p2p: Start downloading historical blocks from common ancestor

mzumsande · alfonsoromanz · commit 65343ec49a6b · 2024-06-27T09:55:04.000+02:00
Otherwise, if the background tip is not an ancestor of the snapshot, blocks in between that ancestor up to the height of the background tip will never be requested.
diff --git a/src/net_processing.cpp b/src/net_processing.cpp
@@ -1533,7 +1533,8 @@ void PeerManagerImpl::TryDownloadingHistoricalBlocks(const Peer& peer, unsigned
         // complete history beneath the snapshot base.
         return;
     }
-
+    // If the background tip is not an ancestor of the snapshot block, we need to start requesting blocks from their last common ancestor.
+    from_tip = LastCommonAncestor(from_tip, target_block);
     FindNextBlocks(vBlocks, peer, state, from_tip, count, std::min<int>(from_tip->nHeight + BLOCK_DOWNLOAD_WINDOW, target_block->nHeight));
 }
 

Original file line number	Diff line number	Diff line change
`@@ -1533,7 +1533,8 @@ void PeerManagerImpl::TryDownloadingHistoricalBlocks(const Peer& peer, unsigned`
`1533`	`1533`	`// complete history beneath the snapshot base.`
`1534`	`1534`	`return;`
`1535`	`1535`	`}`
`1536`		`-`
	`1536`	`+ // If the background tip is not an ancestor of the snapshot block, we need to start requesting blocks from their last common ancestor.`
	`1537`	`+ from_tip = LastCommonAncestor(from_tip, target_block);`
`1537`	`1538`	`FindNextBlocks(vBlocks, peer, state, from_tip, count, std::min<int>(from_tip->nHeight + BLOCK_DOWNLOAD_WINDOW, target_block->nHeight));`
`1538`	`1539`	`}`
`1539`	`1540`