[foreign-memaccess+abi] RFR: 8313238: Improve the performance of strlen for null-terminated strings

[Radoslaw Smogura]

On Thu, 3 Aug 2023 13:52:27 GMT, Per Minborg <pminborg at openjdk.org> wrote:

> This PR proposes to use native calls for determining the string length for C-type strings. 
> 
> Smaller segments (<1024 bytes) is using a trivial call whereas all other segments are using a normal call. We might consider always using regular calls if we think most segments are unbound anyhow.
> 
> The PR also contains a number of new tests, one of which requires a large heap size to run. It is likely that this latter test will not run in most test environments. In such cases, it is silently ignored.

src/java.base/share/classes/jdk/internal/foreign/StringSupport.java line 123:

> 121:                 segment = segment.asSlice(start);
> 122:             }
> 123:             long len = segment.byteSize() < MAX_TRIVIAL_SIZE

When calling `strlen` should it be considered if segments is heap or off-heap?

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PR Review Comment: https://git.openjdk.org/panama-foreign/pull/857#discussion_r1283265679