RFR: 8341735: Rewrite the build/AbsPathsInImage.java test to not load the entire file at once [v6]

[Erik Joelsson]

On Wed, 22 Oct 2025 17:42:18 GMT, Daniel Hu <duke at openjdk.org> wrote:

>> Daniel Hu has updated the pull request incrementally with two additional commits since the last revision:
>> 
>>  - fix incorrect use of inputstream
>>  - remove extraneous variables/imports
>
> test/jdk/build/AbsPathsInImage.java line 187:
> 
>> 185:             }
>> 186:         }
>> 187:     }
> 
> This is an implementation of the [Knuth–Morris–Pratt algorithm](https://en.wikipedia.org/wiki/Knuth%E2%80%93Morris%E2%80%93Pratt_algorithm). I waffled between choosing various string search algorithms, and ultimately settled on this one as it's well suited for this application: the algorithm doesn't skip or backtrack the text being searched and only relies looking at one char at a time. Essentially, the algorithm just creates state machines tailored specifically for string searching; upon each inputted char, an update is made to the searched string's DFA. A related algorithm I looked at that's technically better suited is [Aho–Corasick](https://en.wikipedia.org/wiki/Aho%E2%80%93Corasick_algorithm)? But (to me) it looked significantly more complex (probably requires custom node objects and might have a higher space requirement due to needing to store references to other nodes per node). Of course, I'm not intimately familiar with these algorithms, so I very might be missing ce
 rtain details.
> 
> `createPrefixTables` function is the pre-processing done on the string patterns that creates the "state machines". Basically, it just creates a table of all the available prefixes that the string can jump back to at any current index. `getPrefixIndex` is used both in `createPrefixTables` (the preprocessing) and the actual string matching process itself (in `scanBytes`). It's the failure function or it finds the appropriate index/state/prefix to go back to when a mismatch is found (it can be used for the preprocessing since the preprocessing is simply finding an index/prefix to jump back to at each index).

Sorry if it wasn't clear, but I meant for you to put this in comments in the code.

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PR Review Comment: https://git.openjdk.org/jdk/pull/26030#discussion_r2453155034