# Copyright 2013-2024 Lawrence Livermore National Security, LLC and other
# Spack Project Developers. See the top-level COPYRIGHT file for details.
#
# SPDX-License-Identifier: (Apache-2.0 OR MIT)
"""Utility classes for logging the output of blocks of code.
"""
import atexit
import ctypes
import errno
import io
import multiprocessing
import os
import re
import select
import signal
import sys
import threading
import traceback
from contextlib import contextmanager
from threading import Thread
from types import ModuleType
from typing import Optional
import llnl.util.tty as tty
termios: Optional[ModuleType] = None
try:
import termios as term_mod
termios = term_mod
except ImportError:
pass
# Use this to strip escape sequences
_escape = re.compile(r"\x1b[^m]*m|\x1b\[?1034h|\x1b\][0-9]+;[^\x07]*\x07")
# control characters for enabling/disabling echo
#
# We use control characters to ensure that echo enable/disable are inline
# with the other output. We always follow these with a newline to ensure
# one per line the following newline is ignored in output.
xon, xoff = "\x11\n", "\x13\n"
control = re.compile("(\x11\n|\x13\n)")
[docs]
@contextmanager
def ignore_signal(signum):
"""Context manager to temporarily ignore a signal."""
old_handler = signal.signal(signum, signal.SIG_IGN)
try:
yield
finally:
signal.signal(signum, old_handler)
def _is_background_tty(stream):
"""True if the stream is a tty and calling process is in the background."""
return stream.isatty() and os.getpgrp() != os.tcgetpgrp(stream.fileno())
def _strip(line):
"""Strip color and control characters from a line."""
return _escape.sub("", line)
[docs]
class Unbuffered:
"""Wrapper for Python streams that forces them to be unbuffered.
This is implemented by forcing a flush after each write.
"""
def __init__(self, stream):
self.stream = stream
[docs]
def write(self, data):
self.stream.write(data)
self.stream.flush()
[docs]
def writelines(self, datas):
self.stream.writelines(datas)
self.stream.flush()
def __getattr__(self, attr):
return getattr(self.stream, attr)
def _file_descriptors_work(*streams):
"""Whether we can get file descriptors for the streams specified.
This tries to call ``fileno()`` on all streams in the argument list,
and returns ``False`` if anything goes wrong.
This can happen, when, e.g., the test framework replaces stdout with
a ``StringIO`` object.
We have to actually try this to see whether it works, rather than
checking for the fileno attribute, beacuse frameworks like pytest add
dummy fileno methods on their dummy file objects that return
``UnsupportedOperationErrors``.
"""
# test whether we can get fds for out and error
try:
for stream in streams:
stream.fileno()
return True
except BaseException:
return False
[docs]
class FileWrapper:
"""Represents a file. Can be an open stream, a path to a file (not opened
yet), or neither. When unwrapped, it returns an open file (or file-like)
object.
"""
def __init__(self, file_like):
# This records whether the file-like object returned by "unwrap" is
# purely in-memory. In that case a subprocess will need to explicitly
# transmit the contents to the parent.
self.write_in_parent = False
self.file_like = file_like
if isinstance(file_like, str):
self.open = True
elif _file_descriptors_work(file_like):
self.open = False
else:
self.file_like = None
self.open = True
self.write_in_parent = True
self.file = None
[docs]
def unwrap(self):
if self.open:
if self.file_like:
self.file = open(self.file_like, "w", encoding="utf-8")
else:
self.file = io.StringIO()
return self.file
else:
# We were handed an already-open file object. In this case we also
# will not actually close the object when requested to.
return self.file_like
[docs]
def close(self):
if self.file:
self.file.close()
[docs]
class MultiProcessFd:
"""Return an object which stores a file descriptor and can be passed as an
argument to a function run with ``multiprocessing.Process``, such that
the file descriptor is available in the subprocess."""
