Reimplement prepared statements with LRU cache and statement deduplication (#618)

* Initial commit

* Cleanup and add stats

* Use an arc instead of full clones to store the parse packets

* Use mutex instead

* fmt

* clippy

* fmt

* fix?

* fix?

* fmt

* typo

* Update docs

* Refactor custom protocol

* fmt

* move custom protocol handling to before parsing

* Support describe

* Add LRU for server side statement cache

* rename variable

* Refactoring

* Move docs

* Fix test

* fix

* Update tests

* trigger build

* Add more tests

* Reorder handling sync

* Support when a named describe is sent along with Parse (go pgx) and expecting results

* don't talk to client if not needed when client sends Parse

* fmt :(

* refactor tests

* nit

* Reduce hashing

* Reducing work done to decode describe and parse messages

* minor refactor

* Merge branch 'main' into zain/reimplment-prepared-statements-with-global-lru-cache

* Rewrite extended and prepared protocol message handling to better support mocking response packets and close

* An attempt to better handle if there are DDL changes that might break cached plans with ideas about how to further improve it

* fix

* Minor stats fixed and cleanup

* Cosmetic fixes (#64)

* Cosmetic fixes

* fix test

* Change server drop for statement cache error to a `deallocate all`

* Updated comments and added new idea for handling DDL changes impacting cached plans

* fix test?

* Revert test change

* trigger build, flakey test

* Avoid potential race conditions by changing get_or_insert to promote for pool LRU

* remove ps enabled variable on the server in favor of using an option

* Add close to the Extended Protocol buffer

---------

Co-authored-by: Lev Kokotov <levkk@users.noreply.github.com>

src/admin.rs

@@ -744,6 +744,7 @@ where
         ("age_seconds", DataType::Numeric),
         ("prepare_cache_hit", DataType::Numeric),
         ("prepare_cache_miss", DataType::Numeric),
+        ("prepare_cache_eviction", DataType::Numeric),
         ("prepare_cache_size", DataType::Numeric),
     ];
 
@@ -776,6 +777,10 @@ where
                 .prepared_miss_count
                 .load(Ordering::Relaxed)
                 .to_string(),
+            server
+                .prepared_eviction_count
+                .load(Ordering::Relaxed)
+                .to_string(),
             server
                 .prepared_cache_size
                 .load(Ordering::Relaxed)