plume-model: refactor Searcher to have its own DbPool #809

This PR is another attempt at fixing #799

Instead of relying on a separate actor model, as described, we make use of the fact that DbPool is an Arc, and can be arbitrarily cloned, so we add it to Searcher. Further more, and db_pool.get() acts like sending a message to an Actor: if there are enough connections, the Pool gives us one, if not, tough luck!

this way, we don't need to pass along a conn into the searcher functions.
This should make splitting PlumeRocket up into its components a little easier.

👌

👀

🙋🏻‍♀️

closing in favour of #813

     Io(std::io::Error),
     MissingApProperty,
     NotFound,
     DbPool,

     ///
     /// The panic messages are normally explicit enough for a human to
     /// understand how to fix the issue when they see it.
     pub fn new(db_pool: DbPool) -> Arc<Self> {

         let lang = schema.get_field("lang").unwrap();
         let license = schema.get_field("license").unwrap();
         let conn = self.dbpool.get().unwrap();

         let searcher = self.reader.searcher();
         let res = searcher.search(&query.into_query(), &collector).unwrap();
         let conn = self.dbpool.get().unwrap();

         let conn = match self.dbpool.get() {
             Ok(c) => c,
             Err(_) => return Err(Error::DbPool),

plume-model: refactor Searcher to have its own DbPool #809

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