Associate cached content to the last redirection location, instead of
the first URL of a redirection(s) chain :
- for proper base URL processing in parsers (fixes mantis 636 -
http://mantis.tokeek.de/view.php?id=636)
- to prevent duplicated content in Solr index when recrawling a
redirected URL
- with only light constraint on known indexed documents load date, as it
can already been controlled by the selection query, and the goal of the
job is indeed to recrawl selected documents now
- using the iffresh cache strategy
Required for proper operation when the default system locale is Turkish,
as dottless and dotted i characters have specific case conversion rules
in this language.
When a crawl is started, a new field to exclude content from scraping is
available. The field can be identified with the class name of div tags.
All text contained in such a div tag where the configured class name(s)
match are not indexed, while the remaining page is indexed.
Previously, when checking for the first time the robots.txt policy on a
unknown host (not cached in the robots table), result was always empty
in the /getpageinfo_p.xml api and in the /CrawlCheck_p.html page. Next
calls returned however the correct information.
Some web servers provide both 'Content-Encoding : "gzip"' and
'Content-Type : "application/x-gzip"' HTTP headers on their ".gz" files.
This was annoying to fail on such resources which are not so uncommon,
while non conforming (see RFC 7231 section 3.1.2.2 for
"Content-Encoding" header specification
https://tools.ietf.org/html/rfc7231#section-3.1.2.2)
Thus enable getpageinfo_p API to return something in a reasonable amount
of time on resources over MegaBytes size range.
Support added first with the generic XML parser, for other formats
regular crawler limits apply as usual.
Especially for Turkish speaking users using "tr" as their system default
locale : strings for technical stuff (URLs, tag names, constants...)
must not be lower cased with the default locale, as 'I' doesn't becomes
'i' like in other locales such as "en", but becomes 'ı'.
Using a Reentrant lock instead of the intrinsic synchronization lock
permits limiting the blocking time to acquire a lock.
Useful on a very busy Cache concurrently accessed by many threads : when
the time to acquire a lock is too high, getting/storing content on the
cache becomes inefficient, and it is then better to fall back to loading
remote resources.
Illustrated by the CacheTest stress test and some traces reported in
mantis 751 ( http://mantis.tokeek.de/view.php?id=751 )
When using a public HTTP URL in /IndexImportMediawiki_p.html, the remote
file now is directly streamed and processed, allowing import of several
GB dumps even with a low memory remote peer, and without need to
manually download the dump file first.
following comment "use of properties as header values is discouraged"
in case where (proxy)HTTPClient overwrites values with supplied url.
Use defined request.referer procedure in response class.
This ensure consistent implementation of the url host hash generation
and easier usage finding in source code.
Also added a unit test for this function.
Applied rules :
- when the FTP URL denotes a file resource, stack it as any start URL :
eventually embedded links can be followed applying the usual depth rules
- when the FTP URL denotes a directory, list files under this directory
and stack them for crawl, and repeat the process on sub folders until
crawl depth is reached
When starting a crawl from a file containing thousands of links,
configuration setting "crawler.MaxActiveThreads" is effective to prevent
saturating the system with too many outgoing HTTP connections threads
launched by the crawler.
But robots.txt was not affected by this setting and was indefinitely
increasing the number of concurrently loading threads until most ot the
connections timed out.
To improve performance control, added a pool of threads for Robots.txt,
consistently used in its ensureExist() and massCrawlCheck() methods.
The Robots.txt threads pool max size can now be configured in the
/PerformanceQueus_p.html page, or with the new
"robots.txt.MaxActiveThreads" setting, initialized with the same default
value as the crawler.
Applied strategy : when there is no restriction on domains or
sub-path(s), stack anchor links once discovered by the content scraper
instead of waiting the complete parsing of the file.
This makes it possible to handle a crawling start file with thousands of
links in a reasonable amount of time.
Performance limitation : even if the crawl start faster with a large
file, the content of the parsed file still is fully loaded in memory.
luccioman