core/types: fix immutability guarantees in Block #27844
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This change rearranges the accessor methods in block.go and fixes some minor issues with the copy-on-write logic of block data. As a refresher, the rules around block immutability are as follows: - We copy all data when the block is constructed. This makes the references held inside the block independent of whatever value was passed in. - We copy all header data on access. This is because any change to the header would mess up the cached hash and size values in the block. Calling code is expected to take advantage of this to avoid over-allocating! - When new body data is attached to the block, we create a shallow copy of the block. This ensures block modifications are race-free. - We do not copy body data on access because it does not affect the caches, and also because it would be too expensive. The change corrects these issues: - Block.WithWithdrawals did not create a shallow copy of the block. - Block.WithBody copied the header unnecessarily, and did not preserve withdrawals. However, the bugs did not affect any code in go-ethereum because blocks are *always* created using NewBlockWithHeader().WithBody().WithWithdrawals().
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This change rearranges the accessor methods in block.go and fixes some minor issues with the copy-on-write logic of block data. Fixed issues: - Block.WithWithdrawals did not create a shallow copy of the block. - Block.WithBody copied the header unnecessarily, and did not preserve withdrawals. However, the bugs did not affect any code in go-ethereum because blocks are *always* created using NewBlockWithHeader().WithBody().WithWithdrawals()
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)" This reverts commit d8807c4.
devopsbo3
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)" This reverts commit d8807c4.
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This change rearranges the accessor methods in block.go and fixes some minor issues with the copy-on-write logic of block data. As a refresher, the rules around block immutability are as follows:
We copy all data when the block is constructed. This makes the references held inside the block independent of whatever value was passed in.
We copy all header data on access. This is because any change to the header would mess up the cached hash and size values in the block. Calling code is expected to take advantage of this to avoid over-allocating!
When new body data is attached to the block, we create a shallow copy of the block. This ensures block modifications are race-free.
We do not copy body data on access because it does not affect the caches, and also because it would be too expensive.
The change corrects these issues:
Block.WithWithdrawals did not create a shallow copy of the block.
Block.WithBody copied the header unnecessarily, and did not preserve withdrawals.
However, the bugs did not affect any code in go-ethereum because blocks are always created using NewBlockWithHeader().WithBody().WithWithdrawals().