Document method for reviewers to verify chainTxData

This commit adds the final block hash of the window to getchaintxstats
and documents how reviewers can verify changes to chainTxData.

Author: jnewbery

doc/release-process.md

@@ -24,7 +24,7 @@ Before every major release:
 * Update hardcoded [seeds](/contrib/seeds/README.md), see [this pull request](https://github.com/bitcoin/bitcoin/pull/7415) for an example.
 * Update [`BLOCK_CHAIN_SIZE`](/src/qt/intro.cpp) to the current size plus some overhead.
 * Update `src/chainparams.cpp` chainTxData with statistics about the transaction count and rate. Use the output of the RPC `getchaintxstats`, see
-  [this pull request](https://github.com/bitcoin/bitcoin/pull/12270) for an example.
+  [this pull request](https://github.com/bitcoin/bitcoin/pull/12270) for an example. Reviewers can verify the results by running `getchaintxstats <window_block_count> <window_last_block_hash>` with the `window_block_count` and `window_last_block_hash` from your output.
 * Update version of `contrib/gitian-descriptors/*.yml`: usually one'd want to do this on master after branching off the release - but be sure to at least do it before a new major release
 
 ### First time / New builders

src/rpc/blockchain.cpp

@@ -1526,12 +1526,13 @@ UniValue getchaintxstats(const JSONRPCRequest& request)
             "2. \"blockhash\"  (string, optional) The hash of the block that ends the window.\n"
             "\nResult:\n"
             "{\n"
-            "  \"time\": xxxxx,                (numeric) The timestamp for the final block in the window in UNIX format.\n"
-            "  \"txcount\": xxxxx,             (numeric) The total number of transactions in the chain up to that point.\n"
-            "  \"window_block_count\": xxxxx,  (numeric) Size of the window in number of blocks.\n"
-            "  \"window_tx_count\": xxxxx,     (numeric) The number of transactions in the window. Only returned if \"window_block_count\" is > 0.\n"
-            "  \"window_interval\": xxxxx,     (numeric) The elapsed time in the window in seconds. Only returned if \"window_block_count\" is > 0.\n"
-            "  \"txrate\": x.xx,               (numeric) The average rate of transactions per second in the window. Only returned if \"window_interval\" is > 0.\n"
+            "  \"time\": xxxxx,                         (numeric) The timestamp for the final block in the window in UNIX format.\n"
+            "  \"txcount\": xxxxx,                      (numeric) The total number of transactions in the chain up to that point.\n"
+            "  \"window_final_block_hash\": \"...\",      (string) The hash of the final block in the window.\n"
+            "  \"window_block_count\": xxxxx,           (numeric) Size of the window in number of blocks.\n"
+            "  \"window_tx_count\": xxxxx,              (numeric) The number of transactions in the window. Only returned if \"window_block_count\" is > 0.\n"
+            "  \"window_interval\": xxxxx,              (numeric) The elapsed time in the window in seconds. Only returned if \"window_block_count\" is > 0.\n"
+            "  \"txrate\": x.xx,                        (numeric) The average rate of transactions per second in the window. Only returned if \"window_interval\" is > 0.\n"
             "}\n"
             "\nExamples:\n"
             + HelpExampleCli("getchaintxstats", "")
@@ -1582,6 +1583,7 @@ UniValue getchaintxstats(const JSONRPCRequest& request)
     UniValue ret(UniValue::VOBJ);
     ret.push_back(Pair("time", (int64_t)pindex->nTime));
     ret.push_back(Pair("txcount", (int64_t)pindex->nChainTx));
+    ret.push_back(Pair("window_final_block_hash", pindex->GetBlockHash().GetHex()));
     ret.push_back(Pair("window_block_count", blockcount));
     if (blockcount > 0) {
         ret.push_back(Pair("window_tx_count", nTxDiff));

test/functional/rpc_blockchain.py

@@ -100,28 +100,34 @@ def _test_getblockchaininfo(self):
         assert_greater_than(res['size_on_disk'], 0)
 
     def _test_getchaintxstats(self):
+        self.log.info("Test getchaintxstats")
+
         chaintxstats = self.nodes[0].getchaintxstats(1)
         # 200 txs plus genesis tx
         assert_equal(chaintxstats['txcount'], 201)
         # tx rate should be 1 per 10 minutes, or 1/600
         # we have to round because of binary math
         assert_equal(round(chaintxstats['txrate'] * 600, 10), Decimal(1))
 
-        b1 = self.nodes[0].getblock(self.nodes[0].getblockhash(1))
-        b200 = self.nodes[0].getblock(self.nodes[0].getblockhash(200))
+        b1_hash = self.nodes[0].getblockhash(1)
+        b1 = self.nodes[0].getblock(b1_hash)
+        b200_hash = self.nodes[0].getblockhash(200)
+        b200 = self.nodes[0].getblock(b200_hash)
         time_diff = b200['mediantime'] - b1['mediantime']
 
         chaintxstats = self.nodes[0].getchaintxstats()
         assert_equal(chaintxstats['time'], b200['time'])
         assert_equal(chaintxstats['txcount'], 201)
+        assert_equal(chaintxstats['window_final_block_hash'], b200_hash)
         assert_equal(chaintxstats['window_block_count'], 199)
         assert_equal(chaintxstats['window_tx_count'], 199)
         assert_equal(chaintxstats['window_interval'], time_diff)
         assert_equal(round(chaintxstats['txrate'] * time_diff, 10), Decimal(199))
 
-        chaintxstats = self.nodes[0].getchaintxstats(blockhash=b1['hash'])
+        chaintxstats = self.nodes[0].getchaintxstats(blockhash=b1_hash)
         assert_equal(chaintxstats['time'], b1['time'])
         assert_equal(chaintxstats['txcount'], 2)
+        assert_equal(chaintxstats['window_final_block_hash'], b1_hash)
         assert_equal(chaintxstats['window_block_count'], 0)
         assert('window_tx_count' not in chaintxstats)
         assert('window_interval' not in chaintxstats)
@@ -173,8 +179,7 @@ def _test_gettxoutsetinfo(self):
     def _test_getblockheader(self):
         node = self.nodes[0]
 
-        assert_raises_rpc_error(-5, "Block not found",
-                              node.getblockheader, "nonsense")
+        assert_raises_rpc_error(-5, "Block not found", node.getblockheader, "nonsense")
 
         besthash = node.getbestblockhash()
         secondbesthash = node.getblockhash(199)