Deprecate confusing blockmaxsize, fix getmininginfo output

* This removes block-size-limiting code in favor of GBT clients
  doing the limiting themselves (if at all).
* -blockmaxsize is deprecated and only used to calculate an implied
  blockmaxweight, addressing confusion from multiple users.
* getmininginfo's currentblocksize return value was returning
  garbage values, and has been removed, also removing a
  GetSerializeSize call in some block generation inner loops and
  potentially addressing some performance edge cases.

src/init.cpp

@@ -484,7 +484,7 @@ std::string HelpMessage(HelpMessageMode mode)
 
     strUsage += HelpMessageGroup(_("Block creation options:"));
     strUsage += HelpMessageOpt("-blockmaxweight=<n>", strprintf(_("Set maximum BIP141 block weight (default: %d)"), DEFAULT_BLOCK_MAX_WEIGHT));
-    strUsage += HelpMessageOpt("-blockmaxsize=<n>", strprintf(_("Set maximum block size in bytes (default: %d)"), DEFAULT_BLOCK_MAX_SIZE));
+    strUsage += HelpMessageOpt("-blockmaxsize=<n>", _("Set maximum BIP141 block weight to this * 4. Deprecated, use blockmaxweight"));
     strUsage += HelpMessageOpt("-blockmintxfee=<amt>", strprintf(_("Set lowest fee rate (in %s/kB) for transactions to be included in block creation. (default: %s)"), CURRENCY_UNIT, FormatMoney(DEFAULT_BLOCK_MIN_TX_FEE)));
     if (showDebug)
         strUsage += HelpMessageOpt("-blockversion=<n>", "Override block version to test forking scenarios");
@@ -785,6 +785,15 @@ void InitParameterInteraction()
         if (gArgs.SoftSetBoolArg("-whitelistrelay", true))
             LogPrintf("%s: parameter interaction: -whitelistforcerelay=1 -> setting -whitelistrelay=1\n", __func__);
     }
+
+    if (gArgs.IsArgSet("-blockmaxsize")) {
+        unsigned int max_size = gArgs.GetArg("-blockmaxsize", 0);
+        if (gArgs.SoftSetArg("blockmaxweight", strprintf("%d", max_size * WITNESS_SCALE_FACTOR))) {
+            LogPrintf("%s: parameter interaction: -blockmaxsize=%d -> setting -blockmaxweight=%d (-blockmaxsize is deprecated!)\n", __func__, max_size, max_size * WITNESS_SCALE_FACTOR);
+        } else {
+            LogPrintf("%s: Ignoring blockmaxsize setting which is overridden by blockmaxweight", __func__);
+        }
+    }
 }
 
 static std::string ResolveErrMsg(const char * const optname, const std::string& strBind)

src/miner.cpp

@@ -43,7 +43,6 @@
 // its ancestors.
 
 uint64_t nLastBlockTx = 0;
-uint64_t nLastBlockSize = 0;
 uint64_t nLastBlockWeight = 0;
 
 int64_t UpdateTime(CBlockHeader* pblock, const Consensus::Params& consensusParams, const CBlockIndex* pindexPrev)
@@ -64,7 +63,6 @@ int64_t UpdateTime(CBlockHeader* pblock, const Consensus::Params& consensusParam
 BlockAssembler::Options::Options() {
     blockMinFeeRate = CFeeRate(DEFAULT_BLOCK_MIN_TX_FEE);
     nBlockMaxWeight = DEFAULT_BLOCK_MAX_WEIGHT;
-    nBlockMaxSize = DEFAULT_BLOCK_MAX_SIZE;
 }
 
 BlockAssembler::BlockAssembler(const CChainParams& params, const Options& options) : chainparams(params)
@@ -72,10 +70,6 @@ BlockAssembler::BlockAssembler(const CChainParams& params, const Options& option
     blockMinFeeRate = options.blockMinFeeRate;
     // Limit weight to between 4K and MAX_BLOCK_WEIGHT-4K for sanity:
     nBlockMaxWeight = std::max<size_t>(4000, std::min<size_t>(MAX_BLOCK_WEIGHT - 4000, options.nBlockMaxWeight));
-    // Limit size to between 1K and MAX_BLOCK_SERIALIZED_SIZE-1K for sanity:
-    nBlockMaxSize = std::max<size_t>(1000, std::min<size_t>(MAX_BLOCK_SERIALIZED_SIZE - 1000, options.nBlockMaxSize));
-    // Whether we need to account for byte usage (in addition to weight usage)
-    fNeedSizeAccounting = (nBlockMaxSize < MAX_BLOCK_SERIALIZED_SIZE - 1000);
 }
 
