MP-1: Mempool data structure design

[0xMuang]

MP-1: Mempool data structure design

Goal

Design and implement the core mempool data structures used to store and manage transactions before they are included in a block.

This task focuses solely on defining the foundational in-memory structures. Transaction validation, prioritization, and replacement logic are intentionally deferred to later tasks (MP-2 ~ MP-4).

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Scope

Included in this task:

• Define the main Mempool / TxPool data structure
• Store transactions in memory with the following indices:
  • Indexed by transaction hash
  • Indexed by sender address (nonce-ordered)
• Track mempool size:
  • Total transaction count
  • Total memory usage (bytes)
• Enforce basic pool limits (count and/or size based)

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Out of Scope

Explicitly excluded from this task:

• Transaction validation (nonce, gas, balance checks) — MP-2
• Gas price–based prioritization or selection — MP-3
• Transaction replacement logic — MP-4
• Pending vs queued transaction separation — MP-5
• Transaction removal after block execution

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Design Notes

• The data structures should be designed with future extensions in mind:
  • Gas-based priority queues
  • Transaction replacement and eviction policies
  • Pending/queued transaction separation
• No consensus (CL) or execution (EL) logic should be included at this stage.

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Dependencies

• None

This task provides the foundation required by all subsequent mempool tasks.

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Acceptance Criteria

• Core mempool (Mempool / TxPool) data structure is implemented
• Transactions are indexed by transaction hash
• Transactions are indexed by sender address (nonce-ordered)
• Mempool size limits (count and/or bytes) are enforced
• Unit tests exist for the core mempool data structure

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References

• Reth Transaction Pool
  https://github.com/paradigmxyz/reth/tree/main/crates/transaction-pool
• Go-Ethereum Legacy TxPool
  https://github.com/ethereum/go-ethereum/tree/master/core/txpool