tests/testlib/sigpipe-remote.py

fix: highlight the required configuration and behavior of the fixer tools

The problem is that `hg help fix` didn't mention *how* to configure the tools,
and while I knew that `{rootpath}` existed in the configuration, I missed that
the tools require reading content from stdin.  (I configured `gofmt` to use
`{rootpath}`, and that had the effect of squashing all changes in a file at `.`
into the first commit and emptying that content from its descendants.)

Basically all this does is put a pointer in the default (command level) help to
the extension level help that mentions the configuration, and moves the
extension level help that documents reading from stdin and writing to stdout to
the top to give it more prominence.  The last sentence is adjusted a bit to
reflect the new location.

#!/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')