(retcode):
                retcode = proc_retcode
            stdout += proc_out

    return retcode, stdout