[ETCM-426] Changed the gas limit strategy to a constant one (#820)

Author: Nicolás Tallar

src/main/resources/chains/testnet-internal-gac-genesis.json

@@ -2,10 +2,10 @@
   "extraData": "0x00",
   "nonce": "0x0000000000000042",
   "gasLimit": "0x2fefd8",
-  "_commentAboutDifficulty": "Set to 1000000",
+  "_commentAboutDifficulty": "Set to 1000000, a value closer to the one achieved by our current testnet with our 30 second block rate",
   "difficulty": "0xF4240",
   "ommersHash": "0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347",
-  "_commentAboutTimestamp": "Set to 11/05/2020 @ 12:00am (UTC)",
+  "_commentAboutTimestamp": "Set to 11/05/2020 @ 12:00am (UTC), to be closer to our release date and not affect as much the difficulty calculations",
   "timestamp": "0x5FA34080",
   "coinbase": "0x0000000000000000000000000000000000000000",
   "mixHash": "0x0000000000000000000000000000000000000000000000000000000000000000",

src/main/resources/chains/testnet-internal-nomad-genesis.json

@@ -1,11 +1,12 @@
 {
   "extraData": "0x00",
   "nonce": "0x0000000000000042",
-  "gasLimit": "0x2fefd8",
-  "_commentAboutDifficulty": "Set to 1000000",
+  "_commentAboutGasLimit": "Set to 8 million (value used in ETC mainnet)",
+  "gasLimit": "0x7A1200",
+  "_commentAboutDifficulty": "Set to 1000000, a value closer to the one achieved by our current testnet with our 30 second block rate",
   "difficulty": "0xF4240",
   "ommersHash": "0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347",
-  "_commentAboutTimestamp": "Set to 11/05/2020 @ 12:00am (UTC)",
+  "_commentAboutTimestamp": "Set to 11/05/2020 @ 12:00am (UTC), to be closer to our release date and not affect as much the difficulty calculations",
   "timestamp": "0x5FA34080",
   "coinbase": "0x0000000000000000000000000000000000000000",
   "mixHash": "0x0000000000000000000000000000000000000000000000000000000000000000",

src/main/scala/io/iohk/ethereum/consensus/blocks/BlockGeneratorSkeleton.scala

@@ -163,13 +163,13 @@ abstract class BlockGeneratorSkeleton(
     transactionsForBlock
   }
 
-  //returns maximal limit to be able to include as many transactions as possible
-  protected def calculateGasLimit(parentGas: BigInt): BigInt = {
-    val GasLimitBoundDivisor: Int = 1024
+  /*
+        Returns the same gas limit as the parent block
 
-    val gasLimitDifference = parentGas / GasLimitBoundDivisor
-    parentGas + gasLimitDifference - 1
-  }
+        In Mantis only testnets (and without this changed), this means that all blocks will have the same gasLimit as
+        the genesis block
+   */
+  protected def calculateGasLimit(parentGas: BigInt): BigInt = parentGas
 
   protected def buildMpt[K](entities: Seq[K], vSerializable: ByteArraySerializable[K]): ByteString = {
     val stateStorage = StateStorage.getReadOnlyStorage(EphemDataSource())

src/test/scala/io/iohk/ethereum/consensus/BlockGeneratorSpec.scala

@@ -39,7 +39,7 @@ class BlockGeneratorSpec extends AnyFlatSpec with Matchers with ScalaCheckProper
     val miningTimestamp = 1508751768
 
     val fullBlock = pendingBlock.block.copy(header =
-      pendingBlock.block.header.copy(nonce = minedNonce, mixHash = minedMixHash, unixTimestamp = miningTimestamp)
+      pendingBlock.block.header.copy(nonce = minedNonce, mixHash = minedMixHash, unixTimestamp = miningTimestamp, gasLimit = generatedBlockGasLimit)
     )
     validators.blockHeaderValidator.validate(
       fullBlock.header,
@@ -61,7 +61,7 @@ class BlockGeneratorSpec extends AnyFlatSpec with Matchers with ScalaCheckProper
     val miningTimestamp = 1508752265
 
     val fullBlock = pendingBlock.block.copy(header =
-      pendingBlock.block.header.copy(nonce = minedNonce, mixHash = minedMixHash, unixTimestamp = miningTimestamp)
+      pendingBlock.block.header.copy(nonce = minedNonce, mixHash = minedMixHash, unixTimestamp = miningTimestamp, gasLimit = generatedBlockGasLimit)
     )
     validators.blockHeaderValidator.validate(
       fullBlock.header,
@@ -83,7 +83,7 @@ class BlockGeneratorSpec extends AnyFlatSpec with Matchers with ScalaCheckProper
     val miningTimestamp = 1508752265
 
     val fullBlock = pendingBlock.block.copy(header =
-      pendingBlock.block.header.copy(nonce = minedNonce, mixHash = minedMixHash, unixTimestamp = miningTimestamp)
+      pendingBlock.block.header.copy(nonce = minedNonce, mixHash = minedMixHash, unixTimestamp = miningTimestamp, gasLimit = generatedBlockGasLimit)
     )
 