def __init__(self, fd):
self._connection = None
self._fd = None
if sys.version_info >= (3, 8):
self._connection = multiprocessing.connection.Connection(fd)
else:
self._fd = fd
@property
def fd(self):
if self._connection:
return self._connection._handle
else:
return self._fd
[docs]
def close(self):
if self._connection:
self._connection.close()
else:
os.close(self._fd)
[docs]
def close_connection_and_file(multiprocess_fd, file):
# MultiprocessFd is intended to transmit a FD
# to a child process, this FD is then opened to a Python File object
# (using fdopen). In >= 3.8, MultiprocessFd encapsulates a
# multiprocessing.connection.Connection; Connection closes the FD
# when it is deleted, and prints a warning about duplicate closure if
# it is not explicitly closed. In < 3.8, MultiprocessFd encapsulates a
# simple FD; closing the FD here appears to conflict with
# closure of the File object (in < 3.8 that is). Therefore this needs
# to choose whether to close the File or the Connection.
if sys.version_info >= (3, 8):
multiprocess_fd.close()
else:
file.close()
[docs]
@contextmanager
def replace_environment(env):
"""Replace the current environment (`os.environ`) with `env`.
If `env` is empty (or None), this unsets all current environment
variables.
"""
env = env or {}
old_env = os.environ.copy()
try:
os.environ.clear()
for name, val in env.items():
os.environ[name] = val
yield
finally:
os.environ.clear()
for name, val in old_env.items():
os.environ[name] = val
[docs]
def log_output(*args, **kwargs):
"""Context manager that logs its output to a file.
In the simplest case, the usage looks like this::
with log_output('logfile.txt'):
# do things ... output will be logged
Any output from the with block will be redirected to ``logfile.txt``.
If you also want the output to be echoed to ``stdout``, use the
``echo`` parameter::
with log_output('logfile.txt', echo=True):
# do things ... output will be logged and printed out
The following is available on Unix only. No-op on Windows.
And, if you just want to echo *some* stuff from the parent, use
``force_echo``::
with log_output('logfile.txt', echo=False) as logger:
# do things ... output will be logged
with logger.force_echo():
# things here will be echoed *and* logged
See individual log classes for more information.
This method is actually a factory serving a per platform
(unix vs windows) log_output class
"""
if sys.platform == "win32":
return winlog(*args, **kwargs)
else:
return nixlog(*args, **kwargs)
[docs]
class nixlog:
"""
Under the hood, we spawn a daemon and set up a pipe between this
process and the daemon. The daemon writes our output to both the
file and to stdout (if echoing). The parent process can communicate
with the daemon to tell it when and when not to echo; this is what
force_echo does. You can also enable/disable echoing by typing 'v'.
We try to use OS-level file descriptors to do the redirection, but if
stdout or stderr has been set to some Python-level file object, we
use Python-level redirection instead. This allows the redirection to
work within test frameworks like nose and pytest.
"""
def __init__(
self, file_like=None, echo=False, debug=0, buffer=False, env=None, filter_fn=None
):
"""Create a new output log context manager.
Args:
file_like (str or stream): open file object or name of file where
output should be logged
echo (bool): whether to echo output in addition to logging it
debug (int): positive to enable tty debug mode during logging
buffer (bool): pass buffer=True to skip unbuffering output; note
this doesn't set up any *new* buffering
filter_fn (callable, optional): Callable[str] -> str to filter each
line of output
log_output can take either a file object or a filename. If a
filename is passed, the file will be opened and closed entirely
within ``__enter__`` and ``__exit__``. If a file object is passed,
this assumes the caller owns it and will close it.
By default, we unbuffer sys.stdout and sys.stderr because the
logger will include output from executed programs and from python
calls. If stdout and stderr are buffered, their output won't be
printed in the right place w.r.t. output from commands.
Logger daemon is not started until ``__enter__()``.
"""
self.file_like = file_like
self.echo = echo
self.debug = debug
self.buffer = buffer
self.env = env # the environment to use for _writer_daemon
self.filter_fn = filter_fn
self._active = False # used to prevent re-entry
def __call__(self, file_like=None, echo=None, debug=None, buffer=None):
"""This behaves the same as init. It allows a logger to be reused.
Arguments are the same as for ``__init__()``. Args here take
precedence over those passed to ``__init__()``.
