Consider caching Spdx-Java-library state

[pmonks]

The Spdx-Java-Library is exceptionally expensive to initialise with the basic reference data (license and exception lists, templates etc.). On my laptop it generally takes more than a minute to pull this information down, parse it, and load it into memory.

There may be a way to cache the library's state to disk (e.g. via serialisation, perhaps using nippy) and only incur the cost of initialisation when the lists have changes (which can be determined via an eTag request to the two list URLs).

[pmonks]

A quick experiment with nippy suggests this may not be easy solely from Clojure:

$ clj -Sdeps '{:deps {com.taoensso/nippy {:mvn/version "RELEASE"}}}' -r
user=> (require '[taoensso.nippy :as nippy])
nil
user=> (require '[spdx.licenses :as sl])
nil
user=> (sl/init!)
nil
user=> (require '[spdx.exceptions :as se])
nil
user=> (se/init!)
nil
user=> (require '[spdx.impl.state :as sis])
nil
user=> (nippy/freeze @sis/list-obj)
Execution error (ExceptionInfo) at taoensso.nippy/throw-unfreezable (nippy.clj:999).
Unfreezable type: class org.spdx.library.model.license.ListedLicenses
user=> 

[pmonks]

Raised https://github.com/spdx/Spdx-Java-Library/issues/193 to see if this can be fixed in the underlying Java library (which is a better place for it anyway).

[pmonks]

This is fixed in Spdx-Java-Library v1.1.8.