add test performing a deep reorg with 3 nodes

chia/consensus/blockchain.py

@@ -735,6 +735,8 @@ def clean_block_record(self, height: int) -> None:
         Args:
             height: Minimum height that we need to keep in the cache
         """
+        if self._peak_height is not None and height > self._peak_height - self.constants.BLOCKS_CACHE_SIZE:
+            height = self._peak_height - self.constants.BLOCKS_CACHE_SIZE
         if height < 0:
             return None
         blocks_to_remove = self.__heights_in_cache.get(uint32(height), None)

chia/full_node/full_node.py

@@ -538,7 +538,8 @@ async def short_sync_batch(self, peer: WSChiaConnection, start_height: uint32, t
             )
             if first is None or not isinstance(first, full_node_protocol.RespondBlock):
                 self.sync_store.batch_syncing.remove(peer.peer_node_id)
-                raise ValueError(f"Error short batch syncing, could not fetch block at height {start_height}")
+                self.log.error(f"Error short batch syncing, could not fetch block at height {start_height}")
+                return False
             if not self.blockchain.contains_block(first.block.prev_header_hash):
                 self.log.info("Batch syncing stopped, this is a deep chain")
                 self.sync_store.batch_syncing.remove(peer.peer_node_id)
@@ -716,6 +717,10 @@ async def new_peak(self, request: full_node_protocol.NewPeak, peer: WSChiaConnec
                 return None
 
             if request.height < curr_peak_height + self.config["sync_blocks_behind_threshold"]:
+                # TODO: We get here if we encountered a heavier peak with a
+                # lower height than ours. We don't seem to handle this case
+                # right now. This ends up requesting the block at *our* peak
+                # height.
                 # This case of being behind but not by so much
                 if await self.short_sync_batch(peer, uint32(max(curr_peak_height - 6, 0)), request.height):
                     return None
@@ -1110,6 +1115,11 @@ async def validate_block_batches(
                         self.subscriptions.has_ph_subscription,
                     )
                     await self.hint_store.add_hints(hints_to_add)
+                # Note that end_height is not necessarily the peak at this
+                # point. In case of a re-org, it may even be significantly
+                # higher than _peak_height, and still not be the peak.
+                # clean_block_record() will not necessarily honor this cut-off
+                # height, in that case.
                 self.blockchain.clean_block_record(end_height - self.constants.BLOCKS_CACHE_SIZE)
 
         batch_queue_input: asyncio.Queue[Optional[Tuple[WSChiaConnection, List[FullBlock]]]] = asyncio.Queue(

chia/simulator/block_tools.py

@@ -146,7 +146,10 @@
     NUM_SPS_SUB_SLOT=uint32(16),  # Must be a power of 2
     MAX_SUB_SLOT_BLOCKS=uint32(50),
     EPOCH_BLOCKS=uint32(340),
-    BLOCKS_CACHE_SIZE=uint32(340 + 3 * 50),  # Coordinate with the above values
+    # the block cache must contain at least 3 epochs in order for
+    # create_prev_sub_epoch_segments() to have access to all the blocks it needs
+    # from the cache
+    BLOCKS_CACHE_SIZE=uint32(340 * 3),  # Coordinate with the above values
     SUB_SLOT_TIME_TARGET=600,  # The target number of seconds per slot, mainnet 600
     SUB_SLOT_ITERS_STARTING=uint64(2**10),  # Must be a multiple of 64
     NUMBER_ZERO_BITS_PLOT_FILTER=1,  # H(plot signature of the challenge) must start with these many zeroes

tests/core/full_node/test_full_node.py

@@ -6,6 +6,7 @@
 import logging
 import random
 import time
+import traceback
 from typing import Coroutine, Dict, List, Optional, Tuple
 