With the ``__call__`` function, you can save state between uses
of a single logger. This is useful if you want to remember,
e.g., the echo settings for a prior ``with log_output()``::
logger = log_output()
with logger('foo.txt'):
# log things; user can change echo settings with 'v'
with logger('bar.txt'):
# log things; logger remembers prior echo settings.
"""
if file_like is not None:
self.file_like = file_like
if echo is not None:
self.echo = echo
if debug is not None:
self.debug = debug
if buffer is not None:
self.buffer = buffer
return self
def __enter__(self):
if self._active:
raise RuntimeError("Can't re-enter the same log_output!")
if self.file_like is None:
raise RuntimeError("file argument must be set by either __init__ or __call__")
# set up a stream for the daemon to write to
self.log_file = FileWrapper(self.file_like)
# record parent color settings before redirecting. We do this
# because color output depends on whether the *original* stdout
# is a TTY. New stdout won't be a TTY so we force colorization.
self._saved_color = tty.color._force_color
forced_color = tty.color.get_color_when()
# also record parent debug settings -- in case the logger is
# forcing debug output.
self._saved_debug = tty._debug
# OS-level pipe for redirecting output to logger
read_fd, write_fd = os.pipe()
read_multiprocess_fd = MultiProcessFd(read_fd)
# Multiprocessing pipe for communication back from the daemon
# Currently only used to save echo value between uses
self.parent_pipe, child_pipe = multiprocessing.Pipe()
# Sets a daemon that writes to file what it reads from a pipe
try:
# need to pass this b/c multiprocessing closes stdin in child.
input_multiprocess_fd = None
try:
if sys.stdin.isatty():
input_multiprocess_fd = MultiProcessFd(os.dup(sys.stdin.fileno()))
except BaseException:
# just don't forward input if this fails
pass
with replace_environment(self.env):
self.process = multiprocessing.Process(
target=_writer_daemon,
args=(
input_multiprocess_fd,
read_multiprocess_fd,
write_fd,
self.echo,
self.log_file,
child_pipe,
self.filter_fn,
),
)
self.process.daemon = True # must set before start()
self.process.start()
finally:
if input_multiprocess_fd:
input_multiprocess_fd.close()
read_multiprocess_fd.close()
# Flush immediately before redirecting so that anything buffered
# goes to the original stream
sys.stdout.flush()
sys.stderr.flush()
# Now do the actual output redirection.
self.use_fds = _file_descriptors_work(sys.stdout, sys.stderr)
if self.use_fds:
# We try first to use OS-level file descriptors, as this
# redirects output for subprocesses and system calls.
# Save old stdout and stderr file descriptors
self._saved_stdout = os.dup(sys.stdout.fileno())
self._saved_stderr = os.dup(sys.stderr.fileno())
# redirect to the pipe we created above
os.dup2(write_fd, sys.stdout.fileno())
os.dup2(write_fd, sys.stderr.fileno())
os.close(write_fd)
else:
# Handle I/O the Python way. This won't redirect lower-level
# output, but it's the best we can do, and the caller
# shouldn't expect any better, since *they* have apparently
# redirected I/O the Python way.
# Save old stdout and stderr file objects
self._saved_stdout = sys.stdout
self._saved_stderr = sys.stderr
# create a file object for the pipe; redirect to it.
pipe_fd_out = os.fdopen(write_fd, "w")
sys.stdout = pipe_fd_out
sys.stderr = pipe_fd_out
# Unbuffer stdout and stderr at the Python level
if not self.buffer:
sys.stdout = Unbuffered(sys.stdout)
sys.stderr = Unbuffered(sys.stderr)
# Force color and debug settings now that we have redirected.
tty.color.set_color_when(forced_color)
tty._debug = self.debug
# track whether we're currently inside this log_output
self._active = True
# return this log_output object so that the user can do things
# like temporarily echo some output.
return self
def __exit__(self, exc_type, exc_val, exc_tb):
# Flush any buffered output to the logger daemon.
sys.stdout.flush()
sys.stderr.flush()
# restore previous output settings, either the low-level way or
# the python way
if self.use_fds:
os.dup2(self._saved_stdout, sys.stdout.fileno())
os.close(self._saved_stdout)
os.dup2(self._saved_stderr, sys.stderr.fileno())
os.close(self._saved_stderr)
else:
sys.stdout = self._saved_stdout
sys.stderr = self._saved_stderr
# print log contents in parent if needed.
if self.log_file.write_in_parent:
string = self.parent_pipe.recv()
self.file_like.write(string)
# recover and store echo settings from the child before it dies
try:
self.echo = self.parent_pipe.recv()
except EOFError:
# This may occur if some exception prematurely terminates the
# _writer_daemon. An exception will have already been generated.
pass
# now that the write pipe is closed (in this __exit__, when we restore
# stdout with dup2), the logger daemon process loop will terminate. We
# wait for that here.
self.process.join()
# restore old color and debug settings
tty.color._force_color = self._saved_color
tty._debug = self._saved_debug
self._active = False # safe to enter again
[docs]
@contextmanager
def force_echo(self):
"""Context manager to force local echo, even if echo is off."""
if not self._active:
raise RuntimeError("Can't call force_echo() outside log_output region!")
# This uses the xon/xoff to highlight regions to be echoed in the
# output. We us these control characters rather than, say, a
# separate pipe, because they're in-band and assured to appear
# exactly before and after the text we want to echo.
sys.stdout.write(xon)
sys.stdout.flush()
try:
yield
finally:
sys.stdout.write(xoff)
sys.stdout.flush()
[docs]
class StreamWrapper:
"""Wrapper class to handle redirection of io streams"""
def __init__(self, sys_attr):
self.sys_attr = sys_attr
self.saved_stream = None
if sys.platform.startswith("win32"):
if hasattr(sys, "gettotalrefcount"): # debug build
libc = ctypes.CDLL("ucrtbased")
else:
libc = ctypes.CDLL("api-ms-win-crt-stdio-l1-1-0")
kernel32 = ctypes.WinDLL("kernel32")
# https://docs.microsoft.com/en-us/windows/console/getstdhandle
if self.sys_attr == "stdout":
STD_HANDLE = -11
elif self.sys_attr == "stderr":
STD_HANDLE = -12
else:
raise KeyError(self.sys_attr)
c_stdout = kernel32.GetStdHandle(STD_HANDLE)
self.libc = libc
self.c_stream = c_stdout
else:
self.libc = ctypes.CDLL(None)
self.c_stream = ctypes.c_void_p.in_dll(self.libc, self.sys_attr)
self.sys_stream = getattr(sys, self.sys_attr)
self.orig_stream_fd = self.sys_stream.fileno()
# Save a copy of the original stdout fd in saved_stream
self.saved_stream = os.dup(self.orig_stream_fd)
[docs]
def redirect_stream(self, to_fd):
"""Redirect stdout to the given file descriptor."""
# Flush the C-level buffer stream
if sys.platform.startswith("win32"):
self.libc.fflush(None)
else:
self.libc.fflush(self.c_stream)
# Flush and close sys_stream - also closes the file descriptor (fd)
sys_stream = getattr(sys, self.sys_attr)
sys_stream.flush()
sys_stream.close()
# Make orig_stream_fd point to the same file as to_fd
os.dup2(to_fd, self.orig_stream_fd)
# Set sys_stream to a new stream that points to the redirected fd
new_buffer = open(self.orig_stream_fd, "wb")
new_stream = io.TextIOWrapper(new_buffer)
setattr(sys, self.sys_attr, new_stream)
self.sys_stream = getattr(sys, self.sys_attr)
[docs]
def flush(self):
if sys.platform.startswith("win32"):
self.libc.fflush(None)
else:
self.libc.fflush(self.c_stream)
self.sys_stream.flush()
[docs]
def close(self):
"""Redirect back to the original system stream, and close stream"""
try:
if self.saved_stream is not None:
self.redirect_stream(self.saved_stream)
finally:
if self.saved_stream is not None:
os.close(self.saved_stream)
[docs]
class winlog:
"""
Similar to nixlog, with underlying
functionality ported to support Windows.
Does not support the use of 'v' toggling as nixlog does.
