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[extract_log] Improve extract_log script #559

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merged 3 commits into from
Apr 3, 2018
Merged

[extract_log] Improve extract_log script #559

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3c9c915
[extract_log] Improve extract_log script
yxieca Apr 2, 2018
1491086
Combine pre-handling code with original code
yxieca Apr 3, 2018
82b9c05
Address review issue.
yxieca Apr 3, 2018
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14 changes: 11 additions & 3 deletions ansible/library/extract_log.py
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Original file line number Diff line number Diff line change
Expand Up @@ -92,7 +92,12 @@ def extract_line(directory, filename, target_string):
file = open(path)
result = None
with file:
result = [(filename, line) for line in file if target_string in line and 'nsible' not in line]
# This might be a gunzip file or logrotate issue, there has
# been '\x00's in front of the log entry timestamp which
# messes up with the comparator.
# Prehandle lines to remove these sub-strings
result = [(filename, line.replace('\x00', '')) for line in file if target_string in line and 'nsible' not in line]

return result


Expand Down Expand Up @@ -159,9 +164,12 @@ def extract_latest_line_with_string(directory, filenames, start_string):
for filename in filenames:
target_lines.extend(extract_line(directory, filename, start_string))

sorted_target_lines = sorted(target_lines, cmp=comparator)
target = target_lines[0] if len(target_lines) > 0 else None
for line in target_lines:
if comparator(line, target) > 0:
target = line
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What is the difference from

sorted(target_lines, cmp=comparator)

?

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Sort is sorting the whole array. The best of sorting algorithm is O(N * Log(N)).

We only need the latest entry, which can be obtained by the loop in O(N).

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This is not a huge optimization by itself. I had to open the sort call to debug. And since we could get what we need faster, I figured why not :-)

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in this case you can use max() function from python which is O(N) and just one-liner

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@yxieca yxieca Apr 3, 2018 •
edited
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As we discussed in person. max doesn't take cmp=... parameter and the (key= lamda) method needs to extend string class.


return sorted_target_lines[-1]
return target


def calculate_files_to_copy(filenames, file_with_latest_line):
Expand Down