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# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this file,
# You can obtain one at
# This file contains logging functionality for mach. It essentially provides
# support for a structured logging framework built on top of Python's built-in
# logging framework.
from __future__ import absolute_import, unicode_literals
import blessings
except ImportError:
blessings = None
import codecs
import json
import logging
import six
import sys
import time
# stdout and stderr may not necessarily be set up to write Unicode output, so
# reconfigure them if necessary.
def _wrap_stdstream(fh):
if fh in (sys.stderr, sys.stdout):
encoding = sys.getdefaultencoding()
encoding = "utf-8" if encoding in ("ascii", "charmap") else encoding
if six.PY2:
return codecs.getwriter(encoding)(fh, errors="replace")
return codecs.getwriter(encoding)(fh.buffer, errors="replace")
return fh
def format_seconds(total):
"""Format number of seconds to MM:SS.DD form."""
minutes, seconds = divmod(total, 60)
return "%2d:%05.2f" % (minutes, seconds)
class ConvertToStructuredFilter(logging.Filter):
"""Filter that converts unstructured records into structured ones."""
def filter(self, record):
if hasattr(record, "action") and hasattr(record, "params"):
return True
record.action = "unstructured"
record.params = {"msg": record.getMessage()}
record.msg = "{msg}"
return True
class StructuredJSONFormatter(logging.Formatter):
"""Log formatter that writes a structured JSON entry."""
def format(self, record):
action = getattr(record, "action", "UNKNOWN")
params = getattr(record, "params", {})
return json.dumps([record.created, action, params])
class StructuredHumanFormatter(logging.Formatter):
"""Log formatter that writes structured messages for humans.
It is important that this formatter never be added to a logger that
produces unstructured/classic log messages. If it is, the call to format()
could fail because the string could contain things (like JSON) that look
like formatting character sequences.
Because of this limitation, format() will fail with a KeyError if an
unstructured record is passed or if the structured message is malformed.
def __init__(self, start_time, write_interval=False, write_times=True):
self.start_time = start_time
self.write_interval = write_interval
self.write_times = write_times
self.last_time = None
def format(self, record):
f = record.msg.format(**record.params)
if not self.write_times:
return f
elapsed = self._time(record)
return "%s %s" % (format_seconds(elapsed), f)
def _time(self, record):
t = record.created - self.start_time
if self.write_interval and self.last_time is not None:
t = record.created - self.last_time
self.last_time = record.created
return t
class StructuredTerminalFormatter(StructuredHumanFormatter):
"""Log formatter for structured messages writing to a terminal."""
def set_terminal(self, terminal):
self.terminal = terminal
self._sgr0 = terminal.normal if terminal and blessings else ""
def format(self, record):
f = record.msg.format(**record.params)
if not self.write_times:
return f
t =
# Some processes (notably Clang) don't reset terminal attributes after
# printing newlines. This can lead to terminal attributes getting in a
# wonky state. Work around this by sending the sgr0 sequence after every
# line to reset all attributes. For programs that rely on the next line
# inheriting the same attributes, this will prevent that from happening.
# But that's better than "corrupting" the terminal.
return "%s %s%s" % (t, self._colorize(f), self._sgr0)
def _colorize(self, s):
if not self.terminal:
return s
result = s
reftest = s.startswith("REFTEST ")
if reftest:
s = s[8:]
if s.startswith("TEST-PASS"):
result =[0:9]) + s[9:]
elif s.startswith("TEST-UNEXPECTED"):
result =[0:20]) + s[20:]
elif s.startswith("TEST-START"):
result = self.terminal.yellow(s[0:10]) + s[10:]
elif s.startswith("TEST-INFO"):
result = self.terminal.yellow(s[0:9]) + s[9:]
if reftest:
result = "REFTEST " + result
return result
class LoggingManager(object):
"""Holds and controls global logging state.
An application should instantiate one of these and configure it as needed.
This class provides a mechanism to configure the output of logging data
both from mach and from the overall logging system (e.g. from other
def __init__(self):
self.start_time = time.time()
self.json_handlers = []
self.terminal_handler = None
self.terminal_formatter = None
self.root_logger = logging.getLogger()
# Installing NullHandler on the root logger ensures that *all* log
# messages have at least one handler. This prevents Python from
# complaining about "no handlers could be found for logger XXX."
mach_logger = logging.getLogger("mach")
self.structured_filter = ConvertToStructuredFilter()
self.structured_loggers = [mach_logger]
self._terminal = None
def terminal(self):
if not self._terminal and blessings:
# Sometimes blessings fails to set up the terminal. In that case,
# silently fail.
terminal = blessings.Terminal(stream=_wrap_stdstream(sys.stdout))
if terminal.is_a_tty:
self._terminal = terminal
except Exception:
return self._terminal
def add_json_handler(self, fh):
"""Enable JSON logging on the specified file object."""
# Configure the consumer of structured messages.
handler = logging.StreamHandler(stream=fh)
# And hook it up.
for logger in self.structured_loggers:
def add_terminal_logging(
self, fh=sys.stdout, level=logging.INFO, write_interval=False, write_times=True
"""Enable logging to the terminal."""
fh = _wrap_stdstream(fh)
formatter = StructuredHumanFormatter(
self.start_time, write_interval=write_interval, write_times=write_times
if self.terminal:
formatter = StructuredTerminalFormatter(
self.start_time, write_interval=write_interval, write_times=write_times
handler = logging.StreamHandler(stream=fh)
for logger in self.structured_loggers:
self.terminal_handler = handler
self.terminal_formatter = formatter
def replace_terminal_handler(self, handler):
"""Replace the installed terminal handler.
Returns the old handler or None if none was configured.
If the new handler is None, removes any existing handler and disables
logging to the terminal.
old = self.terminal_handler
if old:
for logger in self.structured_loggers:
if handler:
for logger in self.structured_loggers:
self.terminal_handler = handler
return old
def enable_unstructured(self):
"""Enable logging of unstructured messages."""
if self.terminal_handler:
def disable_unstructured(self):
"""Disable logging of unstructured messages."""
if self.terminal_handler:
def register_structured_logger(self, logger, terminal=True, json=True):
"""Register a structured logger.
This needs to be called for all structured loggers that don't chain up
to the mach logger in order for their output to be captured.
if terminal and self.terminal_handler:
if json:
for handler in self.json_handlers:
def enable_all_structured_loggers(self, terminal=True, json=True):
"""Enable logging of all structured messages from all loggers.
``terminal`` and ``json`` determine which log handlers to operate
on. By default, all known handlers are operated on.
# Glean makes logs that we're not interested in, so we squelch them.
# Remove current handlers from all loggers so we don't double
# register handlers.
for logger in self.root_logger.manager.loggerDict.values():
# Some entries might be logging.PlaceHolder.
if not isinstance(logger, logging.Logger):
if terminal:
if json:
for handler in self.json_handlers:
# Wipe out existing registered structured loggers since they
# all propagate to root logger.
self.structured_loggers = []
self.register_structured_logger(self.root_logger, terminal=terminal, json=json)