 import pytest
@@ -2150,3 +2151,91 @@ async def test_wallet_sync_task_failure(
     assert "update_wallets - fork_height: 10, peak_height: 0" in caplog.text
     assert "Wallet sync task failure" not in caplog.text
     assert not full_node.wallet_sync_task.done()
+
+
+@pytest.mark.anyio
+@pytest.mark.limit_consensus_modes(reason="this test is too slow (for now)")
+async def test_long_reorg_nodes(
+    three_nodes,
+    default_10000_blocks: List[FullBlock],
+    test_long_reorg_blocks: List[FullBlock],
+    self_hostname: str,
+    seeded_random: random.Random,
+):
+    full_node_1, full_node_2, full_node_3 = three_nodes
+
+    blocks = default_10000_blocks[:1600]
+
+    reorg_blocks = test_long_reorg_blocks[:1200]
+
+    # full node 1 has the original chain
+    for block_batch in to_batches(blocks, 64):
+        b = block_batch.entries[0]
+        if (b.height % 128) == 0:
+            print(f"main chain: {b.height:4} weight: {b.weight}")
+        await full_node_1.full_node.add_block_batch(block_batch.entries, PeerInfo("0.0.0.0", 8884), None)
+
+    # full node 2 has the reorg-chain
+    for block_batch in to_batches(reorg_blocks[:-1], 64):
+        b = block_batch.entries[0]
+        if (b.height % 128) == 0:
+            print(f"reorg chain: {b.height:4} weight: {b.weight}")
+        await full_node_2.full_node.add_block_batch(block_batch.entries, PeerInfo("0.0.0.0", 8884), None)
+
+    await connect_and_get_peer(full_node_1.full_node.server, full_node_2.full_node.server, self_hostname)
+
+    # TODO: There appears to be an issue where the node with the lighter chain
+    # fails to initiate the reorg until there's a new block farmed onto the
+    # heavier chain.
+    await full_node_2.full_node.add_block(reorg_blocks[-1])
+
+    def check_nodes_in_sync():
+        try:
+            p1 = full_node_2.full_node.blockchain.get_peak()
+            p2 = full_node_1.full_node.blockchain.get_peak()
+            return p1 == p2
+        except Exception as e:
+            # TODO: understand why we get an exception here sometimes. Fix it or
+            # add comment explaining why we need to catch here
+            traceback.print_exc()
+            print(f"e: {e}")
+            return False
+
+    await time_out_assert(120, check_nodes_in_sync)
+    peak = full_node_2.full_node.blockchain.get_peak()
+    print(f"peak: {str(peak.header_hash)[:6]}")
+
+    p1 = full_node_1.full_node.blockchain.get_peak()
+    p2 = full_node_2.full_node.blockchain.get_peak()
+
+    assert p1.header_hash == reorg_blocks[-1].header_hash
+    assert p2.header_hash == reorg_blocks[-1].header_hash
+
+    blocks = default_10000_blocks[:4000]
+
+    # full node 3 has the original chain, but even longer
+    for block_batch in to_batches(blocks, 64):
+        b = block_batch.entries[0]
+        if (b.height % 128) == 0:
+            print(f"main chain: {b.height:4} weight: {b.weight}")
+        await full_node_3.full_node.add_block_batch(block_batch.entries, PeerInfo("0.0.0.0", 8884), None)
+
+    print("connecting node 3")
+    await connect_and_get_peer(full_node_3.full_node.server, full_node_1.full_node.server, self_hostname)
+    # await connect_and_get_peer(full_node_3.full_node.server, full_node_2.full_node.server, self_hostname)
+
+    def check_nodes_in_sync2():
+        p1 = full_node_1.full_node.blockchain.get_peak()
+        # p2 = full_node_2.full_node.blockchain.get_peak()
+        p3 = full_node_3.full_node.blockchain.get_peak()
+        return p1 == p3
+
+    await time_out_assert(950, check_nodes_in_sync2)
+
+    p1 = full_node_1.full_node.blockchain.get_peak()
+    # p2 = full_node_2.full_node.blockchain.get_peak()
+    p3 = full_node_3.full_node.blockchain.get_peak()
+
+    assert p1.header_hash == blocks[-1].header_hash
+    # assert p2.header_hash == blocks[-1].header_hash
+    assert p3.header_hash == blocks[-1].header_hash