feat(state): Implements reconsider_block method #9260
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arya2
previously approved these changes
Feb 17, 2025
arya2
reviewed
Feb 17, 2025
7 tasks
…m validate_and_commit if a candidate block's hash is in the map of invalidated blocks. Stores invalidated_blocks by height and clears when finalizing. Checks against non finalized tip hash to create a new chain if parnt_chain doesn't exist. Renames ReconsiderError variant NonPreviouslyInvalidatedBlock to MissingInvalidatedBlock.
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This pull request has been removed from the queue for the following reason: Pull request #9260 has been dequeued, merge conditions unmatch:
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elijahhampton
commented
Feb 19, 2025
| /// | ||
| /// This limits the memory for each entry to around: | ||
| /// `256 blocks * 2 MB per block = 0.5 GB` | ||
| pub const MAX_INVALIDATED_BLOCKS: usize = 256; |
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@arya2 Does this make sense to cap it at 256?
arya2
reviewed
Feb 20, 2025
| @@ -235,6 +237,10 @@ impl NonFinalizedState { | |||
| self.insert(side_chain); | |||
| } | |||
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| // Remove all invalidated_blocks at or below the finalized height | |||
| self.invalidated_blocks | |||
| .retain(|height, _blocks| *height > best_chain_root.height); | |||
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If you add a handle to the db as a parameter on reconsider_block(), this should leave invalidated blocks until they are below the best chain root height.
Suggested change
| .retain(|height, _blocks| *height > best_chain_root.height); | |
| .retain(|height, _blocks| *height >= best_chain_root.height); |
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| /// The maximum number of invalidated blocks per entry. | ||
| /// | ||
| /// This limits the memory for each entry to around: | ||
| /// `256 blocks * 2 MB per block = 0.5 GB` | ||
| pub const MAX_INVALIDATED_BLOCKS: usize = 256; |
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If the collection could be mutated by peers, it would be better to track the size of the blocks and start dropping the first ones that were inserted until it's below a size limit, but limiting the number of entries is good enough here as invalidated blocks should only be added via a private RPC interface.
Suggested change
| /// The maximum number of invalidated blocks per entry. | |
| /// | |
| /// This limits the memory for each entry to around: | |
| /// `256 blocks * 2 MB per block = 0.5 GB` | |
| pub const MAX_INVALIDATED_BLOCKS: usize = 256; | |
| /// The maximum number of invalidated block records. | |
| /// | |
| /// This limits the memory use to around: | |
| /// `100 entries * up to 99 blocks * 2 MB per block = 20 GB` | |
| pub const MAX_INVALIDATED_BLOCKS: usize = 100; |
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| let parent_chain = self | ||
| .parent_chain(root_parent_hash) | ||
| .map_err(|_| ReconsiderError::ParentChainNotFound(block_hash)); | ||
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| let modified_chain = match parent_chain { | ||
| // 1. If a parent chain exist use the parent chain | ||
| Ok(parent_chain) => { | ||
| let mut chain = Arc::unwrap_or_clone(parent_chain); | ||
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| for block in Arc::unwrap_or_clone(invalidated_blocks) { | ||
| chain = chain.push(block)?; | ||
| } | ||
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| Arc::new(chain) | ||
| } | ||
| // 2. If a parent chain does not exist create a new chain from the non finalized state tip | ||
| Err(_) => { | ||
| let mut chain = Chain::new( | ||
| &self.network, | ||
| invalidated_root.height.previous().map_err(|_| { | ||
| ReconsiderError::InvalidHeight(Height(invalidated_root.height.0 - 1)) | ||
| })?, | ||
| Default::default(), | ||
| Default::default(), | ||
| Default::default(), | ||
| Default::default(), | ||
| ValueBalance::zero(), | ||
| ); | ||
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| for block in Arc::unwrap_or_clone(invalidated_blocks) { | ||
| chain = chain.push(block)?; | ||
| } | ||
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| Arc::new(chain) | ||
| } | ||
| }; |
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parent_chain() will already return a new fork if the invalidated block's parent is in the non-finalized state. This method shouldn't add a new chain to the non-finalized state if it's root is below the finalized tip.
This method could accept a handle to the db as a parameter and create a new chain if the invalidated block's parent is the finalized tip block, or it could refuse to reconsider blocks unless their parent is in the non-finalized state.
The suggestion below does the latter:
Suggested change
| let parent_chain = self | |
| .parent_chain(root_parent_hash) | |
| .map_err(|_| ReconsiderError::ParentChainNotFound(block_hash)); | |
| let modified_chain = match parent_chain { | |
| // 1. If a parent chain exist use the parent chain | |
| Ok(parent_chain) => { | |
| let mut chain = Arc::unwrap_or_clone(parent_chain); | |
| for block in Arc::unwrap_or_clone(invalidated_blocks) { | |
| chain = chain.push(block)?; | |
| } | |
| Arc::new(chain) | |
| } | |
| // 2. If a parent chain does not exist create a new chain from the non finalized state tip | |
| Err(_) => { | |
| let mut chain = Chain::new( | |
| &self.network, | |
| invalidated_root.height.previous().map_err(|_| { | |
| ReconsiderError::InvalidHeight(Height(invalidated_root.height.0 - 1)) | |
| })?, | |
| Default::default(), | |
| Default::default(), | |
| Default::default(), | |
| Default::default(), | |
| ValueBalance::zero(), | |
| ); | |
| for block in Arc::unwrap_or_clone(invalidated_blocks) { | |
| chain = chain.push(block)?; | |
| } | |
| Arc::new(chain) | |
| } | |
| }; | |
| let parent_chain = self | |
| .parent_chain(root_parent_hash) | |
| .map_err(|_| ReconsiderError::ParentChainNotFound(block_hash))?; | |
| let mut modified_chain = Arc::unwrap_or_clone(parent_chain); | |
| for block in Arc::unwrap_or_clone(invalidated_blocks) { | |
| modified_chain = modified_chain.push(block)?; | |
| } |
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| #[error("Invalid height {0:?}: parent height would be negative")] | ||
| InvalidHeight(block::Height), | ||
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This is no longer needed if the previous suggestion is applied.
Suggested change
| #[error("Invalid height {0:?}: parent height would be negative")] | |
| InvalidHeight(block::Height), |
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Motivation
The changes create and test a reconsider_block method to later be integrated into the zebra RPC. This method reconsiders previously invalidated_blocks into a chain that exist in the chain_set. Closes #8842.
Specifications & References
NonFinalizedStatevia RPC methods #8634reconsider_block()method to theNonFinalizedStatefor validating/committing a previously invalidated block and its invalidated descendents #8842Solution
reconsider_blockmethod toNonFinalizedStatethat allows previously invalidated blocks to be reconsidered and re-inserted into the chain.Tests
Follow-up Work
PR Author's Checklist
PR Reviewer's Checklist