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https://issues.apache.org/jira/browse/PDFBOX-3432?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15387812#comment-15387812
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Michael Doswald commented on PDFBOX-3432:
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commons-primitives doesn't seem to have any Map implementations for primitives.
I've tried the FastUtil and Goldman-Sachs libraries. I've implemented a few
simple benchmarks which I hope would cover the use cases in fontbox:
* Insert key/value pairs in sequential key order
* Insert key/value paris with random keys
* Get value of key with randomly selected keys
The FastUtil Int2IntMap seems to be slower than my simple implementation. The
IntIntHashMap from GS seems to be faster. For the last two benchmarks, only the
sequential insertion is faster with my simple implementation.
So I guess we could use the GS libraries (they seem to have an Apache License
too), but I can't really find the source code for it. It seems the Map
implementations for primitives are generated and not hand-written. Also the
implementation seem to include more features / code than we would really need
in fontbox.
Which solution would you prefer:
* Trying to integrate the GS IntIntHashMap (and possibly strip out all unneeded
features?)
* Using the simple implementation provided in the patch 'rev1'
> Optimize CID to GlyphId mapping (TTF)
> -------------------------------------
>
> Key: PDFBOX-3432
> URL: https://issues.apache.org/jira/browse/PDFBOX-3432
> Project: PDFBox
> Issue Type: Improvement
> Components: FontBox
> Affects Versions: 2.0.2
> Environment: Ubuntu 14.04.4 LTS
> Reporter: Michael Doswald
> Priority: Trivial
> Labels: optimization, performance
> Attachments: PDFBOX-3432_Optimize_CID_to_GlyphId_mapping_rev1.patch,
> pdfbox-performance-PDFBOX-3432.zip
>
>
> TTF fonts map code-points (Code IDs) to glyphs. These are mappings from int
> to int. Because the JDK lacks map classes for primitive types, the code (e.g.
> in CmapSubtable) currently uses Map<Integer,Integer> for those mappings. This
> is inefficient in different ways:
> * Autoboxing/unboxing introduces a performance penalty
> * Boxing to Integer objects has a memory overhead
> * The JDK Map implementation has a big memory overhead for such simple objects
> For efficiency (execution time and memory consumption) I would propose to
> introduce a simple IntIntMap implementation which works with primitive
> integers.
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