Improve gettxoutsetinfo command

* Bugfix: output the correct best block hash (during IBD, it can
  differ from the actual current best block)
* Add height to output
* Add hash_serialized, which is a hash of the entire UTXO state.
  Can be useful to compare two nodes.
* Add total_amount, the sum of all UTXOs' values.

src/main.h

@@ -2096,11 +2096,14 @@ extern CTxMemPool mempool;
 struct CCoinsStats
 {
     int nHeight;
+    uint256 hashBlock;
     uint64 nTransactions;
     uint64 nTransactionOutputs;
     uint64 nSerializedSize;
+    uint256 hashSerialized;
+    int64 nTotalAmount;
 
-    CCoinsStats() : nHeight(0), nTransactions(0), nTransactionOutputs(0), nSerializedSize(0) {}
+    CCoinsStats() : nHeight(0), hashBlock(0), nTransactions(0), nTransactionOutputs(0), nSerializedSize(0), hashSerialized(0), nTotalAmount(0) {}
 };
 
 /** Abstract view on the open txout dataset. */

src/rpcblockchain.cpp

@@ -172,10 +172,13 @@ Value gettxoutsetinfo(const Array& params, bool fHelp)
 
     CCoinsStats stats;
     if (pcoinsTip->GetStats(stats)) {
-        ret.push_back(Pair("bestblock", pcoinsTip->GetBestBlock()->GetBlockHash().GetHex()));
+        ret.push_back(Pair("height", (boost::int64_t)stats.nHeight));
+        ret.push_back(Pair("bestblock", stats.hashBlock.GetHex()));
         ret.push_back(Pair("transactions", (boost::int64_t)stats.nTransactions));
         ret.push_back(Pair("txouts", (boost::int64_t)stats.nTransactionOutputs));
         ret.push_back(Pair("bytes_serialized", (boost::int64_t)stats.nSerializedSize));
+        ret.push_back(Pair("hash_serialized", stats.hashSerialized.GetHex()));
+        ret.push_back(Pair("total_amount", ValueFromAmount(stats.nTotalAmount)));
     }
     return ret;
 }

src/txdb.cpp

@@ -5,6 +5,7 @@
 
 #include "txdb.h"
 #include "main.h"
+#include "hash.h"
 
 using namespace std;
 
@@ -114,6 +115,10 @@ bool CCoinsViewDB::GetStats(CCoinsStats &stats) {
     leveldb::Iterator *pcursor = db.NewIterator();
     pcursor->SeekToFirst();
 
+    CHashWriter ss(SER_GETHASH, PROTOCOL_VERSION);
+    stats.hashBlock = GetBestBlock()->GetBlockHash();
+    ss << stats.hashBlock;
+    int64 nTotalAmount = 0;
     while (pcursor->Valid()) {
         boost::this_thread::interruption_point();
         try {
@@ -128,13 +133,22 @@ bool CCoinsViewDB::GetStats(CCoinsStats &stats) {
                 ssValue >> coins;
                 uint256 txhash;
                 ssKey >> txhash;
-
+                ss << txhash;
+                ss << VARINT(coins.nVersion);
+                ss << (coins.fCoinBase ? 'c' : 'n'); 
+                ss << VARINT(coins.nHeight);
                 stats.nTransactions++;
-                BOOST_FOREACH(const CTxOut &out, coins.vout) {
+                for (unsigned int i=0; i<coins.vout.size(); i++) {
-                    if (!out.IsNull())
+                    const CTxOut &out = coins.vout[i];
+                    if (!out.IsNull()) {
                         stats.nTransactionOutputs++;
+                        ss << VARINT(i+1);
+                        ss << out;
+                        nTotalAmount += out.nValue;
+                    }
                 }
                 stats.nSerializedSize += 32 + slValue.size();
+                ss << VARINT(0);
             }
             pcursor->Next();
         } catch (std::exception &e) {
@@ -143,6 +157,8 @@ bool CCoinsViewDB::GetStats(CCoinsStats &stats) {
     }
     delete pcursor;
     stats.nHeight = GetBestBlock()->nHeight;
+    stats.hashSerialized = ss.GetHash();
+    stats.nTotalAmount = nTotalAmount;
     return true;
 }