 static BlockAssembler::Options DefaultOptions(const CChainParams& params)
@@ -85,20 +79,7 @@ static BlockAssembler::Options DefaultOptions(const CChainParams& params)
     // If only one is given, only restrict the specified resource.
     // If both are given, restrict both.
     BlockAssembler::Options options;
-    options.nBlockMaxWeight = DEFAULT_BLOCK_MAX_WEIGHT;
-    options.nBlockMaxSize = DEFAULT_BLOCK_MAX_SIZE;
-    bool fWeightSet = false;
-    if (gArgs.IsArgSet("-blockmaxweight")) {
     options.nBlockMaxWeight = gArgs.GetArg("-blockmaxweight", DEFAULT_BLOCK_MAX_WEIGHT);
-        options.nBlockMaxSize = MAX_BLOCK_SERIALIZED_SIZE;
-        fWeightSet = true;
-    }
-    if (gArgs.IsArgSet("-blockmaxsize")) {
-        options.nBlockMaxSize = gArgs.GetArg("-blockmaxsize", DEFAULT_BLOCK_MAX_SIZE);
-        if (!fWeightSet) {
-            options.nBlockMaxWeight = options.nBlockMaxSize * WITNESS_SCALE_FACTOR;
-        }
-    }
     if (gArgs.IsArgSet("-blockmintxfee")) {
         CAmount n = 0;
         ParseMoney(gArgs.GetArg("-blockmintxfee", ""), n);
@@ -116,7 +97,6 @@ void BlockAssembler::resetBlock()
     inBlock.clear();
 
     // Reserve space for coinbase tx
-    nBlockSize = 1000;
     nBlockWeight = 4000;
     nBlockSigOpsCost = 400;
     fIncludeWitness = false;
@@ -176,7 +156,6 @@ std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock(const CScript& sc
     int64_t nTime1 = GetTimeMicros();
 
     nLastBlockTx = nBlockTx;
-    nLastBlockSize = nBlockSize;
     nLastBlockWeight = nBlockWeight;
 
     // Create coinbase transaction.
@@ -191,8 +170,7 @@ std::unique_ptr<CBlockTemplate> BlockAssembler::CreateNewBlock(const CScript& sc
     pblocktemplate->vchCoinbaseCommitment = GenerateCoinbaseCommitment(*pblock, pindexPrev, chainparams.GetConsensus());
     pblocktemplate->vTxFees[0] = -nFees;
 
-    uint64_t nSerializeSize = GetSerializeSize(*pblock, SER_NETWORK, PROTOCOL_VERSION);
-    LogPrintf("CreateNewBlock(): total size: %u block weight: %u txs: %u fees: %ld sigops %d\n", nSerializeSize, GetBlockWeight(*pblock), nBlockTx, nFees, nBlockSigOpsCost);
+    LogPrintf("CreateNewBlock(): block weight: %u txs: %u fees: %ld sigops %d\n", GetBlockWeight(*pblock), nBlockTx, nFees, nBlockSigOpsCost);
 
