[node] support self.cache=nil in SQLiteStore

also fix a discrepancy where cli option `--cache-size` is documented as
`0 disables the cache` in `codex/conf.nim`, but previously the value `0` would
result in a cache being constructed with default parameter values for
`CacheStore.new()`

Closes #180

codex/codex.nim

@@ -102,11 +102,11 @@ proc new*(T: type CodexServer, config: CodexConf): T =
     .withTcpTransport({ServerFlags.ReuseAddr})
     .build()
 
-  let cache =
+  var
+    cache: CacheStore
+
   if config.cacheSize > 0:
-      CacheStore.new(cacheSize = config.cacheSize * MiB)
-    else:
-      CacheStore.new()
+    cache = CacheStore.new(cacheSize = config.cacheSize * MiB)
 
   let
     discoveryBootstrapNodes = config.bootstrapNodes

codex/stores/sqlitestore.nim

@@ -70,12 +70,16 @@ method getBlock*(
   ## Save a copy to the cache if present in the database but not in the cache
   ##
 
+  if not self.cache.isNil:
     trace "Getting block from cache or database", cid
+  else:
+    trace "Getting block from database", cid
 
   if cid.isEmpty:
     trace "Empty block, ignoring"
     return success cid.emptyBlock.some
 
+  if not self.cache.isNil:
     without cachedBlkOpt =? await self.cache.getBlock(cid), error:
       trace "Unable to read block from cache", cid, error = error.msg
 
@@ -96,6 +100,7 @@ method getBlock*(
     trace "Unable to construct block from data", cid, error = error.msg
     return failure error
 
+  if not self.cache.isNil:
     let
       putCachedRes = await self.cache.putBlock(blk)
 
@@ -111,7 +116,10 @@ method putBlock*(
   ## Save a copy to the cache
   ##
 
+  if not self.cache.isNil:
     trace "Putting block into database and cache", cid = blk.cid
+  else:
+    trace "Putting block into database", cid = blk.cid
 
   if blk.isEmpty:
     trace "Empty block, ignoring"
@@ -127,6 +135,7 @@ method putBlock*(
     trace "Unable to store block in database", key = blkKey.id, error = putRes.error.msg
     return failure putRes.error
 
+  if not self.cache.isNil:
     let
       putCachedRes = await self.cache.putBlock(blk)
 
@@ -141,12 +150,16 @@ method delBlock*(
   ## Delete a block from the database and cache
   ##
 
+  if not self.cache.isNil:
     trace "Deleting block from cache and database", cid
+  else:
+    trace "Deleting block from database", cid
 
   if cid.isEmpty:
     trace "Empty block, ignoring"
     return success()
 
+  if not self.cache.isNil:
     let
       delCachedRes = await self.cache.delBlock(cid)
 

tests/codex/stores/testsqlitestore.nim

@@ -15,7 +15,8 @@ import pkg/codex/stores
 
 import ../helpers
 
-suite "SQLite Store":
+proc runSuite(cache: bool) =
+  suite "SQLite Store " & (if cache: "(cache enabled)" else: "(cache disabled)"):
     randomize()
 
     var
@@ -37,7 +38,12 @@ suite "SQLite Store":
     setup:
       removeDir(repoDir)
       require(not dirExists(repoDir))
+
+      if cache:
         store = SQLiteStore.new(repoDir)
+      else:
+        store = SQLiteStore.new(repoDir, nil)
+
       newBlock = randomBlock()
 
     teardown:
@@ -56,7 +62,7 @@ suite "SQLite Store":
         blkKey = blkKeyRes.get
 
       var
-      # bypass cache
+        # bypass enabled cache
         containsRes = await store.datastore.contains(blkKey)
 
       assert containsRes.isOk
@@ -67,7 +73,7 @@ suite "SQLite Store":
 
       check: putRes.isOk
 
-    # bypass cache
+      # bypass enabled cache
       containsRes = await store.datastore.contains(blkKey)
 
       assert containsRes.isOk
@@ -88,7 +94,7 @@ suite "SQLite Store":
           assert kRes.isOk
 
           let
-          # bypass cache
+            # bypass enabled cache
             pRes = await store.datastore.put(kRes.get, b.data)
 
           assert pRes.isOk
@@ -99,7 +105,7 @@ suite "SQLite Store":
       assert blkKeyRes.isOk
 
       var
-      # bypass cache
+        # bypass enabled cache
         putRes = await store.datastore.put(blkKeyRes.get, newBlock.data)
 
       assert putRes.isOk
@@ -116,7 +122,7 @@ suite "SQLite Store":
           assert kRes.isOk
 
           let
-          # bypass cache
+            # bypass enabled cache
             pRes = await store.datastore.put(kRes.get, b.data)
 
           assert pRes.isOk
@@ -134,7 +140,7 @@ suite "SQLite Store":
         blkOpt.isSome
         blkOpt.get == newBlock
 
-    # get from cache
+      # get from enabled cache
       getRes = await store.getBlock(newBlock.cid)
 
       check: getRes.isOk
@@ -223,3 +229,6 @@ suite "SQLite Store":
       check:
         delRes.isOk
         not (await newBlock.cid in store)
+
+runSuite(cache = true)
+runSuite(cache = false)