guava

Part of the problem is that handles on directories on which one can then use the the *at family of syscalls are not first-class citizens in many programming languages. Which in turn might be due to portability concerns with windows, e.g. Java's SecureDirectoryStream isn't available there[0]. Apparently windows does have an openat-like API[1], but it's low-level. Programmers aren't using them because the language standard libraries point them in the wrong direction. [0] https://github.com/google/guava/wiki/Release21#user-content-... [1] https://github.com/rust-lang/rust/blob/1c63ec48b8cbf553d291a...

Google Guava has industrial strength implementation documented here[1] with sources here [2]. Tests and hints on how to drive this: [3] [1] https://guava.dev/releases/snapshot-jre/api/docs/com/google/... [2] https://github.com/google/guava/blob/master/guava/src/com/go... [3] https://github.com/google/guava/blob/master/guava-tests/test...

Yes, a hash map that expires objects and loads new KV when key isn't present inside https://github.com/google/guava/wiki/CachesExplained

To compliment most other posters, they would use Maven Central: https://search.maven.org/ Here is an example library from Google called "Guava": https://search.maven.org/artifact/com.google.guava/guava/31.... You can find the source code on GitHub: https://github.com/google/guava On the right side of the page, you can find eleven (!) different wants to include this dependency (and) all of its transitive dependencies with just a few lines of configuration. Here is a list of the Top 10 downloads of open source Java libraries: https://mvnrepository.com/popular?p=1

Instead of pointing a finger at Facebook, I'd scoff at C++ and the way in which the language has grown where orgs build up their own utility libraries rather than depend on a standard library. That said, this is an issue for other languages as well. Another example: the "Google core libraries for Java": https://github.com/google/guava