[GitHub] tawek opened a new pull request #22: Introduce caching for tracking files.

[GitBox <gi...@apache.org>]

tawek opened a new pull request #22: Introduce caching for tracking files.
URL: https://github.com/apache/maven-resolver/pull/22
 
 
   Reason:
   The tracking file manager typically in large m2e projects will be used
   hundreds of times (due to hundreds of artifacts). If the projects are
   refreshed the files are re-read again and again. This could amount to as
   much as 43% of time spent in m2e MavenBuilder (in my scenario on Windows
   platform)
   
   Changes:
   This commit introduces the read cache for tracking files assuming that
   those files do not change frequently (or at all).
   The cache entries are verified once per minute if the underlying file
   had changed its lastModified timestamp and if so they are re-read. If
   the file timestamp had not changed the entry is valid for one more
   minute.
   
   Additionally since on Windows canonicalization is expensive operation it
   is also being cached.
   
   Cached properties are defensively copied when returned.
   
   TODOs:
    - the cache is unbounded and there is no clearing policy based on LRU
    and maximum size (for instance). However for typical usages this will
    not be a problem since number of artifacts is probably couple of
    thousands and should not pose a problem for memory.
   
   I'm making this PR without much hope of approving it - this may not be something that is perceived as problematic by maintainers of this library, but I've stumbled on this issue while profiling m2e builds which are taking quite long (and I've decided to do something about it).
   

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