view tests/killdaemons.py @ 49378:094a5fa3cf52 stable 6.2

procutil: make stream detection in make_line_buffered more correct and strict

In make_line_buffered(), we don’t want to wrap the stream if we know that lines
get flushed to the underlying raw stream already.

Previously, the heuristic was too optimistic. It assumed that any stream which
is not an instance of io.BufferedIOBase doesn’t need wrapping. However, there
are buffered streams that aren’t instances of io.BufferedIOBase, like
Mercurial’s own winstdout.

The new logic is different in two ways:

First, only for the check, if unwraps any combination of WriteAllWrapper and
winstdout.

Second, it skips wrapping the stream only if it is an instance of io.RawIOBase
(or already wrapped). If it is an instance of io.BufferedIOBase, it gets
wrapped. In any other case, the function raises an exception. This ensures
that, if an unknown stream is passed or we add another wrapper in the future,
we don’t wrap the stream if it’s already line buffered or not wrap the stream
if it’s not line buffered. In fact, this was already helpful during development
of this change. Without it, I possibly would have forgot that WriteAllWrapper
needs to be ignored for the check, leading to unnecessary wrapping if stdout is
unbuffered.

The alternative would have been to always wrap unknown streams. However, I
don’t think that anyone would benefit from being less strict. We can expect
streams from the standard library to be subclassing either io.RawIOBase or
io.BufferedIOBase, so running Mercurial in the standard way should not regress
by this change. Py2exe might replace sys.stdout and sys.stderr, but that
currently breaks Mercurial anyway and also these streams don’t claim to be
interactive, so this function is not called for them.

#!/usr/bin/env python3

import os
import signal
import sys
import time

if os.name == 'nt':
    import ctypes

    _BOOL = ctypes.c_long
    _DWORD = ctypes.c_ulong
    _UINT = ctypes.c_uint
    _HANDLE = ctypes.c_void_p

    ctypes.windll.kernel32.CloseHandle.argtypes = [_HANDLE]
    ctypes.windll.kernel32.CloseHandle.restype = _BOOL

    ctypes.windll.kernel32.GetLastError.argtypes = []
    ctypes.windll.kernel32.GetLastError.restype = _DWORD

    ctypes.windll.kernel32.OpenProcess.argtypes = [_DWORD, _BOOL, _DWORD]
    ctypes.windll.kernel32.OpenProcess.restype = _HANDLE

    ctypes.windll.kernel32.TerminateProcess.argtypes = [_HANDLE, _UINT]
    ctypes.windll.kernel32.TerminateProcess.restype = _BOOL

    ctypes.windll.kernel32.WaitForSingleObject.argtypes = [_HANDLE, _DWORD]
    ctypes.windll.kernel32.WaitForSingleObject.restype = _DWORD

    def _check(ret, expectederr=None):
        if ret == 0:
            winerrno = ctypes.GetLastError()
            if winerrno == expectederr:
                return True
            raise ctypes.WinError(winerrno)

    def kill(pid, logfn, tryhard=True):
        logfn('# Killing daemon process %d' % pid)
        PROCESS_TERMINATE = 1
        PROCESS_QUERY_INFORMATION = 0x400
        SYNCHRONIZE = 0x00100000
        WAIT_OBJECT_0 = 0
        WAIT_TIMEOUT = 258
        WAIT_FAILED = _DWORD(0xFFFFFFFF).value
        handle = ctypes.windll.kernel32.OpenProcess(
            PROCESS_TERMINATE | SYNCHRONIZE | PROCESS_QUERY_INFORMATION,
            False,
            pid,
        )
        if handle is None:
            _check(0, 87)  # err 87 when process not found
            return  # process not found, already finished
        try:
            r = ctypes.windll.kernel32.WaitForSingleObject(handle, 100)
            if r == WAIT_OBJECT_0:
                pass  # terminated, but process handle still available
            elif r == WAIT_TIMEOUT:
                _check(ctypes.windll.kernel32.TerminateProcess(handle, -1))
            elif r == WAIT_FAILED:
                _check(0)  # err stored in GetLastError()

            # TODO?: forcefully kill when timeout
            #        and ?shorter waiting time? when tryhard==True
            r = ctypes.windll.kernel32.WaitForSingleObject(handle, 100)
            # timeout = 100 ms
            if r == WAIT_OBJECT_0:
                pass  # process is terminated
            elif r == WAIT_TIMEOUT:
                logfn('# Daemon process %d is stuck')
            elif r == WAIT_FAILED:
                _check(0)  # err stored in GetLastError()
        except:  # re-raises
            ctypes.windll.kernel32.CloseHandle(handle)  # no _check, keep error
            raise
        _check(ctypes.windll.kernel32.CloseHandle(handle))


else:

    def kill(pid, logfn, tryhard=True):
        try:
            os.kill(pid, 0)
            logfn('# Killing daemon process %d' % pid)
            os.kill(pid, signal.SIGTERM)
            if tryhard:
                for i in range(10):
                    time.sleep(0.05)
                    os.kill(pid, 0)
            else:
                time.sleep(0.1)
                os.kill(pid, 0)
            logfn('# Daemon process %d is stuck - really killing it' % pid)
            os.kill(pid, signal.SIGKILL)
        except ProcessLookupError:
            pass


def killdaemons(pidfile, tryhard=True, remove=False, logfn=None):
    if not logfn:
        logfn = lambda s: s
    # Kill off any leftover daemon processes
    try:
        pids = []
        with open(pidfile) as fp:
            for line in fp:
                try:
                    pid = int(line)
                    if pid <= 0:
                        raise ValueError
                except ValueError:
                    logfn(
                        '# Not killing daemon process %s - invalid pid'
                        % line.rstrip()
                    )
                    continue
                pids.append(pid)
        for pid in pids:
            kill(pid, logfn, tryhard)
        if remove:
            os.unlink(pidfile)
    except IOError:
        pass


if __name__ == '__main__':
    if len(sys.argv) > 1:
        (path,) = sys.argv[1:]
    else:
        path = os.environ["DAEMON_PIDS"]

    killdaemons(path, remove=True)