Add empty / miss lru cache

Empties were handled by the leaf cache previously

Author: arnetheduck

execution_chain/db/aristo/aristo_init/rocks_db/rdb_desc.nim

@@ -62,6 +62,8 @@ type
     rdBranchLru*: LruCache[VertexID, (VertexID, uint16)]
     rdBranchSize*: int
 
+    rdEmptyLru*: LruCache[VertexID,tuple[]] ## Read cache
+
   AristoCFs* = enum
     ## Column family symbols/handles and names used on the database
     AdmCF = "AriAdm"                   ## Admin column family name

execution_chain/db/aristo/aristo_init/rocks_db/rdb_get.nim

@@ -196,6 +196,16 @@ proc getVtx*(
       )
       return ok(move(rc.value))
 
+  block:
+    var rc =
+      if GetVtxFlag.PeekCache in flags:
+        rdb.rdEmptyLru.peek(rvid.vid)
+      else:
+        rdb.rdEmptyLru.get(rvid.vid)
+    if rc.isOk():
+      rdbVtxLruStats[rvid.to(RdbStateType)][RdbVertexType.Empty].inc(true)
+      return ok(VertexRef(nil))
+
   # Otherwise fetch from backend database
   # A threadvar is used to avoid allocating an environment for onData
   var res {.threadvar.}: Result[VertexRef, AristoError]
@@ -210,6 +220,9 @@ proc getVtx*(
 
   if not gotData:
     rdbVtxLruStats[rvid.to(RdbStateType)][RdbVertexType.Empty].inc(false)
+    if GetVtxFlag.PeekCache notin flags:
+      rdb.rdEmptyLru.put(rvid.vid, default(tuple[]))
+
     return ok(VertexRef(nil))
 
   if res.isErr():

execution_chain/db/aristo/aristo_init/rocks_db/rdb_init.nim

@@ -99,6 +99,7 @@ proc init*(rdb: var RdbInst, opts: DbOptions, baseDb: RocksDbInstanceRef) =
   rdb.rdKeyLru = typeof(rdb.rdKeyLru).init(rdb.rdKeySize)
   rdb.rdVtxLru = typeof(rdb.rdVtxLru).init(rdb.rdVtxSize)
   rdb.rdBranchLru = typeof(rdb.rdBranchLru).init(rdb.rdBranchSize)
+  rdb.rdEmptyLru = typeof(rdb.rdEmptyLru).init(rdb.rdVtxSize) # reuse vtx cache size
 
   if opts.rdbPrintStats:
     let

execution_chain/db/aristo/aristo_init/rocks_db/rdb_put.nim

@@ -105,6 +105,8 @@ proc putVtx*(
       else:
         discard rdb.rdVtxLru.update(rvid.vid, vtx)
 
+    rdb.rdEmptyLru.del(rvid.vid)
+
     if key.isValid:
       if rdb.rdKeyLru.len < rdb.rdKeyLru.capacity:
         rdb.rdKeyLru.put(rvid.vid, key)
@@ -126,6 +128,9 @@ proc putVtx*(
     rdb.rdVtxLru.del rvid.vid
     rdb.rdKeyLru.del rvid.vid
 
+    if rdb.rdEmptyLru.len < rdb.rdEmptyLru.capacity:
+      rdb.rdEmptyLru.put(rvid.vid, default(tuple[]))
+
   ok()
 
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