[ETCM-186] Fix strict pick

Author: Nicolas Tallar

src/main/scala/io/iohk/ethereum/blockchain/sync/regular/BlockFetcher.scala

@@ -68,14 +68,15 @@ class BlockFetcher(
   private def handleCommands(state: BlockFetcherState): Receive = {
     case PickBlocks(amount) => state.pickBlocks(amount) |> handlePickedBlocks(state) |> fetchBlocks
     case StrictPickBlocks(from, atLeastWith) =>
-      val minBlock = from.min(atLeastWith).max(1)
-      log.debug("Strict Pick blocks from {} to {}", from, atLeastWith)
+      val fromCapped = from.max(1)
+      val minBlock = fromCapped.min(atLeastWith).max(1)
+      log.debug("Strict Pick blocks from {} to {}", fromCapped, atLeastWith)
       log.debug("Lowest available block is {}", state.lowestBlock)
 
       val newState = if (minBlock < state.lowestBlock) {
         state.invalidateBlocksFrom(minBlock, None)._2
       } else {
-        state.strictPickBlocks(from, atLeastWith) |> handlePickedBlocks(state)
+        state.strictPickBlocks(fromCapped, atLeastWith) |> handlePickedBlocks(state)
       }
 
       fetchBlocks(newState)

src/main/scala/io/iohk/ethereum/blockchain/sync/regular/BlockFetcherState.scala

@@ -107,9 +107,15 @@ case class BlockFetcherState(
       None
     }
 
+  /**
+    * Returns all the ready blocks but only if 2 block number bounds are included:
+    * - lower = min(from, atLeastWith)
+    * - upper = max(from, atLeastWith)
+    */
   def strictPickBlocks(from: BigInt, atLeastWith: BigInt): Option[(NonEmptyList[Block], BlockFetcherState)] = {
     val lower = from.min(atLeastWith)
     val upper = from.max(atLeastWith)
+
     readyBlocks.some
       .filter(_.headOption.exists(block => block.number <= lower))
       .filter(_.lastOption.exists(block => block.number >= upper))

src/main/scala/io/iohk/ethereum/blockchain/sync/regular/BlockImporter.scala

@@ -105,7 +105,11 @@ class BlockImporter(
 
   private def importBlocks(blocks: NonEmptyList[Block]): ImportFn =
     importWith {
-      log.debug("Attempting to import blocks starting from {}", blocks.head.number)
+      log.debug(
+        "Attempting to import blocks starting from {} and ending with {}",
+        blocks.head.number,
+        blocks.last.number
+      )
       Future
         .successful(resolveBranch(blocks))
         .flatMap {

src/test/scala/io/iohk/ethereum/blockchain/sync/regular/BlockFetcherStateSpec.scala

@@ -33,6 +33,5 @@ class BlockFetcherStateSpec extends TestKit(ActorSystem()) with AnyWordSpecLike
         newState.knownTop shouldEqual newBestBlock.number
       }
     }
-
   }
 }