Merge #10357: Allow setting nMinimumChainWork on command line

eac64bb7a [qa] Test nMinimumChainWork (Suhas Daftuar)
0311836f6 Allow setting nMinimumChainWork on command line (Suhas Daftuar)

Pull request description:

  As discussed briefly here: https://botbot.me/freenode/bitcoin-core-dev/2017-02-28/?msg=81712308&page=4

  This adds a hidden command line option for setting `nMinimumChainWork`, which allows us to test this parameter in our functional tests, as well as allowing for niche use cases like syncing nodes that are otherwise disconnected from the network.

  See also #10345, which proposes a new use of `nMinimumChainWork`.

Tree-SHA512: fe4d8f4f289697615c98d8760f1cc74c076110310ea0b5b875fcab78c127da9195b4eb84148aebacc7606c246e5773d3f13bd5d9559d0a8bffac20a3a28c62df

2 files changed, 82 insertions, 0 deletions

diff --git a/test/functional/minchainwork.py b/test/functional/minchainwork.py
new file mode 100755
index 0000000000..c7579d2548
--- /dev/null
+++ b/test/functional/minchainwork.py
@@ -0,0 +1,81 @@
+#!/usr/bin/env python3
+# Copyright (c) 2017 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Test logic for setting nMinimumChainWork on command line.
+
+Nodes don't consider themselves out of "initial block download" until
+their active chain has more work than nMinimumChainWork.
+
+Nodes don't download blocks from a peer unless the peer's best known block
+has more work than nMinimumChainWork.
+
+While in initial block download, nodes won't relay blocks to their peers, so
+test that this parameter functions as intended by verifying that block relay
+only succeeds past a given node once its nMinimumChainWork has been exceeded.
+"""
+
+import time
+
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import sync_blocks, connect_nodes, assert_equal
+
+# 2 hashes required per regtest block (with no difficulty adjustment)
+REGTEST_WORK_PER_BLOCK = 2
+
+class MinimumChainWorkTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.setup_clean_chain = True
+        self.num_nodes = 3
+        self.extra_args = [[], ["-minimumchainwork=0x65"], ["-minimumchainwork=0x65"]]
+        self.node_min_work = [0, 101, 101]
+
+    def setup_network(self):
+        # This test relies on the chain setup being:
+        # node0 <- node1 <- node2
+        # Before leaving IBD, nodes prefer to download blocks from outbound
+        # peers, so ensure that we're mining on an outbound peer and testing
+        # block relay to inbound peers.
+        self.setup_nodes()
+        for i in range(self.num_nodes-1):
+            connect_nodes(self.nodes[i+1], i)
+
+    def run_test(self):
+        # Start building a chain on node0.  node2 shouldn't be able to sync until node1's
+        # minchainwork is exceeded
+        starting_chain_work = REGTEST_WORK_PER_BLOCK # Genesis block's work
+        self.log.info("Testing relay across node %d (minChainWork = %d)", 1, self.node_min_work[1])
+
+        starting_blockcount = self.nodes[2].getblockcount()
+
+        num_blocks_to_generate = int((self.node_min_work[1] - starting_chain_work) / REGTEST_WORK_PER_BLOCK)
+        self.log.info("Generating %d blocks on node0", num_blocks_to_generate)
+        hashes = self.nodes[0].generate(num_blocks_to_generate)
+
+        self.log.info("Node0 current chain work: %s", self.nodes[0].getblockheader(hashes[-1])['chainwork'])
+
+        # Sleep a few seconds and verify that node2 didn't get any new blocks
+        # or headers.  We sleep, rather than sync_blocks(node0, node1) because
+        # it's reasonable either way for node1 to get the blocks, or not get
+        # them (since they're below node1's minchainwork).
+        time.sleep(3)
+
+        self.log.info("Verifying node 2 has no more blocks than before")
+        self.log.info("Blockcounts: %s", [n.getblockcount() for n in self.nodes])
+        # Node2 shouldn't have any new headers yet, because node1 should not
+        # have relayed anything.
+        assert_equal(len(self.nodes[2].getchaintips()), 1)
+        assert_equal(self.nodes[2].getchaintips()[0]['height'], 0)
+
+        assert self.nodes[1].getbestblockhash() != self.nodes[0].getbestblockhash()
+        assert_equal(self.nodes[2].getblockcount(), starting_blockcount)
+
+        self.log.info("Generating one more block")
+        self.nodes[0].generate(1)
+
+        self.log.info("Verifying nodes are all synced")
+        self.sync_all()
+        self.log.info("Blockcounts: %s", [n.getblockcount() for n in self.nodes])
+
+if __name__ == '__main__':
+    MinimumChainWorkTest().main()
diff --git a/test/functional/test_runner.py b/test/functional/test_runner.py
index 59c236ce15..8dbe6247ee 100755
--- a/test/functional/test_runner.py
+++ b/test/functional/test_runner.py
@@ -121,6 +121,7 @@ BASE_SCRIPTS= [
     'bip65-cltv-p2p.py',
     'uptime.py',
     'resendwallettransactions.py',
+    'minchainwork.py',
 ]
 
 EXTENDED_SCRIPTS = [