fix a few corner cases and revert last batch for `SpanBatch` when error happens

[zhiqiangxu]

According to this code, parent.Timestamp==current.Timestamp is also invalid.

This PR also fixes checkFull so that it only marks ErrCompressorFull when co.compressed.Len() > co.target instead of co.compressed.Len() >= co.target, because when co.compressed.Len() == co.target, we actually want to include the current block into the channel instead of trying to revert to the compressed previous data.

This PR also added a call to revertLastBatch when error happened downstream.

[coderabbitai[bot]]

Walkthrough

Walkthrough

The updates across various components primarily focus on enhancing error handling and rollback mechanisms, refining method parameters, and adjusting logical conditions in timestamp and batch processing. These changes aim to improve the robustness and accuracy of transaction and batch operations within the system.

Changes

File Path	Change Summary
.../span_batch.go	Modified timestamp comparison from > to >=, introduced lastParentCheck and lastL1OriginCheck fields, and added revertLastBatch method.
.../span_batch_tx.go	Changed size parameter in setDecoded method to an unnamed parameter _.
.../span_batch_txs.go	Added revertLastTxs method to revert changes made by the AddTxs method.
.../channel_builder_test.go	Imported sync/atomic, added incrementalBlockTime, updated block time setting, and modified test functions for new conditions and error handling.
.../span_channel_out.go	Updated return type of AddSingularBatch to (err error), added error handling with deferred function, and adjusted compressor full check logic.

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Recent Review Details

Configuration used: .coderabbit.yml Review profile: CHILL

Commits

Files that changed from the base of the PR and between b8587bc6a01b03c0a15a55bad2ce9800f7cb4eec and 399ee21f64eb9808e4efcf5e2ed7fb81ac4405b0.

Files selected for processing (2)

• op-batcher/batcher/channel_builder_test.go (5 hunks)
• op-node/rollup/derive/span_channel_out.go (3 hunks)

Files skipped from review as they are similar to previous changes (1)

• op-node/rollup/derive/span_channel_out.go

Additional comments not posted (5)

op-batcher/batcher/channel_builder_test.go (5)

9-9: Added import for sync/atomic to support atomic operations on incrementalBlockTime.

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48-49: Introduced incrementalBlockTime of type atomic.Uint64 for managing block times atomically.

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57-57: Modified newMiniL2BlockWithNumberParent to use incrementalBlockTime.Add(2) for setting block time, ensuring sequential block times are correctly spaced.

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83-83: Updated ChannelBuilder_OutputFramesMaxFrameIndex test to include derive.SkipOptimize = true, addressing test scenarios where compression might increase data size.

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559-573: > :memo: NOTE

This review was outside the diff hunks and was mapped to the diff hunk with the greatest overlap. Original lines [549-570]

Adjusted MaxFrameSize in TestChannelBuilder_FullShadowCompressor to handle the compressor full error more accurately, ensuring the test reflects the intended behavior when the compressor is full.

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[trianglesphere]

@zhiqiangxu op-batcher tests are failing with this change

[zhiqiangxu]

I added a SkipOptimize which is only set to true for test, as I met a case where the size before compressing(969) is smaller than the size after compressing(985). In this situation there's no way to choose a proper MaxFrameSize to make co.target smaller than 969 but bigger than 985.

I also found a couple other issues, described at the beginning of the post.

[zhiqiangxu]

Some really cool ideas in this PR, thanks for putting it together! I have some comments around testing and edge-cases, but also wanted to leave a high-level comment:

Span Batch Reverting is a helpful feature, but I think the amount of complexity it brings in does not currently justify its benefit. Seems like the largest benefit is that it prevents Span Batches from being added to during an error in AddSingularBatch, because presumably on retry the same batch would be added again. To address this with less complexity, the SpanBatch itself could check,

• If the same timestamp as the last batch, and the same content (hash), just ignore it
• If the same timestamp as the last content, and different content, panic

This would cover cases where an error in the Span Channel Out might redrive content into the SpanBatch, and would not require defer behavior to mutate the SpanBatch.

We could even make it something the Span Channel Out manages, with a new function, func (sb SpanBatch)AlreadyHas(b Batch) bool, so the SpanChannelOut could avoid redriving batches altogether.

Span Batches don't currently need the ability to revert, because the Span Channel Out keeps a double-buffer of RLP encoded Raw Span Batches. If the newly added batch exceeds the threshold, the previous RLP buffer is used. This is like a revert, but at the serialized level.

I think this argument is based on assumptions on what kind of error can actually happen downstream, right?

IMHO we'll achieve cleaner separation of concern if we can get rid of such assumptions.

[github-actions[bot]]

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