[
https://issues.apache.org/jira/browse/AUTOTAG-24?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Hubert Law updated AUTOTAG-24:
-------------------------------
Description:
Despite AUTOTAG-21 the regex still eats up CPU time due to the inefficiency of
the pattern {{s*$}} which, in case of long consecutive white-space in the
middle of the body, consumes O(n^2^) time while failing to match (since it will
attempt to start matching at each white space position).
Matching the actual non-whitespace content directly may be more efficient in
this case, e.g
{code:java}
private static final Pattern PATTERN =
Pattern.compile("^\\s*(\\S(?:.*\\S)?)\\s*$");
if (body != null) {
final Matcher matcher = PATTERN.matcher(body);
if (matcher.matches()) {
body = matcher.group(1);
} else {
body = null;
}
}{code}
Backtracking is limited to the final white spaces, in linear time.
was:
Despite AUTOTAG-21 the regex still eats up CPU time due to the inefficiency of
the pattern {{s*$}} which, in case of long consecutive white-space in the
middle of the body, consumes O(n^2^) time while failing to match (since it will
attempt to start matching at each white space position).
Matching the actual non-whitespace content directly may be more efficient in
this case, e.g
{{private static final Pattern PATTERN =
Pattern.compile("}}{{^\\s*(\\S(?:.*\\S)?)\\s*$");}}
{{if (body != null) {}}
{{ final Matcher matcher = PATTERN.matcher(body);}}
{{ if (matcher.matches()) {}}
{{ body = matcher.group(1);}}
{{ } else {}}
{{ body = null;}}
{{ } }}
{{}}}
Backtracking is limited to the final white spaces, in linear time.
> Efficiency of regular expression under AbstractModelBody.evaluateAsString
> --------------------------------------------------------------------------
>
> Key: AUTOTAG-24
> URL: https://issues.apache.org/jira/browse/AUTOTAG-24
> Project: Tiles Autotag
> Issue Type: Improvement
> Affects Versions: 1.2.0
> Reporter: Hubert Law
> Priority: Minor
> Labels: regex
>
> Despite AUTOTAG-21 the regex still eats up CPU time due to the inefficiency
> of the pattern {{s*$}} which, in case of long consecutive white-space in the
> middle of the body, consumes O(n^2^) time while failing to match (since it
> will attempt to start matching at each white space position).
> Matching the actual non-whitespace content directly may be more efficient in
> this case, e.g
> {code:java}
> private static final Pattern PATTERN =
> Pattern.compile("^\\s*(\\S(?:.*\\S)?)\\s*$");
> if (body != null) {
> final Matcher matcher = PATTERN.matcher(body);
> if (matcher.matches()) {
> body = matcher.group(1);
> } else {
> body = null;
> }
> }{code}
> Backtracking is limited to the final white spaces, in linear time.
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