wtimediff

#!/usr/bin/env python
# wtimediff (part of ossobv/vcutil) // wdoekes/2015 // Public Domain
#
# Reads log files from stdin and outputs the time difference between
# consecutive lines.
#
# Usage:
#
#   $ wtimediff < logfile
#   (outputs log lines preceded by the time offset since the previous line)
#
# Example:
#
#   $ printf 'abc 12:12:12.12\n18:18:18 foo\n0:00:00.666666 bar\n' |
#       wtimediff
#
# Output:
#
#   >       0.0      abc 12:12:12.12
#   >  +21965.88     18:18:18 foo
#   >  +20502.666666 0:00:00.666666 bar
#
# Limitations:
#
#   * Matches time strings [H]H:MM:SS[.sss...] only and ignores date
#     strings completely.
#   * Alternatively, matches unixtime (1650218400), if only that is
#     found on the line.
#
from datetime import datetime, timedelta
import re
import sys


# Match the first occurrence of H:MM:SS.sss...
time_re = re.compile(r'(?:^|.*?[^\d])(\d{1,2}):(\d{2}):(\d{2})(?:\.(\d+))?')
unixtime_re = re.compile(r'(?:^|.*?[^\d])([1-9][0-9]{9})(?:$|[^\d])')
prevtime = None

for line in sys.stdin:
    match = time_re.match(line)
    try:
        if match:
            hour, min_, sec, usec = match.groups()
            hour, min_, sec = int(hour), int(min_), int(sec)
            usec = int(('%s000000' % (usec or 0,))[0:6])
            if prevtime:
                curtime = datetime(
                    prevtime.year, prevtime.month, prevtime.day,
                    hour, min_, sec, usec)
                if curtime < prevtime:
                    curtime += timedelta(days=1)
                assert (curtime - prevtime).days == 0
            else:
                # May fail for bad times with ValuError.
                curtime = datetime(1970, 1, 1, hour, min_, sec, usec)
        else:
            match = unixtime_re.match(line)
            if match:
                curtime = datetime.fromtimestamp(int(match.groups()[0]))
            else:
                raise ValueError('No time found')

        if not prevtime:
            diff = '0.0' + (' ' * 5)
        else:
            td = (curtime - prevtime)
            diff = '%+6d.%-6s' % (  # 1+5+1+6=13
                td.seconds,
                ('%06d' % (td.microseconds,)).rstrip('0') or '0')
        prevtime = curtime

        sys.stdout.write(' %13s %s' % (diff, line))

    except ValueError:  # from datetime()
        sys.stderr.write('(skipped: %s)\n' % (line.strip(),))

# vim: set ts=8 sw=4 sts=4 et ai: