tests/testlib/sigpipe-remote.py

interfaces: introduce and use a protocol class for the `mpatch` module

See f2832de2a46c for details when this was done for the `bdiff` module.

Two things worth pointing out-

  1) The `cffi` module "inherits" the `pure` implementation of `patchedsize()`
     because of its wildcard import.
  2) It's odd that the `mpatchError` lives in both `pure` and `cext` modules.

I initially thought to move the exception into the new class, and make the
existing class name an alias to the class in the new location, but the exception
is created in C code by the `cext` module, so that won't work.  I don't think a
protocol class is approriate, because there's nothing special about the class to
distinguish from any other `Exception`.  Fortunately, nobody is catching this
exception in core, so we can kick the can down the road.

#!/usr/bin/env python3

import io
import os
import subprocess
import sys
import time


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


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')