Solr Adapter Optimistic Locking

[tpendragon]

Create a shared spec in lib/valkyrie/specs/shared_specs/, but don't include it in lib/valkyrie/specs/shared_specs.rb

Create a Valkyrie::Persistence::StaleObjectError

Child of #286

[tpendragon]

Try using _version_ key: https://lucene.apache.org/solr/guide/6_6/updating-parts-of-documents.html#UpdatingPartsofDocuments-OptimisticConcurrency

[awead]

Add the _version_field to the document that is sent to Solr. The value would be the value of optimistic_lock_tag.

[awead]

Example test:

>  resource = Valkyrie::Resource.find(id)
>  RSolr::Client.update(id, { foo: "bar" })
>  resource.save
=> Error!

[awead]

If you provide the incorrect version, Solr returns 409:

(byebug) document = { id: "b994b8ec-8eb3-4070-aa7d-f75897ab12be", foo_tesim: "bar", _version_:"1234" }
{:id=>"b994b8ec-8eb3-4070-aa7d-f75897ab12be", :foo_tesim=>"bar", :_version_=>"1234"}
(byebug) solr.add [document]
*** RSolr::Error::Http Exception: RSolr::Error::Http - 409 Conflict
Error: {
  "responseHeader":{
    "status":409,
    "QTime":0},
  "error":{
    "metadata":[
      "error-class","org.apache.solr.common.SolrException",
      "root-error-class","org.apache.solr.common.SolrException"],
    "msg":"version conflict for b994b8ec-8eb3-4070-aa7d-f75897ab12be expected=1234 actual=1607421963757682688",
    "code":409}}