1 # Copyright (C) 2010, 2012 Google Inc. All rights reserved. 2 # 3 # Redistribution and use in source and binary forms, with or without 4 # modification, are permitted provided that the following conditions are 5 # met: 6 # 7 # * Redistributions of source code must retain the above copyright 8 # notice, this list of conditions and the following disclaimer. 9 # * Redistributions in binary form must reproduce the above 10 # copyright notice, this list of conditions and the following disclaimer 11 # in the documentation and/or other materials provided with the 12 # distribution. 13 # * Neither the name of Google Inc. nor the names of its 14 # contributors may be used to endorse or promote products derived from 15 # this software without specific prior written permission. 16 # 17 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 18 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 19 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 20 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 21 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 22 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 23 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 24 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 25 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 26 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 27 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 28 29 import logging 30 import os 31 import sys 32 import time 33 34 LOG_HANDLER_NAME = 'MeteredStreamLogHandler' 35 36 37 class MeteredStream(object): 38 """ 39 This class implements a stream wrapper that has 'meters' as well as 40 regular output. A 'meter' is a single line of text that can be erased 41 and rewritten repeatedly, without producing multiple lines of output. It 42 can be used to produce effects like progress bars. 43 """ 44 45 @staticmethod 46 def _erasure(txt): 47 num_chars = len(txt) 48 return '\b' * num_chars + ' ' * num_chars + '\b' * num_chars 49 50 @staticmethod 51 def _ensure_newline(txt): 52 return txt if txt.endswith('\n') else txt + '\n' 53 54 def __init__(self, stream=None, verbose=False, logger=None, time_fn=None, pid=None, number_of_columns=None): 55 self._stream = stream or sys.stderr 56 self._verbose = verbose 57 self._time_fn = time_fn or time.time 58 self._pid = pid or os.getpid() 59 self._isatty = self._stream.isatty() 60 self._erasing = self._isatty and not verbose 61 self._last_partial_line = '' 62 self._last_write_time = 0.0 63 self._throttle_delay_in_secs = 0.066 if self._erasing else 10.0 64 self._number_of_columns = sys.maxint 65 if self._isatty and number_of_columns: 66 self._number_of_columns = number_of_columns 67 68 self._logger = logger 69 self._log_handler = None 70 if self._logger: 71 log_level = logging.DEBUG if verbose else logging.INFO 72 self._log_handler = _LogHandler(self) 73 self._log_handler.setLevel(log_level) 74 self._logger.addHandler(self._log_handler) 75 76 def __del__(self): 77 self.cleanup() 78 79 def cleanup(self): 80 if self._logger: 81 self._logger.removeHandler(self._log_handler) 82 self._log_handler = None 83 84 def write_throttled_update(self, txt): 85 now = self._time_fn() 86 if now - self._last_write_time >= self._throttle_delay_in_secs: 87 self.write_update(txt, now) 88 89 def write_update(self, txt, now=None): 90 self.write(txt, now) 91 if self._erasing: 92 self._last_partial_line = txt[txt.rfind('\n') + 1:] 93 94 def write(self, txt, now=None, pid=None): 95 now = now or self._time_fn() 96 pid = pid or self._pid 97 self._last_write_time = now 98 if self._last_partial_line: 99 self._erase_last_partial_line() 100 if self._verbose: 101 now_tuple = time.localtime(now) 102 msg = '%02d:%02d:%02d.%03d %d %s' % (now_tuple.tm_hour, now_tuple.tm_min, now_tuple.tm_sec, int((now * 1000) % 1000), pid, self._ensure_newline(txt)) 103 elif self._isatty: 104 msg = txt 105 else: 106 msg = self._ensure_newline(txt) 107 108 self._stream.write(msg) 109 110 def writeln(self, txt, now=None, pid=None): 111 self.write(self._ensure_newline(txt), now, pid) 112 113 def _erase_last_partial_line(self): 114 num_chars = len(self._last_partial_line) 115 self._stream.write(self._erasure(self._last_partial_line)) 116 self._last_partial_line = '' 117 118 def flush(self): 119 if self._last_partial_line: 120 self._stream.write('\n') 121 self._last_partial_line = '' 122 self._stream.flush() 123 124 def number_of_columns(self): 125 return self._number_of_columns 126 127 128 class _LogHandler(logging.Handler): 129 def __init__(self, meter): 130 logging.Handler.__init__(self) 131 self._meter = meter 132 self.name = LOG_HANDLER_NAME 133 134 def emit(self, record): 135 self._meter.writeln(record.getMessage(), record.created, record.process) 136
