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LSST Data Management Base Package
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utils.py
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1#!/usr/bin/env python
2#
3# LSST Data Management System
4#
5# Copyright 2016 AURA/LSST.
6#
7# This product includes software developed by the
8# LSST Project (http://www.lsst.org/).
9#
10# This program is free software: you can redistribute it and/or modify
11# it under the terms of the GNU General Public License as published by
12# the Free Software Foundation, either version 3 of the License, or
13# (at your option) any later version.
14#
15# This program is distributed in the hope that it will be useful,
16# but WITHOUT ANY WARRANTY; without even the implied warranty of
17# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18# GNU General Public License for more details.
19#
20# You should have received a copy of the LSST License Statement and
21# the GNU General Public License along with this program. If not,
22# see <https://www.lsstcorp.org/LegalNotices/>.
23#
24
25__all__ = [
26 "traceSetAt",
27 "temporaryLogLevel",
28 "LogRedirect",
29 "enable_notebook_logging",
30 "disable_notebook_logging",
31]
32
33from contextlib import contextmanager
34import os
35import sys
36import threading
37
38from lsst.log import Log
39
40
41def traceSetAt(name, number):
42 """Adjusts logging level to display messages with the trace number being
43 less than or equal to the provided value.
44
45 Parameters
46 ----------
47 name : `str`
48 Name of the logger.
49 number : `int`
50 The trace number threshold for display.
51 """
52 for i in range(6):
53 level = Log.INFO if i > number else Log.DEBUG
54 Log.getLogger('TRACE%d.%s' % (i, name)).setLevel(level)
55
56
57@contextmanager
58def temporaryLogLevel(name, level):
59 """A context manager that temporarily sets the level of a `Log`.
60
61 Parameters
62 ----------
63 name : `str`
64 Name of the log to modify.
65 level : `int`
66 Integer enumeration constant indicating the temporary log level.
67 """
68 log = Log.getLogger(name)
69 old = log.getLevel()
70 log.setLevel(level)
71 try:
72 yield
73 finally:
74 log.setLevel(old)
75
76
78 """Redirect a logging file descriptor to a Python stream.
79
80 Parameters
81 ----------
82 fd : `int`
83 File descriptor number, usually 1 for standard out, the default log
84 output location.
85 dest : `io.TextIOBase`
86 Destination text stream, often `sys.stderr` for ipython or Jupyter
87 notebooks.
88 encoding : `str`
89 Text encoding of the data written to fd.
90 errors : `str`
91 Encoding error handling.
92
93 Notes
94 -----
95 Inspired by `this Stack Overflow answer
96 <https://stackoverflow.com/questions/41216215>`_
97 """
98
99 def __init__(self, fd=1, dest=sys.stderr, encoding="utf-8", errors="strict"):
100 self._fd = fd
101 self._dest = dest
102 # Save original filehandle so we can restore it later.
103 self._filehandle = os.dup(fd)
104
105 # Redirect `fd` to the write end of the pipe.
106 pipe_read, pipe_write = os.pipe()
107 os.dup2(pipe_write, fd)
108 os.close(pipe_write)
109
110 # This thread reads from the read end of the pipe.
111 def consumer_thread(f, data):
112 while True:
113 buf = os.read(f, 1024)
114 if not buf:
115 break
116 data.write(buf.decode(encoding, errors))
117 os.close(f)
118 return
119
120 # Spawn consumer thread with the desired destination stream.
121 self._thread = threading.Thread(target=consumer_thread, args=(pipe_read, dest))
122 self._thread.start()
123
124 def finish(self):
125 """Stop redirecting output.
126 """
127
128 # Cleanup: flush streams, restore `fd`
129 self._dest.flush()
130 # This dup2 closes the saved file descriptor, which is now the write
131 # end of the pipe, causing the thread's read to terminate
132 os.dup2(self._filehandle, self._fd)
133 os.close(self._filehandle)
134 self._thread.join()
135
136
137_redirect = None
138
139
140def enable_notebook_logging(dest=sys.stderr):
141 """Enable notebook output for log4cxx messages."""
142 global _redirect
143 if _redirect is None:
144 _redirect = LogRedirect(dest=dest)
145
146
148 """Stop notebook output for log4cxx messages."""
149 global _redirect
150 if _redirect is not None:
151 _redirect.finish()
152 _redirect = None
__init__(self, fd=1, dest=sys.stderr, encoding="utf-8", errors="strict")
Definition utils.py:99
setLevel(loggername, level)
disable_notebook_logging()
Definition utils.py:147
enable_notebook_logging(dest=sys.stderr)
Definition utils.py:140
traceSetAt(name, number)
Definition utils.py:41
temporaryLogLevel(name, level)
Definition utils.py:58