     // Import Block, to create some existing state
@@ -132,7 +132,7 @@ class BlockGeneratorSpec extends AnyFlatSpec with Matchers with ScalaCheckProper
     val miningTimestamp = 1508752389
 
     val fullBlock = pendingBlock.block.copy(header =
-      pendingBlock.block.header.copy(nonce = minedNonce, mixHash = minedMixHash, unixTimestamp = miningTimestamp)
+      pendingBlock.block.header.copy(nonce = minedNonce, mixHash = minedMixHash, unixTimestamp = miningTimestamp, gasLimit = generatedBlockGasLimit)
     )
     validators.blockHeaderValidator.validate(
       fullBlock.header,
@@ -165,7 +165,7 @@ class BlockGeneratorSpec extends AnyFlatSpec with Matchers with ScalaCheckProper
     val miningTimestamp = 1508752492
 
     val fullBlock = pendingBlock.block.copy(header =
-      pendingBlock.block.header.copy(nonce = minedNonce, mixHash = minedMixHash, unixTimestamp = miningTimestamp)
+      pendingBlock.block.header.copy(nonce = minedNonce, mixHash = minedMixHash, unixTimestamp = miningTimestamp, gasLimit = generatedBlockGasLimit)
     )
 
     validators.blockHeaderValidator.validate(
@@ -233,7 +233,7 @@ class BlockGeneratorSpec extends AnyFlatSpec with Matchers with ScalaCheckProper
 
     val fullBlock =
       pendingBlock.block.copy(header =
-        pendingBlock.block.header.copy(nonce = minedNonce, mixHash = minedMixHash, unixTimestamp = miningTimestamp)
+        pendingBlock.block.header.copy(nonce = minedNonce, mixHash = minedMixHash, unixTimestamp = miningTimestamp, gasLimit = generatedBlockGasLimit)
       )
     validators.blockHeaderValidator.validate(
       fullBlock.header,
@@ -323,7 +323,7 @@ class BlockGeneratorSpec extends AnyFlatSpec with Matchers with ScalaCheckProper
 
     val fullBlock =
       pendingBlock.block.copy(header =
-        pendingBlock.block.header.copy(nonce = minedNonce, mixHash = minedMixHash, unixTimestamp = miningTimestamp)
+        pendingBlock.block.header.copy(nonce = minedNonce, mixHash = minedMixHash, unixTimestamp = miningTimestamp, gasLimit = generatedBlockGasLimit)
       )
     validators.blockHeaderValidator.validate(fullBlock.header, blockchain.getBlockHeaderByHash) shouldBe Right(
       BlockHeaderValid
@@ -355,7 +355,7 @@ class BlockGeneratorSpec extends AnyFlatSpec with Matchers with ScalaCheckProper
 
     val fullBlock =
       pendingBlock.block.copy(header =
-        pendingBlock.block.header.copy(nonce = minedNonce, mixHash = minedMixHash, unixTimestamp = miningTimestamp)
+        pendingBlock.block.header.copy(nonce = minedNonce, mixHash = minedMixHash, unixTimestamp = miningTimestamp, gasLimit = generatedBlockGasLimit)
       )
     validators.blockHeaderValidator.validate(fullBlock.header, blockchain.getBlockHeaderByHash) shouldBe Right(
       BlockHeaderValid
@@ -400,7 +400,7 @@ class BlockGeneratorSpec extends AnyFlatSpec with Matchers with ScalaCheckProper
     val miningTimestamp = 1499721182
 
     val fullBlock = pendingBlock.block.copy(header =
-      pendingBlock.block.header.copy(nonce = minedNonce, mixHash = minedMixHash, unixTimestamp = miningTimestamp)
+      pendingBlock.block.header.copy(nonce = minedNonce, mixHash = minedMixHash, unixTimestamp = miningTimestamp, gasLimit = generatedBlockGasLimit)
     )
     validators.blockHeaderValidator.validate(fullBlock.header, blockchain.getBlockHeaderByHash) shouldBe Right(
       BlockHeaderValid
@@ -432,7 +432,7 @@ class BlockGeneratorSpec extends AnyFlatSpec with Matchers with ScalaCheckProper
     val miningTimestamp = 1508752698
 
     val fullBlock = pendingBlock.block.copy(header =
-      pendingBlock.block.header.copy(nonce = minedNonce, mixHash = minedMixHash, unixTimestamp = miningTimestamp)
+      pendingBlock.block.header.copy(nonce = minedNonce, mixHash = minedMixHash, unixTimestamp = miningTimestamp, gasLimit = generatedBlockGasLimit)
     )
     validators.blockHeaderValidator.validate(fullBlock.header, blockchain.getBlockHeaderByHash) shouldBe Right(
       BlockHeaderValid
@@ -562,6 +562,10 @@ class BlockGeneratorSpec extends AnyFlatSpec with Matchers with ScalaCheckProper
     lazy val blockExecution =
       new BlockExecution(blockchain, blockchainConfig, consensus.blockPreparator, blockValidation)
 
+    // FIXME: the change in gas limit voting strategy caused the hardcoded nonce and mixHash in this file to be invalid
+    //        The gas limit of all the generated blocks has to be set to the old strategy of increasing as much as possible
+    //        the gas limit, if not PoW validations will fail
+    val generatedBlockGasLimit = 16733003
   }
 }