rpc: Improve getblockstats

- Fix getblockstats for block height 0 which previously returned an error.
- Introduce alternative utxo_*_actual statistics which exclude unspendables: Genesis block, BIP30, unspendable outputs
- Update test data
- Explicitly test Genesis block results

Author: fjahr

src/rpc/blockchain.cpp

@@ -593,6 +593,10 @@ static CBlockUndo GetUndoChecked(BlockManager& blockman, const CBlockIndex* pblo
 {
     AssertLockHeld(::cs_main);
     CBlockUndo blockUndo;
+
+    // The Genesis block does not have undo data
+    if (pblockindex->nHeight == 0) return blockUndo;
+
     if (blockman.IsBlockPruned(pblockindex)) {
         throw JSONRPCError(RPC_MISC_ERROR, "Undo data not available (pruned data)");
     }
@@ -1771,8 +1775,10 @@ static RPCHelpMan getblockstats()
                 {RPCResult::Type::NUM, "total_weight", /*optional=*/true, "Total weight of all non-coinbase transactions"},
                 {RPCResult::Type::NUM, "totalfee", /*optional=*/true, "The fee total"},
                 {RPCResult::Type::NUM, "txs", /*optional=*/true, "The number of transactions (including coinbase)"},
-                {RPCResult::Type::NUM, "utxo_increase", /*optional=*/true, "The increase/decrease in the number of unspent outputs"},
+                {RPCResult::Type::NUM, "utxo_increase", /*optional=*/true, "The increase/decrease in the number of unspent outputs (not discounting op_return and similar)"},
                 {RPCResult::Type::NUM, "utxo_size_inc", /*optional=*/true, "The increase/decrease in size for the utxo index (not discounting op_return and similar)"},
+                {RPCResult::Type::NUM, "utxo_increase_actual", /*optional=*/true, "The increase/decrease in the number of unspent outputs, not counting unspendables"},
+                {RPCResult::Type::NUM, "utxo_size_inc_actual", /*optional=*/true, "The increase/decrease in size for the utxo index, not counting unspendables"},
             }},
                 RPCExamples{
                     HelpExampleCli("getblockstats", R"('"00000000c937983704a73af28acdec37b049d214adbda81d7e2a3dd146f6ed09"' '["minfeerate","avgfeerate"]')") +
@@ -1803,7 +1809,7 @@ static RPCHelpMan getblockstats()
     const bool do_medianfee = do_all || stats.count("medianfee") != 0;
     const bool do_feerate_percentiles = do_all || stats.count("feerate_percentiles") != 0;
     const bool loop_inputs = do_all || do_medianfee || do_feerate_percentiles ||
-        SetHasKeys(stats, "utxo_size_inc", "totalfee", "avgfee", "avgfeerate", "minfee", "maxfee", "minfeerate", "maxfeerate");
+        SetHasKeys(stats, "utxo_increase", "utxo_increase_actual", "utxo_size_inc", "utxo_size_inc_actual", "totalfee", "avgfee", "avgfeerate", "minfee", "maxfee", "minfeerate", "maxfeerate");
     const bool loop_outputs = do_all || loop_inputs || stats.count("total_out");
     const bool do_calculate_size = do_mediantxsize ||
         SetHasKeys(stats, "total_size", "avgtxsize", "mintxsize", "maxtxsize", "swtotal_size");
@@ -1825,7 +1831,9 @@ static RPCHelpMan getblockstats()
     int64_t swtxs = 0;
     int64_t total_size = 0;
     int64_t total_weight = 0;
+    int64_t utxos = 0;
     int64_t utxo_size_inc = 0;
+    int64_t utxo_size_inc_actual = 0;
     std::vector<CAmount> fee_array;
     std::vector<std::pair<CAmount, int64_t>> feerate_array;
     std::vector<int64_t> txsize_array;
@@ -1838,7 +1846,18 @@ static RPCHelpMan getblockstats()
         if (loop_outputs) {
             for (const CTxOut& out : tx->vout) {
                 tx_total_out += out.nValue;
-                utxo_size_inc += GetSerializeSize(out, PROTOCOL_VERSION) + PER_UTXO_OVERHEAD;
+
+                size_t out_size = GetSerializeSize(out, PROTOCOL_VERSION) + PER_UTXO_OVERHEAD;
+                utxo_size_inc += out_size;
+
+                // The Genesis block and the repeated BIP30 block coinbases don't change the UTXO
+                // set counts, so they have to be excluded from the statistics
+                if (pindex.nHeight == 0 || (IsBIP30Repeat(pindex) && tx->IsCoinBase())) continue;
+                // Skip unspendable outputs since they are not included in the UTXO set
+                if (out.scriptPubKey.IsUnspendable()) continue;
+
+                ++utxos;
+                utxo_size_inc_actual += out_size;
             }
         }
 