"""
def __init__(
self, file_like=None, echo=False, debug=0, buffer=False, env=None, filter_fn=None
):
self.env = env
self.debug = debug
self.echo = echo
self.logfile = file_like
self.stdout = StreamWrapper("stdout")
self.stderr = StreamWrapper("stderr")
self._active = False
self._ioflag = False
self.old_stdout = sys.stdout
self.old_stderr = sys.stderr
def __enter__(self):
if self._active:
raise RuntimeError("Can't re-enter the same log_output!")
if self.logfile is None:
raise RuntimeError("file argument must be set by __init__ ")
# Open both write and reading on logfile
if isinstance(self.logfile, io.StringIO):
self._ioflag = True
# cannot have two streams on tempfile, so we must make our own
sys.stdout = self.logfile
sys.stderr = self.logfile
else:
self.writer = open(self.logfile, mode="wb+")
self.reader = open(self.logfile, mode="rb+")
# Dup stdout so we can still write to it after redirection
self.echo_writer = open(os.dup(sys.stdout.fileno()), "w")
# Redirect stdout and stderr to write to logfile
self.stderr.redirect_stream(self.writer.fileno())
self.stdout.redirect_stream(self.writer.fileno())
self._kill = threading.Event()
def background_reader(reader, echo_writer, _kill):
# for each line printed to logfile, read it
# if echo: write line to user
try:
while True:
is_killed = _kill.wait(0.1)
# Flush buffered build output to file
# stdout/err fds refer to log file
self.stderr.flush()
self.stdout.flush()
line = reader.readline()
if self.echo and line:
echo_writer.write("{0}".format(line.decode()))
echo_writer.flush()
if is_killed:
break
finally:
reader.close()
self._active = True
with replace_environment(self.env):
self._thread = Thread(
target=background_reader, args=(self.reader, self.echo_writer, self._kill)
)
self._thread.start()
return self
def __exit__(self, exc_type, exc_val, exc_tb):
if self._ioflag:
sys.stdout = self.old_stdout
sys.stderr = self.old_stderr
self._ioflag = False
else:
self.writer.close()
self.echo_writer.flush()
self.stdout.flush()
self.stderr.flush()
self._kill.set()
self._thread.join()
self.stdout.close()
self.stderr.close()
self._active = False
[docs]
@contextmanager
def force_echo(self):
"""Context manager to force local echo, even if echo is off."""
if not self._active:
raise RuntimeError("Can't call force_echo() outside log_output region!")
yield
def _writer_daemon(
stdin_multiprocess_fd,
read_multiprocess_fd,
write_fd,
echo,
log_file_wrapper,
control_pipe,
filter_fn,
):
"""Daemon used by ``log_output`` to write to a log file and to ``stdout``.
The daemon receives output from the parent process and writes it both
to a log and, optionally, to ``stdout``. The relationship looks like
this::
Terminal
|
| +-------------------------+
| | Parent Process |
+--------> | with log_output(): |
| stdin | ... |
| +-------------------------+
| ^ | write_fd (parent's redirected stdout)
| | control |
| | pipe |
| | v read_fd
| +-------------------------+ stdout
| | Writer daemon |------------>
+--------> | read from read_fd | log_file
stdin | write to out and log |------------>
+-------------------------+
Within the ``log_output`` handler, the parent's output is redirected
to a pipe from which the daemon reads. The daemon writes each line
from the pipe to a log file and (optionally) to ``stdout``. The user
can hit ``v`` to toggle output on ``stdout``.
In addition to the input and output file descriptors, the daemon
interacts with the parent via ``control_pipe``. It reports whether
``stdout`` was enabled or disabled when it finished and, if the
``log_file`` is a ``StringIO`` object, then the daemon also sends the
logged output back to the parent as a string, to be written to the
``StringIO`` in the parent. This is mainly for testing.
