Merge #16404: qa: Test ZMQ notification after chain reorg

abdfc5e89b687f73de4ab97e924c29cc27e71c15 qa: Test ZMQ notification after chain reorg (João Barbosa)
aa2622a726bc0f02152d79c888a332694678a989 qa: Refactor ZMQ test (João Barbosa)
6bc1ff915dd495f05985d3402a34dbfc3b6a08b4 doc: Add note regarding ZMQ block notification (João Barbosa)

Pull request description:

Top commit has no ACKs.

Tree-SHA512: b93237adc8c84b3aa72ccc28097090eabcb006cf408083218bebf6fec703bd0de2ded80b6879e77096872e14ba9402a6d3f923b146a54d4c4e41dcb862c3e765

doc/zmq.md

@@ -154,7 +154,9 @@ using other means such as firewalling.
 
 Note that when the block chain tip changes, a reorganisation may occur
 and just the tip will be notified. It is up to the subscriber to
-retrieve the chain from the last known block to the new tip.
+retrieve the chain from the last known block to the new tip. Also note
+that no notification occurs if the tip was in the active chain - this
+is the case after calling invalidateblock RPC.
 
 There are several possibilities that ZMQ notification can get lost
 during transmission depending on the communication type you are

test/functional/interface_zmq.py

@@ -12,11 +12,10 @@ from test_framework.test_framework import BitcoinTestFramework
 from test_framework.messages import dashhash
 from test_framework.util import (
     assert_equal,
+    connect_nodes,
     hash256,
     )
 
-ADDRESS = "tcp://127.0.0.1:28332"
-
 def dashhash_helper(b):
     return encode(dashhash(b)[::-1], 'hex_codec').decode('ascii')
 
@@ -48,62 +47,59 @@ class ZMQTest (BitcoinTestFramework):
         self.skip_if_no_py3_zmq()
         self.skip_if_no_bitcoind_zmq()
 
-    def setup_nodes(self):
+    def run_test(self):
         import zmq
+        self.ctx = zmq.Context()
+        try:
+            self.test_basic()
+            self.test_reorg()
+        finally:
+            # Destroy the ZMQ context.
+            self.log.debug("Destroying ZMQ context")
+            self.ctx.destroy(linger=None)
 
-        # Initialize ZMQ context and socket.
+    def test_basic(self):
         # All messages are received in the same socket which means
         # that this test fails if the publishing order changes.
         # Note that the publishing order is not defined in the documentation and
         # is subject to change.
-        self.zmq_context = zmq.Context()
+        import zmq
-        socket = self.zmq_context.socket(zmq.SUB)
+        address = 'tcp://127.0.0.1:28332'
+        socket = self.ctx.socket(zmq.SUB)
         socket.set(zmq.RCVTIMEO, 60000)
-        socket.connect(ADDRESS)
+        socket.connect(address)
 
         # Subscribe to all available topics.
-        self.hashblock = ZMQSubscriber(socket, b"hashblock")
+        hashblock = ZMQSubscriber(socket, b"hashblock")
-        self.hashtx = ZMQSubscriber(socket, b"hashtx")
+        hashtx = ZMQSubscriber(socket, b"hashtx")
-        self.rawblock = ZMQSubscriber(socket, b"rawblock")
+        rawblock = ZMQSubscriber(socket, b"rawblock")
-        self.rawtx = ZMQSubscriber(socket, b"rawtx")
+        rawtx = ZMQSubscriber(socket, b"rawtx")
 
-        self.extra_args = [
-            ["-zmqpub%s=%s" % (sub.topic.decode(), ADDRESS) for sub in [self.hashblock, self.hashtx, self.rawblock, self.rawtx]],
-            []
-        ]
-        self.add_nodes(self.num_nodes, self.extra_args)
-        self.start_nodes()
 
