annotate tests/testlib/sigpipe-remote.py @ 47618:27ff81547d35

sigpipe-remote: simply delegate pipe forwarding to subprocess we can kill

Instead of using sophisticated logics with thread a non blocking pipes, we
simply spawn two new process in charge of reading the pipe and sending the
result to the client. When it is time to cut the pipe we violently kill them
without any remorse. This close the pipe regardless of any in progress `os.read`
call.

Ironically this is the very same things as what the initial shell setup was
doing, but in Python.

This makes the test pass run properly on Windows. This also reveal that the
Windows behavior is broken as the transaction is not properly rollback. However
this is an adventure for another time. Making the test behave properly was
enough effort.

Differential Revision: https://phab.mercurial-scm.org/D11087

#!/usr/bin/env python3
from __future__ import print_function

import io
import os
import subprocess
import sys
import time

# we cannot use mercurial.testing as long as python2 is not dropped as the test will only install the mercurial module for python2 in python2 run

if isinstance(sys.stdout.buffer, io.BufferedWriter):
    print('SIGPIPE-HELPER: script need unbuffered output', file=sys.stderr)
    sys.exit(255)

DEBUG_FILE = os.environ.get('SIGPIPE_REMOTE_DEBUG_FILE')
if DEBUG_FILE is None:
    debug_stream = sys.stderr.buffer
else:
    debug_stream = open(DEBUG_FILE, 'bw', buffering=0)

SYNCFILE1 = os.environ.get('SYNCFILE1')
SYNCFILE2 = os.environ.get('SYNCFILE2')
if SYNCFILE1 is None:
    print('SIGPIPE-HELPER: missing variable $SYNCFILE1', file=sys.stderr)
    sys.exit(255)
if SYNCFILE2 is None:
    print('SIGPIPE-HELPER: missing variable $SYNCFILE2', file=sys.stderr)
    sys.exit(255)


def _timeout_factor():
    """return the current modification to timeout"""
    default = int(os.environ.get('HGTEST_TIMEOUT_DEFAULT', 360))
    current = int(os.environ.get('HGTEST_TIMEOUT', default))
    if current == 0:
        return 1
    return current / float(default)


def wait_file(path, timeout=10):
    timeout *= _timeout_factor()
    start = time.time()
    while not os.path.exists(path):
        if (time.time() - start) > timeout:
            raise RuntimeError(b"timed out waiting for file: %s" % path)
        time.sleep(0.01)


def write_file(path, content=b''):
    with open(path, 'wb') as f:
        f.write(content)


# end of mercurial.testing content

if sys.version_info[0] < 3:
    print('SIGPIPE-HELPER: script should run with Python 3', file=sys.stderr)
    sys.exit(255)


def sysbytes(s):
    return s.encode('utf-8')


def sysstr(s):
    return s.decode('latin-1')


debug_stream.write(b'SIGPIPE-HELPER: Starting\n')

TESTLIB_DIR = os.path.dirname(sys.argv[0])
WAIT_SCRIPT = os.path.join(TESTLIB_DIR, 'wait-on-file')

hooks_cmd = '%s 10 %s %s'
hooks_cmd %= (
    WAIT_SCRIPT,
    SYNCFILE2,
    SYNCFILE1,
)

try:
    cmd = ['hg']
    cmd += sys.argv[1:]
    sub = subprocess.Popen(
        cmd,
        bufsize=0,
        close_fds=True,
        stdin=sys.stdin,
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE,
    )

    basedir = os.path.dirname(sys.argv[0])
    worker = os.path.join(basedir, 'sigpipe-worker.py')

    cmd = [sys.executable, worker]

    stdout_worker = subprocess.Popen(
        cmd,
        bufsize=0,
        close_fds=True,
        stdin=sub.stdout,
        stdout=sys.stdout,
        stderr=sys.stderr,
    )

    stderr_worker = subprocess.Popen(
        cmd,
        bufsize=0,
        close_fds=True,
        stdin=sub.stderr,
        stdout=sys.stderr,
        stderr=sys.stderr,
    )
    debug_stream.write(b'SIGPIPE-HELPER: Redirection in place\n')
    os.close(sub.stdout.fileno())
    os.close(sub.stderr.fileno())
    debug_stream.write(b'SIGPIPE-HELPER: pipes closed in main\n')

    try:
        wait_file(sysbytes(SYNCFILE1))
    except RuntimeError as exc:
        msg = sysbytes(str(exc))
        debug_stream.write(b'SIGPIPE-HELPER: wait failed: %s\n' % msg)
    else:
        debug_stream.write(b'SIGPIPE-HELPER: SYNCFILE1 detected\n')
    stdout_worker.kill()
    stderr_worker.kill()
    stdout_worker.wait(10)
    stderr_worker.wait(10)
    debug_stream.write(b'SIGPIPE-HELPER: worker killed\n')

    debug_stream.write(b'SIGPIPE-HELPER: creating SYNCFILE2\n')
    write_file(sysbytes(SYNCFILE2))
finally:
    debug_stream.write(b'SIGPIPE-HELPER: Shutting down\n')
    if not sys.stdin.closed:
        sys.stdin.close()
    try:
        sub.wait(timeout=30)
    except subprocess.TimeoutExpired:
        msg = b'SIGPIPE-HELPER: Server process failed to terminate\n'
        debug_stream.write(msg)
        sub.kill()
        sub.wait()
        msg = b'SIGPIPE-HELPER: Server process killed\n'
    else:
        msg = b'SIGPIPE-HELPER: Server process terminated with status %d\n'
        msg %= sub.returncode
        debug_stream.write(msg)
    debug_stream.write(b'SIGPIPE-HELPER: Shut down\n')