[ https://issues.apache.org/jira/browse/PDFBOX-5575?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Tilman Hausherr updated PDFBOX-5575: ------------------------------------ Affects Version/s: 2.0.27 > optimize LZWFilter > ------------------ > > Key: PDFBOX-5575 > URL: https://issues.apache.org/jira/browse/PDFBOX-5575 > Project: PDFBox > Issue Type: Improvement > Affects Versions: 2.0.27, 3.0.0 PDFBox > Reporter: Axel Howind > Priority: Minor > Attachments: optimize_LZWFilter.patch > > > I ran the PDFBox tests with a profiler and saw that LZWFilter used quite a > bunch of time, so I thought I might look at the code. I just looked at it > totally out of context and tried to understand what is done there and what > could be changed without altering results. > * made the private mehtods static > * changed the variable/method parameter 'earlyChange' from integer to > boolean because I thought tha would be more readable > * some minor tweaks > * it looks like codeTable is initialized quite often and everytime, 256 > length 1 byte arrays are created, so I pre-allocate those byte arrays so that > they can be shared by all code tables. [~tilman] I assumed the contents of > the codeTable entries will not be changed, and my analysis of the code seems > to prove that (also the passing unit tests). Just please have a look at this > so I don't break anything. > * it took me some time to fully understand what findPatternCode() does and > why it checks the codeTable in reverse order. I more or less recreated that > method from scratch and I think it should now always be faster: for patterns > of length 1 no iteration is done, and for longer patterns iteration stops > once the correct entry is found. As this is the most notable change, please > take a closer look. Unit tests pass. -- This message was sent by Atlassian Jira (v8.20.10#820010) --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@pdfbox.apache.org For additional commands, e-mail: dev-h...@pdfbox.apache.org