Arguments:
stdin_multiprocess_fd (int): input from the terminal
read_multiprocess_fd (int): pipe for reading from parent's redirected
stdout
echo (bool): initial echo setting -- controlled by user and
preserved across multiple writer daemons
log_file_wrapper (FileWrapper): file to log all output
control_pipe (Pipe): multiprocessing pipe on which to send control
information to the parent
filter_fn (callable, optional): function to filter each line of output
"""
# If this process was forked, then it will inherit file descriptors from
# the parent process. This process depends on closing all instances of
# write_fd to terminate the reading loop, so we close the file descriptor
# here. Forking is the process spawning method everywhere except Mac OS
# for Python >= 3.8 and on Windows
if sys.version_info < (3, 8) or sys.platform != "darwin":
os.close(write_fd)
# 1. Use line buffering (3rd param = 1) since Python 3 has a bug
# that prevents unbuffered text I/O.
# 2. Python 3.x before 3.7 does not open with UTF-8 encoding by default
in_pipe = os.fdopen(read_multiprocess_fd.fd, "r", 1, encoding="utf-8")
if stdin_multiprocess_fd:
stdin = os.fdopen(stdin_multiprocess_fd.fd)
else:
stdin = None
# list of streams to select from
istreams = [in_pipe, stdin] if stdin else [in_pipe]
force_echo = False # parent can force echo for certain output
log_file = log_file_wrapper.unwrap()
try:
with keyboard_input(stdin) as kb:
while True:
# fix the terminal settings if we recently came to
# the foreground
kb.check_fg_bg()
# wait for input from any stream. use a coarse timeout to
# allow other checks while we wait for input
rlist, _, _ = _retry(select.select)(istreams, [], [], 1e-1)
# Allow user to toggle echo with 'v' key.
# Currently ignores other chars.
# only read stdin if we're in the foreground
if stdin in rlist and not _is_background_tty(stdin):
# it's possible to be backgrounded between the above
# check and the read, so we ignore SIGTTIN here.
with ignore_signal(signal.SIGTTIN):
try:
if stdin.read(1) == "v":
echo = not echo
except IOError as e:
# If SIGTTIN is ignored, the system gives EIO
# to let the caller know the read failed b/c it
# was in the bg. Ignore that too.
if e.errno != errno.EIO:
raise
if in_pipe in rlist:
line_count = 0
try:
while line_count < 100:
# Handle output from the calling process.
try:
line = _retry(in_pipe.readline)()
except UnicodeDecodeError:
# installs like --test=root gpgme produce non-UTF8 logs
line = "<line lost: output was not encoded as UTF-8>\n"
if not line:
return
line_count += 1
# find control characters and strip them.
clean_line, num_controls = control.subn("", line)
# Echo to stdout if requested or forced.
if echo or force_echo:
output_line = clean_line
if filter_fn:
output_line = filter_fn(clean_line)
sys.stdout.write(output_line)
# Stripped output to log file.
log_file.write(_strip(clean_line))
if num_controls > 0:
controls = control.findall(line)
if xon in controls:
force_echo = True
if xoff in controls:
force_echo = False
if not _input_available(in_pipe):
break
finally:
if line_count > 0:
if echo or force_echo:
sys.stdout.flush()
log_file.flush()
except BaseException:
tty.error("Exception occurred in writer daemon!")
traceback.print_exc()
finally:
# send written data back to parent if we used a StringIO
if isinstance(log_file, io.StringIO):
control_pipe.send(log_file.getvalue())
log_file_wrapper.close()
close_connection_and_file(read_multiprocess_fd, in_pipe)
if stdin_multiprocess_fd:
close_connection_and_file(stdin_multiprocess_fd, stdin)
# send echo value back to the parent so it can be preserved.
control_pipe.send(echo)
def _retry(function):
"""Retry a call if errors indicating an interrupted system call occur.
Interrupted system calls return -1 and set ``errno`` to ``EINTR`` if
certain flags are not set. Newer Pythons automatically retry them,
but older Pythons do not, so we need to retry the calls.
This function converts a call like this:
syscall(args)
and makes it retry by wrapping the function like this:
_retry(syscall)(args)
This is a private function because EINTR is unfortunately raised in
different ways from different functions, and we only handle the ones
relevant for this file.
"""
def wrapped(*args, **kwargs):
while True:
try:
return function(*args, **kwargs)
except IOError as e:
if e.errno == errno.EINTR:
continue
raise
except select.error as e:
if e.args[0] == errno.EINTR:
continue
raise
return wrapped
def _input_available(f):
return f in select.select([f], [], [], 0)[0]