[Sitemaps] limit on "bad url" log messages

[sebastian-nagel]

If a sitemap is erroneously detected as plain-text sitemap (cf. #144), SiteMapParser may report all or most of the file content as "bad url". This may result

• either in many log messages:

2016-12-22 13:55:26.628 c.s.SiteMapParser [WARN] Bad url: [<?xml version="1.0" encoding="UTF-8"?>]
2016-12-22 13:55:26.628 c.s.SiteMapParser [WARN] Bad url: [<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:news="http://www.google.com/schemas/sitemap-news/0.9">]
2016-12-22 13:55:26.628 c.s.SiteMapParser [WARN] Bad url: [                <url>]
2016-12-22 13:55:26.628 c.s.SiteMapParser [WARN] Bad url: [        <loc>http://www.azonline.de/Sport/Fussball/1.-Bundesliga/2640159-Hamburger-SV-Bruchhagen-Lasse-mich-bei-der-Sportchef-Suche-nicht-hetzen</loc>]
2016-12-22 13:55:26.628 c.s.SiteMapParser [WARN] Bad url: [        <news:news>]
2016-12-22 13:55:26.628 c.s.SiteMapParser [WARN] Bad url: [            <news:publication>]
2016-12-22 13:55:26.628 c.s.SiteMapParser [WARN] Bad url: [                <news:name>Allgemeine Zeitung</news:name>]
2016-12-22 13:55:26.628 c.s.SiteMapParser [WARN] Bad url: [                <news:language>ger</news:language>]
2016-12-22 13:55:26.628 c.s.SiteMapParser [WARN] Bad url: [            </news:publication>]
2016-12-22 13:55:26.628 c.s.SiteMapParser [WARN] Bad url: [            <news:publication_date>2016-12-22T14:52:00Z</news:publication_date>]
2016-12-22 13:55:26.628 c.s.SiteMapParser [WARN] Bad url: [            <news:title>Hamburger SV : Bruchhagen: Lasse mich bei der Sportchef-Suche nicht hetzen</news:title>]
2016-12-22 13:55:26.628 c.s.SiteMapParser [WARN] Bad url: [        </news:news>]
2016-12-22 13:55:26.628 c.s.SiteMapParser [WARN] Bad url: [    </url>]
2016-12-22 13:55:26.628 c.s.SiteMapParser [WARN] Bad url: [                        <url>]
... (5000 lines following)

• or even in one very long message (more than 180 kB in a single line):

2016-12-22 14:43:22.173 c.s.SiteMapParser [WARN] Bad url: [<?xml version="1.0" encoding="UTF-8"?> <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" xmlns:n="http://www.google.com/schemas/sitemap-news/0.9"> <url> <loc>http://www.hotnews.ro/stiri-politic-21489493-liviu-dragnea-cer-public-serviciilor-secrete-spuna-daca-exista-vreo-problema-securitate-legata-sotul-premierului-propus-sevil-shhaideh.htm</loc> <n:news> <n:publication> <n:name>HotNews.ro</n:name> <n:language>ro</n:language> </n:publication> <n:genres>PressRelease</n:genres> <publication_date>2016-12-22T16:16:35</publication_date> <n:title><![CDATA[Liviu Dragnea: Cer public serviciilor secrete sa spuna daca exista vreo problema de securitate legata de sotul premierului propus Sevil Shhaideh]]></n:title> <n:keywords><![CDATA[]]></n:keywords> </n:news> </url> ...

There should be a limit on both the max. number of lines and the line length, logged as error. This avoids consequential errors, e.g.:

2016-12-22 14:43:22,176 ERROR Unable to write to stream UDP:localhost:514 for appender syslog
2016-12-22 14:43:22,176 ERROR An exception occurred processing Appender syslog org.apache.logging.log4j.core.appender.AppenderLoggingException: Error flushing stream UDP:localhost:514
...
Caused by: java.io.IOException: Message too long (sendto failed)