-    def run_test(self):
+        self.restart_node(0, ["-zmqpub%s=%s" % (sub.topic.decode(), address) for sub in [hashblock, hashtx, rawblock, rawtx]])
-        try:
+        connect_nodes(self.nodes[0], 1)
-            self._zmq_test()
-        finally:
-            # Destroy the ZMQ context.
-            self.log.debug("Destroying ZMQ context")
-            self.zmq_context.destroy(linger=None)
-
-    def _zmq_test(self):
         num_blocks = 5
         self.log.info("Generate %(n)d blocks (and %(n)d coinbase txes)" % {"n": num_blocks})
         genhashes = self.nodes[0].generatetoaddress(num_blocks, ADDRESS_BCRT1_UNSPENDABLE)
+
         self.sync_all()
 
         for x in range(num_blocks):
             # Should receive the coinbase txid.
-            txid = self.hashtx.receive()
+            txid = hashtx.receive()
 
             # Should receive the coinbase raw transaction.
-            hex = self.rawtx.receive()
+            hex = rawtx.receive()
             assert_equal(hash256(hex), txid)
 
             # Should receive the generated block hash.
-            hash = self.hashblock.receive().hex()
+            hash = hashblock.receive().hex()
             assert_equal(genhashes[x], hash)
             # The block should only have the coinbase txid.
             assert_equal([txid.hex()], self.nodes[1].getblock(hash)["tx"])
 
             # Should receive the generated raw block.
-            block = self.rawblock.receive()
+            block = rawblock.receive()
             assert_equal(genhashes[x], dashhash_helper(block[:80]))
 
         if self.is_wallet_compiled():
@@ -112,23 +108,47 @@ class ZMQTest (BitcoinTestFramework):
             self.sync_all()
 
             # Should receive the broadcasted txid.
-            txid = self.hashtx.receive()
+            txid = hashtx.receive()
             assert_equal(payment_txid, txid.hex())
 
             # Should receive the broadcasted raw transaction.
-            hex = self.rawtx.receive()
+            hex = rawtx.receive()
             assert_equal(payment_txid, hash256(hex).hex())
 
 
         self.log.info("Test the getzmqnotifications RPC")
         assert_equal(self.nodes[0].getzmqnotifications(), [
-            {"type": "pubhashblock", "address": ADDRESS, "hwm": 1000},
+            {"type": "pubhashblock", "address": address, "hwm": 1000},
-            {"type": "pubhashtx", "address": ADDRESS, "hwm": 1000},
+            {"type": "pubhashtx", "address": address, "hwm": 1000},
-            {"type": "pubrawblock", "address": ADDRESS, "hwm": 1000},
+            {"type": "pubrawblock", "address": address, "hwm": 1000},
-            {"type": "pubrawtx", "address": ADDRESS, "hwm": 1000},
+            {"type": "pubrawtx", "address": address, "hwm": 1000},
         ])
 
         assert_equal(self.nodes[1].getzmqnotifications(), [])
 
+    def test_reorg(self):
+        import zmq
+        address = 'tcp://127.0.0.1:28333'
+        socket = self.ctx.socket(zmq.SUB)
+        socket.set(zmq.RCVTIMEO, 60000)
+        socket.connect(address)
+        hashblock = ZMQSubscriber(socket, b'hashblock')
+
+        # Should only notify the tip if a reorg occurs
+        self.restart_node(0, ['-zmqpub%s=%s' % (hashblock.topic.decode(), address)])
+
+        # Generate 1 block in nodes[0] and receive all notifications
+        self.nodes[0].generatetoaddress(1, ADDRESS_BCRT1_UNSPENDABLE)
+        assert_equal(self.nodes[0].getbestblockhash(), hashblock.receive().hex())
+
+        # Generate 2 blocks in nodes[1]
+        self.nodes[1].generatetoaddress(2, ADDRESS_BCRT1_UNSPENDABLE)
+
+        # nodes[0] will reorg chain after connecting back nodes[1]
+        connect_nodes(self.nodes[0], 1)
+
+        # Should receive nodes[1] tip
+        assert_equal(self.nodes[1].getbestblockhash(), hashblock.receive().hex())
+
 if __name__ == '__main__':
     ZMQTest().main()