@@ -1880,7 +1899,9 @@ static RPCHelpMan getblockstats()
                 const CTxOut& prevoutput = coin.out;
 
                 tx_total_in += prevoutput.nValue;
-                utxo_size_inc -= GetSerializeSize(prevoutput, PROTOCOL_VERSION) + PER_UTXO_OVERHEAD;
+                size_t prevout_size = GetSerializeSize(prevoutput, PROTOCOL_VERSION) + PER_UTXO_OVERHEAD;
+                utxo_size_inc -= prevout_size;
+                utxo_size_inc_actual -= prevout_size;
             }
 
             CAmount txfee = tx_total_in - tx_total_out;
@@ -1940,6 +1961,8 @@ static RPCHelpMan getblockstats()
     ret_all.pushKV("txs", (int64_t)block.vtx.size());
     ret_all.pushKV("utxo_increase", outputs - inputs);
     ret_all.pushKV("utxo_size_inc", utxo_size_inc);
+    ret_all.pushKV("utxo_increase_actual", utxos - inputs);
+    ret_all.pushKV("utxo_size_inc_actual", utxo_size_inc_actual);
 
     if (do_all) {
         return ret_all;

test/functional/data/rpc_getblockstats.json

@@ -142,7 +142,9 @@
       "totalfee": 0,
       "txs": 1,
       "utxo_increase": 2,
-      "utxo_size_inc": 163
+      "utxo_increase_actual": 1,
+      "utxo_size_inc": 163,
+      "utxo_size_inc_actual": 75
     },
     {
       "avgfee": 4460,
@@ -179,7 +181,9 @@
       "totalfee": 4460,
       "txs": 2,
       "utxo_increase": 3,
-      "utxo_size_inc": 236
+      "utxo_increase_actual": 2,
+      "utxo_size_inc": 236,
+      "utxo_size_inc_actual": 148
     },
     {
       "avgfee": 24906,
@@ -216,7 +220,9 @@
       "totalfee": 74720,
       "txs": 4,
       "utxo_increase": 5,
-      "utxo_size_inc": 384
+      "utxo_size_inc": 384,
+      "utxo_increase_actual": 4,
+      "utxo_size_inc_actual": 296
     }
   ]
-}
+}

test/functional/rpc_getblockstats.py

@@ -161,6 +161,14 @@ def run_test(self):
         assert_raises_rpc_error(-1, 'getblockstats hash_or_height ( stats )', self.nodes[0].getblockstats, '00', 1, 2)
         assert_raises_rpc_error(-1, 'getblockstats hash_or_height ( stats )', self.nodes[0].getblockstats)
 
+        self.log.info('Test block height 0')
+        genesis_stats = self.nodes[0].getblockstats(0)
+        assert_equal(genesis_stats["blockhash"], "0f9188f13cb7b2c71f2a335e3a4fc328bf5beb436012afca590b1a11466e2206")
+        assert_equal(genesis_stats["utxo_increase"], 1)
+        assert_equal(genesis_stats["utxo_size_inc"], 117)
+        assert_equal(genesis_stats["utxo_increase_actual"], 0)
+        assert_equal(genesis_stats["utxo_size_inc_actual"], 0)
+
 
 if __name__ == '__main__':
     GetblockstatsTest().main()