Replace bytes_serialized with bogosize

Author: sipa

doc/release-notes.md

@@ -42,9 +42,15 @@ Low-level RPC changes
   - The `gettxoutsetinfo` RPC reports `hash_serialized_2` instead of `hash_serialized`,
     which does not commit to the transaction versions of unspent outputs, but does
     commit to the height and coinbase information.
+  - The `gettxoutsetinfo` response now contains `disk_size` and `bogosize` instead of
+    `bytes_serialized`. The first is a more accurate estimate of actual disk usage, but
+    is not deterministic. The second is unrelated to disk usage, but is a
+    database-independent metric of UTXO set size: it counts every UTXO entry as 50 + the
+    length of its scriptPubKey.
   - The `getutxos` REST path no longer reports the `txvers` field in JSON format,
     and always reports 0 for transaction versions in the binary format
 
+
 - Error codes have been updated to be more accurate for the following error cases:
   - `getblock` now returns RPC_MISC_ERROR if the block can't be found on disk (for
   example if the block has been pruned). Previously returned RPC_INTERNAL_ERROR.

src/rpc/blockchain.cpp

@@ -781,11 +781,12 @@ struct CCoinsStats
     uint256 hashBlock;
     uint64_t nTransactions;
     uint64_t nTransactionOutputs;
+    uint64_t nBogoSize;
     uint256 hashSerialized;
     uint64_t nDiskSize;
     CAmount nTotalAmount;
 
-    CCoinsStats() : nHeight(0), nTransactions(0), nTransactionOutputs(0), nTotalAmount(0) {}
+    CCoinsStats() : nHeight(0), nTransactions(0), nTransactionOutputs(0), nBogoSize(0), nDiskSize(0), nTotalAmount(0) {}
 };
 
 static void ApplyStats(CCoinsStats &stats, CHashWriter& ss, const uint256& hash, const std::map<uint32_t, Coin>& outputs)
@@ -800,6 +801,8 @@ static void ApplyStats(CCoinsStats &stats, CHashWriter& ss, const uint256& hash,
         ss << VARINT(output.second.out.nValue);
         stats.nTransactionOutputs++;
         stats.nTotalAmount += output.second.out.nValue;
+        stats.nBogoSize += 32 /* txid */ + 4 /* vout index */ + 4 /* height + coinbase */ + 8 /* amount */ +
+                           2 /* scriptPubKey len */ + output.second.out.scriptPubKey.size() /* scriptPubKey */;
     }
     ss << VARINT(0);
 }
@@ -904,7 +907,8 @@ UniValue gettxoutsetinfo(const JSONRPCRequest& request)
             "  \"bestblock\": \"hex\",   (string) the best block hash hex\n"
             "  \"transactions\": n,      (numeric) The number of transactions\n"
             "  \"txouts\": n,            (numeric) The number of output transactions\n"
-            "  \"hash_serialized\": \"hash\",   (string) The serialized hash\n"
+            "  \"bogosize\": n,          (numeric) A meaningless metric for UTXO set size\n"
+            "  \"hash_serialized_2\": \"hash\", (string) The serialized hash\n"
             "  \"disk_size\": n,         (numeric) The estimated size of the chainstate on disk\n"
             "  \"total_amount\": x.xxx          (numeric) The total amount\n"
             "}\n"
@@ -922,6 +926,7 @@ UniValue gettxoutsetinfo(const JSONRPCRequest& request)
         ret.push_back(Pair("bestblock", stats.hashBlock.GetHex()));
         ret.push_back(Pair("transactions", (int64_t)stats.nTransactions));
         ret.push_back(Pair("txouts", (int64_t)stats.nTransactionOutputs));
+        ret.push_back(Pair("bogosize", (int64_t)stats.nBogoSize));
         ret.push_back(Pair("hash_serialized_2", stats.hashSerialized.GetHex()));
         ret.push_back(Pair("disk_size", stats.nDiskSize));
         ret.push_back(Pair("total_amount", ValueFromAmount(stats.nTotalAmount)));

test/functional/blockchain.py

@@ -49,6 +49,7 @@ def _test_gettxoutsetinfo(self):
         assert_equal(res['transactions'], 200)
         assert_equal(res['height'], 200)
         assert_equal(res['txouts'], 200)
+        assert_equal(res['bogosize'], 17000),
         assert_equal(res['bestblock'], node.getblockhash(200))
         size = res['disk_size']
         assert size > 6400
@@ -65,6 +66,7 @@ def _test_gettxoutsetinfo(self):
         assert_equal(res2['total_amount'], Decimal('0'))
         assert_equal(res2['height'], 0)
         assert_equal(res2['txouts'], 0)
+        assert_equal(res2['bogosize'], 0),
         assert_equal(res2['bestblock'], node.getblockhash(0))
         assert_equal(len(res2['hash_serialized_2']), 64)
 
@@ -76,6 +78,7 @@ def _test_gettxoutsetinfo(self):
         assert_equal(res['transactions'], res3['transactions'])
         assert_equal(res['height'], res3['height'])
         assert_equal(res['txouts'], res3['txouts'])
+        assert_equal(res['bogosize'], res3['bogosize'])
         assert_equal(res['bestblock'], res3['bestblock'])
         assert_equal(res['hash_serialized_2'], res3['hash_serialized_2'])