     // Fill in header
     pblock->hashPrevBlock  = pindexPrev->GetBlockHash();
@@ -239,22 +217,13 @@ bool BlockAssembler::TestPackage(uint64_t packageSize, int64_t packageSigOpsCost
 // - transaction finality (locktime)
 // - premature witness (in case segwit transactions are added to mempool before
 //   segwit activation)
-// - serialized size (in case -blockmaxsize is in use)
 bool BlockAssembler::TestPackageTransactions(const CTxMemPool::setEntries& package)
 {
-    uint64_t nPotentialBlockSize = nBlockSize; // only used with fNeedSizeAccounting
     for (const CTxMemPool::txiter it : package) {
         if (!IsFinalTx(it->GetTx(), nHeight, nLockTimeCutoff))
             return false;
         if (!fIncludeWitness && it->GetTx().HasWitness())
             return false;
-        if (fNeedSizeAccounting) {
-            uint64_t nTxSize = ::GetSerializeSize(it->GetTx(), SER_NETWORK, PROTOCOL_VERSION);
-            if (nPotentialBlockSize + nTxSize >= nBlockMaxSize) {
-                return false;
-            }
-            nPotentialBlockSize += nTxSize;
-        }
     }
     return true;
 }
@@ -264,9 +233,6 @@ void BlockAssembler::AddToBlock(CTxMemPool::txiter iter)
     pblock->vtx.emplace_back(iter->GetSharedTx());
     pblocktemplate->vTxFees.push_back(iter->GetFee());
     pblocktemplate->vTxSigOpsCost.push_back(iter->GetSigOpCost());
-    if (fNeedSizeAccounting) {
-        nBlockSize += ::GetSerializeSize(iter->GetTx(), SER_NETWORK, PROTOCOL_VERSION);
-    }
     nBlockWeight += iter->GetTxWeight();
     ++nBlockTx;
     nBlockSigOpsCost += iter->GetSigOpCost();

src/miner.h

@@ -139,13 +139,11 @@ private:
 
     // Configuration parameters for the block size
     bool fIncludeWitness;
-    unsigned int nBlockMaxWeight, nBlockMaxSize;
-    bool fNeedSizeAccounting;
+    unsigned int nBlockMaxWeight;
     CFeeRate blockMinFeeRate;
 
     // Information on the current status of the block
     uint64_t nBlockWeight;
-    uint64_t nBlockSize;
     uint64_t nBlockTx;
     uint64_t nBlockSigOpsCost;
     CAmount nFees;

src/policy/policy.h

@@ -16,8 +16,6 @@
 class CCoinsViewCache;
 class CTxOut;
 
-/** Default for -blockmaxsize, which controls the maximum size of block the mining code will create **/
-static const unsigned int DEFAULT_BLOCK_MAX_SIZE = 750000;
 /** Default for -blockmaxweight, which controls the range of block weights the mining code will create **/
 static const unsigned int DEFAULT_BLOCK_MAX_WEIGHT = 3000000;
 /** Default for -blockmintxfee, which sets the minimum feerate for a transaction in blocks created by mining code **/

src/rpc/mining.cpp

@@ -196,7 +196,6 @@ UniValue getmininginfo(const JSONRPCRequest& request)
             "\nResult:\n"
             "{\n"
             "  \"blocks\": nnn,             (numeric) The current block\n"
-            "  \"currentblocksize\": nnn,   (numeric) The last block size\n"
             "  \"currentblockweight\": nnn, (numeric) The last block weight\n"
             "  \"currentblocktx\": nnn,     (numeric) The last block transaction\n"
             "  \"difficulty\": xxx.xxxxx    (numeric) The current difficulty\n"
@@ -215,7 +214,6 @@ UniValue getmininginfo(const JSONRPCRequest& request)
 
     UniValue obj(UniValue::VOBJ);
     obj.push_back(Pair("blocks",           (int)chainActive.Height()));
-    obj.push_back(Pair("currentblocksize", (uint64_t)nLastBlockSize));
     obj.push_back(Pair("currentblockweight", (uint64_t)nLastBlockWeight));
     obj.push_back(Pair("currentblocktx",   (uint64_t)nLastBlockTx));
     obj.push_back(Pair("difficulty",       (double)GetDifficulty()));

src/validation.h

@@ -161,7 +161,6 @@ extern CTxMemPool mempool;
 typedef std::unordered_map<uint256, CBlockIndex*, BlockHasher> BlockMap;
 extern BlockMap mapBlockIndex;
 extern uint64_t nLastBlockTx;
-extern uint64_t nLastBlockSize;
 extern uint64_t nLastBlockWeight;
 extern const std::string strMessageMagic;
 extern CWaitableCriticalSection csBestBlock;

test/functional/mining.py

@@ -38,7 +38,6 @@ class MiningTest(BitcoinTestFramework):
         mining_info = node.getmininginfo()
         assert_equal(mining_info['blocks'], 200)
         assert_equal(mining_info['chain'], 'regtest')
-        assert_equal(mining_info['currentblocksize'], 0)
         assert_equal(mining_info['currentblocktx'], 0)
         assert_equal(mining_info['currentblockweight'], 0)
         assert_equal(mining_info['difficulty'], Decimal('4.656542373906925E-10'))